Subscriber access provided by MT ROYAL COLLEGE
Review
Nanostructured electrochemical biosensors for labelfree detection of water- and food-borne pathogens Nekane Reta, Christopher P Saint, Andrew Michelmore, Beatriz Prieto-Simon, and Nicolas H. Voelcker ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b13943 • Publication Date (Web): 25 Jan 2018 Downloaded from http://pubs.acs.org on January 26, 2018
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
ACS Applied Materials & Interfaces is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
Nanostructured electrochemical biosensors for label-free detection of water- and food-borne pathogens Nekane Reta,a Christopher P. Saint,b Andrew Michelmore,a,c Beatriz Prieto-Simon,*,a,d and Nicolas H. Voelcker
a
*,a,d,e
Future Industries Institute, University of South Australia, Mawson Lakes, South Australia 5095, Australia b
Natural & Built Environments Research Centre, School of Natural & Built Environments, University of South Australia, Mawson Lakes, South Australia 5095, Australia
c
School of Engineering, University of South Australia, Mawson Lakes, South Australia 5095, Australia d
Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Vic 3052, Australia
e
Melbourne Centre for Nanofabrication, Victorian Node of the Australian National Fabrication Facility, Clayton, Victoria, 3168, Australia
Corresponding authors: Prof. Nicolas H. Voelcker, Dr. Beatriz Prieto-Simon Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria, 3052, Australia Tel: +61 3 99039230
email:
[email protected] [email protected] Keywords: pathogen detection, label-free detection, environmental monitoring, food safety, nanoscale materials,
nanochannels,
electrochemical
ACS Paragon Plus Environment
biosensing
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 2 of 59
Abstract The emergence of nanostructured materials has opened new horizons in the development of next generation biosensors. Being able to control the design of the electrode interface at the nanoscale combined with the intrinsic characteristics of the nanomaterials engenders novel biosensing platforms with improved capabilities. The purpose of this review is to provide a comprehensive and critical overview of the latest trends in emerging nanostructured electrochemical biosensors. A detailed description
and
discussion
of
recent
approaches
to
construct
label-free
electrochemical
nanostructured electrodes is given with special focus on pathogen detection for environmental monitoring and food safety. This includes the use of nanoscale materials such as nanotubes, nanowires, nanoparticles and nanosheets, as well as porous nanostructured materials including nanoporous anodic alumina, mesoporous silica, porous silicon and polystyrene nanochannels. These platforms may pave the way towards the development of point-of-care portable electronic devices for applications ranging from environmental analysis to biomedical diagnostics.
2 ACS Paragon Plus Environment
Page 3 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
1 Introduction
The presence of human pathogens in water and food is a major concern due to their rapid growth and harmful effects on health. The World Health Organization reported in 2007 that worldwide waterand food-borne infections account for about 4 billion episodes of diarrhea per year, resulting in about 1
1 to 2 million deaths . Pathogens responsible for water- and food-borne outbreaks include bacteria, viruses and toxins 2-6. Figure 1 shows images of the most relevant pathogens that have been related to cause adverse effects on human health. Bacteria such as Salmonella typhi (S. typhi), Escherichia coli (E. coli), Listeria monocytogenes (L. monocytogenes), and Campylobacter are generally responsible for most illnesses, in conjugation with viruses such as hepatitis (A, B) and norovirus (NoV). They can be found on ready-to eat food, raw or undercooked meat, shellfish and in poor sanitation environments. Amongst toxins, mycotoxins and enterotoxins have been associated with diseases. Mycotoxins are secondary metabolites produced by fungi and fungi-like organisms, 7
aflatoxin being one of the most harmful . Aflatoxins (AFs), generated by certain Aspergillus, Penicillium and Fusarium species, can be found in crops (i.e. corn, wheat) and nuts 8. Other mycotoxins that can cause adverse effects are ochratoxins, sterigmatocystin, trichlothecenes, zearelenone and fumonisins 9. Enterotoxins, peptides generally released by Gram-positive bacteria, have been associated with food poisoning and toxic shock syndrome
10
. Enterotoxins produced by
Staphylococcus aureus (S. aureus) are responsible for the most food poisoning cases as a result of contaminated food ingestion (dairy and meat products) and improperly stored food products
11-12
.
Table 1 summarizes the sources of the most significant water- and food-borne pathogens, the number of microorganisms or amount of toxin required to cause an infection, as well as the associated symptoms.
3 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 4 of 59
Figure 1. Electron microscopy images of (A) S. typhi, (B) E. coli (C) L. monocytogenes (D) Campylobacter, (E) hepatitis A virus, (F) NoV, (G) Aspergillus parasiticus (A. parasiticus) and (H) S. aureus. Reproduced with permission from: (A) ref 13. Copyright 2006 Elsevier, (B, H) ref 14. Copyright 2000 American Association for the Advancement of Science, (C) ref 15. Copyright 2015 Multidisciplinary Digital Publishing Institute, (D) ref 16. Copyright 2011 American Society for Microbiology, (E) ref 17. Copyright 2016 Pixnio, (F) ref 18. Copyright 2010 PLOS, (G) ref 19. Copyright 2003 Oxford Academics.
Conventional methods of pathogen detection rely on specific microbiological and biochemical identification. They are based on culture and colony counting, immunological interactions and the polymerase chain reaction (PCR). Among all of these methods, culture and colony-based confirmation assays are the most accurate and reliable for pathogen detection. Although these methods are highly sensitive and often allow the detection of a single bacterium, they are time consuming and labor intensive as they may take up to 7-10 days to perform 3. Immunology-based methods rely on antibody and antigen interactions and have been widely used for the detection of bacterial cells, viruses and toxins 20. Those require shorter assay times compared to traditional culture methods. However, they still lack the ability to detect pathogens in real time and can be potentially affected by interferences. Additionally, the limited affinity and specificity of the antibody to the microorganism in some cases leads to low sensitivity and selectivity, respectively
21
. PCR techniques
have distinct advantages over culture and immunological methods, including high specificity,
4 ACS Paragon Plus Environment
Page 5 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
sensitivity and accuracy. In spite of their advantages, PCR requires a skilled operator and can be expensive to perform
22
. Thus, the development of new, less expensive tools providing equally reliable
results over much shorter time frames is key to preventing health and safety problems caused by pathogen contamination in food or drinking water. Electrochemical biosensors provide high sensitivity, selectivity and robustness at low cost
23-24
. When
a specific sensing strategy and detection technique are combined, biosensors can be developed for label-free detection, which presents shorter analysis time and simplicity over labelled strategies
25
.
Another important feature is their ability to be miniaturized and therefore potential for portable in-situ analysis. All these characteristics taken together with the unique properties of nanostructured materials provide an attractive means for the development of novel platforms with improved sensitivity for water- and food-borne pathogens 26. Nanostructured materials have emerged in the last decade as powerful materials for electrode fabrication in the biosensing field
27
. The novel features of nanomaterials have enabled significant
improvements in the sensing capabilities of biosensors.
28
. Here, the latest trends to design label-free
nanostructured electrodes will be discussed. This includes the use of nanoscale materials including nanotubes, nanowires, nanoparticles and nanosheets, as well as porous nanostructures featuring arrays of nanochannels such as nanoporous anodic alumina, mesoporous silicon, porous silicon and polystyrene nanochannels. The most relevant strategies for the detection of water- and food-borne contamination will also be highlighted.
5 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
Page 6 of 59
Table 1. Common water- and food-borne pathogens.
Pathogen
Source
Infectious dose
Symptoms
Ref.
Stomach pain, diarrhea,
3, 29-33
(no microorganisms) S. typhi
● Raw milk and dairy products, raw or undercooked
15 – 20
poultry and meat, seafood, chocolate and salads.
nausea, headache, fever, chills.
● Lack of safe water, poor sanitation and hygiene. E. coli O157:H7
● Raw milk and dairy products, raw or undercooked eggs,
< 10
poultry and meat, seafood and leafy vegetables.
Stomach pain, diarrhea,
3, 33-34
nausea, headache, fever, chills.
● Lack of safe water, poor sanitation and hygiene. L. monocytogenes
● Raw milk, soft cheese, raw poultry and meat, seafood
< 1000
and leafy vegetables.
Fever, chills, headache,
3, 31, 35
diarrhea.
● Lack of safe water, poor sanitation and hygiene. Campylobacter
● Raw milk, raw or undercooked meat and poultry.
400 – 500
Fever,
headache,
diarrhea, ●Lack of safe water, poor sanitation and hygiene. abdominal pain.
ACS Paragon Plus Environment
nausea,
3, 36-37
Page 7 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
ACS Applied Materials & Interfaces
Pathogen
Source
Infectious dose
Symptoms
Ref.
Fever, malaise, anorexia,
3, 38-40
o
(n microorganisms)
Hepatitis A virus
● Milk and dairy products, shellfish, fruits, vegetables and
100 – 1000
iced drinks.
nausea, jaundice.
● Lack of safe water, poor sanitation and hygiene.
NoV
● Raw oysters or shellfish, berries and salads.
Median
dose
that
Nausea,
vomiting,
causes infection in 50%
diarrhea,
stomach
of individuals (ID50) =
crumps, muscle cramps.
41-48
● Contaminated water, ice and frozen products.
AFs
● Lack of safe water, poor sanitation and hygiene.
18 virus particles
● Corn, cereals, nuts (pistachio, peanut), spices (black
< 15 µg/kg, per total
Hemorrhage, acute liver
pepper, chilies), dried fruits and in a lesser amount in milk
AFs (B1, B2, G1, G2)
damage,
and dairy products.
49-53
edema,
abdominal pain.
● Lack of safe water, poor sanitation and hygiene.
7
ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
Pathogen
Source
Infectious dose
Page 8 of 59
Symptoms
Ref.
o
(n microorganisms)
Enterotoxin from S.
● Raw milk, cheese, meat products, salads, pastries and
aureus
custards.
20 – 100 ng
Nausea,
diarrhea,
10-11, 54-59
abdominal pain, cramps.
● Food improperly handled and stored.
8
ACS Paragon Plus Environment
Page 9 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
2 Electrochemical biosensors based on nanoscale materials The use of nanoscale materials in the design of electrochemical biosensors is a rapidly expanding area. Nanoscale materials such as nanotubes, nanowires, nanoparticles and nanosheets have been extensively incorporated in electrode construction. This is attributed to their remarkable characteristics such as high surface-to-volume ratio and excellent electrical properties, which have led to the development of sensing platforms with outstanding performance. The following section will provide a comprehensive overview of the recent trends for the fabrication of these nanoscale biosensors. The latest approaches will be discussed in detail and the most significant platforms for water- and foodborne pathogen detection will be described.
2.1
Nanotubes
Nanotubes as building blocks in the design of electrochemical sensors have attracted much interest over the past few years. Nanotubes consisting of organic or inorganic materials and exhibiting conductive or semi-conductive properties have been prepared. Amongst all of them, carbon nanotubes (CNTs) have paved the way for promising electrochemical biosensors since their discovery in the 1990s. Other nanotube structures based on titanium dioxide have also been employed, to a lesser extent, in the electrochemical biosensing field. The following section will introduce the different types of CNTs and their structures, as well as different approaches employed for the design of labelfree CNT-based electrochemical biosensors. Some promising examples will be highlighted with special focus on pathogen detection. Finally, strategies employing titanium dioxide nanotubes for electrochemical biosensors will be described. CNTs can be divided into two classes: single-walled carbon nanotubes (SWCNTs), which consist of a single cylindrical hollow tube with 0.4 to 2 nm diameter, and multi-walled carbon nanotubes (MWCNTs), which are made of multiple concentric tubes 3.4 Å apart with 2 – 100 nm diameters
60
.
The electrical behavior varies between both types, where MWCNTs behave similar to metals and SWCNTs can feature both metallic and semi-conductor character depending on their geometric structure such as chirality and tube diameter
61
. The chirality is related to the angle at which the
9 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 10 of 59
graphene sheet is rolled up to form a SWCNT and can be defined by a lattice vector with integers (n,m) (Figure 2). Nanotubes with metallic properties are in “armchair” configuration while “chiral” and “zigzag” structures are semiconductors. The diameter of the SWCNT also plays an important role in the electronic behavior, where small diameter nanotubes only possess conductive or semi-conductive properties. As the diameter of the tube increases the band gap tends to zero, resulting in a zero-gap semiconductor.
62
.The high electronic conductivity is particularly interesting for electrochemical
detection platforms as it enhances the electrocatalytic activity or the electron transfer reaction between redox species and the electrode
63
2
. Furthermore, their large surface area (1315 m /g)
64
provides a favorable environment to immobilize biomolecules, as well as, remarkable mechanical strength. All these features of CNTs have been exploited for the development of highly sensitive electrochemical platforms 65.
Figure 2. (A) Schematic of the folding procedure to form different configurations of SWCNTs from planar graphene sheet according to their chiral angle (ɸ). C is a roll-up vector that is defined as: C=na1+ma2, where a1 and a2 are the primitive lattice vectors of the hexagonal lattice and n and m are integers. (B) MWCNT structure with several concentric tubes. Reproduced with permission from ref 66. Copyright 2015 Frontiers.
Several strategies have been employed to design electrochemical biosensors incorporating CNTs. These include CNT-coated electrodes, CNT-composite electrodes, vertically-aligned CNT (VA-CNT)
10 ACS Paragon Plus Environment
Page 11 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
electrodes and CNT-based field-effect transistors (FET) (Figure 3)
67
. Coating or depositing CNTs
layers on conventional electrodes such as glassy carbon electrodes (GCE) has been done by spraying, drop casting or electrodeposition techniques
68
. When using this method, it is extremely 69
important to obtain a uniform CNT coating in order to enhance the electrocatalytic activity
. The
performance of CNT-composite electrodes also depends on the homogeneity of the CNT dispersion within the binder employed. Coatings on electrodes are typically fabricated by mixing the CNTs with a polymer matrix using a variety of binders (mineral oil, Teflon or epoxy resins)
63
. A way to obtain an
effective CNT coating from an electrochemical perspective is by using VA-CNTs
65
. Electrodes
modified with VA-CNTs have shown excellent performance due to an increase in the charge transfer rate when compared to the CNTs randomly oriented
70
. VA-CNTs can be prepared by physical or
chemical methods. Physical methods are based on growing CNTs directly on certain substrates employing template-assisted or template-free procedures
71
, while chemical methods rely on
assembling CNTs by covalent bonds, metal-assisted chelation and electrostatic interaction
72
. CNTs
have also been widely integrated in FETs, mainly via chemical vapor deposition (CVD). Typically, these devices consist of a single CNT or a network of CNTs acting as a conduction channel between a source and a drain electrode, and a change in conductivity upon the interaction of the biomolecule with the CNT surface is the common biosensing mechanism 73.
