DNA-Mediated Nanoscale MetalâOrganic Frameworks for

Subscriber access provided by CAL STATE UNIV SAN FRANCISCO

Article

DNA-Mediated Nanoscale Metal-Organic Frameworks for Ultrasensitive Photoelectrochemical Enzyme-Free Immunoassay Guangyao Zhang, Dan Shan, HaiFeng Dong, Serge Cosnier, Khalid Abdullah Al-Ghanim, Zubair Ahmad, Shahid Mahboob, and Xueji Zhang Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.analchem.8b03762 • Publication Date (Web): 20 Sep 2018 Downloaded from http://pubs.acs.org on September 21, 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 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 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.

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 35 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

Analytical Chemistry

DNA-Mediated Nanoscale Metal− −Organic Frameworks for Ultrasensitive Photoelectrochemical Enzyme-Free Immunoassay

Guangyao Zhang,†,‡ Dan Shan,§ Haifeng Dong,†,‡ Serge Cosnier, ⊥ Khalid Abdullah Al-Ghanem,⸠ Zubair Ahmad,⸠ Shahid Mahboob,⸠,⸠ and Xueji Zhang*,†,‡ †

Beijing Advanced Innovation Center for Material Genome Engineering, ‡

Beijing Key Laboratory for Bioengineering and Sensing Technology, Research Center for Bioengineering and Sensing Technology, School of Chemistry and Biological Engineering,

University of Science and Technology Beijing, Beijing 100083, China §

School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China

⊥University

of Grenoble Alpes-CNRS, DCM UMR 5250, F-38000 Grenoble, France

⸠

Department of Zoology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia ⸠

Department of Zoology, Government College University, Faisalabad, Pakistan

*Corresponding Author *Email: [email protected]. Fax: +86-10-62332126 1

ACS Paragon Plus Environment

Analytical Chemistry 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

ABSTRACT: A novel enzyme-free photoelectrochemical (PEC) immunoassay was developed for the ultrasensitive detection of prostate specific antigen (PSA) based on the DNA-mediated nanoscale zirconium-porphyrin MOFs (NMOFs). By virtue of the intrinsic coordination between unsaturated zirconium sites of the NMOFs frameworks and phosphonate groups, the 5'-phosphorylared ss-DNA-tagged antibody (Ab-DNA) conjugate with a consecutive stretch of guanines as a spacer could be loaded on the NMOFs easily, obtaining a novel type of Ab-DNA-functionalized NMOFs complex. Additionally, as a photocathode PEC active nanomaterial, NMOFs exhibited a significant enhanced photocurrent response with the presence of dopamine under oxygen-containing aqueous media at −0.3 V (vs Ag/AgCl). Furthermore, with the aid of the electrochemical grafting of polyamidoamine (PAMAM) dendrimers functionalized interface, the novel type of Ab-DNA−NMOFs further served as PEC signal nanoprobe for the ultrasensitive PSA immunoassay. Under optimal conditions, the corresponding immunosensor possessed a wide calibration range of 1 pg mL−1 to 10 ng mL−1 and a limit of detection (LOD) of 0.2 pg mL−1. This present work demonstrated the promising application of DNA-mediated NMOFs in developing highly sensitive, environmentally friendly, and cost-effective PEC biosensors.

INTRODUCTION Photoelectrochemical (PEC) bioanalysis is a newly promising bio-analytical technique based on the photoinduced electron transfer (PET) processes among analyte, photoactive species, and electrode with photoirradiation.1-5 Up to the present, PEC bioanalysis has been widely applied to the detection of various biomolecules, including nucleic acid sequence, tumor marker, enzymatic activity, and cancer 2


Page 2 of 35

Page 3 of 35 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


cells.6-11 The increasing demands for PEC bioanalysis have greatly promoted the design synthesis of functionalized nanomaterials. To date, diverse functional nanomaterials,

such

carbon-nanomaterials,15

as

metal-based

hybrid

semiconductor

organic-inorganic

nanomaterials,12-14

nanostructures,16

and

complexes,17,18 have been employed as PEC sensing platforms to address various targets of interest. Among them, metal−organic frameworks (MOFs) have been attracting tremendous attention in the field of bioanalysis and biosensors because of their diverse structures and specific multifunctional sites, facilitating specific molecular recognition.19-22

MOFs are rapidly emerging as a class of modular crystalline, and porous materials formed by the self-assembled co-crystallization of metal ions and organic ligands. Owing to controllable synthesis, porosity and structural flexibility, these materials have achieved increasing applications in industrial catalysis,23 gas adsorption and purification,24 sustainable energy,25 biomedicine,26 and sensor system.27 The synthesis of biofunctionalized MOFs with specific molecular recognition capabilities is a prerequisite for bioanalytical applications. Especially, it has been well documented that oligonucleotide-functionalized MOFs particles could be employed for bioanalysis and biosensors.28,29 More recently, Mirkin and co-workers reported new strategies for preparing DNA-functionalized MOF nanoparticles using either covalent conjugation or terminal phosphate-modified oligonucleotides.30,31 These DNA-functionalized MOF nanoparticles have exhibited great promise for diverse applications including stimuli-responsive switch, photodynamic therapy, and drug delivery and controlled release.32-34 However, these covalent conjugation methods based on incorporating pendant reactive moieties (e.g., −NH2, −N3, −COOH) are usually expensive, 3



Page 4 of 35

time-consuming, and inefficient. Therefore, the coordination chemistry-based strategy for the surface functionalization of the external metal nodes of MOF nanoparticles with unmodified oligonucleotides is being widely concerned. For example, an intrinsic coordination-based method for preparing DNA−MOFs using unmodified oligonucleotides was developed for intracellular delivery of therapeutic nucleic acids by Fan and co-workers.35 Li and co-workers reported a simple coordination chemistry-based strategy for functional DNA-mediated surface engineering of porphyrin-based Zr6 nanoscale MOFs for targeted cancer imaging and specific immune activation.36 On the other hand, Bujoli and co-workers reported the ss-DNA probes containing a poly(dG) spacer effectively assembled on the zirconium phosphonate modified surfaces depending on the "zirconium-(OPO3-poly(dG) DNA)" coordination bonds.37-39 More recently, we introduced the idea of developing a simple and cost-effective

coordination

chemistry-based

strategy

for

preparing

DNA-functionalized magnetic zirconium hexacyanoferrate(II) nanoparticles (ZrHCF MNPs) for the ultrasensitive electrochemical DNA assay.40 Moreover, on the basis of the coordination binding zirconium to phosphate groups of biomolecules, we also reported that zirconium-porphyrin MOFs were successfully utilized to develop a novel electrochemiluminescence (ECL) protein kinase activity (PKA) biosensor and the label-free PEC sensing of a phosphoprotein.41,42 In this work, on the basis of the DNA-mediated nanoscale zirconium-porphyrin MOFs (NMOFs), we developed a novel enzyme-free PEC immunoassay for the ultrasensitive detection of prostate specific antigen (PSA) as a world-recognized biomarker

for

clinical

evaluation

of

prostatic

cancer.43

The

intrinsic

coordination-based method was utilized for preparing a novel type of functional 4


