Biological Molecules-Governed Plasmonic Nanoparticle Dimers with

Nov 2, 2017 - (14) Au NP–QD heterodimers displayed a chiral response of approximately −5 mdeg in the Au plasmonic region, originating from the asy...
0 downloads 12 Views 2MB Size
Subscriber access provided by READING UNIV

Perspective

Biological Molecules-Governed Plasmonic Nanoparticle Dimers With Tailored Optical Behaviors Yuan Zhao, Maozhong Sun, Wei Ma, Hua Kuang, and Chuanlai Xu J. Phys. Chem. Lett., Just Accepted Manuscript • DOI: 10.1021/acs.jpclett.7b01781 • Publication Date (Web): 02 Nov 2017 Downloaded from http://pubs.acs.org on November 5, 2017

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.

The Journal of Physical Chemistry Letters 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 23

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 Journal of Physical Chemistry Letters

1

Biological Molecules-governed Plasmonic Nanoparticle

2

Dimers with Tailored Optical Behaviors

3

Yuan Zhao1, Maozhong Sun2, Wei Ma2, Hua Kuang2*, and Chuanlai Xu2* 1

4 5 6

Engineering; 2International Joint Research Laboratory for Biointerface and Biodetection, State Key Lab of Food

7

*

8

ABSTRACT:

9

Self-assembly opens new avenues to direct the organization of nanoparticles (NPs) into discrete

10

structures with predefined configuration and association numbers. Plasmonic NP dimers provide a

11

well-defined system for investigating the plasmonic coupling and electromagnetic (EM)

12

interaction in arrays of NPs. The programmability and structural plasticity of biomolecules offers

13

a convenient platform for constructing of NP dimers in a controllable way. Plasmonic coupling of

14

NPs enables dimers to exhibit tunable optical properties, such as surface-enhanced Raman

15

scattering (SERS), chirality, photoluminescence and electrochemiluminescence (ECL) properties,

16

which can be tailored by altering the biomolecules, the building blocks with distinct compositions,

17

sizes and morphology, the interparticle distances, as well as the geometric configuration of the

18

constituent NPs. An overview of recent developments in biological molecules-governed NP

19

dimers, the tailored optical behaviors, and challenges in enhancing optical signals and proposing

20

plasmonic biosensors have been discussed in this Perspective.

Key Lab of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material

Science and Technology, Wuxi, Jiangsu, 214122, PRC Corresponding Authors: [email protected]; [email protected]

21 22

TOC graphic

23

1

ACS Paragon Plus Environment

The Journal of Physical Chemistry Letters

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

1

Self-assembly offers a scalable and versatile way to organize individual NPs into

2

sophisticated nanostructures, allowing rational structural design leading to nanostructures with

3

novel collective plasmonic properties and functions.1-3 In comparison to other NP assemblies, such

4

as trimers, pyramids, helices, chains, oligomers and superstructures, dimers are particularly

5

interesting because their structure is simple and they serve as a model system that can provide

6

fundamental insights into the interactions between NPs in close proximity.4-6 When two NPs are

7

close, the individual plasmonic couple to dimers results in the shift of localized surface plasmon

8

resonance (LSPR) in the extinction spectrum and significant enhancement of the EM field,

9

especially in the interparticle junction between two plasmons.7,8 Detailed understanding of the

10

interaction between optical properties and dimeric structures provides fundamental science on the

11

collective coupling of NP oligomers and their superstructures. The greater depth of mechanism

12

helps to know the role of key parameters in optical coupling, optical enhancement and generating,

13

spontaneously chiral induction, etc., in nature which will accelerate the development of

14

technologies based on plasmonic, chiroptical and excitonic effects.

15

The assembly of NP dimers is an appealing means to control the plasmonic properties of

16

nanostructures. The special dimeric geometry enables NP dimers to exhibit unique optical

17

activities (SERS, chirality, photoluminescence and ECL enhancement), which can be tuned by

18

controlling the size, morphology, interparticle distances and orientation of the constituent NPs.

19

Dimeric structures can be produced using biological linkers,9 and the assembly and disassembly of

20

NP dimers engineered by biological molecules fabricates the ordered superstructures and induces

21

potential application for the development of novel in situ and ultrasensitive biosensors and the

22

fabrication of electrochemic, chiroptical and SERS active based portal optical devices. In this

23

contribution, we familiarize the recent achievements in biological molecules-governed

24

self-assembly of homo- and/or hetero-plasmonic NP dimers, and highlight insights into the unique

25

optical activities with potential tailored behaviors and functionalities. By and large, we are only on

26

the initial stages for practical applications of NPs assemblies. Further, we attempt to make our

27

speculation on the challenges and future direction of biological molecules-governed plasmonic NP

28

dimers fabrications and nanoscale optoelectronic and photonic devices.