Figure 3. Strategies to fabricate CNT-based biosensors: (A) CNT-coated electrode, (B) CNTcomposite, (C) VA-CNTs and (D) CNT-based FET.
11 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 12 of 59
Modifications of the CNT-based electrodes to attach biomolecules as recognition elements have been perfomed by non-covalent and covalent routes
74-75
. Non-covalent approaches include physical
adsorption or entrapment on the CNTs using polymer hydrogels and sol-gel chemistry. Covalent attachments are generally performed by conjugating the carboxyl groups on oxidized CNTs to form amide bonds or by non-selective attack using highly reactive species such as nitrenes and aryl diazonium salts 66. Zelada-Guillen developed highly sensitive potentiometric SWCNT-based sensors modified with aptamers for real-time measurements of different bacteria, including E. coli typhi
76
, S. aureus
77
and S.
78
. These aptasensors were fabricated by depositing a 30 µm-thick SWCNT layer on a GCE by
spray deposition. Then, an aptamer specific to one of the target bacteria mentioned above was covalently bound to the carboxylic groups of the external CNT walls via carbodiimide chemistry. The sensing principle is based on ion-to-electron transduction. Binding of the bacteria to the aptamer provokes a conformational change in the aptamer, separating the negatively charged phosphate groups on the aptamer from the SWCNT walls. This causes a change in the charge of the SWCNT that is recorded as a change in the electrode potential. The aptasensor for S. typhi detection was the most sensitive, being able to detect a single colony-forming unit (cfu) in less than a minute 78. Figure 4 shows the potentiometric response of the sensor when it was exposed to a stepwise concentration of 6
S. typhi from 0.2 cfu/mL to 10
cfu/mL and the corresponding linear relation between the
electromotive force (EMF) measured between the working and reference electrodes and the logarithm of S. typhi concentration. The slope greatly decreased after 103 cfu/mL, reaching a plateau at 106 cfu/mL, due to possible saturation of the available binding sites. E. coli and Lactobacillus casei, showed no significant potentiometric response, demonstrating good selectivity of the sensor. Moreover, the aptasensor was regenerated by incubation in 2 M NaCl for 30 min, and was stable over three months. This platform represents a very promising development towards a point-of-analysis electrochemical device.
12 ACS Paragon Plus Environment
Page 13 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
Figure 4. (A) Potentiometric response of the aptasensor for the increasing concentration of S. typhi bacteria, and (B) corresponding calibration curve. Reproduced with permission from ref 78. Copyright 2009 ACS Wiley-VCH.
Andrade et al. developed an impedimetric biosensor for Gram-negative bacteria such as Klebsiella pneumoniae (K. pneumoniae) and E. coli
79
. In this approach, an Au electrode was functionalized with
cysteine to introduce amine groups by a self-assembled monolayer (SAM). The carboxylic groups of the
MWCNTs
were
activated
by
1-(3-dimethylaminopropyl)-3-ethylcarbodiimide
(EDC)/N-
hydroxysuccinimide (NHS) to bind first to the amine groups on the Au electrode and then to clavanin A, an antimicrobial peptide used as a capture probe, forming stable amide bonds. The performance of these biosensors was studied using electrochemical impedance spectroscopy (EIS) in a threeelectrode cell containing the CNT-modified Au as working electrode (WE), platinum as auxiliary electrode (AE) and Ag/AgCl as reference electrode (RE). These impedance spectra were fitted to an equivalent circuit model that enabled the calculation of the charge-transfer resistance (RCT), the circuit element commonly employed to follow affinity binding. RCT increased with increasing concentration of both Gram-negative bacteria (E. coli and K. pneumoniae), while the tested Gram-positive bacteria (Enterococcus faecalis (E. faecalis) and Bacillus subtilis (B. subtilis) gave no significant change in the 2
5
biosensor response. The developed biosensors exhibited a linear working range from 10 to 10 and 102 to 106 cfu/mL for E. coli and K. pneumoniae, respectively, with 100 cfu/mL being the lowest concentration detected for both bacterial species.
13 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 14 of 59
A CNT-chitosan biocomposite electrode was prepared to detect sterigmatocystin, a carcinogenic mycotoxin found in food 80. SWCNTs were dispersed in chitosan solution and cast on the surface of a Au electrode. Then, aflatoxin oxidase (AFO) enzymes were immobilized onto the composite via electrostatic and hydrophobic interactions. The CNT-chitosan biocomposite provided a favorable environment to maintain the native conformation and electrocatalytic activity of the enzyme, while enhancing the direct electron transfer between the enzyme and the electrode surface. The enzymatic sensor, based on the voltammetric detection of the enzymatic product H2O2, exhibited a limit of detection (LOD) of 3 ng/mL that was comparable to those obtained by chromatographic detection techniques but was achieved within a shorter time (~10 s). Moreover, this sensor exhibited good stability in a dry state at 4 °C for about 1 month with a retained enzymatic activity of 85.6 % and good reproducibility. Other sol-gel CNTs enzymatic composites have also been fabricated to detect mycotoxins 81-82. CNTs have also been widely integrated in FETs to target E. coli 86-87
and T7 bacteriophage
85
. Villazar et al.
86
83-85
, Salmonella infantis (S. infantis)
fabricated the selective CNT network-FET
immunosensor for S. infantis detection. The CNT networks were fabricated on a silicon dioxide layer by CVD. Both source and drain electrodes were screen-printed with Ag ink, and an Al layer on the back of the silicon was used as the gate electrode to monitor the effect of gate voltage on current flow upon the bacterial binding. Current decreased with increasing concentration of S. infantis from 100 to 500 cfu/mL, while no changes were observed upon incubation with Shigella bacterium. The LOD of the device was not determined, but considerable current changes were recorded after incubating the immunosensor with100 cfu/mL of S. infantis for 1 h. Further experiments would be required to determine if this device can detect S. infantis in real samples and if the working range could be further extended. Titanium dioxide or titania nanotubes (TNT) have also been employed to detect various analytes
88
.
Mandal et al. prepared screen-printed carbon electrodes (SPCEs) with TNT by the drop casting method, followed by the attachment of the antibody to detect penicillin-binding protein, a marker for methicillin-resistant S. aureus
89
. The TNT-modified immunosensor monitors protein-antibody
14 ACS Paragon Plus Environment
Page 15 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
interaction by measuring changes in current by cyclic voltammetry (CV), allowing detection of 1 ng/µL, and being unaffected by other proteins such as bovine serum albumin (BSA).
2.2
Nanowires
Progress and development using nanowires as biosensing platforms has rapidly grown over the last decade
90
. Nanowires are defined as one-dimensional fibril-like nanostructures of diameters ranging
from tens of nanometers to a couple of hundred nanometers
91
. Several types of nanowires including
those based on semiconductors (e.g. Si, InP, InAs, GaN), metals (e.g. Au) and metal oxides (e.g. TiO2, ZnO) have been employed to construct sensing platforms
92-93
. The excellent electrical
properties, tunable morphology and ease of functionalization of silicon nanowires (SiNWs) have led to the development of a wide range of SiNW-based biosensors over the years. Most of these biosensors use nanowires configured as FETs 73, 94. SiNW-based biosensors can be fabricated by bottom-up and top-down approaches, metal-catalyzed CVD and metal-assisted electroless etching being the most common representative techniques, respectively
90
. The perfomance of a SiNW biosensor is infuenced by several factors such as
nanowire diameter, carrier density and mobility, and surface chemistry 95. It has been found that small diameters and lower doping density result in more sensitive FET-based biosensors
96-97
. Thus, it is
particularly important to fabricate SiNWs with appropiate dimension and doping density in order to develop a highly sensitive biosensing platform. The surface of SiNWs can be modified by silanization or photochemical hydrosilylation in order to introduce functional groups that can be further reacted with different bioreceptors. Silanization is commonly employed to introduce amine-, thiol- or aldehydeterminated functional groups 90, while photochemical hydrosilylation is used to form stable Si-C bonds 98
. Several examples of SiNW-FET biosensors for both bacteria and viruses detection are discussed
below. Patolsky et al. fabricated a real-time SiNW-FET array for the electrical detection of both influenza-A virus and adenovirus
99
. This study demonstrated single virus detection with high selectivity. It
consisted of two nanowires modified with anti-influenza A and anti-adenovirus antibodies, respectively. Figure 5A shows the sensing principle consisting of monitoring the change on the SiNW
15 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 16 of 59
surface upon the virus particle binding and release event. Briefly, specific binding of a single virus particle to the antibody produces a change in the conductance that is characteristic to the surface charge of the virus particle. Upon an increase in the pH, the virus particle releases from the SiNW surface and conductance returns to the baseline value. Figure 5B shows real-time conductance changes when the SiNW-based influenza immunosensor was incubated with a single influenza virus particle (1 and 4 arrows), while in Figure 5C no changes were seen upon non-specific virus incubation. Moreover, the capability of multiplexed detection was also demonstrated by parallel measurements of influenza A and adenovirus. This sensor thus shows promise as a device for the simultaneous detection of large numbers of different viral threats.
Figure 5. (A) Schematic of virus particle binding to and release from SiNW-based immunosensors (left), with the corresponding changes in conductance as a function of time (right). Conductance change of the anti-influenza antibody-modified SiNW when incubating with (B) influenza A virus particle and (C) paramyxovirus and adenovirus. Arrows 1 and 4 indicate introduction of the virus and the remaining arrows represent incubation with buffer. Reproduced with permission from ref 99. Copyright 2004 Proceedings of the National Academy of Sciences, U.S.A.
16 ACS Paragon Plus Environment
Page 17 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
Recently, Shen et al. also reported a highly selective immunosensor for influenza A virus detection using a SiNW-FET biosensor
100
. This platform was able to detect 29 virus particles/µL within minutes
in clinical exhaled breath condensate samples, without significant effect of other interfering viruses or particles. Another highly sensitive platform based on a SiNW-FET device was developed by Zhang et al. to detect Dengue serotype 2 (DEN-2) virus
101
. This biosensor was combined with the reverse-
transcription PCR (RT-PCR) technique to select and amplify a specific fragment of DEN-2 genome sequences. Here, the detection principle was based on DNA hybridization. Briefly, the SiNW surface was first silanized with (3-aminopropyl)trimethoxysilane (APTES) to immobilize a specific peptide nucleic acid (PNA), a neutral peptide to minimize repulsion and facilitate hybridization event with the complementary and negatively charged DNA sequence. Hybridization of PNA and a specific DNA fragment of DEN-2 caused an accumulation of negative charge on the surface, inducing an increase in the resistance of the nanowire. This SiNW sensor achieved low detection levels (10 fM of the amplicons) within 30 minutes. Although SiNWs are the most common type of nanowires for biosensing applications, wires made of TiO2 have also been employed for direct electrochemical detection of bacteria
102
. A TiO2 nanowire bundle-based immunosensor was connected to an Au
microelectrode for the sensitive impedimetric detection of L. monocytogenes. This platform exhibited good performance, with a LOD of 500 cfu/mL achieved within 1 h assay time and without significant changes in the impedance response with other foodborne pathogens such as E. coli O157:H7, S. typhi and S. aureus.
2.3
Nanoparticles
Nanoparticles (NPs) are generally defined as particles smaller than 100 nm in size. Their physical, chemical and electronic properties have attracted great interest in the construction of novel sensing platforms. These properties depend on the kind and number of atoms that form the particle
103
. Many
types of NPs such as metal, metal oxide and semiconductors have been used to design electrochemical biosensors
104
. Metal NPs (MNPs) such as Au (AuNPs), Ag (AgNPs) and Pt (PtNPs)
are the most frequently employed
105
. This is attributed to their excellent conductivity, large surface-to-
volume ratio, inert nature and biocompatibility. MNPs provide a suitable microenvironment for biomolecule immobilization retaining their biological activity, and promoting electron transfer between
17 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
the immobilized biomolecules and the electrode surface
Page 18 of 59
106-107
. Furthermore, they have been used as
labels or tags to amplify the signal of the biorecognition event, as well as, for multiplexed detection. However, this review focuses on label-free detection and thus this will not be covered here and has been reviewed elsewhere
28, 103, 108-109
. The following section will focus on describing different
approaches to design MNP-modified biosensors for label-free electrochemical detection. MNP morphology, assembly and modification play a significant role in the performance of the MNPbased biosensors
110
. In general, they are prepared by chemical reduction of the corresponding metal
salt in aqueous organic phase and in the presence of a stabilizer/surface protector. This surface protector binds to their surface to avoid their aggregation by improving stability and solubility, as well as, providing the desired charge and chemical groups
111-112
. Colloidal AuNPs are typically prepared
by reducing chloroauric acid with sodium acetate in aqueous media, and stabilized by ions, biological molecules and polymers
113
. Compared to AuNPs, the synthesis of monodisperse AgNPs has been
more challenging since they are prone to corrosion and aggregation in solution
1t4
. Reduction of silver
nitrate by sodium borohydride in the presence of different citrate, polymer and biological molecules, is the most common method to prepare AgNPs
115-117
. PtNPs are frequently synthesized by
hexachloroplatinic acid reduction with citric acid and modified with biological molecules to increase stability
118
. Although impressive progress has been made in the synthesis of MNPs, precise control
over monodispersity, morphology and surface chemistry remains challenging 110. MNPs have been directly assembled onto the electrode surface, or incorporated with other nanomaterials and polymers to form sophisticated electrode architectures. One of the preferred strategies to modify electrode surfaces with MNPs is by means of self-assembly. This is a simple and versatile approach to form highly ordered monolayers with different functional groups
110, 119
. The
majority of the self-assembled monolayers (SAMs) are based on the affinity between thiol/amine groups and noble metal surfaces, providing a high degree of control over the molecular architecture of the biorecognition interface
110
. Recent work from Liu et al. has demonstrated a stable and robust
AuNP-modified GCE using SAMs
120
. This resulted in excellent electron transfer ability and low
background signal. Scheme 1 shows the different strategies for the fabrication on AuNP-modified GCE for sensing applications. Briefly, a GCE was modified either with 4-aminophenyl or 4-thiophenol to introduce amine- or thiol- terminal groups, respectively. AuNPs were subsequently tethered to the
18 ACS Paragon Plus Environment
Page 19 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
surface, forming S-Au and NH-Au bonds. Moreover, the amine-terminated electrode was also modified to form diazonium groups, followed by AuNP immobilization to form phenyl-Au bonds (GCPh-AuNPs). Amongst all of them, the GC-Ph-AuNP electrode exhibited the highest stability in an aqueous environment, with less particle losses over time. Other SAM strategies using cysteamine have been used to immobilize AuNPs and AgNPs on Au electrodes 121-123.
Scheme 1. Fabrication of stable AuNP-modified GCEs via self-assembly. Reproduced with permission from ref 120. Copyright 2015 ACS Publications.