Page 5 of 35 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


DNA-mediated nanoscale zirconium-porphyrin MOFs (NMOFs). Significantly, we found that ss-DNA-tagged antibody (Ab-DNA) conjugate can be stably loaded on the NMOFs via coordination binding between the unsaturated zirconium sites on NMOFs and the phosphonate groups from the 5'-phosphorylared Ab-DNA with a consecutive stretch of guanines as a spacer, obtaining the Ab-DNA-functionalized NMOFs. As a proof-of-concept for PEC immunoassay, we construct the carboxyl-terminated polyamidoamine (PAMAM) dendrimers modified functional interface to load antibodies more effectively, as shown in Scheme 1, with the aid of the stable and excellent PEC properties of NMOFs, Ab-DNA−NMOFs were employed as an efficient PEC signal transduction platform for the ultrasensitive non-enzyme immunoassay

of

PSA.

It

is

hoped

that

the

functional

DNA-mediated

zirconium-porphyrin MOFs and MOF-based PEC bioanalysis strategies would have potential applications in ultrasensitive biosensing.

EXPERIMENTAL SECTION Materials and Reagents. Zirconium (IV) chloride octahydrate (ZrOCl2), Zirconium(IV)

chloride

N,N-dimethylformamide cyclohexane-1-carboxylate

(ZrCl4),

benzoic

(DMF),

acid,

dichloroacetic

acid,

sulfosuccinimidyl-4-(N-maleimidomethyl)

(sulfo-SMCC),

dithiothreitol

(DTT),

N-(2-Hydroxyethyl)piperazine-N'-(2-ethanesulfonic acid), sodium salt (HEPES), dopamine, N-(3-Dimethylaminopropyl)-N-ethyl-carbodiimide hydrochloride (EDC), N-hydroxysuccinimide (NHS), 3-aminopropyltriethoxysilane (APTES), bovine serum albumin

(BSA) and carboxyl-terminated PAMAM

(G4.5-COOH

PAMAM)

dendrimers was purchased from Sigma-Aldrich Chemical Co., Ltd. (Shanghai, China). Meso-tetra(4-carboxyphenyl)porphyrin (TCPP) was ordered from J&K Scientific Ltd. (Shanghai, China). Prostate specific antigen (PSA), mouse monoclonal anti-PSA 5



Page 6 of 35

antibodies (clone no. P27B1 as Ab1 and P27A10 as Ab2), Human serum albumin (HSA), and immunoglobulin (IgG) were purchased from Shuangliu Zhenglong Biochem Lab (Chengdu, China). TE buffer (10 mM Tris-HCl, containing 1 mM EDTA and 0.3 M NaCl, pH 7.9) was used for the preparation of oligonucleotide stock solutions. PBS1 (55 mM phosphate, containing 150 mM NaCl, 20 mM EDTA, pH 7.4) and PBS2 (55 mM phosphate, containing 150 mM NaCl, 5 mM EDTA, pH 7.4) were used

to

prepare

the

Ab-DNA

conjugate.

DNA

(5'-GGGGGGTTGCGCCAGAGTCCTAT-(CH2)6-SH-3') were obtained from Sangon Biotechnology Inc. (Shanghai, China). Potassium ferricyanide [K3Fe(CN)6], and potassium ferrocyanide [K4Fe(CN)6] were purchased from Sinopharm Chemical Reagent Co., Ltd. (Beijing, China). All other reagents were of analytical grade and were used without further purification. Ultrapure water obtained from a Millipore water purification system (≥18 MΩ, Milli−Q, Millipore) was used in all assays. 10 mM pH 7.4 HEPES containing 0.3 M KCl solution was employed as aqueous electrolyte solution for photoelectrochemical measurements. Apparatus. Transmission electron microscopy (TEM) analysis was carried out using a digital transmission electron microscope (Hitachi HT7700 Exalens, Japan). The surface morphology was examined by field emission scanning electron microscope (FESEM) (Supra 55 VP, Zeiss, Oberkochen, Germany). UV−vis absorption spectra were obtained using a UV-3600 UV−vis−NIR spectrophotometer (Shimadzu Co. Kyoto, Japan). The X-ray photoelectron spectroscopy (XPS) experiments were carried out on K-Alpha (Thermo Fisher Scientific Co., USA). The Gaussian-Lorentzian distribution was used for fitting the spectra for each peak, in order to determine the binding energy of the core levels of the different elements. Fourier-transformation infrared (FTIR) spectra were obtained with an IR-Prestige-21 FTIR spectrometer 6


Page 7 of 35 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


(Shimadzu Co., Japan). Powder X-ray diffraction patterns (PXRD) were recorded on a Bruker D8-Focus Bragg−Brentano X-ray Powder diffractometer equipped with a Cu sealed tube (λ= 1.54178 Å) at room temperature. Static water contact angle measurements were performed by the sessile drop technique using an Optical Tensionmeter (Theta Lite, Finland) under ambient laboratory conditions. A drop of distilled water was applied to the surface of bare and modified ITO glass plates, and the contact angle measurements were carried out within 30 s of the contact. Electrochemical impedance spectroscopy (EIS) measurements were carried out using an Autolab PGSTAT30 (Eco chemie, The Netherlands) controlled by NOVA 1.10 software. The EIS measurements were performed in 0.1 M KCl containing 5 mM Fe(CN)63−/4− (1:1). The amplitude of the applied sine wave potential was 5 mV. The impedance measurements were recorded at a bias potential of 290 mV within the frequency range of 0.1 Hz to 10 kHz. PEC measurements were performed on PEAC 200A (Tianjin AiDa Hengsheng Technology Co., Ltd., China) with a purple light source (375 nm, 10 mW cm−2) as the accessory light source. A CHI 660D electrochemical workstation (Shanghai Chenhua Instruments Co., China) was used for electrochemical measurements. All electrochemical and photoelectrochemical studies were performed with a conventional three electrode system. A modified indium tin oxide (ITO) electrode (1×0.5 cm) was used as working electrodes. An Ag/AgCl electrode and a Pt wire electrode were used as reference and counter electrodes, respectively. Synthesis of NMOFs. The nanoscale PCN-222/MOF-545 (NMOF) was synthesized based on a previous literature reported method with minor modifications.44 Typically, ZrOCl2 (37.5 mg, 0.116 mmol) and TCPP (6.5 mg, 0.008 mmol) were dissolved in DMF (16.25 mL) in a 22 mL borosilicate vial with a 7