29

Biological molecules-mediated NP assembly possesses unique bio-recognition for the 2

ACS Paragon Plus Environment

Page 2 of 23

Page 3 of 23

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 Journal of Physical Chemistry Letters

1

preparation of high-yield dimers, and provides an orientational avenue for the adjustment of

2

plasmonic coupling by tuning the interparticle gaps.

3

NP dimers assembled by DNA/origami with tailored interparticle gaps. LSPR of NP assemblies

4

is not only related to the shape, size, charge, and dielectric environment of its structural units but

5

also strongly dependent on its spatial order and interparticle gaps. This enables LSPR to be

6

controlled by deterministically positioning plasmonic units at predetermined sites, and in this

7

regard DNA molecules effectively regulate the spacing and the spatial configuration of two NPs.10

8

Plasmonic metal NP dimers, semiconductor NP dimers and plasmonic metal-semiconductor

9

hybrid NP dimers were constructed through the formation of DNA duplex, including Au NP

10

dimers (Figure 1a),11,12 Au nanorod (NR) dimers, Au NR-Au NP dimers (Figure 1b),13 quantum

11

dot (QD) dimers, Au NP-QD dimers, Ag NP-QD dimers(Figure 1c),14 etc. 11,13,15,16 The reversible

12

switching of the interparticle distance between two NPs in the dimers was achieved by regulating

13

the length of dsDNA, or hybridizing/removing the ssDNA strand,13,17 or minimized through

14

formation of a Y-shaped DNA duplex (Figure 1a).11,12 In addition, the light irradiation correlated

15

reversibly regulation of chemical bond in DNA-bridged NP dimers enabled new developments in

16

the field of programmed NP organization.18 Importantly, DNA origami provide more freedom for

17

fabrication of NP dimers with high yields with predefined interparticle gaps (1 to 2 nm) and angles

18

(Figure 1d).19 Based on DNA design, DNA hybridization driven NP assembly is a powerful

19

strategy in constructing desired structures through programmable sequence, predictable structure

20

and precise molecule length of DNA. However, the DNA sequence hybridization based complex

21

superstructures fabrication with detailed 3D geometrical parameters still remains challenging in

22

which the mature DNA design, and linker routes between design and structure as well as

23

application are extremely important for future. On the contrary, the tunable positions of NPs and

24

the flexible design of the origami provides additional opportunities for tuning the angles, 3D

25

locations, complex superstructures constructions enabling the precise control of the 3D

26

configurations.16,20 In general, it is still a challenge to deliberately control the number and the sites

27

of DNA on NPs, which is important for solid format, large scale fabrication 3D strctures,

28

especially for the anisotropic NPs and exotic shaped NPs.

29

Programmable construction of large-scale NP dimers by polymerase chain reaction (PCR). 3

ACS Paragon Plus Environment

The Journal of Physical Chemistry Letters

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

1

Accurate control of high-yield plasmonic NP dimers is critical to obtain reproducible optical

2

signal. PCR assembly strategy alternatively provides an efficient and programmable platform for

3

engineering large-scale NP dimers constructions. The precise modification of one primer on NPs

4

enabled the accurate construction of NP dimers, while high primer concentration would from of

5

NP chains, oligomers and superstructures, etc.21-24 The number of PCR cycles played an important

6

role for the yield of NP dimers and the formation of different structured assemblies.25 Our group

7

developed PCR to fabricate high-yield Au NP dimers and Au NR dimers (Figure 1f-i).23,26 The

8

amplification length of primers determined the interparticle gaps between NPs.27 The tunable

9

yields, diverse NPs superstructures, and the interparticle gaps as well as geometries can be tuned

10

by of PCR primer, template length, and PCR cycles. Compared to DNA hybridization, the PCR

11

technologies provide automatically fabrication strategy at low template DNA that could use for

12

ultrasensitive DNA detection, and large scale of NPs superstructures constructions.

13

Aptamers/proteins/amino acids guided NP dimers for the flexible biosensor applications.