MNPs have also been incorporated on electrode surfaces by the layer-by-layer technique
124-126
. This
technique relies on the electrostatic interaction between anionic and cationic polyelectrolytes and provides highly ordered architectures with accurate control over the composition, number of layers, as well as, the thickness of the multilayer assemblies at nanoscale level 127. As an example, Sungwoo et al. developed a multilayer structure based on catalase-encapsulated AuNPs by electrostatic assembly of anionic poly(sodium 4-styrene sulfonate) and cationic poly(allylamine hydrochloride) polyelectrolyte 126
. This multilayer assembly allowed electrostatic charge reversal and structure modifications by
19 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 20 of 59
adjusting the pH. Near the isoelectric point of catalase (pH 5.2), dispersed catalase-encapsulated AuNPs could be altered to form colloidal or network architectures. Besides, high loading of catalase, as well as, effective electron transfer, high catalytic activity toward H2O2 was achieved. To further enhance the electronic, electrochemical and mechanical properties of the electrode surface, MNPs have been combined with several nanomaterials and polymers
110,
128-129
.
Nanomaterials such as graphene and CNTs have become ideal candidates to pair with MNPs for the development of electrochemical biosensors. Wang et al. fabricated AuNP-modified graphene impedimetric immunosensors to detect E. coli O157:H7 in food samples
130
. AuNPs were deposited
on a graphene-modified nitrocellulose membrane filter and functionalized with streptavidin followed by biotinylated antibody immobilization and subsequent blocking with BSA. EIS was employed to detect E. coli O157:H7, exhibiting a wide linear detection range from 1.5 x 102 to 1.5 x 107 cfu/mL and a LOD of 150 cfu/mL in 30 min. Moreover, this platform was succesfully tested with E. coli O157:H7 contaminated food samples such as beef and cucumber, showing LOD of 1.5 x 104 cfu/mL and 1.5 x 3
10 cfu/mL, respectively. This platform also possessed a high tolerance to mechanical stress. Wang et al. reported an ultrasensitive AuNP-SWCNT composite biosensor in which SWCNTs arrays were coated with AuNPs by electrodeposition
131
. This composite was functionalized with DNA to
detect human hepatitis B and papilloma viruses and showed the ability to detect as low as 1 aM of complementary 21- and 24-base hepatitis B and papilloma DNA, respectively. The low detection limit was achieved due to the synergistic effect of AuNPs and CNTs. Other MNPs such as PtNPs are often combined with CNTs to further improve the surface-to-volume ratio and electrocatalytic activity
129
132
133
Here, PtNPs were embedded in CNTs arrays
or simply decorated the surface of the CNTs
PtNP-modified CNTs can also be entrapped in a sol-gel matrix on the electrode surface
.
.
134
.
Incorporation of MNPs with polymer matrices to form three-dimensional molecular networks offers the possibility to engineer biosensors with improved electrical and mechanical properties because they provide several advantages such as prevention of MNP oxidation and coalescence, and stability enhancement of the nanocomposite 135. Au and AgNPs are the most common MNPs entrapped in solgels including silica gels for electrochemical sensing 136-139. Commercial AuNP-coated SPCEs have been employed to detect murine norovirus (MNV)
140
. Here,
AuNPs were modified with a thiolated MNV-specific DNA aptamer. Binding of the virus to the
20 ACS Paragon Plus Environment
Page 21 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
immobilized aptamer caused a decrease in the current intensity that was measured by square wave voltammetry (SVW). These aptasensors achieved a LOD of 180 virus particles in buffer, and were unaffected by other gastrointestinal viruses including vesicular stomatitis virus and vaccinia virus and human serum albumin. A similar aptasensor was also reported by the same group for the detection of vaccinia virus 141.
2.4
Nanosheets
Nanosheets or layered materials are two-dimensional nanostructures with thicknesses from about 1 to 100 nm
142
. Graphene, a single-atom thick sheet of carbon atoms packed into a two-dimensional
hexagonal lattice, is the most commonly employed nanosheet for electrochemical sensing. Graphene exhibits distinct features that are very attractive for sensing, such as excellent electrical conductivity, 2
large surface area (2630 m /g) and remarkable mechanical strength
143-144
. The material can be
produced by mechanical exfoliation, epitaxial growth of silicon carbide, chemical reduction of graphite oxide and unzipping of CNTs
145-146
. Of these methods, graphite oxide reduction is one of the most
economically viable one for mass production
147
. This method offers the possibility of introducing
several functionalities to the electrode, as well as to form hybrid nanomaterials during the reduction procedure due to the ease of functionalization with carboxyl, epoxy, hydroxyl and carbonyl reactive groups
143
. The epoxy and hydroxyl groups are located on the faces of each graphene oxide (GO)
sheet, while the carboxyl groups are usually found at the edge
148
.
Strategies for incorporating graphene in biosensing are similar to those employed for CNTs, and include graphene-coated conventional electrodes, graphene composites and using graphene in FETbased devices
149
. Graphene sheets are usually deposited on GCE via the drop casting method
Hybridization with chitosan
154-156
, NPs
157-158
and a combination of both
159-160
162-166
.
to form graphene
nanocomposites for improved performance characteristics have been widely studied has also been incorporated in FET devices
150-153
161
. Graphene
and proven to be more sensitive than conventional
metallic electrodes and similar to SiNW-based FETs 167. Zhou et al. constructed a chemically reduced GO-modified GCE by drop casting to detect DNA via direct oxidation
168
. Here, the GO-modified GCE was incubated with single-stranded DNA (ssDNA) or
double stranded DNA (dsDNA) and the oxidation currents of DNA nucleobases (adenine, thymine,
21 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 22 of 59
cytosine and guanine) were measured by chronoamperometric measurements. Discrimination was achieved due to the different oxidation potentials of each nucleobase and the large electrochemical potential window of graphene. A GO-chitosan nanocomposite was developed to detect S. typhi specific DNA
156
. The GO-chitosan
mixture was first spin-coated on indium tin oxide (ITO) electrodes and the amine groups of the chitosan were reacted with glutaraldehyde to covalently immobilize the amino-modified ssDNA probe. The DNA hybridization event was evaluated monitoring the oxidation of the redox probe methylene blue (MB), used as an intercalator, by differential pulse voltammetry (DPV). When the biosensor was incubated with the complementary target DNA, the hybridization event occurred and thus MB could not intercalate in the ssDNA probe, while exposure to a non-complementary DNA allowed MB binding to the ssDNA and hence MB oxidation peak could be electrochemically measured. Biosensor response for a wide range of complementary target DNA from 10 fM to 50 nM. The MB oxidation peak decreased with increasing concentration of target DNA due to the hybridization event. The developed biosensors exhibited a LOD of 10 fM and 100 fM in buffer and spiked serum samples, respectively. Furthermore, this biosensor was thermally regenerated in aqueous solution and an activity loss of 20% was observed after the 6th use. Stability was also demonstrated to be up to 15 days at 4˚C. Tiwari et al. modified GO with chitosan, as well, as iron oxide NPs to detect E. coli O157:H7 specific DNA by means of EIS
169
. The detection principle was based on DNA hybridization that caused an
increase in Rct and showed a good LOD of 10 fM over a wide linear range of 10 fM to 10 µM. Mohanty and Berry developed a FET-based graphene DNA sensor that was able to detect a single bacterium of Bacillus cereus, a Gram-positive bacterium commonly found as a contaminant in food 170
. Here, ssDNAs were physically adsorbed on the graphene sheets by π-interactions between bases
of the DNA and graphene. Conductance increased upon hybridization of the target bacterial ssDNA. Although this work demonstrated the ability to detect small concentrations of bacteria, it should be noted that electrical measurements were conducted under a dry nitrogen atmosphere, which is not practical in real-world applications. Huang et al. fabricated a graphene-based FET by CVD to detect E. coli bacteria
171
. Graphene was
non-covalently functionalized with 1-pyrenebutanoic acid succinimidyl ester by π-π interaction, followed by the covalent attachment of the antibody via succinimidyl ester groups. Ethanolamine was
22 ACS Paragon Plus Environment
Page 23 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
used to quench the remaining succinimidyl esters. The sensing mechanism was based on the field effect produced by the negatively-charged bacterial walls that induced an increase in the hole density and thus in conductance. This immunosensor could detect concentrations of E. coli of 10 cfu/mL in 5
phosphate buffer saline (PBS), while 10 cfu/mL P. aeruginosa did not cause any significant change in signal, demonstrating the high specificity of the biosensor.
3 Electrochemical biosensors based on porous nanostructured materials Porous nanostructured materials including nanoporous anodic alumina (NAA) (pSi) 181-182
174-175
, mesoporous metal oxides
176-178
, mesoporous organosilicas
179-180
172-173
, porous silicon
and porous polymers
have proven their value as high-performing sensor platforms due to high specific surface-to-
area ratio, as well as, versatile chemistry. The large surface area of these materials can enhance the sensitivity of the device due to the increase in the number of immobilized bioreceptors and thus available binding sites. Due to these properties, porous nanomaterials have emerged as attractive platforms to detect a wide range of analytes. Some porous nanostructured materials also offer the possibility to exploit a promising sensing strategy based on nanochannel blockage (NB) among other sensing strategies. This strategy affords the possibility to engineer molecular recognition capabilities by simply tuning the morphology of the nanochannels. It consists of measuring the blockage caused by the analyte when it binds to the immobilized capture probes in the channel walls as shown in Scheme 2. This blockage could be due to steric or electrostatic effects or a combination of both. Voltammetric and impedimetric techniques are commonly employed to electrochemically measure NB, leading to highly sensitive analysis platforms. In the example shown in Scheme 2, the blockage caused by the antigen (blue ball in the scheme) binding in the channels produces a decrease in the voltammetric signal of the oxidation of K4[Fe(CN)6 to K3[Fe(CN)6], which is proportional to the quantity of antigen captured in the channels. Moreover, this strategy can significantly minimize matrix effects when working with real samples by controlling the nanochannel diameter due to the filtering capabilities of these materials
183
. In other
words, species larger than the nanochannel diameter are not able to diffuse through the channel for
23 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 24 of 59
steric reasons, and thus the effect of species that could interfere in the binding event is reduced. The simplicity of this label-free strategy combined with highly sensitive electrochemical techniques offers the possibility to develop high-performing platforms that could be adapted to point-of-care portable devices.
Scheme 2. Scheme of the sensing principle based on NB for label-free detection. (Above) Porous nanochannel-modified electrode and functionalized with capture probes (red diamonds). (Below) DPV traces prior and after analyte (blue balls) binding.
Porous nanostructured materials, exploiting NB, have been successfully incorporated on conventional electrode surfaces such as Au, Pt and C. Of these, NAA has been most commonly employed, followed by MPS and then pSi. Recently, nanochannels formed by nanosphere assembly have also taken advantage of this sensing approach. The following section will give key examples of the electrode preparation and applications using these materials.
24 ACS Paragon Plus Environment
Page 25 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
3.1.1
Nanoporous anodic alumina (NAA)
NAA membranes (NAAMs) integrated onto different transducers have been extensively used to detect and quantify analytes based on NB strategy
173
. These membranes are typically prepared by
electrochemical anodization of high purity Al in acid electrolytes consisting of aqueous solutions of sulphuric, oxalic or phosphoric acid, followed by the dissolution of the oxide layer at the bottom of the pores
184
. They can also be fabricated directly on an ITO substrate by depositing an Al layer via CVD
as recently reported
185
. This alternative is particularly exciting due to the conductive properties of
ITO, which can therefore be employed as an electrotransducer. Moreover, NAA is rich in hydroxyl groups, which can be easily functionalized. Silanes or organic acids are generally used to modify the channels, followed by the desired bioreceptor immobilization
186-187
. NAA biosensors using the NB
approach and combined with voltammetric or impedimetric techniques have been reported for bacteriophage 188, virus 189-191, DNA 192-196, and protein 183, 197-200 detection. Smirnov’s group pioneered the use of NAAMs exploiting NB for electrochemical biosensors
201
. Here,
NAAMs with two channel diameters (20 and 200 nm) were covalently modified with ssDNA to detect target DNA by monitoring impedance changes upon DNA hybridization. This resulted in the blockage of the pore, increasing the pore resistance for the 20 nm channel diameter NAA biosensor, while no significant changes were observed for the 200 nm channel diameter one. This was attributed to the short length of dsDNA compared to channel diameter. The same group has recently reported NAA immunosensors to detect MS2 bacteriophage using EIS
188
. Sensor response to different MS2
concentrations (10 – 1870 pfu/mL) was monitored using two nanochannel diameters (73 and 97 nm). It was found the larger channel diameter exhibited higher sensitivity, given by the slope of the fitting curve, and LOD of 7 pfu/mL. The specificity of the immunosensors was also tested by incubating MS2 and Qβ bacteriophage mixtures in 1:1 ratio and proved to be unaffected. Toh’s group has also employed NAAMs for the fabrication of electrochemical biosensors based on NB
189, 198
. A NAAM was
grown on a Pt disk electrode, by sputtering a thick Al film (300 – 500 nm), followed by anodization
202
.
Nanochannels were functionalized with antibodies via physical adsorption to detect West Nile virus (WNV) (Figure 6), and in particular, WNV protein domain III (WNV-DIII) and West Nile virus particles using alternating current voltammetry (ACV) in the presence of ferrocenemethanol as a redox probe 189
. The effect of the antibody concentration used for membrane modification, and the pH and ionic
25 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 26 of 59
strength of the incubation solution, were investigated to determine the optimal sensing conditions, and found to be 0.2 µg/mL of antibody, pH 7.6 and 0.1 M NaCl. This platform showed a low LOD for both WNV-DIII (4 pg/mL) and WNV particles (2 particles/100 mL), similar to PCR-based techniques. Moreover, the performance of the immunosensor in WNV spiked blood serum was successfully demonstrated. This platform and sensing approach was also applied to the ultrasensitive detection of Dengue virus particles pneumophila DNA
190
and real time cDNA PCR sample of Dengue virus
194
, as well as, Legionella
193
, being able to detect as low as 1 cfu/mL, 9.55 x 10-12 M and 3.1 x 10-13 M, -12
respectively. The same group improved the LOD of Dengue virus DNA down to 1 x 10 both sides of the NAA membrane with Pt (50 – 100 nm thickness)
203
M by coating
. By coating both sides of the
membrane, the resistance of the solution on the nanochannel entry or “mouth” was eliminated.
Figure 6. (A) SEM image of the NAAM surface (above) and thickness (below) and (B) immunosensor scheme for the detection of WNV-DIII and WNV particles. Reproduced with permission from ref 189 (Copyright 2009 ACS Publications) and ref 190 (Copyright 2012 Elsevier).