Teflon-lined cap. Dichloroacetic acid (0.25 mL, 3.0 mmol) was added, and the resulting solution was heated at 130 ºC for 18 hours. After cooling down to room temperature, dark purple rod-shaped nanocrystals were harvested by centrifugation. Synthesis of microscale PCN-222/MOF-545. The microscale PCN-222/MOF-545 was prepared based on the previous report.45 Typically, ZrCl4 (75 mg, 0.322 mmol), TCPP (30 mg, 0.038 mmol), and benzoic acid (1750 mg) were dissolved in DMF (10 mL) of DMF in a 20 mL pyrex vial. The mixture was heated at 130 ºC for 18 hours. After cooling down to room temperature, purple needle shaped crystals were harvested by centrifugation. Preparation of Ab2-DNA conjugate. The Ab2-DNA conjugate was prepared by a modified coupling procedure.46 Briefly, anti-PSA antibody (2 mg mL−1) was first reacted with a 20-fold molar excess of SMCC in PBS1 for 2 h at room temperature. The obtained Ab2-SMCC was purified by ultrafiltration using a 100 KD Millipore (10 000 rpm, 10 min). In parallel, 12 µL of 100 µM thiolated DNA was reduced with 16

µL of 100 mM DTT in PBS1 at 37 ºC for 1 h. The reduced DNA was purified by ultrafiltration using a 10 KD Millipore (10 000 rpm, 10 min). Then, the resulting Ab2-SMCC and DNA were mixed in 200 µL of PBS2, incubated overnight at 4 ºC, and purified by ultrafiltration using a 100 KD Millipore (10 000 rpm, 10 min) for several times to remove the unreacted DNA. The obtained Ab2-DNA conjugate was collected at a concentration of 6.0 µM in PBS2, which was diluted with PBS2 at 100-fold prior to use. Preparation of Ab2-DNA− −NMOFs. The as-synthesized NMOFs were redispersed into 1 mL ultrapure water and incubated with 10 µM Ab2-DNA, and mixed solution 8


Page 8 of 35

Page 9 of 35 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


was vigorously shaken overnight. Afterward, 100 µL HEPES buffer (1 M, pH 7.4) and 50 µL NaCl solution (2 M) were slowly added to the mixture under stirring. After brief incubation, excess Ab2-DNA was removed by centrifugation and washing, and the obtained Ab2-DNA−NMOFs were dispersed in 1 mL of ultrapure water before its stepwise application. Fabrication of the PEC immunosensor. The fabrication procedure of the PEC immunoassay is illustrated in Scheme 1. Before modification, the ITO glass plate was washed with acetone, ethanol, and water in ultrasonic bath sequentially. Then ITO glass plate was immersed in a solution of 1:1 (v/v) ethanol/NaOH (1 M) for 15 min to active the surface. After rinsed with pure water and dried under N2 flow, the ITO glass plate was immersed in 2% APTES solution prepared in ethanol for 1.5 h to form a self-assembled monolayer (SAM) of APTES. The glass plate was then rinsed with ethanol in order to remove excess APTES and dried under N2 flow, obtained the APTES modified ITO electrode (ITO/APTES).47 Then, according to the previous reported method about modification of ITO electrode with PAMAM dendrimers,48,49 the modified electrode was placed in an aqueous 0.1 M LiClO4 solution containing 10

µM PAMAM and potential sweep in the range of 1.20~1.75 V (vs Ag/AgCl) was performed at a scan rate of 10 mV s−1 for three cycles. After the electro-oxidative grafting of PAMAM, the modified ITO was rinsed with pure water and dried under N2 flow, obtained ITO/APTES/PAMAM modified electrode. The carboxyl groups of ITO/APTES/PAMAM were activated by immersion in an aqueous solution containing 20 mg mL−1 EDC and 10 mg mL−1 NHS for 1 h at room temperature, followed by 9



thoroughly rinsing with washing buffer to wash off the excess EDC and NHS. Next, 30 µL of 0.1 mg mL−1 Ab1 was pipetted onto the resulting electrode for 16 h at 4 ºC. After rinsed with the washing buffer to remove physically adsorbed Ab1, the resulting Ab1 modified electrode (ITO/APTES/PAMAM/Ab1) was blocked with 1.0 wt.% BSA for 2 h at 4 ºC, and washed with the washing buffer thoroughly to obtain ITO/APTES/PAMAM/Ab1/BSA. Then, 30 µL of PSA with different concentrations was casted onto the electrode for an incubation at 37 ºC for 1 h followed by washing with washing buffer. Subsequently, the as-prepared immunosensor was incubated with 30 µL of Ab2-DNA−NMOFs at 37 ºC for 90 min. After rinsing, the assembled electrode would generate PEC signal in the aqueous solution containing 1 mM dopamine at −0.3 V (vs Ag/AgCl) and gave the quantitative criteria for the proposed immunosensor.

RESULTS AND DISCUSSION Characterization of the NMOFs and Ab2-DNA− −NMOFs. PCN-222/MOF-545, a porphyrinic Zr6 MOF, was chosen as a model system. The advantages of this approach can be proved through its excellent stability, outstanding biocompatibility and noticeable optical properties.50 If the size of MOF crystal is scaled down to nanoscale, the formed nanomaterials can be employed as ideal platform for bioanalysis and biosensors. Nanoscale PCN-222/MOF-525 (NMOF) was synthesized based on a reported bottom-up approach method with minor modifications.44 The morphology of the as-synthesized NMOFs was observed by TEM (Figure 1A) and SEM (Figure S1). The observed morphology is uniform, and exists as rod-shaped size distribution with 10


Page 10 of 35

Page 11 of 35 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


mean sizes of ≈100 nm in length and a width of about 20 nm. The main diffraction peaks of NMOFs appeared at 2.4º, 4.8º, 7.1º, and 9.8º in the powder X-ray diffraction (PXRD) pattern (Figure S2), which are consistent with the simulated XRD pattern of PCN-222 reported previously.44,45 Meanwhile, NMOFs was compared with the TCPP ligand by FTIR spectra (Figure S3), and the positions of the peaks matched with the TCPP ligand, indicated that all the TCPP units were assembled successfully in the NMOFs. Then, we prepared the Ab2-DNA−NMOFs by employing 5′-polyG terminal DNA modified Ab2 based on the coordination of its phosphate groups with the unsaturated zirconium sites on the surface of NMOFs. TEM image of the Ab2-DNA−NMOFs shows that they remain monodisperse in size and a width of about 27 nm without obvious shape change and aggregation (Figure 1B). This 7 nm increase in width is consistent with the addition of Ab2-DNA conjugate loading onto the NMOFs. In addition, the coordination between the NMOFs and Ab2-DNA conjugate was investigated by the XPS survey scans (Figure S4). In addition to the peaks of C, N, O, and Zr elements shown, the P2p peak at 132.5 eV was observed in the spectrum of Ab2-DNA−NMOFs (Figure S4A,B), attributing to the phosphate groups of Ab2-DNA conjugate. Meanwhile, the coordination is mainly derived from the unsaturated zirconium sites of the NMOFs and phosphate groups of the 5′-polyG terminal DNA modified Ab2. High resolution Zr3d spectra were also recorded to observe the difference between the NMOFs and Ab2-DNA−NMOFs (Figure 1C,D). The Zr3d spectrum exhibits two main peaks at 181 and 183.3 eV (Figure 1C) for the NMOFs. After the Ab2-DNA conjugate was immobilized, a slight peak shift to higher binding energy was observed for the Zr3d peaks (Figure 1D). Two other components centered at 181.7 and 184.1 eV are obtained, attributed to the decomposition of Zr−O−P from 11