14

Biological molecules, especially for aptamers featured with multiple functional groups are utilized

15

for functionalization of NPs, and their unique bio-recognition offers an especially powerful

16

positioning tool for the orientational assembly of high-yield dimers.1 A self-assembled Au

17

nanostar dimers based on the Hg2+ mediated T-T base pair of ssDNA had been developed as a

18

SERS sensor for Hg2+ detection (Figure 2a),28 which is similar for Ag+ mediated C-C base pairing

19

of chiroptical Au NP heterodimers for sensing of Ag+.29 Alternatively, aptamer-guided Au NP

20

homodimers and heterodimers were constructed exhibited with strong optical signal for the

21

sensitive and selective detection of ATP, bisphenol A, prostate-specific antigen (PSA) and

22

dopamine, etc (Figure 2b).30-34 Despite of DNA aptamers, antibody that direct adsorption at an

23

appropriate pH or N-hydroxysuccinimide-coupling chemistry can be assembled into dimers

24

though antigen-mediated recognition,35 which can be used ultrasensitive detection of

25

microcystin-LR and PSA (Figure 2c-d).26,35 Besides, electrostatic attraction of small molecules

26

could use for assemblies,36 for example, glutathione (GSH) fabricated Au NRs dimer (Figure 2e)37

27

and cysteine fabricated Au NP dimers by multibody attractive forces for chiral recognition of 20

28

pM L-cysteine (Figure 2f).38 Taking advantage of the high specificity of recognition, the

29

developed biological molecules (aptamer, antibody) governed scalable dimers can be served as 4

ACS Paragon Plus Environment

Page 4 of 23

Page 5 of 23

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 Journal of Physical Chemistry Letters

1

bio-responsive materials for the development of novel chiroplasmonic sensors in the ultratrace

2

analysis of targets, while the small molecules triggered dimers are significant for SERS or

3

luminescence based sensor in biological conditions. Future challenges are still existed in regarding

4

to reversible, 3D configuration controllable and intensive optical signals generating in high yield

5

dimers.

6

Building more “hot spots” between adjacent NPs and enhancing the EM field in and around

7

the plasmonic NP dimers is critical to tune and amplify the SERS signals.

8

Composition, sizes and detailed geometry. In comparison to homodimers formed by same metal,

9

heterodimers, such as Au NP-Ag NP dimers with spatial configuration, exhibited LSPR spectrum

10

covering from the visible to near-infrared range (Figure 3a),12,39-41 and usually anisotropic NP

11

dimers generated strong Raman signals.42 Specially, Au NR dimers in side-by-side mode showed

12

enhanced SERS activity than end-to-end mode.23,33 SERS signal of plasmonic NPs could be

13

maximized by roughening the surface,12 for example, LSPR of branched NPs, including nanostars,

14

nanoflowers, nanotriangles and nanocubes, can be tuned by variation of their aspect ratio and the

15

formation of multi-sharp tips.12,28,43 For example, Au nanostar dimers allowed for strong

16

plasmonic field enhancement that enabled single molecule detection.28,44 Different SERS active

17

materials can be obtained through sophisticated NPs synthesis technology. Strong individual

18

SERS active materials will help to enhance Raman signals when NPs of different materials were

19

assembled together. Future work could be interesting for fabrication new materials, and

20

construction optimal SERS active materials.

21

Building intense “hot spots” by tuning the interparticle gaps. One important parameter for

22

producing strong Raman enhancement was controlling the interparticle gaps. Small gaps can be

23

achieved by controlling the length of DNA, their hybridization modes, and the depositing of metal

24

shells, polymer layers.45,46 The small gap helps to generate huge near field enhancement that

25

makes single-molecule level possible.35,47 For example, Y-shaped DNA hybridization manner

26

assembled Au NP dimers demonstrated maximal Raman enhancement (Figure 3b).48 Besides,

27

small gaps (3.3 ± 1.0 nm ) of Au NP dimers demonstrated local field enhancements of several

28

orders of magnitude through detection of a small number of dye molecules (Figure 3c).49 Despite

29

of metal materials, graphene with unique electronic, mechanical, and thermal properties that have 5

ACS Paragon Plus Environment

The Journal of Physical Chemistry Letters

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

1

induced Au NP dimers with superior SERS signals.50 Furtherly, shell deposition can be used for

2

reducing interparticle gaps, tuning the size, shape and composition of NPs for amplification of EM

3

field.25,33,51 The Ag shell deposition on Au NP dimers or Au NRs dimers achieved SERS-based

4

single-molecule detection (Figure 3d).51,52 or ultrasensitive detection for dopamine with limit of

5

detection (LOD) as 0.006 pM.33 The ultrasensitive sensor could resist matrix interference that is

6

good for real sample.