Merkoçi’s laboratory has also extensively explored and reviewed this sensing approach for electrochemical sensors based on NAAMs
173, 204-205
, with special focus on protein and DNA detection
26 ACS Paragon Plus Environment
Page 27 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
for clinical diagnostics
183, 192, 197, 199-200
.
Here, commercial NAAMs with 20 or 200 nm channel
diameter were physically fixed onto commercial SPCEs and placed in a methacrylate cell as shown in Figure 7. These electrodes were functionalized with different capture probes including antibodies, ssDNA and aptamers. NB was measured by means of DPV. They firstly reported a label-free immunosensor to detect human immunoglobulin G (IgG) in blood samples
197
. Channel walls were
first silanized with APTES followed by the covalent attachment of anti-human IgG antibodies. The main parameters influencing the immunoassay, such as antibody concentration, incubation and reaction time, were optimized as shown in Figure 7C. The optimized conditions were used to investigate the effect of the channel diameter (20 vs. 200 nm) in the detection of human IgG. It was found that the smallest channel diameter could detect 2.5 times lower concentrations than the largesized one. The sensitivity of the large-sized channel diameter (200 nm) was further improved using two approaches. The first consisted of using labels in a sandwich immunoassay-based strategy 183
(Figure 7D)
. AuNPs tags of two different sizes (i.e. 20 and 80 nm) were employed to amplify the
signal, as well as, enhance the NB effect by using them as blocking agents inside the channel. The biosensor using 80 nm-sized AuNP-modified detection antibody allowed the detection of 2 µg/mL human IgG, a ten-fold enhancement compared to the detection using 20 nm AuNP-modified detection antibody, and 250 times lower than the label-free assay (500 µg/mL). Moreover, protein LOD decreased to 50 ng/mL by increasing the AuNPs size with Ag metal deposition after binding inside of the NAA surface, which further enhanced the blockage of the channels upon the biorecognition event and the redox probe diffusion (Figure 7E). The second strategy was based on using a larger redox indicator
200
. Prussian Blue NPs coated by polyvinylpyrrolidone, that were 4 nm in size, were chosen
as an alternative to the small [Fe(CN)6]
4-
ions employed in the label-free assay. The larger redox
indicator was expected to increase the steric effects along the channel and thus hinder their diffusion towards the transducer. This approach remarkably improved the performance of the biosensor, showing an excellent LOD of 34 pg/mL and allowing the detection of proteins at levels encountered in clinical samples.
27 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 28 of 59
Figure 7. (A) Set up of the NAAM electrode. (B) SEM images of the top surface (left) and crosssection (right) of the membrane. (C) Optimization of the antibody concentration (a), antibody adsorption time (b), and immunological reaction time (c), to obtain the best sensing performance using 200 nm NAA (the optimal values circled in red). (D) Illustration of the different immunoassay strategies to detect human IgG by label-free assay (1) and sandwich assay with AuNP-modified antibody (2) and Ag coated AuNPs-modified antibody (3). (E) DPV voltammograms obtained after incubating 5 µg/mL of IgG directly (a), or with 20 nm-sized AuNPs-modified antibody (b), 80 nm-sized AuNPs-modified antibody (c) and 80 nm-sized AuNPs-modified antibody after Ag deposition (d).
28 ACS Paragon Plus Environment
Page 29 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
Reproduced with permission from ref 173 (Copyright 2016 Elsevier) and ref 197 (Copyright 2010 Elsevier). Kant et al.
206
recently investigated the influence of the NAAM geometry (i.e. nanochannel diameter
and length) using a model analyte-bioreceptor interaction: biotin-streptavidin. The sensing performance was evaluated by measuring changes in the channel resistance and conductance by non-faradaic EIS for different sized nanochannels. NAAMs were first functionalized with 2carboxyethyl phosphonic acid to introduce carboxylic groups. Then, the top and bottom surface functionalization was removed with air plasma for 30 s in order to just modify the inner channel walls. The inner channels were modified with streptavidin via EDC/NHS chemistry. The performance of the biosensor with three channel diameters (25, 45 and 65 nm) was first studied by incubating in different biotin concentrations. The results showed that biotin-streptavidin binding caused significant changes of surface charge and conductivity and thus in the channel resistivity, which was found to be a key parameter to study the performance of the biosensor. Changes in the channel resistivity were larger in magnitude for the smallest nanochannel (25 nm) due to charged streptavidin-biotin complexes being closer to each other and more sensitive to oscillation of ions inside the channel compared to the larger nanochannels (45 and 65 nm). Since the biosensors with the smallest nanochannel diameter exhibited greater sensitivity, NAA platforms with 25 nm channel diameter with different nanochannel lengths (4.5, 9, 13.5 and 18 µm) were fabricated to investigate the influence of the channel length in the sensing performance. Long nanochannels (> 10 µm) were observed to hinder the diffusion of the analyte due to the higher nanochannel resistance, thus small changes were observed inside the channel. It was concluded that NAAMs with nanochannel diameter of 25 nm and length up to 10 µm exhibited the best performance. This work shows that nanochannel dimensions play a crucial role in achieving the desired sensing capabilities.
3.1.2
Mesoporous silica (MPS)
MPS features highly ordered structures with tunable channel diameter (2 – 50 nm) and shape, and 2
high surface area (up to 1500 m /g)
27
. This material is easy to functionalize, due to its hydroxyl-
terminated surface. Fabrication strategies are based on nanoparticles and surfactant self-assembly as
29 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 30 of 59
templates, followed by the subsequent removal of these templates, resulting in the final porous structure
207
. Highly ordered MPS films have started receiving attention for biosensing
207-209
.
Jin et al. constructed a MPS-based electrochemical immunosensor harnessing the NB sensing strategy
210
. MPS was synthesized following the protocol described in
211-213
and selectively modified
so that the biorecognition event could only take place in the channels. This was achieved by modifying the internal channel walls with antibodies and the external ones with trimethylsilyl chloride (TMC). Briefly, the external surface was modified with TMC using the hydroxyl groups on the surface prior to template removal and hence mesoporous channel formation. After template removal, the hydroxyl groups in the internal walls were modified with APTES, followed by antibody immobilization. The antibody-modified MPS was then attached to the ITO surface for the simultaneous detection of proteins. Biosensors performance was improved by incorporating AuNPs
214
and SWCNTs
215
in the
MPS channel to promote electron transfer. Other MPS platforms integrated on screen-printed graphite electrodes (SPGEs)
216
and GCE
213
were also successfully developed. However, these techniques
relied on sandwich assay strategies, increasing the analysis time and cost due to the use of additional immunoreagents. Although MPS NB-based biosensors were successfully fabricated, most of the approaches relied on the use of signal amplification (AuNPs, CNTs) or labelled strategies, making the analysis expensive and time-consuming. Further research, based on label-free detection and without the use of decorations for electron transfer enhancement would be required determining the feasibility of MPS for a simple, cost-effective biosensor based on NB.
3.1.3
Porous silicon (pSi)
pSi provides an attractive means to detect a broad range of target analytes due to its large specific 2
surface area (up to 800 m /g) and ease of functionalization
217
. The average pore size and thickness
can be easily adjusted to allow the penetration of different sized species. pSi is commonly fabricated by electrochemical anodization of single crystalline Si in an aqueous HF solution, resulting in a hydride-terminated surface. This hydride-terminated surface is modified by oxidation, silanization, hydrosilylation and thermal carbonization techniques. Most of the pSi electrochemical biosensors
30 ACS Paragon Plus Environment
Page 31 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
developed take advantage of the large surface area provided 174-175, 218-222, while pSi electrodes relying on NB to transduce analyte binding have only been reported by our group
223
. This work showed the
potential of pSi membranes to exploit NB effect as a promising sensing strategy. Figure 8A shows the pSi membrane-modified Au electrode fabrication that consisted of the electrochemical anodization of Si, followed by the detachment from the Si substrate by applying a series of high current pulses and transferred to the gold-coated slide. pSi membranes, consisting of Si nanochannels arrays, were functionalized with anti-MS2 antibodies for the direct detection of MS2 bacteriophage in water samples. This was achieved by thermal hydrosilylation with undecylenic acid to obtain a carboxylterminated surface, followed by the EDC/NHS activation to immobilize the anti-MS2 antibodies (Figure 8B). The performance of the immunosensor was investigated using DPV for three different sized channel diameters (85, 57 and 40 nm) for a wide range of MS2 concentrations (1 – 1010 pfu/mL) in PBS buffer as shown in Figure 8C. The oxidation current decreased for the increasing concentration of MS2 for all the immunosensors and the immunosensor with the largest nanochannel diameter (85 nm) showed the highest sensitivity with an excellent LOD of 6 pfu/mL. Moreover, the feasibility to detect MS2 in spiked reservoir water samples was also successfully demonstrated and was unaffected by interfering species that could be present in water samples. Detection limits at levels encountered in wastewater and sewage impacted wetlands were achieved (Figure 8E). The excellent performance of this platform highlights its potential to be used in water quality measurements for in-the-field applications.
31 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 32 of 59
Figure 8. (A) Schematic of the pSi membrane-modified Au electrode fabrication. (B) Functionalization of the pSi membrane-based electrode. (C) (Left to right) DPV voltammograms for the anti-MS2 immunosensors with average nanochannel diameter of 85, 57 and 40 nm for the increasing concentration of MS2 bacteriophage in buffer. (D) Dose response curves for all immunosensors modified with either MS2-specific antibodies or non-specific antibodies (control) in buffer. (E) Dose response curves of MS2 in river water (orange) and buffer (blue) for the 85 nm nanochannel diameter immunosensor. Reproduced with permission from ref 223. Copyright 2016 Elsevier.
32 ACS Paragon Plus Environment
Page 33 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
3.1.4
Polystyrene (PS) nanochannels
A very interesting strategy based on the self-assembly of polystyrene (PS) nanospheres to fabricate nanochannel arrays was recently proposed for electrochemical analysis (Figure 9)
224
. PS
nanochannels were fabricated on ITO electrodes, screen printed onto a polyethylene terephthalate substrate, by depositing a monolayer of PS nanospheres using a dip-coating technique. The spaces between the assembled nanospheres generate well-ordered inter-particle space or nanochannels. Two sizes of nanosphere were employed, 200 nm and 500 nm, with resulting inter-particle spacings (nanochannel diameter) of 24 nm and 65 nm, respectively. The formed nanochannel arrays were used for immunoglobulin G (IgG) detection (chosen as a model analyte) by functionalizing the carboxyl-terminated nanospheres with an anti-IgG antibody using EDC/NHS chemistry. The immobilized antibodies form an immunocomplex inside the nanochannels after capturing IgG, partially blocking the diffusion of the redox probe along the channel, resulting in a decrease in the DPV signal. The biosensor developed using 200 nm nanospheres exhibited the lowest LOD (580 ng/mL) with excellent selectivity for IgG against other proteins that could be present in real samples. Furthermore, performance in human urine samples was also better in terms of LOD than others previously reported by the same group using a NB approach based on NAA substrates
183, 197
. The improvement in
sensitivity can be attributed to the decrease of the length of the nanochannels from 60 µm (NAA) to 200 – 500 nm (PS). Moreover, the ease of fabrication and robustness of this platform may bring about new opportunities to develop sensing platforms based on this technology.
33 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 34 of 59
Figure 9. Electrochemical biosensors based on PS nanosphere assembly to form well-ordered PS nanosphere channel arrays (based on inter-particle distance). (A) SEM images of PS monolayer on ITO electrode with 200 nm (up) and 500 nm (down) size nanospheres. (B) Schematic representation of the sensing strategy based on the channel blockage. (C) DPV spectra for the increasing concentrations of IgG from top to bottom: 1, 50, 100, 200 and 300 µg/mL in 1 mM K3[Fe(CN)6]/0.1 M NaNO3. (D) Dose response curves of IgG for the monolayers prepared using 200 nm sized (solid line) and 500 nm sized nanospheres (dashed line). Reproduced with permission from ref 224. Copyright 2015 Royal Society of Chemistry.
The most significant nanostructured biosensors employed for the detection of pathogens and toxins described in this review are summarized in Table 2. This table includes the different target pathogen/toxin detected, the type of nanostructured platform employed and some of the most important characteristic of a biosensor such as detection technique, LOD, detection range and the final application.
34 ACS Paragon Plus Environment
Page 35 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
ACS Applied Materials & Interfaces
Table 2. Most significant electrochemical nanostructured biosensors for pathogen and toxins detection.
Pathogen/ toxin
Platform
Detection
LOD
Detection range
Application
Ref.
EIS
100 cfu/mL
102 – 105 cfu/mL
----
79
EIS
150 cfu/mL
1.5 x 102 – 1.5 x 107
Beef
cfu/mL
cucumber
technique E. coli
MWCNTs-modified electrode AuNPs-graphene electrode
and
130
samples Graphene-FET
I
vs
V
10 cfu/mL
102 – 105 cfu/mL
----
171
10 fM
10 fM – 10 µM
----
169
100 cfu/mL
100 – 500 cfu/mL
----
86
1 cfu/mL
0.2 – 106 cfu/mL
Fruit juice and
78
measurements
E. coli specific
GO- iron oxide NP
DNA
and
EIS
chitosan
composite S. infantis
CNT-FET
I
vs
V
measurements SWCNTs-modified
EMF
electrode
(Potentiometric)
S. typhi specific
GO-chitosan
DPV
DNA
composite
S. typhi
vs
time
milk samples 10 fM
10 fM – 50 nM
Serum samples
156
35
ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
Pathogen/ toxin
Platform
Detection
LOD
Detection range
EIS
100 cfu/mL
CV
Page 36 of 59
Application
Ref.
10 – 10 cfu/mL
6
----
79
3 ng/mL
10 – 1480 ng/mL
----
80
Conductance vs
1
virus
----
----
99
time
particle
Conductance vs.
1
virus
----
----
99
time
particle
Conductance vs.
29
virus
2.85 – 2.85 x 103
Clinical exhaled
100
time
particle /µL
virus particle /µL
breath samples
10 fM of the
1
technique K. pneumoniae
MWCNTs-modified
2
electrode
Sterigmatocystin
SWCNT-chitosan composite-modified electrode
Adenovirus
Influenza A
SiNW-FET
SiNW-FET
SiNW-FET
DEN-2 virus DNA
SiNW-FET combined
I
sequences
with RT-PCR
measurements
amplicons
amplicons
L.
TiO2
EIS
500 cfu/mL
monocytogenes
modified electrode
Pathogen/ toxin
Platform
Detection
LOD
nanowire-
vs
V
–
100
fm
of
----
101
10 – 107 cfu/mL
----
102
Detection range
Application
Ref.