Page 12 of 35

the coordination of the NMOFs and Ab2-DNA conjugate. Moreover, the UV-visible absorption spectrum of NMOFs and Ab2-DNA−NMOFs was shown in Figure 1E. A Soret band at 421 nm tailing with four Q bands located at 523, 561, 593, 650 nm were observed in the UV-visible absorption spectrum of NMOFs (Figure 1E, curve a), corresponding to the TCPP ligands assembled on the frameworks.51 After the Ab2-DNA conjugate was coordinated joint on the surface of NMOFs, in comparison with

NMOFs,

the

UV-visible

absorption

spectrum

of

Ab2-DNA−NMOFs

simultaneously showed the characteristic absorption peaks of TCPP ligands and a absorption peak located at 276 nm (Figure 1E, curve b), which was derived from the characteristic absorption peak of Ab2-DNA conjugate (Figure S5).52 These results suggest that Ab2-DNA conjugate can be assembled on the surface of NMOFs through "zirconium−(OPO3-poly(dG) DNA)" coordination bonds to maintain Ab2-DNA terminal-oriented on the surface of NMOFs (Figure 1F). Consequently, this novel type of Ab-DNA-functionalized NMOFs complex, that is, Ab-DNA−NMOFs, can be simply obtained through the simple and cost-effective coordination chemistry-based method. Furthermore, this strategy has no effect on the activity of biomolecules and the properties of the NMOFs, and is expected to further achieve bioanalysis and biosensing applications.

PEC Investigations. In our previous work, zirconium-porphyrin MOFs (MOF-525 and PCN-222) have exhibited excellent electrochemiluminescence (ECL) and PEC properties in the aqueous solutions.40,41 Hereon, NMOFs are very likely to possess excellent PEC activity for bioanalysis and biosensors. Then, we studied the PEC behavior of NMOFs with the presence of dissolved oxygen and dopamine. As shown in Figure 2A, after deoxygenation with N2 for 20 12


Page 13 of 35 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


min, a slight and insignificant photocurrent response was observed (Figure 2A, curve a). The cathodic photocurrent increased in the O2-containing atmosphere (Figure 2A, curve b), indicating that the dissolved oxygen molecule serves as electron acceptor in this PEC system. With the presence of dopamine, the photocurrent response increased obviously (Figure 2A, curve c), demonstrating that dopamine serves as the suitable electron donor,53 which greatly promotes the generation of photocurrent. Meanwhile, we made a comparison of the PEC responses of microscale PCN-222/MOF-545 and NMOFs. Under the identical test conditions, the cathodic photocurrent intensity of NMOFs is around two times higher than that of microscale PCN-222/MOF-545 (Figure S6). It reveals that when the size of PCN-222/MOF-545 crystal is scaled down to nanoscale, the TCPP active sites on the frameworks can be more easily interacted with the dissolved oxygen and dopamine, resulting in a stronger photocurrent response. According to the mechanism of cathodic photocurrent generation of PCN-222 we have previously reported,42 specifically, as illustrated in Figure 2B, TCPP ligands on the NMOFs frameworks are excited under light irradiation, electron transfer takes place, and generate the electron−hole pairs, while make the enriched dissolved oxygen in the nanocage to be reduced to O2•−. When dopamine, an electron donor, is introduced into the system, it is oxidized by NMOFs and scavenges the holes, leading to more electrons occupied on the conduction-band of NMOFs because of its energy level (−4.91 eV) between the conduction-band and valence-band of NMOFs. Meanwhile, this process makes the transfer of more electrons from the conduction-band of NMOFs to dissolved oxygen, resulting in a stronger photocurrent signal. In other words, dopamine effectively inhibits the recombination of electron−hole pairs, and promote the process of electron transfer, so that an enhanced 13



cathodic photocurrent generates. Furthermore, it is worth noting that the applied bias potential has a paramount influence on the PEC system. Figure 2C depicted the cathodic photocurrent responses on ITO/NMOFs in the different applied bias potential. As the potential is negatively shifted, the cathodic photocurrent gradually increases. Meanwhile, according to our statistical data curve (Figure 2D), starting from −0.3 V (vs Ag/AgCl), the background current is increasing and the cathodic photocurrent response is not stable (Figure 2D, curve a), attributing to the stronger cathodic electrochemical reduction. In contrast, upon biasing the electrode at E = −0.3 V, ITO/NMOFs exhibited a lower background current, and the strongest and the relatively stable cathodic photocurrent response. It indicates that dopamine molecule in electron donating state is oxidized by NMOFs and scavenges the valence-band holes, and the concomitant transfer of the conduction-band electrons to the oxygen molecule electron acceptor, then the oxidized dopamine can be electrochemically reduced to the surface of the electrode at E = −0.3 V, thus providing electrons to the PEC system continuously, resulting in the enhanced and steady-state cathodic photocurrent observed. Therefore, all the photocurrent responses were collected at E = −0.3 V (vs Ag/AgCl) in the follow-up immunoassay tests.