7

Locating the “hot spots” at optimized substrates. The geometry of the metallic substrate has been

8

proven to be associated with the local field enhancement and consequently induces enhancement.

9

A metallic solid support gives rise to a dramatic increase by many orders of magnitude in SERS

10

intensity than in the case of dielectric supports (Figure 3e).53 Generally, NPs and NRs dimers

11

undergo a large boost in the accumulation of hotspots.42 SERS signal of NP dimers is sensitive to

12

the distance between NPs and the metal film.53 The fabrication of well-defined NP dimers on

13

metal film substrate as a uniform SERS substrate has important implications to improve the

14

effciency of EM coupling.

15

Plasmonic coupling between two NPs with nanometer gaps offers many new possibilities for

16

tailoring its optical response, as well as the amplitude in enhancement and spatial distribution of

17

the associated local field.54 NP dimers turned out to be superior over single NP regarding their

18

performances in EM field enhancements.55 While, the subtle changes in the conductive junction

19

area of NP dimers, NPs separations (gaps) and symmetry breaking using different sizes and

20

compositions, as well as the interferences from SERS substrates, can readily and controllably

21

introduce various plasmon modes and change the EM field. The future challenges are related to

22

high yield NP dimer for producing large scale SERS substrate, multi-parameter tunable ultrastrong

23

hot spot generating mechanism and real applications studies about stability and repeatability for

24

developing sensors. The orientational assembly of high-yield NP dimers potentially provides new

25

ways for overcoming SERS detection repeatability and stability issues when engineered properly.

26

NP dimers exhibited chiroptical activities which can be tailored by altering the templates,

27

the distribution of geometrical parameters of the assembly, and the spatial configuration of

28

the constituent NPs.

29

Chiral Au NR dimers and Au NP dimers. The unique anisotropic properties and the near-infrared 6

ACS Paragon Plus Environment

Page 6 of 23

Page 7 of 23

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 Journal of Physical Chemistry Letters

1

plasmonic bands make Au NRs highly desirable for the fabrication of plasmonic chiral

2

nanostructures.56 Au NR dimers can be assembled by reconfigurable DNA origami bundles,

3

bifacial DNA origami template, a soft 2D DNA origami template, and PCR technique (Figure

4

4).20,23,57-59 Au NR dimers fabricated by origami bundles can be switched between different

5

conformational states by adding specifically designed DNA fuel strands (Figure 4a),2,60 Overall,

6

the DNA origami enabled rich modulated geometries for investigating plasmonic chirality of Au

7

NR by rational design (Figure 4b).58 The flexible and soft 2D DNA origami provided additional

8

choice for studying spatial configuration correlated chiroplasmonics of Au NR dimers,20 in which

9

the origins of chirality was due to symmetrical breaking of the angled NR dimer conformation

10

(Figure 4c).23,59 The angled Au NRs confirmation was coming from breaking of enantiomeric

11

equivalence of the NR pairs, leading to the formation of twisted chiral systems. Comparably,

12

chiral Au NPs was usually constructed by DNA linker, in which chiral signals was tunable by

13

interparticle gaps and the sizes of NPs (Figure 4d).61 Generally, larger size (25 nm) and medium

14

gap (e.g., 26 bp DNA) showed strong circular dichroism (CD) response,61 due to the intense

15

absorbance of circularly polarized light. The ellipsoidal shapes for large Au NPs resulted in

16

distinct dihedral angle and broke the symmetric properties and induced the intense chiroptical

17

activities. This geometrical chirality is different from the induced chirality coming from interfacial

18

interaction between NP surface and chiral molecule.62 Corresponding to angled conformation

19

switching, the optical activity of Au NP dimer was reversible when interacted with biological

20

macromolecules.63 The biological systems triggered signal switching may allow the advancement

21

of smart probes for in situ monitoring of biochemistry/life sciences process. Additionally, the

22

unprecedented level of spatial and chiroptical effect control enabled by DNA structures potentially

23

for developing smart chiral plasmonic devices.