36
ACS Paragon Plus Environment
Page 37 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
ACS Applied Materials & Interfaces
technique Hepatitis B virus
AuNP-SWCNT
DNA
composite
EIS
1
aM
of
1 – 106 aM
----
130
1 – 106 aM
----
130
20 – 120 aM
----
140
complement ary 21-base DNA
Papilloma
virus
DNA
AuNP-SWCNT
EIS
composite
1
aM
of
complement ary 24-base DNA
MNV
AuNP-modified
SWV
SPCEs
MS2
pSiM-modified
bacteriophage
electrode NAAM-modified
180
virus
particles 10
DPV
6 pfu/mL
1 – 10 pfu/mL
Reservoir water
223
EIS
7 pfu/mL
10 – 1870 pfu/mL
----
188
Detection
LOD
Detection range
Application
Ref.
electrode
Pathogen/ toxin
Platform
technique
37
ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
WNV
NAAM-modified electrode
ACV
4 pg/mL of
5 – 55 pg/mL of
WNV-DIII
WNV-DII and 0.03 –
and 2
0.6 cfu/mL
Page 38 of 59
Blood serum
189
particles/100 mL of WNV particles
38
ACS Paragon Plus Environment
Page 39 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
4 Summary and outlook Research on point-of-care devices is underpinned by electrochemical sensing platforms that allow direct, label-free detection, due to their feasibility to perform near real-time measurements and ease of handling. The simplicity in the measurement is sometimes achieved by a more sophisticated design of the sensing platform, often involving the use of nanomaterials that own excellent electrical conductivity and mechanical strength, large surface area, easy functionalization, and unique morphology. The use of nanostructured materials is rapidly expanding in the field of electrochemical biosensors. The unique properties of the emerging nanomaterials have paved the way for remarkable improvements in the sensing capabilities. These nanomaterials fall squarely into two main categories: nanoscale and porous nanomaterials. The use of nanoscale materials to prepare electrodes includes nanotubes, nanowires, nanoparticles and nanosheets; with carbon nanotubes, silicon nanowires, metal nanoparticles and graphene being the most employed. Amongst them, 2D materials are gaining interest for the development of FET devices. Porous nanostructured materials such as nanoporous anodic alumina, mesoporous silicon and porous silicon have also had a major impact on the field. Amongst them, porous nanostructured materials exploiting NB, as sensing strategy, are promising platforms for a direct and simple detection system that could be adapted to point-of-care devices. These materials are expected to play a key role in the development of devices for single molecule detection. New advances in nanofabrication will make nanoscale materials accessible to the broad research community and enable the development of highly performing analysis devices. Despite this progress, there are still several challenges that need to be overcome to make these devices commercially available for environmental monitoring and food quality control. This includes addressing the ability to handle real-world sample matrices and integration of the transducers into easy-to-use devices. Therefore, as we transition into the next generation of biosensors, the aim will be to better engineer the surface of the electrode to avoid non-specific adsorption of interfering species and combine the sensors with microfluidics solutions and electronic components for signal read-out to achieve integrated devices that can be reduced to practice.
Acknowledgment Author acknowledges the top-up scholarship funding from the National Centre of Excellence in Desalination Australia (NCEDA). This work was performed in part at the Melbourne Centre for
ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 40 of 59
Nanofabrication (MCN) in the Victorian Node of the Australian National Fabrication Facility (ANFF). The authors thank Marc Cirera for his help with the schematics (http://marccirera.com/).
40 ACS Paragon Plus Environment
Page 41 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
4.1 References (1)
Heymann, D. L.; Prentice, T.; Reinders, L. T., The World Health Report 2007: A Safer Future:
Global Public Health Security in the 21st Century. World Health Organization: 2007. (2)
Sharma, S.; Sachdeva, P.; Virdi, J. S., Emerging Water-Borne Pathogens. Adv. Appl.
Microbiol. 2003, 61, 424–428. (3)
Velusamy, V.; Arshak, K.; Korostynska, O.; Oliwa, K.; Adley, C., An Overview of Foodborne
Pathogen Detection: In the Perspective of Biosensors. Biotechnol. Adv. 2010, 28, 232–254. (4)
Morris, J. G.; Potter, M. E., Foodborne infections and intoxications. 4th ed.; Academic: Oxford,
2013. (5)
Meng, J.; Doyle, M. P., Emerging and Evolving Microbial Foodborne Pathogens. Bull. Inst.
Pasteur 1998, 96, 151–163. (6)
Alocilja, E. C.; Radke, S. M., Market Analysis of Biosensors for Food Safety. Biosens.
Bioelectron. 2003, 18, 841–846. (7)
Bryden, W. L., Mycotoxins in the Food Chain: Human Health Implications. Asia Pac. J. Clin.
Nutr. 2007, 16, 95–101. (8)
Creppy, E. E., Update of Survey, Regulation and Toxic Effects of Mycotoxins in Europe.
Toxicol. Lett. 2002, 127, 19–28. (9)
Hussein, H. S.; Brasel, J. M., Toxicity, Metabolism, and Impact of Mycotoxins on Humans and
Animals. Toxicology 2001, 167, 101–134. (10) Landgraf, M.; Destro, M. T., Staphylococcal Food Poisoning A2 - Morris, J. Glenn. In Foodborne Infections and Intoxications,4th ed; Potter, M. E., Ed. Academic Press: San Diego, 2013; Chapter 28, pp 389–400. (11) Argudín, M. Á.; Mendoza, M. C.; Rodicio, M. R., Food Poisoning and Staphylococcus Aureus Enterotoxins. Toxins 2010, 2, 1751. (12) Pinchuk, I. V.; Beswick, E. J.; Reyes, V. E., Staphylococcal Enterotoxins. Toxins 2010, 2, 2177. (13) White, A.; Burns, D.; Christensen, T. W., Effective Terminal Sterilization Using Supercritical Carbon Dioxide. J. Biotechnol. 2006, 123, 504–515. (14) Belaaouaj, A. a.; Kim, K. S.; Shapiro, S. D., Degradation of Outer Membrane Protein A in Escherichia coli Killing by Neutrophil Elastase. Science 2000, 289, 1185–1187.
41 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 42 of 59
(15) Odedina, G.; Vongkamjan, K.; Voravuthikunchai, S., Potential Bio-Control Agent from Rhodomyrtus Tomentosa against Listeria Monocytogenes. Nutrients 2015, 7, 5346. (16) Xie, Y.; He, Y.; Irwin, P. L.; Jin, T.; Shi, X., Antibacterial Activity and Mechanism of Action of Zinc Oxide Nanoparticles against Campylobacter Jejuni. Appl. Environ. Microbiol. 2011, 77, 2325– 2331. (17) Parton, B., Hepatitis https://pixnio.com/science/microscopy-images/hepatitis/hepatitis-a-virushav-an-rna-virus-that-can-survive-up-to-a-month-at-room-temperature. Accessed 10 Oct 2016. (18) Tan, M., Jiang, X., Norovirus Gastroenteritis, Carbohydrate Receptors, and Animal Models. PLOS Pathonges 2010, 6, e1000983. (19) Gonçalves, S. S.; Cano, J. F.; Stchigel, A. M.; Melo, A. S.; Godoy-Martinez, P. C.; Correa, B.; Guarro, J., Molecular phylogeny and phenotypic variability of clinical and environmental strains of Aspergillus flavus. Fungal Biol. 2012, 116, 1146–1155. (20) Iqbal, S. S.; Mayo, M. W.; Bruno, J. G.; Bronk, B. V.; Batt, C. A.; Chambers, J. P., A Review of Molecular Recognition Technologies for Detection of Biological Threat Agents. Biosens. Bioelectron.
2000, 15, 549–578. (21) Meng, J.; Doyle, M. P., Introduction. Microbiological Food Safety. Microbes. Infect. 2002, 4, 395–397. (22) Toze, S., PCR and the Detection of Microbial Pathogens in Water and Wastewater. Water Res. 1999, 33, 3545–3556. (23) Bakker, E., Electrochemical Sensors. Anal. Chem. 2004, 76 (12), 3285–3298. (24) Grieshaber, D.; MacKenzie, R.; Vörös, J.; Reimhult, E., Electrochemical Biosensors - Sensor Principles and Architectures. Sensors 2008, 8, 1400. (25) Vestergaard, M.; delanji; Kerman, K.; Tamiya, E., An Overview of Label-free Electrochemical Protein Sensors. Sensors 2007, 7, 3442. (26) Campas, M.; Garibo, D.; Prieto-Simon, B., Novel Nanobiotechnological Concepts in Electrochemical Biosensors for the Analysis of Toxins. Analyst 2012, 137, 1055–1067. (27) Asefa, T.; Duncan, C. T.; Sharma, K. K., Recent Advances in Nanostructured Chemosensors and Biosensors. Analyst 2009, 134, 1980–1990. (28) Walcarius, A.; Minteer, S. D.; Wang, J.; Lin, Y.; Merkoci, A., Nanomaterials for BioFunctionalized Electrodes: Recent Trends. J. Mater. Chem. B 2013, 1, 4878–4908.
42 ACS Paragon Plus Environment
Page 43 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
(29) Camps, N.; Dominguez, A.; Company, M.; Perez, M.; Pardos, J.; Llobet, T.; Usera, M. A.; Salleras, L., A Foodborne Outbreak of Salmonella Infection due to Overproduction of Egg-Containing Foods for a Festival. Epidemiol. Infect. 2005, 133, 817–822. (30) Forshell, L. P.; Wierup, M., Salmonella Contamination: a Significant Challenge to the Global Marketing of Animal Food Products. Rev. Sci. Tech. Off. Int. Epiz 2006, 25, 541–554. (31) Cabedo, L.; Picart i Barrot, L.; Teixidó i Canelles, A., Prevalence of Listeria Monocytogenes and Salmonella in Ready-to-Eat Food in Catalonia, Spain. J. Food Prot. 2008, 71, 855–859. (32) Hald, T., Pathogen Updates: Salmonella A2 - Morris, J. Glenn. In Foodborne Infections and Intoxications, 4th ed; Potter, M. E., Ed. Academic Press: San Diego, 2013, Chapter 5, pp 67–97. (33) Brandl, M. T.; Amundson, R., Leaf Age as a Risk Factor in Contamination of Lettuce with Escherichia Coli O157:H7 and Salmonella Enterica. Appl. Environ. Microbiol. 2008, 74 , 2298–2306. (34) Estrada-Garcia, T.; Hodges, K.; Hecht, G. A.; Tarr, P. I., Escherichia coli A2 - Morris, J. Glenn. In Foodborne Infections and Intoxications , 4th ed, Potter, M. E., Ed. Academic Press: San Diego,
2013, Chapter 8, pp 129–164. (35) Wang, S.; Orsi, R. H., Listeria A2 - Morris, J. Glenn. In Foodborne Infections and Intoxications, 4th ed, Potter, M. E., Ed. Academic Press: San Diego, 2013, Chapter 11, pp 199–216. (36) Nachamkin, I., Chronic effects of Campylobacter infection. Microbes. Infect. 2002, 4, 399–403. (37) Perez-Perez, G. I.; Kienesberger, S., Campylobacter A2 - Morris, J. Glenn. In Foodborne Infections and Intoxications , 4th ed, Potter, M. E., Ed. Academic Press: San Diego, 2013, Chapter 9, pp 165–185. (38) Sharapov, U. M., Hepatitis A A2 - Morris, J. Glenn. In Foodborne Infections and Intoxications, 4th ed, Potter, M. E., Ed. Academic Press: San Diego, 2013, Chapter 18, pp 279–286. (39) Acheson, D.; Fiore, A. E., Hepatitis A Transmitted by Food. Clin. Infect. Dis. 2004, 38, 705– 715. (40) Wheeler , C.; Vogt , T. M.; Armstrong , G. L.; Vaughan , G.; Weltman , A.; Nainan , O. V.; Dato, V.; Xia , G.; Waller , K.; Amon , J.; Lee , T. M.; Highbaugh-Battle , A.; Hembree , C.; Evenson , S.; Ruta , M. A.; Williams , I. T.; Fiore , A. E.; Bell , B. P., An Outbreak of Hepatitis A Associated with Green Onions. N. Engl. J. Med. 2005, 353 , 890–897. (41) David, S. T.; McIntyre, L.; MacDougall, L.; Kelly, D.; Liem, S.; Schallié, K.; McNabb, A.; Houde, A.; Mueller, P.; Ward, P.; Trottier, Y.-L.; Brassard, J., An Outbreak of Norovirus Caused by
43 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 44 of 59
Consumption of Oysters from Geographically Dispersed Harvest Sites, British Columbia, Canada, 2004. Foodborne Path. Dis. 2007, 4, 349–358. (42) Johnston, C. P.; Qiu, H.; Ticehurst, J. R.; Dickson, C.; Rosenbaum, P.; Lawson, P.; Stokes, A. B.; Lowenstein, C. J.; Kaminsky, M.; Cosgrove, S. E.; Green, K. Y.; Perl, T. M., Outbreak Management and Implications of a Nosocomial Norovirus Outbreak. Clin. Infect. Dis. 2007, 45, 534– 540. (43) Webby, R. J.; Carville, K. S.; Kirk, M. D.; Greening, G.; Ratcliff, R. M.; Crerar, S. K.; Dempsey, K.; Sarna, M.; Stafford, R.; Patel, M.; Hall, G., Internationally Distributed Frozen Oyster Meat Causing Multiple Outbreaks of Norovirus Infection in Australia. Clin. Infect. Dis. 2007, 44, 1026–1031. (44) Glass , R. I.; Parashar , U. D.; Estes , M. K., Norovirus Gastroenteritis. N. Engl. J. Med. 2009, 361, 1776–1785. (45) Jones, M.; Karst, S. M., Noroviruses A2 - Morris, J. Glenn. In Foodborne Infections and Intoxications, 4th ed, Potter, M. E., Ed. Academic Press: San Diego, 2013, Chapter 17, pp 261–277. (46) Hoebe, C. J. P. A.; Vennema, H.; de Roda Husman, A. M.; van Duynhoven, Y. T. H. P., Norovirus Outbreak among Primary Schoolchildren Who Had Played in a Recreational Water Fountain. J. Infect. Dis. 2004, 189, 699–705. (47) Teunis, P. F. M.; Moe, C. L.; Liu, P.; E. Miller, S.; Lindesmith, L.; Baric, R. S.; Le Pendu, J.; Calderon, R. L., Norwalk Virus: How Infectious is it? J. Med. Virol. 2008, 80, 1468–1476. (48) Torok, V., Review of Foodborne Viruses in Shellfish and Current Detection Methodologies. , South Australian Research & Development Institute, Adelaide, 2013. (49) Lewis, L.; Onsongo, M.; Njapau, H.; Schurz-Rogers, H.; Luber, G.; Kieszak, S.; Nyamongo, J.; Backer, L.; Dahiye, A. M.; Misore, A.; DeCock, K.; Rubin, C.; The Kenya Aflatoxicosis Investigation, G., Aflatoxin Contamination of Commercial Maize Products during an Outbreak of Acute Aflatoxicosis in Eastern and Central Kenya. Environ. Health Perspect. 2005, 113, 1763–1767. (50) Heather, S.; Azziz-Baumgartner, E.; Marianne, B.; Ramesh, V. B.; Robert, B.; Marie-Noel, B.; DeCock, K.; Abby, D.; Groopman, J.; Kerstin, H.; Sara, H. H.; Jeffers, D.; Jolly, C.; Pauline, J.; Gilbert, N. K.; Lewis, L.; Xiumei, L.; Luber, G.; Leslie, M.; Patience, M.; Marina, M.; Misore, A.; Njapau, H.; Ong, C.-N.; Mary, T. K. O.; Samuel, W. P.; Park, D.; Manish, P.; Timothy, P.; Maya, P.; Pronczuk, J.; Rogers, H. S.; Rubin, C.; Myrna, S.; Arthur, S.; Gordon, S.; Joerg, S.; Wild, C.; Jonathan, T. W.;
44 ACS Paragon Plus Environment
Page 45 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
Wilson, D., Workgroup Report: Public Health Strategies for Reducing Aflatoxin Exposure in Developing Countries. Environ. Health Perspect. 2006, 114, 1898–1903. (51) Pitt, J. I.; Hocking, A. D., Mycotoxins in Australia: Biocontrol of Aflatoxin in Peanuts. Mycopathologia 2006, 162, 233–243. (52) El-Nezami, H. S.; Nicoletti, G.; Neal, G. E.; Donohue, D. C.; Ahokas, J. T., Aflatoxin M1 in Human Breast Milk Samples from Victoria, Australia and Thailand. Food Chem. Toxicol 1995, 33, 173–179. (53) Juan, C.; Zinedine, A.; Moltó, J. C.; Idrissi, L.; Mañes, J., Aflatoxins Levels in Dried Fruits and Nuts from Rabat-Salé area, Morocco. Food Control 2008, 19, 849–853. (54) Pillsbury, A.; Chiew, M.; Bates, J.; Sheppeard, V., An outbreak of staphylococcal Food Poisoning in a Commercially Catered Buffet. Commun. Dis. Intell. 2013, 37, 144–148. (55) Fletcher, S. M.; Boonwaat, L.; Moore, T.; Chavada, R.; Conaty, S., Investigating an Outbreak of Staphylococcal Food Poisoning among Travellers across two Australian States. Western Pac. Surveill. Response J. 2015, 6, 17–21. (56) Le Loir, Y.; Baron, F.; Gautier, M., Staphylococcus Sureus and Food Poisoning. Genet. Mol. Res. 2003, 2, 63–76. (57) Schmid-Hempel, P.; Frank, S. A., Pathogenesis, Virulence, and Infective Dose. PLoS Pathog.