Construction of PEC Immunosensor. The self-assembled process of the proposed immunosensor was further investigated by contact angle (CA) measurement and EIS. Figure 3A displays the CA images of the different modified ITO. Clearly, the CA of hydroxyl functionalized ITO was measured to be 38º analogous to a hydrophilic surface (Figure 3A, image a). A significant increase in CA, 63º for the APTES modified ITO was found due to hydrophobic alkyl chains of APTES 14


Page 14 of 35

Page 15 of 35 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


molecules present on it (Figure 3A, image b). Subsequently, the PAMAM dendrimers were assembled through the electrochemical cyclic voltammetric scanning reaction, and the anodic currents diminished in the subsequent scans (Figure S7), which are consistent with the electrochemical grafting of dendrimers reported previously.48 This observation suggested the electrochemical oxidation of dendrimers followed by the formation of PAMAM film on the APTES modified ITO surface. As a result, the hydrophobic behavior altered to hydrophilic after loading the PAMAM containing a large number of hydrophilic groups of carboxyl groups, and the CA was reduced to 40º (Figure 3A, image c). However, upon immobilization of hydrophobic protein antibody (Ab1) on ITO/APTES/PAMAM through dehydration condensation reaction, the CA significantly increased to 71º (Figure 3A, image d), demonstrating that the electrochemical grafting of carboxyl-terminated dendrimers functionalized interface is more conducive to antibody loading. This means that the self-assembled functionalized immune-sensing interface can be successfully constructed. Meanwhile, EIS was applied to characterize the self-assembled process of the proposed immunosensor by using Fe(CN)64−/3− as a sensitive redox probe. Figure 3B represents the Nyquist diagram of the electrodes prepared at various stages of surface modification. The diameter of the semicircle in the impedance spectra represents the charge transfer resistance (Rct), related to the difficulty of electron transfer of a ferricyanide-redox probe between the solution and the electrode. As shown in Figure 3B, when APTES was modified onto the surface of ITO, the Rct decreased (Figure 3B, curve b), indicating easy electronic transport at the electrode solution interface. Afterwards, with the electrochemical interaction between ITO/APTES modified electrode and the PAMAM dendrimers, the value of Rct increased significantly (Figure 3B, curve c), suggesting that the dendrimer was immobilized on the surface of 15



electrode. When the Ab1 was loaded on the electrode surface, the Rct value further increased (Figure 3B, curve d). After being blocked with BSA, the Rct value further increased again (Figure 3B, curve e). Then, the Rct value further increased after the immunological recognition (Figure 3B, curve f). In contract, the subsequent immobilization of Ab2-DNA−NMOFs, induces a marked decrease of the Rct value. Meanwhile, as shown in inset of Figure 3B, the Rct value decreased significantly after modified NMOFs (inset of Figure 3B, curve h), demonstrating that NMOFs can significantly improve the electron transfer capacity of the modified electrode. It can be confirmed that the electron transfer resistance changed consistently with sequential assembly fabrication of the PEC immunosensor for PSA assay.

Optimization of Detection Conditions. In order to achieve the excellent PEC detection signals for the immunosensor, the incubation time was an important parameter affecting the analytical performance of the PEC immunosensor. As shown in Figure S8A, with the increasing incubation time of Ab1 and PSA, the cathodic photocurrent greatly increased and achieved a plateau after 60 min, indicating the immune recognition reaction nearly reached the maximum. Therefore, 60 min was sufficient and selected as the optimal incubation time. In addition, the effect of incubation time of PSA and Ab2-DNA−NMOFs on the cathodic photocurrent responses was evaluated (Figure S8B). When the incubation time was more than 90 min, no obvious cathodic photocurrent increase was observed. Thus, 90 min was employed for the optimal incubation time.

PEC Immunoassay Performance. Figure 4A showed the PEC responses of the proposed immunosensor measured at various concentrations of PSA under the optimal 16


Page 16 of 35

Page 17 of 35 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


experimental conditions. It is seen that the PEC signal increases with the increasing concentrations of PSA. And the resulting calibration curve is illustrated in Figure 4B. The photocurrent was proportional to the logarithm value of the PSA concentration in a range of 1 pg mL−1 to 10 ng mL−1. The linear relationship can be represented as Ipc (nA) = −161.25 − 12.53 log C (g mL−1) with a correlation coefficient of 0.997. The limit of detection (LOD) was estimated to be 0.2 pg mL−1 (signal-to-noise ratio of 3), which is comparable to or lower than some previous reports (Table S1). Meanwhile, the selectivity of proposed immunosensor was evaluated by comparing the cathodic photocurrent changes to some typical interfering proteins, such as human serum albumin (HSA) and immunoglobulin (IgG) (Figure S9). It can be observed that the cathodic photocurrent responses of HSA and IgG are very close to the blank test. These results indicate the immunosensor has excellent selectivity for PSA. Moreover, stable PEC response was observed when the biosensor was tested through 12 repeated ON/OFF illumination cycles (Figure S10). And the photocurrent responses of the immunosensor still remained stable after storage at 4 ºC for two weeks, demonstrating satisfactory reproducibility and stability. Overall, this good analytical performance should be attributed to the dendrimers functionalized sensing interface and the excellent PEC activity of DNA-media NMOFs nanoprobe. The wide detection range, high sensitivity, good selectivity, acceptable reproducibility, and satisfactory stability of this PEC immunoassay indicate its great potential in point-of-care testing.

Application in Real Sample Analysis. To evaluate the feasibility of the present immunosensor’s application in real sample analysis, recovery experiments were performed by adding 10 pg mL−1 PSA solution into 10% (v/v) diluted healthy human 17



Page 18 of 35

serum samples; the recovery was 96% and the corresponding relative error was calculated to be 8.7%, suggesting great accuracy and reliability of the proposed PEC immunosensor for the detection of real samples.

CONCLUTIONS In

summary,

this

work

presented

a

novel

DNA-mediated

nanoscale

zirconium-porphyrin MOFs, NMOFs as tracing tag for the accurate and sensitive enzyme-free PEC immunoassay of PSA as model analyte. Specifically, on the basis of coordination between zirconium centers of the NMOFs and phosphonate groups from the 5′-poly(dG) terminal of Ab2-DNA, the Ab2-DNA−NMOFs can be easily obtained. Meanwhile, the NMOFs exhibit relatively stable and excellent PEC response toward dopamine under oxygen-containing aqueous media at −0.3 V (vs Ag/AgCl). In addition, the electrochemical grafting of carboxyl-terminated PAMAM dendrimers functionalized interface is more conducive to antibody loading. Taking full use of these advantages, we have demonstrated the DNA-mediated NMOFs serving as signal nanoprobe for an ultrasensitive PEC immunoassay. Therefore, the coordination chemistry-based strategy for obtaining DNA-mediated NMOFs not only extends the properties and applications of nanoscale zirconium-porphyrin MOFs, but also provides a new promising platform for bioanalysis and biosensing.

ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website at DOI: 18


Page 19 of 35 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


SEM, XRD, FTIR spectrum, XPS, UV-visible absorption spectrum, comparison of photocurrent responses between microscale PCN-222 and NMOFs, CVs, optimization of incubation time, selectivity and stability of the PEC immunosensor, and Table S1. (PDF)

AUTHOR INFORMATION Corresponding Author *Email: [email protected]. Fax: +86-10-62332126 ORCID Guangyao Zhang: 0000-0002-7159-5166 Xueji Zhang: 0000-0002-0035-3821 Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT

This research was supported by Special Foundation for State Major Research Program of China (Grant Nos. 2016YFC0106602 and 2016YFC0106601), National Natural Science Foundation of China (Grant No. 21727815) to XZ and China Postdoctoral Science Foundation (Grant No. 2018M630067) to GZ. The authors (KAA and SM) would like to express their sincere appreciation to the Deanship of Scientific Research at King Saud University for its funding of this research through the Research Group Project No. RGP-1435-012. 19



Page 20 of 35

REFERENCES (1) Willner, I.; Patolsky, F.;Wasserman, J. Photoelectrochemistry with Controlled DNA‐Cross‐Linked CdS nanoparticle arrays. Angew. Chem., Int. Ed. 2001, 40, 1861−1864. (2) Zhao, W.-W.; Xu, J.-J.; Chen, H.-Y. Photoelectrochemical Bioanalysis: The State of the Art. Chem. Soc. Rev. 2015, 44, 729−741. (3) Zhao, W.-W.; Xu, J.-J.; Chen, H.-Y. Photoelectrochemical DNA Biosensors. Chem. Rev. 2014, 114, 7421−7441. (4) Zhao, W.-W.; Xu, J.-J.; Chen, H.-Y. Photoelectrochemical Immunoassays. Anal. Chem. 2018, 90, 615−627. (5) Zhou, H.; Liu, J.; Zhang, S. Quantum Dot-Based Photoelectric Conversion for Biosensing Applications. TrAC, Trends Anal. Chem. 2015, 67, 56−73. (6) Ye, C.; Wang, M. Q.; Luo, H. Q.; Li, N. B. Label-Free Photoelectrochemical “Off– On” Platform Coupled with G-Wire-Enhanced Strategy for Highly Sensitive MicroRNA Sensing in Cancer Cells. Anal. Chem. 2017, 89, 11697−11702. (7) Li, C.; Wang, H.; Shen, J; Tang, B. Cyclometalated Iridium Complex-Based Label-Free Photoelectrochemical Biosensor for DNA Detection by Hybridization Chain Reaction Amplification. Anal. Chem. 2015, 87, 4283−4291. (8) Zeng, X.; Ma, S.; Bao, J.; Tu, W.; Dai, Z. Using Graphene-Based Plasmonic Nanocomposites

to

Quench

Energy

from

Quantum

Dots

for

Photoelectrochemical Aptasensing. Anal. Chem. 2013, 85, 11720−11724. 20


Signal-On

Page 21 of 35 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


(9) Yu, X.; Wang, Y.; Chen, X.; Wu, K.; Chen, D.; Ma, M.; Huang, Z.; Wu, W.; Li, C. White-Light-Exciting, Dots/Polymerized

Layer-by-Layer-Assembled

Ionic

Liquid

Hybrid

Film

ZnCdHgSe

Quantum

for

Sensitive

Highly

Photoelectrochemical Immunosensing of Neuron Specific Enolase. Anal. Chem. 2015, 87, 4237−4244. (10) Zhang, N.; Ruan, Y.-F.; Zhang, L.-B.; Zhao, W.-W.; Xu, J.-J.; Chen, H.-Y. Nanochannels Photoelectrochemical Biosensor. Anal. Chem. 2018, 90, 2341−2347. (11) Wang, K.; Zhang, R.; Sun, N.; Li, X.; Wang, J.; Cao, Y.; Pei, R. Near-Infrared Light-Driven Photoelectrochemical Aptasensor Based on the Upconversion Nanoparticles and TiO2/CdTe Heterostructure for Detection of Cancer Cells. ACS Appl. Mater. Interfaces 2016, 8, 25834−25839. (12) Gill, G.; Zayats, M. Willner, I. Semiconductor Quantum Dots for Bioanalysis. Angew. Chem., Int. Ed. 2008, 47, 7602−7625. (13)

Golub,

E.;

Niazov,

A.;

Freeman,

R.;

Zatsepin,

M.;

Willner,

I.

Photoelectrochemical Biosensors Without External Irradiation: Probing Enzyme Activities

and

DNA

Sensing

Using

Hemin/G-Quadruplex-Stimulated

Chemiluminescence Resonance Energy Transfer (CRET) Generation of Photocurrents. J. Phys. Chem. C 2012, 116, 13827−13834. (14) Han, Q.; Wang, R.; Xing, B.; Chi, H.; Wu, D.; Wei, Q. Label-Free Photoelectrochemical Aptasensor for Tetracycline Detection Based on Cerium Doped CdS Sensitized BiYWO6. Biosens. Bioelectron. 2018, 106, 7−13. (15) Hu, C.; Zheng, J.; Su, X.; Wang, J.; Wu, W.; Hu, S. Ultrasensitive All-Carbon 21



Page 22 of 35

Photoelectrochemical Bioprobes for Zeptomole Immunosensing of Tumor Markers by an Inexpensive Visible Laser Light. Anal. Chem. 2013, 85, 10612−10619. (16) Bellani, S.; Ghadirzadeh, A.; Meda, L.; Savoini, A.; Tacca, A.; Marra, G.; Meira, R.; Morgado, J.; Fonzo, F. D.; Antognazza, M. R. Hybrid Organic/Inorganic Nanostructures for Highly Sensitive Photoelectrochemical Detection of Dissolved Oxygen in Aqueous Media. Adv. Funct. Mater. 2015, 25, 4531−4538. (17) Tang, J.; Zhang, Y.; Kong, B.; Wang, Y.; Da, P.; Li, J.; Elzatahry, A. A.; Zhao, D.; Gong,

X.;

Zheng,

G.

Solar-Driven

Photoelectrochemical

Probing

of

Nanodot/Nanowire/Cell Interface. Nano Lett. 2014, 14, 2702−2708. (18) Hao, N.; Zhang, Y.; Zhong, H.; Zhou, Z.; Hua, R.; Qian, J.; Liu, Q.; Li, H.; Wang, K. Design of a Dual Channel Self-Reference Photoelectrochemical Biosensor. Anal. Chem. 2017, 89, 10133−10136. (19) Wilmer, C. E.; Leaf, M.; Lee, C. Y.; Farha, O. K.; Hauser, B. G.; Hupp, J. T.; Snurr, R. Q. Large-Scale Screening of Hypothetical Metal–Organic Frameworks. Nat. Chem. 2011, 4, 83−89. (20) Millward, A. R.; Yaghi, O. M. Metal−Organic Frameworks with Exceptionally High Capacity for Storage of Carbon Dioxide at Room Temperature. J. Am. Chem. Soc. 2005, 127, 17998−17999. (21) Foo, M. L.; Matsuda, R.; Kitagawa, S. Functional Hybrid Porous Coordination Polymers. Chem. Mater. 2014, 26, 310−322. (22) Furukawa, S.; Reboul, J.; Diring, S.; Sumida, K.; Kitagawa, S. Structuring of Metal–Organic Frameworks at the Mesoscopic/Macroscopic Scale. Chem. Soc. Rev. 22