24

Different compositions and shapes of NPs constructed heterodimers. The compositions of two

25

building blocks possessed critical effect on the chiroptical response. The prolate shapes of

26

individual Au NPs and Ag NPs induced the generation of scissor-like geometry with the long axes

27

of NPs forming a dihedral angle of 9º. Taking into account of the anisotropic properties of Au NRs

28

and the prolate shapes of Au NPs, Au NR-Au NP heterodimers exhibited interesting chiroptical

29

responses, originating from the finger-crossed chiral construction (Figure 4e),13 in which CD 7

ACS Paragon Plus Environment

The Journal of Physical Chemistry Letters

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

1

signals showed decreased intensity and a small redshift due to the decreased EM field with

2

increasing gaps from 15 bp to 80 bp. Au NPs and Ag NPs heterodimers assembled by

3

antigen-antibody bridges exhibited startlingly intense chiroplasmonic properties (Figure 4f).26

4

Heterogeneously asymmetric chiral dimers are fundamental to systematically and completely

5

understand the mechanism of chirality. Semiconductor dimers/plasmonic NP-semiconductor

6

dimers were also explored and exhibited diverse distinct chiroptical bands and intensity (Figure

7

4g).14 Au NP-QD heterodimers displayed a chiral response of approximately -5 mdeg in the Au

8

plasmonic region, originating from the asymmetrical dipole-dipole interaction.64 For Ag NP-QD

9

heterodimers, a strong positive CD signal of about 13 mdeg in the characteristic Ag plasmonic

10

band was obtained. The high electronic oscillation of Ag NPs strengthened the dipole interaction,

11

enabling the stronger CD response than that of Au NP-QD heterodimers. The structural left- and

12

right-handed configurations based on various NPs size and compositions are amendable for future

13

nanoscale enantioselective construction, and provide valuable strategies for tailoring chiroptical

14

properties.

15 16

Shell-engineered chiral NP dimers with tailorable chiral responses. CD intensity and bands can

17

be largely tuned by excessive metal deposition. A pronounced blue shift of CD peak for Au NP

18

helices was achieved by depositing of Ag shells and Au-Ag alloy shells (Figure 5a).65 The Ag@Au

19

NP assemblies surprisingly showed a red-shifted and amplified reversal of the optical rotation

20

spectral signature (Figure 5b).66 Similarly, the chirality of Au NP heterodimers was tailored by

21

deposition of single or double Ag/Au shells.25 CD bands of Au NP heterodimers blue-shifted from

22

525 nm to 418 nm after Ag shell deposition, and exhibited a 61 nm red-shift after Au shell

23

deposition (Figure 5c-d). Not entirely surprisingly, chiroptical bands of CD returned to 525 nm

24

after the second deposition of Au shell or Ag shell (Figure 5e-f).25 This strategy provides a new

25

way to “tune” the peak position of CD bands, and specially, displayed amplified chiral intensity,

26

attributing to the bridged interparticle gaps between two NPs and the increased aspect ratios of

27

NPs. The metal type of shell determined the position of CD bands, and the shell thickness mainly

28

tuned the intensity (Figure 5g).67 For example, the CD bands of Au NR dimers was significantly

29

transited and amplified by deposition of Ag shell (Figure 5h).32 Shell deposition intensified the 8

ACS Paragon Plus Environment

Page 8 of 23

Page 9 of 23

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 Journal of Physical Chemistry Letters

1

hot-spot chirality, and evidently guided the enantiomorphous chiral configuration, resulting in a

2

startlingly intense, asymmetric, dipolar coupling strength.

3

Chiroptical properties of NP dimers not only can be tailored by changing the building blocks,

4

the interparticle gaps and the orientational arrangements of NPs, but the metal deposition that

5

opened a potential avenue for tuning the CD intensity and positions. However, there are still

6

challenges to investigate the dynamic and reversible chiral responses of NP dimers in spatially and

7

temporally controlled assembly ways. It is important to further organize large-scale chiral NP

8

dimers into macroscopic chiral metamaterials for the development of smart chiral plasmonic

9

devices.

10

Plasmonic coupling strength of NP dimers is of great research interest to adjust the quantum

11

efficiency of photoluminescence and ECL.

12

Plasmonic NP dimers engineered tunable photophysical properties of fluorescent probes.