2007, 3, 147. (58) Sonawane, S. K.; Arya, S. S.; LeBlanc, J. G.; Jha, N., Use of Nanomaterials in the Detection of Food Contaminants. Eur. J. Food Res. Rev. 2014, 4, 301–317. (59) Stephen Inbaraj, B.; Chen, B. H., Nanomaterial-based Sensors for Detection of Foodborne Bacterial Pathogens and Toxins as well as Pork Adulteration in Meat Products. J. Food Drug Anal.
2016, 24, 15–28. (60) Haddon, R. C., Carbon Nanotubes. Accounts of Chemical Research 2002, 35 (12), 997–997. (61) Odom, T. W.; Huang, J.-L.; Kim, P.; Lieber, C. M., Structure and Electronic Properties of Carbon Nanotubes. J. Phys. Chem. B 2000, 104, 2794–2809. (62) Ajayan, P. M., Nanotubes from Carbon. Chem. Rev. 1999, 99, 1787–1800. (63) Merkoçi, A.; Pumera, M.; Llopis, X.; Pérez, B.; del Valle, M.; Alegret, S., New materials for electrochemical sensing VI: Carbon nanotubes. Trends Anal. Chem. 2005, 24, 826–838.
45 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 46 of 59
(64) Peigney, A.; Laurent, C.; Flahaut, E.; Bacsa, R. R.; Rousset, A., Specific Surface Area of Carbon Nanotubes and Bundles of Carbon Nanotubes. Carbon 2001, 39, 507–514. (65) Wang, J., Carbon-Nanotube Based Electrochemical Biosensors: A Review. Electroanal. 2005, 17, 7–14. (66) Tilmaciu, C.-M.; MORRIS, M. C., Carbon Nanotube Biosensors. Front. Chem. 2015, 3. (67) Prieto-Simón, B.; Bandaru, N. M.; Saint, C.; Voelcker, N. H., Tailored Carbon Nanotube Immunosensors for the Detection of Microbial Contamination. Biosens. Bioelectron. 2015, 67, 642– 648. (68) Yáñez-Sedeño, P.; Pingarrón, J. M.; Riu, J.; Rius, F. X., Electrochemical Sensing based on Carbon Nanotubes. Trends Anal. Chem. 2010, 29, 939–953. (69) Zelada-Guillén, G. A.; Blondeau, P.; Rius, F. X.; Riu, J., Carbon nanotube-Based Aptasensors for the Rapid and Ultrasensitive Detection of Bacteria. Methods 2013, 63, 233–238. (70) Gooding, J. J., Nanostructuring Electrodes with Carbon Nanotubes: A review on Electrochemistry and Applications for Sensing. Electrochim. Acta 2005, 50, 3049–3060. (71) Huang, L.; Jia, Z.; O'Brien, S., Orientated Assembly of Single-Walled Carbon Nanotubes and Applications. J. Mater. Chem. 2007, 17, 3863–3874. (72) Diao, P.; Liu, Z., Vertically Aligned Single-Walled Carbon Nanotubes by Chemical Assembly – Methodology, Properties, and Applications. Adv. Mater. 2010, 22, 1430–1449. (73) Allen, B. L.; Kichambare, P. D.; Star, A., Carbon Nanotube Field-Effect-Transistor-Based Biosensors. Adv. Mater. 2007, 19, 1439–1451. (74) Lei, J.; Ju, H., Nanotubes in Biosensing. Wiley Interdiscip. Rev. Nanomed. Nanobiotechnol.
2010, 2, 496–509. (75) Katz, E.; Willner, I., Biomolecule-Functionalized Carbon Nanotubes: Applications in Nanobioelectronics. ChemPhysChem 2004, 5, 1084–1104. (76) Zelada-Guillén, G. A.; Bhosale, S. V.; Riu, J.; Rius, F. X., Real-Time Potentiometric Detection of Bacteria in Complex Samples. Anal. Chem. 2010, 82, 9254–9260. (77) Zelada-Guillén, G. A.; Sebastián-Avila, J. L.; Blondeau, P.; Riu, J.; Rius, F. X., Label-free Detection of Staphylococcus Aureus in Skin Using Real-Time Potentiometric Biosensors Based on Carbon Nanotubes and Aptamers. Biosens. Bioelectron. 2012, 31, 226–232.
46 ACS Paragon Plus Environment
Page 47 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
(78) Zelada-Guillén, G. A.; Riu, J.; Düzgün, A.; Rius, F. X., Immediate Detection of Living Bacteria at Ultralow Concentrations Using a Carbon Nanotube Based Potentiometric Aptasensor. Angew. Chem. Int. Ed. 2009, 48, 7334–7337. (79) Andrade, C. A. S.; Nascimento, J. M.; Oliveira, I. S.; de Oliveira, C. V. J.; de Melo, C. P.; Franco, O. L.; Oliveira, M. D. L., Nanostructured Sensor Based on Carbon Nanotubes and Clavanin A for Bacterial Detection. Colloids Surf. B Biointerfaces 2015, 135, 833–839. (80) Chen, J.; Liu, D.; Li, S.; Yao, D., Development of an Amperometric Enzyme Electrode Biosensor for Sterigmatocystin Detection. Enzyme Microb. Technol. 2010, 47, 119–126. (81) Li, S. c.; Chen, J. h.; Cao, H.; Yao, D. s.; Liu, D. l., Amperometric Biosensor for Aflatoxin B1 Based on Aflatoxin-Oxidase Immobilized on Multiwalled Carbon Nanotubes. Food Control 2011, 22, 43–49. (82) Yao, D.-s.; Cao, H.; Wen, S.; Liu, D.-l.; Bai, Y.; Zheng, W.-j., A Novel Biosensor for Sterigmatocystin Constructed by Multi-Walled Carbon Nanotubes (MWNT) Modified with Aflatoxin– Detoxifizyme (ADTZ). Bioelectrochemistry 2006, 68, 126–133. (83) So, H.-M.; Park, D.-W.; Jeon, E.-K.; Kim, Y.-H.; Kim, B. S.; Lee, C.-K.; Choi, S. Y.; Kim, S. C.; Chang, H.; Lee, J.-O., Detection and Titer Estimation of Escherichia Coli Using AptamerFunctionalized Single-Walled Carbon-Nanotube Field-Effect Transistors. Small 2008, 4, 197–201. (84) Zhang, X.; Wang, D.; Yang, D.; Li, S.; Shen, Z., Electronic detection of Escherichia coli O157
︰ H7 Using Single-Walled Carbon Nanotubes Field-Effect Transistor Biosensor. Engineering 2013, 4, 94. (85) García-Aljaro, C.; Cella, L. N.; Shirale, D. J.; Park, M.; Muñoz, F. J.; Yates, M. V.; Mulchandani,
A.,
Carbon
Nanotubes-Based
Chemiresistive
Biosensors
for
Detection
of
Microorganisms. Biosens. Bioelectron. 2010, 26, 1437–1441. (86) Villamizar, R. A.; Maroto, A.; Rius, F. X.; Inza, I.; Figueras, M. J., Fast detection of Salmonella Infantis with Carbon Nanotube Field Effect Transistors. Biosens. Bioelectron. 2008, 24, 279–283. (87) Lerner, M. B.; Goldsmith, B. R.; McMillon, R.; Dailey, J.; Pillai, S.; Singh, S. R.; Johnson, A. T. C., A Carbon Nanotube Immunosensor for Salmonella. AIP Adv.2011, 1, 042127. (88) Bai, J.; Zhou, B., Titanium Dioxide Nanomaterials for Sensor Applications. Chem. Rev. 2014, 114, 10131–10176.
47 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 48 of 59
(89) Mandal, S. S.; Navratna, V.; Sharma, P.; Gopal, B.; Bhattacharyya, A. J., Titania NanotubeModified Screen Printed Carbon Electrodes Enhance the Sensitivity in the Electrochemical Detection of Proteins. Bioelectrochemistry 2014, 98, 46–52. (90) Wang, Y.; Wang, T.; Da, P.; Xu, M.; Wu, H.; Zheng, G., Silicon Nanowires for Biosensing, Energy Storage, and Conversion. Adv. Mater. 2013, 25, 5177–5195. (91) Zhang, X.-E.; Men, D.; Wei, H., Nanowire Biosensors. In Encyclopedia of Biophysics, Roberts, G. C. K., Ed. Springer Berlin Heidelberg: Berlin, Heidelberg, 2013, pp 1691–1693. (92) Patolsky, F.; Zheng, G.; Lieber, C. M., Nanowire-Based Biosensors. Anal. Chem. 2006, 78, 4260–4269. (93) Ramgir, N. S.; Yang, Y.; Zacharias, M., Nanowire-Based Sensors. Small 2010, 6, 1705–1722. (94) Chen, K.-I.; Li, B.-R.; Chen, Y.-T., Silicon Nanowire Field-Effect Transistor-Based Biosensors for Biomedical Diagnosis and Cellular Recording Investigation. Nano Today 2011, 6, 131–154. (95) Zhang, G.-J.; Ning, Y., Silicon Nanowire Biosensor and its Applications in Disease Diagnostics: A Review. Anal. Chim. Acta 2012, 749, 1-15. (96) Li, Z.; Rajendran, B.; Kamins, T. I.; Li, X.; Chen, Y.; Williams, S. R., Silicon nanowires for Sequence-Specific DNA Sensing: Device Fabrication and Simulation. Appl. Phys. A 2005, 80, 12571263. (97) Nair, P. R.; Alam, M. A., Design Considerations of Silicon Nanowire Biosensors. IEEE Trans. Electron Dev. 2007, 54, 3400–3408. (98) Zhang, G.-J.; Chua, J. H.; Chee, R.-E.; Agarwal, A.; Wong, S. M.; Buddharaju, K. D.; Balasubramanian, N., Highly Sensitive Measurements of PNA-DNA Hybridization using Oxide-Etched Silicon Nanowire Biosensors. Biosens. Bioelectron. 2008, 23, 1701–1707. (99) Patolsky, F.; Zheng, G.; Hayden, O.; Lakadamyali, M.; Zhuang, X.; Lieber, C. M., Electrical Detection of Single Viruses. Proc. Natl. Acad. Sci. U.S.A. 2004, 101, 14017–14022. (100) Shen, F.; Wang, J.; Xu, Z.; Wu, Y.; Chen, Q.; Li, X.; Jie, X.; Li, L.; Yao, M.; Guo, X.; Zhu, T., Rapid Flu Diagnosis Using Silicon Nanowire Sensor. Nano Lett. 2012, 12, 3722–3730. (101) Zhang, G.-J.; Zhang, L.; Huang, M. J.; Luo, Z. H. H.; Tay, G. K. I.; Lim, E.-J. A.; Kang, T. G.; Chen, Y., Silicon Nanowire Biosensor for Highly Sensitive and Rapid Detection of Dengue virus. Sens. Actuators B Chem. 2010, 146, 138–144.
48 ACS Paragon Plus Environment
Page 49 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
(102) Wang, R.; Ruan, C.; Kanayeva, D.; Lassiter, K.; Li, Y., TiO2 Nanowire Bundle Microelectrode Based Impedance Immunosensor for Rapid and Sensitive Detection of Listeria Monocytogenes. Nano Lett. 2008, 8, 2625–2631. (103) Wang, J., Nanomaterial-Based Electrochemical Biosensors. Analyst 2005, 130 (4), 421-426. (104)
Luo, X.; Morrin, A.; Killard, A. J.; Smyth, M. R., Application of Nanoparticles in
Electrochemical Sensors and Biosensors. Electroanal. 2006, 18, 319–326. (105) Pérez-López, B.; Merkoçi, A., Nanoparticles for the Development of Improved (Bio)sensing Systems. Analytical and BioAnal. Chem. 2011, 399, 1577–1590. (106)
Wang, F.; Hu, S., Electrochemical Sensors based on Metal and Semiconductor
Nanoparticles. Microchim. Acta 2009, 165, 1–22. (107) Cao, X.; Ye, Y.; Liu, S., Gold Nanoparticle-Based Signal Amplification for Biosensing. Anal. Biochem. 2011, 417, 1–16. (108) Merkoçi, A., Electrochemical Biosensing with Nanoparticles. FEBS Journal 2007, 274, 310– 316. (109) Penn, S. G.; He, L.; Natan, M. J., Nanoparticles for Bioanalysis. Curr. Opin. Chem. Biol.