Page 23 of 35 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


2014, 43, 5700−5734. (23) Corma, A.; García, H.; Llabrés i Xamena, F. X. Engineering Metal Organic Frameworks for Heterogeneous Catalysis. Chem. Rev. 2010, 110, 4606−4655. (24) Suh, M. P.; Park, H. J.; Prasad, T. K.; Lim, D.-W. Hydrogen Storage in Metal– Organic Frameworks. Chem. Rev. 2012, 112, 782−835. (25) Sheberla, D.; Bachman, J. C.; Elias, J. S.; Sun, C.-J.; Shao-Horn, Y.; Dincă, M. Conductive MOF Electrodes for Stable Supercapacitors with High Areal Capacitance. Nat. Mater. 2016, 16, 220−224. (26) Horcajada, P.; Gref, R.; Baati, T.; Allan, P. K.; Maurin, G.; Couvreur, P.; Férey, G.; Morris, R. E.; Serre, C. Metal–Organic Frameworks in Biomedicine. Chem. Rev. 2012, 112, 1232−1268. (27) Kreno, L. E.; Leong, K.; Farha, O. K.; Allendorf, M.; Van Duyne, R. P.; Hupp, J. T. Metal–Organic Framework Materials as Chemical Sensors. Chem. Rev. 2012, 112, 1105−1125. (28) Xie, S.; Ye, J.; Yuan, Y. Chai, Y.; Yuan, R. A Multifunctional Hemin@Metal– Organic Framework and Its Application to Construct an Electrochemical Aptasensor for Thrombin Detection. Nanoscale 2015, 7, 18232−18238. (29) Cui, L.; Wu, J.; Li, J.; Ju, H. Electrochemical Sensor for Lead Cation Sensitized with a DNA Functionalized Porphyrinic Metal–Organic Framework. Anal. Chem. 2015, 87, 10635−10641. (30) Morris, W.; Briley, W. E.; Auyeung, E.; Cabezas, M. D.; Mirkin, C. A. Nucleic Acid–Metal Organic Framework (MOF) Nanoparticle Conjugates. J. Am. Chem. Soc. 23



Page 24 of 35

2014, 136, 7261−7264. (31) Wang, S.; McGuirk, C. M.; Ross, M. B.; Wang, S.; Chen, P.; Xing, H.; Liu, Y.; Mirkin,

C.

A.

General

and

Direct

Method

for

Preparing

Oligonucleotide-Functionalized Metal–Organic Framework Nanoparticles. J. Am. Chem. Soc. 2017, 139, 9827−9830. (32) Kahn, J. S.; Freage, L.; Enkin, N.; Garcia, M. A. A.; Willner, I. Stimuli‐ Responsive DNA‐Functionalized Metal–Organic Frameworks (MOFs). Adv. Mater. 2017, 29, 1602782. (33) He, L. C.; Brasino, M.; Mao, C. C.; Cho, S.; Park, W.; Goodwin, A. P.; Cha, J. N. DNA‐Assembled

Core‐Satellite

Upconverting‐Metal–Organic

Framework

Nanoparticle Superstructures for Efficient Photodynamic Therapy. Small 2017, 13, 1700504. (34) Chen, W.-H.; Yu, X.; Liao, W.-C.; Sohn, Y. S.; Cecconello, A.; Kozell, A.; Nechushtai, R.; Willner, I. ATP‐Responsive Aptamer‐Based Metal–Organic Framework Nanoparticles (NMOFs) for the Controlled Release of Loads and Drugs. Adv. Funct. Mater. 2017, 27, 1702102. (35) Wang, Z.; Fu, Y.; Kang, Z.; Liu, X.; Chen, N.; Wang, Q.; Tu, Y.; Wang, L.; Song, S.; Ling, D.; Song, H.; Kong, X.; Fan, C. Organelle-Specific Triggered Release of Immunostimulatory Oligonucleotides from Intrinsically Coordinated DNA–Metal– Organic Frameworks with Soluble Exoskeleton. J. Am. Chem. Soc. 2017, 139, 15784−15791. (36) Ning, W.; Di, Z.; Yu, Y.; Zeng, P.; Di, C.; Chen, D.; Kong, X.; Nie, G.; Zhao, Y.; 24


Page 25 of 35 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


Li,

L. Imparting

Designer Biorecognition Functionality to Metal–Organic

Frameworks by a DNA‐Mediated Surface Engineering Strategy. Small 2018, 14, 1703812. (37) Nonglaton, G.; Benitez, I. O.; Guisle, I.; Pipelier, M.; Leger, J.; Dubreuil, D.; Tellier, C.; Talham, D. R.; Bujoli, B. New Approach to Oligonucleotide Microarrays Using Zirconium Phosphonate-Modified Surfaces. J. Am. Chem. Soc. 2004, 126, 1497−1502. (38) Monot, J.; Petit, M.; Lane, S. M.; Guisle, I.; Leger, J.; Tellier, C.; Talham, D. R.; Bujoli, B. Towards Zirconium Phosphonate-Based Microarrays for Probing DNA−Protein Interactions: Critical Influence of the Location of the Probe Anchoring Groups. J. Am. Chem. Soc. 2008, 130, 6243−6251. (39) Lane, S. M.; Monot, J.; Petit, M.; Tellier, C.; Bujoli, B.; Talham, D. R. Poly(dG) Spacers Lead to Increased Surface Coverage of DNA Probes: An XPS Study of Oligonucleotide Binding to Zirconium Phosphonate Modified Surfaces. Langmuir 2008, 24, 7394−7399. (40) Zhang, G.-Y.; Deng, S.-Y.; Cai, W.-R.; Cosnier, S.; Zhang, X.-J.; Shan, D. Magnetic Zirconium Hexacyanoferrate(II) Nanoparticle as Tracing Tag for Electrochemical DNA Assay. Anal. Chem. 2015, 87, 9093−9100. (41) Zhang, G.-Y.; Cai, C.; Cosnier, S.; Zeng, H.-B.; Zhang, X.-J.; Shan, D. Zirconium–Metalloporphyrin Frameworks as a Three-in-One Platform Possessing Oxygen Nanocage, Electron Media, and Bonding Site for Electrochemiluminescence Protein Kinase Activity Assay. Nanoscale 2016, 8, 11649−11657. 25