2003, 7, 609–615. (110) Wang, J., Electrochemical Biosensing Based on Noble Metal Nanoparticles. Microchim. Acta
2012, 177, 245–270. (111) Bönnemann, H.; Richards, Ryan M., Nanoscopic Metal Particles − Synthetic Methods and Potential Applications. Eur. J. Inorg. Chem. 2001, 2001, 2455–2480. (112) Niemeyer, C. M., Nanoparticles, Proteins, and Nucleic Acids: Biotechnology Meets Materials Science. Angew. Chem. Int. Ed. 2001, 40, 4128–4158. (113) Guo, S.; Wang, E., Synthesis and Electrochemical Applications of Gold Nanoparticles. Anal. Chim. Acta 2007, 598, 181–192. (114) Zhang, J.; Lakowicz, J. R., Enhanced Luminescence of Phenyl-phenanthridine Dye on Aggregated Small Silver Nanoparticles. J. Phys. Chem. B 2005, 109, 8701–8706. (115) Cao, Y.; Wang, J.; Xu, Y.; Li, G., Sensing Purine Nucleoside Phosphorylase Activity by using silver nanoparticles. Biosens. Bioelectron. 2010, 25, 1032–1036. (116) Doty, R. C.; Tshikhudo, T. R.; Brust, M.; Fernig, D. G., Extremely Stable Water-Soluble Ag Nanoparticles. Chem. Mater. 2005, 17, 4630–4635.
49 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 50 of 59
(117) Naik, R. R.; Stringer, S. J.; Agarwal, G.; Jones, S. E.; Stone, M. O., Biomimetic Synthesis and Patterning of Silver Nanoparticles. Nat. Mater. 2002, 1, 169–172. (118) Peng, Z.; Yang, H., Designer Platinum Nanoparticles: Control of Shape, Composition in Alloy, Nanostructure and Electrocatalytic Property. Nano Today 2009, 4, 143–164. (119)
Gooding, J. J.; Ciampi, S., The Molecular Level Modification of Surfaces: from Self-
Assembled Monolayers to Complex Molecular Assemblies. Chem. Soc. Rev. 2011, 40, 2704–2718. (120) Liu, G.; Luais, E.; Gooding, J. J., The Fabrication of Stable Gold Nanoparticle-Modified Interfaces for Electrochemistry. Langmuir 2011, 27, 4176–4183. (121) Zhou, N.; Wang, J.; Chen, T.; Yu, Z.; Li, G., Enlargement of Gold Nanoparticles on the Surface of a Self-Assembled Monolayer Modified Electrode: A Mode in Biosensor Design. Anal. Chem. 2006, 78, 5227–5230. (122) Zhang, J.; Ting, B. P.; Jana, N. R.; Gao, Z.; Ying, J. Y., Ultrasensitive Electrochemical DNA Biosensors Based on the Detection of a Highly Characteristic Solid-State Process. Small 2009, 5, 1414–1417. (123) Liu, S.; Leech, D.; Ju, H., Application of Colloidal Gold in Protein Immobilization, Electron Transfer, and Biosensing. Anal. Lett. 2003, 36, 1–19. (124) Zhao, W.; Xu, J.-J.; Chen, H.-Y., Electrochemical Biosensors Based on Layer-by-Layer Assemblies. Electroanal. 2006, 18, 1737–1748. (125)
Lost, R. M.; Crespilho, F. N., Layer-by-Layer Self-Assembly and Electrochemistry:
Applications in biosensing and bioelectronics. Biosens. Bioelectron. 2012, 31, 1–10. (126) Sungwoo, K.; Jeongju, P.; Jinhan, C., Layer-by-Layer Assembled Multilayers Using CatalaseEncapsulated Gold Nanoparticles. Nanotechnology 2010, 21, 375702. (127) Hammond, P. T., Form and Function in Multilayer Assembly: New Applications at the Nanoscale. Adv. Mater. 2004, 16, 1271–1293. (128) Chu, H.; Wei, L.; Cui, R.; Wang, J.; Li, Y., Carbon Nanotubes combined with Inorganic Nanomaterials: Preparations and Applications. Coordin. Chem. Rev. 2010, 254, 1117–1134. (129) Wildgoose, G. G.; Banks, C. E.; Compton, R. G., Metal Nanoparticles and Related Materials Supported on Carbon Nanotubes: Methods and Applications. Small 2006, 2, 182–193.
50 ACS Paragon Plus Environment
Page 51 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
(130) Wang, Y.; Ping, J.; Ye, Z.; Wu, J.; Ying, Y., Impedimetric immunosensor based on Gold Nanoparticles Modified Graphene paper for Label-Free Detection of Escherichia coli O157:H7. Biosens. Bioelectron. 2013, 49, 492–498. (131) Wang, S.; Li, L.; Jin, H.; Yang, T.; Bao, W.; Huang, S.; Wang, J., Electrochemical Detection of Hepatitis B and Papilloma Virus DNAs using SWCNT Srray Coated with Gold Nanoparticles. Biosens. Bioelectron. 2013, 41, 205–210. (132)
Wen, Z.; Ci, S.; Li, J., Pt Nanoparticles Inserting in Carbon Nanotube Arrays:
Nanocomposites for Glucose Biosensors. J. Phys. Chem. C 2009, 113, 13482–13487. (133) Li, J.; Yu, Q.; Peng, T., Electrocatalytic Oxidation of Hydrogen Peroxide and Cysteine at a Glassy Carbon Electrode Modified with Platinum Nanoparticle-deposited Carbon Nanotubes. Analytical Sciences 2005, 21, 377–381. (134) Qiaocui, S.; Tuzhi, P.; Yunu, Z.; Yang, C. F., An Electrochemical Biosensor with Cholesterol Oxidase/ Sol-Gel Film on a Nanoplatinum/Carbon Nanotube Electrode. Electroanal. 2005, 17, 857– 861. (135) Toledano, R.; Mandler, D., Electrochemical Codeposition of Thin Gold Nanoparticles/Sol−Gel Nanocomposite Films. Chem. Mater. 2010, 22, 3943–3951. (136) Kannan, P.; John, S. A., Highly Sensitive Determination of Hydroxylamine using Fused Gold Nanoparticles Immobilized on Sol–Gel Film Modified Gold Electrode. Anal. Chim. Acta 2010, 663, 158–164. (137) Manivannan, S.; Ramaraj, R., Core-shell Au/Ag Nanoparticles Embedded in Silicate Sol-Gel Network for Sensor Application Towards Hydrogen Peroxide. J. Chem. Sci. 2009, 121, 735–743. (138) Taheri, A.; Noroozifar, M.; Khorasani-Motlagh, M., Investigation of a New Electrochemical Cyanide Sensor Based on Ag Nanoparticles Embedded in a Three-Dimensional Sol–Gel. J. Electroanal. Chem. 2009, 628, 48–54. (139) Bharathi, S.; Joseph, J.; Lev, O., Electrodeposition of Thin Gold Films from an Aminosilicate Stabilized Gold Sol. Electrochem. Solid State Lett. 1999, 2, 284–287. (140) Giamberardino, A.; Labib, M.; Hassan, E. M.; Tetro, J. A.; Springthorpe, S.; Sattar, S. A.; Berezovski, M. V.; DeRosa, M. C., Ultrasensitive Norovirus Detection Using DNA Aptasensor Technology. PLoS ONE 2013, 8, e79087.
51 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 52 of 59
(141) Labib, M.; Zamay, A. S.; Berezovski, M. V., Multifunctional Electrochemical Aptasensor for Aptamer Clones Screening, Virus Quantitation in Blood and Viability Assessment. Analyst 2013, 138, 1865–1875. (142)
Coleman, J. N.; Lotya, M.; O’Neill, A.; Bergin, S. D.; King, P. J.; Khan, U.; Young, K.;
Gaucher, A.; De, S.; Smith, R. J.; Shvets, I. V.; Arora, S. K.; Stanton, G.; Kim, H.-Y.; Lee, K.; Kim, G. T.; Duesberg, G. S.; Hallam, T.; Boland, J. J.; Wang, J. J.; Donegan, J. F.; Grunlan, J. C.; Moriarty, G.; Shmeliov, A.; Nicholls, R. J.; Perkins, J. M.; Grieveson, E. M.; Theuwissen, K.; McComb, D. W.; Nellist, P. D.; Nicolosi, V., Two-Dimensional Nanosheets Produced by Liquid Exfoliation of Layered Materials. Science 2011, 331, 568–571. (143) Du, D.; Yang, Y.; Lin, Y., Graphene-Based Materials for Biosensing and Bioimaging. MRS Bull.2012, 37, 1290–1296. (144) Shao, Y.; Wang, J.; Wu, H.; Liu, J.; Aksay, I. A.; Lin, Y., Graphene Based Electrochemical Sensors and Biosensors: A Review. Electroanal. 2010, 22, 1027–1036. (145) Geim, A. K.; Novoselov, K. S., The Rise of Graphene. Nat Mater 2007, 6, 183–191. (146) Liu, J.; Liu, Z.; Barrow, C. J.; Yang, W., Molecularly Engineered Graphene Surfaces for Sensing Applications: A Review. Anal. Chim. Acta 2015, 859, 1–19. (147) Park, S.; Ruoff, R. S., Chemical Methods for the Production of Graphenes. Nat. Nano. 2009, 4, 217–224. (148) Georgakilas, V.; Otyepka, M.; Bourlinos, A. B.; Chandra, V.; Kim, N.; Kemp, K. C.; Hobza, P.; Zboril, R.; Kim, K. S., Functionalization of Graphene: Covalent and Non-Covalent Approaches, Derivatives and Applications. Chem. Rev. 2012, 112, 6156–6214. (149) Yang, C.; Denno, M. E.; Pyakurel, P.; Venton, B. J., Recent Trends in Carbon NanomaterialBased Electrochemical Sensors for Biomolecules: A Review. Anal. Chim. Acta 2015, 887, 17–37. (150)
Hou, S.; Kasner, M. L.; Su, S.; Patel, K.; Cuellari, R., Highly Sensitive and Selective
Dopamine Biosensor Fabricated with Silanized Graphene. J. Phys. Chem. C 2010, 114 (35), 14915– 14921. (151)
Kim, Y.-R.; Bong, S.; Kang, Y.-J.; Yang, Y.; Mahajan, R. K.; Kim, J. S.; Kim, H.,
Electrochemical Detection of Dopamine in the Presence of Ascorbic Acid Using Graphene Modified Electrodes. Biosens. Bioelectron. 2010, 25, 2366–2369.
52 ACS Paragon Plus Environment
Page 53 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
(152) Wang, Y.; Li, Y.; Tang, L.; Lu, J.; Li, J., Application of Graphene-Modified Electrode for Selective Detection of Dopamine. Electrochem. Commun. 2009, 11, 889–892. (153) Unnikrishnan, B.; Palanisamy, S.; Chen, S.-M., A Simple Electrochemical Spproach to Fabricate a Glucose Biosensor Based on Graphene–Glucose Oxidase Biocomposite. Biosens. Bioelectron. 2013, 39, 70–75. (154) Xu, H.; Dai, H.; Chen, G., Direct Electrochemistry and Electrocatalysis of Hemoglobin Protein Entrapped in Graphene and Chitosan Composite Film. Talanta 2010, 81, 334–338. (155)
Kang, X.; Wang, J.; Wu, H.; Aksay, I. A.; Liu, J.; Lin, Y., Glucose Oxidase-Graphene-
Chitosan Modified Electrode for Direct Electrochemistry and Glucose Sensing. Biosens. Bioelectron.
2009, 25, 901–905. (156) Singh, A.; Sinsinbar, G.; Choudhary, M.; Kumar, V.; Pasricha, R.; Verma, H. N.; Singh, S. P.; Arora, K., Graphene Oxide-Chitosan Nanocomposite Based Electrochemical DNA Biosensor for Detection of Typhoid. Sens. Actuators B Chem. 2013, 185, 675–684. (157) Yin, P. T.; Kim, T.-H.; Choi, J.-W.; Lee, K.-B., Prospects for Graphene-Nanoparticle-Based Hybrid Sensors. Phys. Chem. Chem. Phys. 2013, 15, 12785–12799. (158) Wang, Q.; Su, J.; Xu, J.; Xiang, Y.; Yuan, R.; Chai, Y., Dual Amplified, Sensitive Electrochemical Detection of Pathogenic Sequences Based on Biobarcode Labels and Functional Graphene Modified Electrode. Sens. Actuators B Chem. 2012, 163, 267–271. (159) Shan, C.; Yang, H.; Han, D.; Zhang, Q.; Ivaska, A.; Niu, L., Graphene/AuNPs/Chitosan Nanocomposites Film for Glucose Biosensing. Biosens. Bioelectron. 2010, 25, 1070–1074. (160) Zhou, K.; Zhu, Y.; Yang, X.; Li, C., Electrocatalytic Oxidation of Glucose by the Glucose Oxidase Immobilized in Graphene-Au-Nafion Biocomposite. Electroanal. 2010, 22 (3), 259-264. (161) Artiles, M. S.; Rout, C. S.; Fisher, T. S., Graphene-Based Hybrid Materials and Devices for Biosensing. Adv. Drug Deliv. Rev. 2011, 63, 1352–1360. (162) Zhan, B.; Li, C.; Yang, J.; Jenkins, G.; Huang, W.; Dong, X., Graphene Field-Effect Transistor and Its Application for Electronic Sensing. Small 2014, 10, 4042–4065. (163) Ohno, Y.; Maehashi, K.; Matsumoto, K., Chemical and Biological Sensing Applications Based on Graphene Field-Effect Transistors. Biosens. Bioelectron. 2010, 26, 1727–1730. (164) Ohno, Y.; Maehashi, K.; Matsumoto, K., Label-Free Biosensors Based on Aptamer-Modified Graphene Field-Effect Transistors. J. Am. Chem. Soc. 2010, 132, 18012–18013.
53 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 54 of 59
(165) Meric, I.; Han, M. Y.; Young, A. F.; Ozyilmaz, B.; Kim, P.; Shepard, K. L., Current Saturation in Zero-Bandgap, Top-Gated Graphene Field-Effect Transistors. Nat. Nano. 2008, 3, 654–659. (166) Huang, Y.; Dong, X.; Shi, Y.; Li, C. M.; Li, L.-J.; Chen, P., Nanoelectronic Biosensors Based on CVD Grown Graphene. Nanoscale 2010, 2, 1485–1488. (167)
Cohen-Karni, T.; Qing, Q.; Li, Q.; Fang, Y.; Lieber, C. M., Graphene and Nanowire
Transistors for Cellular Interfaces and Electrical Recording. Nano Lett. 2010, 10, 1098–1102. (168) Zhou, M.; Zhai, Y.; Dong, S., Electrochemical Sensing and Biosensing Platform Based on Chemically Reduced Graphene Oxide. Anal. Chem. 2009, 81, 5603–5613. (169) Tiwari, I.; Singh, M.; Pandey, C. M.; Sumana, G., Electrochemical Genosensor Based on Graphene Oxide Modified Iron Oxide-Chitosan Hybrid Nanocomposite for Pathogen Detection. Sens. Actuators B Chem. 2015, 206, 276–283. (170) Mohanty, N.; Berry, V., Graphene-Based Single-Bacterium Resolution Biodevice and DNA Transistor: Interfacing Graphene Derivatives with Nanoscale and Microscale Biocomponents. Nano Lett. 2008, 8, 4469–4476. (171) Huang, Y.; Dong, X.; Liu, Y.; Li, L.-J.; Chen, P., Graphene-Based Biosensors for Detection of Bacteria and Their Metabolic Sctivities. J. Mater. Chem. 2011, 21, 12358–12362. (172)
Kumeria, T.; Santos, A., Sensing and Biosensing Applications of Nanoporous Anodic
Alumina. In Electrochemically Engineered Nanoporous Materials: Methods, Properties and Applications, Losic, D.; Santos, A., Eds. Springer International Publishing: Cham, 2015, pp 187–218. (173) De la Escosura-Muñiz, A.; Merkoçi, A., Nanochannels for Electrical Biosensing. Trends Anal. Chem. 2016, 79, 134–150. (174) RoyChaudhuri, C., A Review on Porous Silicon Based Electrochemical Biosensors: Beyond Surface Area Enhancement Factor. Sens. Actuators B Chem. 2015, 210, 310–323. (175) Harraz, F. A., Porous Silicon Chemical Sensors and Biosensors: A Review. Sens. Actuators B Chem. 2014, 202, 897–912. (176) Walcarius, A., Mesoporous materials and electrochemistry. Chem. Soc. Rev. 2013, 42, 4098– 4140. (177) Walcarius, A., Mesoporous Materials-Based Electrochemical Sensors. Electroanalysis 2015, 27, 1303–1340.
54 ACS Paragon Plus Environment
Page 55 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
(178) Walcarius, A.; Minteer, S. D.; Wang, J.; Lin, Y.; Merkoci, A., Nanomaterials for biofunctionalized electrodes: recent trends. J. Mater. Chem. B 2013, 1, 4878–4908. (179) Van Der Voort, P.; Esquivel, D.; De Canck, E.; Goethals, F.; Van Driessche, I.; RomeroSalguero, F. J., Periodic Mesoporous Organosilicas: from simple to complex bridges; a comprehensive overview of functions, morphologies and applications. Chem. Soc. Rev. 2013, 42, 3913–3955. (180) Mizoshita, N.; Tani, T.; Inagaki, S., Syntheses, properties and applications of periodic mesoporous organosilicas prepared from bridged organosilane precursors. Chem. Soc. Rev. 2011, 40, 789–800. (181) Gerard, M.; Chaubey, A.; Malhotra, B. D., Application of conducting polymers to biosensors. Biosens. Bioelectron. 2002, 17, 345–359. (182) Dhand, C.; Das, M.; Datta, M.; Malhotra, B. D., Recent advances in polyaniline based biosensors. Biosens. Bioelectron. 2011, 26, 2811–2821. (183) De la Escosura-Muñiz, A.; Merkoçi, A., A Nanochannel/Nanoparticle-Based Filtering and Sensing Platform for Direct Detection of a Cancer Biomarker in Blood. Small 2011, 7, 675–682. (184) Santos, A.; Kumeria, T.; Losic, D., Nanoporous Anodic Alumina: A Versatile Platform for Optical Biosensors. Materials 2014, 7 (6), 4297. (185)
Foong, T. R. B.; Sellinger, A.; Hu, X., Origin of the Bottlenecks in Preparing Anodized
Aluminum Oxide (AAO) Templates on ITO Glass. ACS Nano 2008, 2, 2250–2256. (186) Debrassi, A.; Ribbera, A.; de Vos, W. M.; Wennekes, T.; Zuilhof, H., Stability of (Bio)Functionalized Porous Aluminum Oxide. Langmuir 2014, 30, 1311–1320. (187) Md Jani, A. M.; Losic, D.; Voelcker, N. H., Nanoporous Anodic Aluminium Oxide: Advances in Surface Engineering and Emerging Applications. Prog. Mat. Sci. 2013, 58, 636–704. (188) Chaturvedi, P.; Rodriguez, S. D.; Vlassiouk, I.; Hansen, I. A.; Smirnov, S. N., Simple and Versatile Detection of Viruses Using Anodized Alumina Membranes. ACS Sensors 2016, 1, 488–492. (189) Nguyen, B. T. T.; Koh, G.; Lim, H. S.; Chua, A. J. S.; Ng, M. M. L.; Toh, C.-S., MembraneBased Electrochemical Nanobiosensor for the Detection of Virus. Anal. Chem. 2009, 81, 7226–7234.
55 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 56 of 59
(190) Nguyen, B. T. T.; Peh, A. E. K.; Chee, C. Y. L.; Fink, K.; Chow, V. T. K.; Ng, M. M. L.; Toh, C.-S., Electrochemical Impedance Spectroscopy Characterization of Nanoporous Alumina Dengue Virus Biosensor. Bioelectrochemistry 2012, 88, 15–21. (191) Peh, A. E. K.; Li, S. F. Y., Dengue Virus Detection using Impedance Measured across Nanoporous Aluminamembrane. Biosens. Bioelectron. 2013, 42, 391–396. (192) De la Escosura-Muniz, A.; Mekoci, A., Nanoparticle Based Enhancement of Electrochemical DNA Hybridization Signal using Nanoporous Electrodes. Chem. Commun. 2010, 46, 9007–9009. (193) Rai, V.; Deng, J.; Toh, C.-S., Electrochemical Nanoporous Alumina Membrane-Based Labelfree DNA Biosensor for the Detection of Legionella Sp. Talanta 2012, 98, 112–117. (194) Rai, V.; Hapuarachchi, H. C.; Ng, L. C.; Soh, S. H.; Leo, Y. S.; Toh, C.-S., Ultrasensitive c DNA Detection of Dengue Virus RNA Using Electrochemical Nanoporous Membrane-Based Biosensor. PLoS ONE 2012, 7, e42346. (195) Ye, W. W.; Shi, J. Y.; Chan, C. Y.; Zhang, Y.; Yang, M., A Nanoporous Membrane Based Impedance Sensing Platform for DNA Sensing with Gold Nanoparticle Amplification. Sens. Actuators B Chem. 2014, 193, 877–882. (196)
Li, S.-J.; Li, J.; Wang, K.; Wang, C.; Xu, J.-J.; Chen, H.-Y.; Xia, X.-H.; Huo, Q., A
Nanochannel Array-Based Electrochemical Device for Quantitative Label-free DNA Analysis. ACS Nano 2010, 4, 6417–6424. (197) De la Escosura-Muñiz, A.; Merkoçi, A., Label-free Voltammetric Immunosensor Using a Nanoporous Membrane Based Platform. Electrochem. Commun. 2010, 12, 859–863. (198) Koh, G.; Agarwal, S.; Cheow, P.-S.; Toh, C.-S., Development of a Membrane-based Electrochemical Immunosensor. Electrochim. Acta 2007, 53, 803–810. (199) De la Escosura-Muñiz, A.; Chunglok, W.; Surareungchai, W.; Merkoçi, A., Nanochannels for Diagnostic of Thrombin-Related Diseases in Human Blood. Biosens. Bioelectron. 2013, 40, 24–31. (200) Espinoza-Castañeda, M.; Escosura-Muñiz, A. d. l.; Chamorro, A.; Torres, C. d.; Merkoçi, A., Nanochannel Array Device Operating Through Prussian Blue Nanoparticles for Sensitive Label-Free Immunodetection of a Cancer Biomarker. Biosens. Bioelectron. 2015, 67, 107–114. (201) Vlassiouk, I.; Takmakov, P.; Smirnov, S., Sensing DNA Hybridization via Ionic Conductance through a Nanoporous Electrode. Langmuir 2005, 21, 4776–4778.
56 ACS Paragon Plus Environment
Page 57 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
(202) Koh, G.; Agarwal, S.; Cheow, P.-S.; Toh, C.-S., Characterization of the Barrier Layer of Nanoporous Alumina Films Prepared Using Two Different Contact Configurations. Electrochim. Acta
2007, 52, 2815–2821. (203)
Deng, J.; Toh, C.-S., Impedimetric DNA Biosensor Based on a Nanoporous Alumina
Membrane for the Detection of the Specific Oligonucleotide Sequence of Dengue Virus. Sensors
2013, 13, 7774. (204) De la Escosura-Muñiz, A.; Merkoçi, A., Nanochannels Preparation and Application in Biosensing. ACS Nano 2012, 6, 7556–7583. (205) De la Escosura-Muñiz, A.; Espinoza-Castañeda, M.; Merkoçi, A., Protein and DNA Electrochemical Sensing Using Anodized Aluminum Oxide Nanochannel Arrays. In Nanoporous Alumina: Fabrication, Structure, Properties and Applications, Losic, D.; Santos, A., Eds. Springer International Publishing: Cham, 2015; Chapter 9, 271–291. (206)
Kant, K.; Yu, J.; Priest, C.; Shapter, J. G.; Losic, D., Impedance nanopore biosensor:
influence of pore dimensions on biosensing performance. Analyst 2014, 139, 1134–1140. (207) Walcarius, A.; Kuhn, A., Ordered Porous Thin Films in Electrochemical Analysis. Trends Anal. Chem. 2008, 27, 593–603. (208)
Hasanzadeh, M.; Shadjou, N.; De la Guardia, M.; Eskandani, M.; Sheikhzadeh, P.,
Mesoporous Silica-Based Materials for Use in Biosensors. Trends Anal. Chem. 2012, 33, 117–129. (209) Hasanzadeh, M.; Shadjou, N.; Omidinia, E.; Eskandani, M.; De la Guardia, M., Mesoporous Silica Materials for Use in Electrochemical Immunosensing. Trends Anal. Chem. 2013, 45, 93–106. (210) Lin, J.; Wei, Z.; Mao, C., A Label-Free Immunosensor Based on Modified Mesoporous Silica for Simultaneous Determination of Tumor Markers. Biosens. Bioelectron. 2011, 29, 40–45. (211) Zhao, D.; Feng, J.; Huo, Q.; Melosh, N.; Fredrickson, G. H.; Chmelka, B. F.; Stucky, G. D., Triblock Copolymer Syntheses of Mesoporous Silica with Periodic 50 to 300 Angstrom Pores. Science
1998, 279, 548–552. (212) Zhao, D.; Huo, Q.; Feng, J.; Chmelka, B. F.; Stucky, G. D., Nonionic Triblock and Star Diblock Copolymer and Oligomeric Surfactant Syntheses of Highly Ordered, Hydrothermally Stable, Mesoporous Silica Structures. J. Am. Chem. Soc. 1998, 120, 6024–6036. (213) Lin, J.; He, C.; Zhang, S., Immunoassay Channels for α-Fetoprotein Based on Encapsulation of Biorecognition Molecules into SBA-15 Mesopores. Anal. Chim. Acta 2009, 643, 90–94.
57 ACS Paragon Plus Environment
ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
(214)
Page 58 of 59
Lin, J.; Wei, Z.; Chu, P., A Label-Free Immunosensor by Controlled Fabrication of
Monoclonal Antibodies and Gold Nanoparticles Inside the Mesopores. Anal. Biochem. 2012, 421, 97– 102. (215)
Lin, J.; Wei, Z.; Zhang, H.; Shao, M., Sensitive Immunosensor for the Label-Free
Determination of Tumor Marker Based on Carbon Nanotubes/Mesoporous Silica and Graphene Modified Electrode. Biosens. Bioelectron. 2013, 41, 342–347. (216) Wu, J.; Yan, Y.; Yan, F.; Ju, H., Electric Field-Driven Strategy for Multiplexed Detection of Protein Biomarkers Using a Disposable Reagentless Electrochemical Immunosensor Array. Anal. Chem. 2008, 80, 6072–6077. (217)
Jane, A.; Dronov, R.; Hodges, A.; Voelcker, N. H., Porous Silicon Biosensors on the
Advance. Trends Biotechnol. 2009, 27, 230–239. (218) Archer, M.; Christophersen, M.; Fauchet, P. M., Macroporous Silicon Electrical Sensor for DNA Hybridization Detection. Biomed. Microdevices 2004, 6, 203–211. (219) Archer, M.; Fauchet, P. M., Electrical sensing of DNA Hybridization in Porous Silicon Layers. Phys. Status Solidi 2003, 198, 503–507. (220) Lugo, J.; Ocampo, M.; Kirk, A.; Plant, D.; Fauchet, P., Electrochemical sensing of DNA with Porous Silicon Layers. J. New Mat. Electr. Sys. 2007, 10, 113–116. (221) Reddy, R. R. K.; Basu, I.; Bhattacharya, E.; Chadha, A., Estimation of Triglycerides by a Porous Silicon Based Potentiometric Biosensor. Curr. Appl. Phys. 2003, 3, 155–161. (222) Vamvakaki, V.; Chaniotakis, N. A., DNA Stabilization and Hybridization Detection on Porous Silicon Surface by EIS and Total Reflection FT-IR Spectroscopy. Electroanal. 2008, 20, 1845-1850. (223) Reta, N.; Michelmore, A.; Saint, C.; Prieto-Simón, B.; Voelcker, N. H., Porous Silicon Membrane-Modified Electrodes for Label-Free Voltammetric Detection of MS2 Bacteriophage. Biosens. Bioelectron. 2016, 80, 47–53. (224)
De la Escosura-Muñiz, A. d. l.; Espinoza-Castañeda, M.; Hasegawa, M.; Philippe, L.;
Merkoçi, A., Nanoparticles-based Nanochannels Assembled on a Plastic Flexible Substrate for LabelFree Immunosensing. Nano Res. 2014, 8, 1180–1188.
58 ACS Paragon Plus Environment
Page 59 of 59 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Applied Materials & Interfaces
Nanomaterial-modified electrodes for label-free sensing of water- and food-borne pathogens 218x143mm (96 x 96 DPI)
ACS Paragon Plus Environment