Page 26 of 35

(42) Zhang, G.-Y.; Zhuang, Y.-H.; Shan, D.; Su, G.-F.; Cosnier, S.; Zhang, X.-J. Zirconium-Based Porphyrinic Metal–Organic Framework (PCN-222): Enhanced Photoelectrochemical Response and Its Application for Label-Free Phosphoprotein Detection. Anal. Chem. 2016, 88, 11207−11212. (43) Yang, L.; Li, Y.; Zhang, Y.; Fan, D.; Pang, X.; Wei, Q.; Du, B. 3D Nanostructured Palladium-Functionalized Graphene-Aerogel-Supported Fe3O4 for Enhanced Ru(bpy)32+-Based Electrochemiluminescent Immunosensing of Prostate Specific Antigen. ACS Appl. Mater. Interfaces 2017, 9, 35260−35267. (44) Kelty, M. L. Morris, W.; Gallagher, A. T.; Anderson, J. S.; Brown, K. A.; Mirkin, C. A.; Harris, T. D. High-Throughput Synthesis and Characterization of Nanocrystalline Porphyrinic Zirconium Metal–Organic Frameworks. Chem. Commun. 2016, 52, 7854−7857. (45) Feng, D.; Gu, Z.-Y.; Li, J.-R.; Jiang, H.-L.; Wei, Z.; Zhou, H.-C. Zirconium‐ Metalloporphyrin

PCN‐222:

Mesoporous

Metal–Organic

Frameworks

with

Ultrahigh Stability as Biomimetic Catalysts. Angew. Chem., Int. Ed. 2012, 51, 10307−10310. (46) Söderberg, O.; Gullberg, M.; Jarvius, M.; Ridderstråle, K.; Leuchowius, K.-J.; Jarvius, J.; Wester, K.; Hydbring, P.; Bahram, F.; Larsson, L.-G.; Landegren, U. Direct Observation of Individual Endogenous Protein Complexes in situ by Proximity Ligation. Nat. Methods 2006, 3, 995−1000. (47) Ren, X.; Yan, J.; Wu, D.; Wei, Q.; Wan, Y. Nanobody-Based Apolipoprotein E Immunosensor for Point-of-Care Testing. ACS Sens. 2017, 2, 1267−1271. 26


Page 27 of 35 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


(48) Lee, S. B.; Ju, Y.; Kim, Y.; Koo, C. M.; Kim, J. Electrooxidative Grafting of Amine-Terminated Dendrimers Encapsulating Nanoparticles for Spatially Controlled Surface Functionalization of Indium Tin Oxide. Chem. Commun. 2013, 49, 8913−8915. (49)

Kim,

Y.;

Kim,

Dendrimer-Encapsulated

J.

Modification

Nanoparticles

To

of

Indium Provide

Tin

Oxide

Enhanced

with Stable

Electrochemiluminescence of Ru(bpy)32+/Tripropylamine While Preserving Optical Transparency of Indium Tin Oxide for Sensitive Electrochemiluminescence-Based Analyses. Anal. Chem. 2014, 86, 1654−1660. (50) Bai, Y.; Dou, Y.; Xie, L.-H.; Rutledge, W.; Li, J.-R.; Zhou, H.-C. Zr-Based Metal–Organic Frameworks: Design, Synthesis, Structure, and Applications. Chem. Soc. Rev. 2016, 45, 2327−2367. (51) Rochford, J.; Chu, D.; Hagfeldt, A.; Galoppini, E. Tetrachelate Porphyrin Chromophores for Metal Oxide Semiconductor Sensitization: Effect of the Spacer Length and Anchoring Group Position. J. Am. Chem. Soc. 2007, 129, 4655−4665. (52) Zhou, Z.; Xiang, Y.; Tong, A.; Lu, Y. Simple and Efficient Method to Purify DNA–Protein Conjugates and Its Sensing Applications. Anal. Chem. 2014, 86, 3869−3875. (53) Ma, H.; Zhao, Y.; Liu, Y.; Zhang, Y.; Wu, D.; Li, H.; Wei, Q. A Compatible Sensitivity Enhancement Strategy for Electrochemiluminescence Immunosensors Based on the Biomimetic Melanin-Like Deposition. Anal. Chem. 2017, 89, 13049−13053. 27



28


Page 28 of 35

Page 29 of 35 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


Scheme 1

Scheme 1 Schematic Illustration of the DNA-Mediated NMOFs-based PEC Immunosensor for PSA Assay.

29



Figure 1

Figure 1 TEM images of NMOFs (A) and Ab2-DNA−NMOFs (B), Inset: Enlarged morphology. The high-resolution XPS response of Zr3d core energy levels for NMOFs (C) and Ab2-DNA−NMOFs (D). (E) UV-visible spectra of NMOFs (a) and 30


Page 30 of 35

Page 31 of 35 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


Ab2-DNA−NMOFs (b). (F) Illustration of the coordination between 5′-poly(dG) spacer terminal of DNA-Ab2 and NMOFs surface. Figure 2

Figure 2 (A) Cathodic photocurrent responses of ITO/NMOFs after deoxygenation with N2 for 20 min (a), 0 min (b), and 0 min + 1 mM dopamine (c) in 0.1 M pH 7.4 HEPES buffer solution at E = −0.3 V (vs Ag/AgCl). (B) Schematic representation of cathodic photocurrent generation based on ITO/NMOFs, CB: conduction-band; VB: valence-band. (C) Cathodic photocurrent responses of ITO/NMOFs in the different applied bias potential (0, −0.1, −0.2, −0.3, and −0.4 V, from curves a to e) in 0.1 M pH 31



7.4 HEPES buffer solution with the presence of 1 mM dopamine. (D) Effect of applied bias potential on the cathodic photocurrent responses (curve a: OFF, curve b: ON). Inset B: Effect of applied bias potential on the difference value of cathodic photocurrent responses before and after the light source switch. Error bars, SD, n = 3.

32


Page 32 of 35

Page 33 of 35 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


Figure 3

Figure 3 (A) Contact angle measurement images and (B) EIS for each immobilized step in 0.1 M KCl solution containing 5 mM Fe(CN)64−/3−: bare ITO (a), ITO/APTES (b),

ITO/APTES/PAMAM

ITO/APTES/PAMAM/Ab1/BSA

(c), (e),

ITO/APTES/PAMAM/Ab1

ITO/APTES/PAMAM/Ab1/BSA/PSA

(d), (f),

ITO/APTES/PAMAM/Ab1/BSA/PSA/Ab2-DNA−NMOFs (g), ITO/NMOFs (h). Inset B: Equivalent circuit.

33



Figure 4

Figure 4 (A) Cathodic photocurrent responses of the immunosensor at different concentration of PSA. (B) The calibration plots of cathodic photocurrent increment versus the logarithm of PSA concentration. Error bars, SD, n = 3.

34


Page 34 of 35

Page 35 of 35 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


For TOC only

35


DNA-Mediated Nanoscale MetalâOrganic Frameworks for

Recommend Documents

DNA-Mediated Nanoscale MetalâOrganic Frameworks for