13

Plasmonic NP dimers with a nanometric gap can be acted as efficient optical antennas for the

14

fluorescence enhancement.68 The fluorescence of a dye molecule positioned in Au NP dimers with

15

23 nm gap was enhanced 117 folds (Figure 6a).69 Similarly, DNA-templated 60 and 80 nm Au NP

16

dimers, featuring one fluorescent molecule, provided quantum yields in the range of 45%-70%

17

(Figure 6b).70 DNA origami driven 80 nm Ag NP dimers served as optical antennas could yield a

18

fluorescence enhancement of more than 2 orders of magnitude throughout the visible spectral

19

range (Figure 6c).71 Importantly, despite of interparticle gap, fluorescence intensity enhancement

20

can be also contributed by the dimer-film gap.72,73 The controllability of dye-DNA binding is

21

necessary to adjust the orientation of molecular transition dipole in the NP dimers and enhance the

22

intensity. For NP dimers, the distribution of geometrical parameters, such as NP size, shape, and

23

spacing in the dimer, has influences on the fluorescence intensity enhancements. Future

24

applications are appealing based on fluorescence enhancement, such as ultrasensitive biosensors,

25

optical device for display and lightning. It still remains a challenge to produce circularly polarized

26

luminescence (CPL) signals at nanoscale inorganic materials system. Based on chiral dimers, the

27

conditions and key parameters are interesting to investigate for generating CPL.

28

The strong EM field of plasmonic NP dimers promoted ECL enhancement. The LSPR of Au

29

NPs could increase both the excitation rate and the emission factor of luminophores.74 Au NPs/ 9

ACS Paragon Plus Environment

The Journal of Physical Chemistry Letters

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

1

films were used as surface-enhanced sources for ECL signal amplification of Ru(bpy)32+ and QDs.

2

The ECL properties of emitting species could be improved significantly by adjusting the distance

3

between metallic surfaces and emitting species, due to the distance dependent energy transfer

4

between the excitons in the QDs and plasmons in the metal surface (Figure 6d).75-77 Furtherly, the

5

enhanced ECL intensities of CdS film in the presence of Au NP dimers were dramatically 1.6-fold

6

higher than that of Au monomer. When two NPs get closer, the ‘‘hot spot’’ becomes stronger

7

(Figure 6e).78 The plasmon coupling of NP dimers with an appropriate interparticle gap enhanced

8

the ECL of emitting species. This will avoid the exploration of a variety of ways to enhance the

9

ECL emission, novel emitting species and the intramolecular electron transfer of the

10

donor-acceptor systems, etc. NP dimers driven ECL enhancement should be expended to other

11

inorganic, organic and upconversion ECL systems.

12

Future Directions. Research activities in the field of NP dimers have been blossoming throughout

13

the past decades. The recent developments of NP assembly have led to the availability of a large

14

portfolio of fabrication methods to access a wide range of NP dimers with tunable geometries. NP

15

dimers are easy to fabricate, and substantially exhibit distinct and tailorable optical properties.

16

Studies on NP dimers will provide fundamental insights into the interactions between NPs in close

17

proximity. The establishment of NP dimers is generally performed in solution, as it paves the way

18

to a broad range of applications. Despite the many advantages, long-standing challenges

19

associated with NP dimers-based research remain: (i) Apart from the widely reported isotropic NP

20

dimers, dimers of anisotropic NPs with known confirmation give rise to more distinct plasmon

21

resonances but are difficult to prepare in high yields; (ii) The isotropic nature of isotropic NPs

22

prevents the selective binding of molecules on surfaces. The regiospecific functionalization of a

23

myriad of exotic shaped NPs, such as stars, flowers, wires, triangles, and plates, permits the

24

accurate controllable the geometrical orientation of two NPs. Site-selective and region specific

25

controllable NP assembly will provide chance for investigating relationship between geometrical

26

configuration and optical activities, as well correlated signal enhancement, tuning studies; (iii) The

27

combination of different materials with distinctive properties and asymmetric shapes in NP dimers

28

is an effective way to explore their synergistic effect for NP dimers, e.g. alloy NPs and Janus NPs;

29

(iv) Based on high yield NP dimers as unit, the large scale superstructure fabrications with 10

ACS Paragon Plus Environment

Page 10 of 23

Page 11 of 23

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 Journal of Physical Chemistry Letters

1

designed spatial configuration is interesting for investigating the collective properties for optical

2

enhancement; (v)Beside the conventional optical properties, the unique EM field between NPs

3

will endow NP dimers with remarkable electrical and magnetic performances. The CPL,

4

vibrational circular dichroism (VCD) and Raman optical activity (ROA) as well as

5

magneto-optical activities are vital for exploring multi-optical activities. Further studies of

6

electromagnetic properties resulting from higher ordered NP dimers are also needed since they are

7

essential for more applications; (vi) The amplified optical properties promote NP dimers for the

8

development of novel biosensors and in vivo reporter, but the stability of NP dimers in biological

9

complex medium is still a challenge. The dynamic biological switchable configuration of NP

10

dimers provide much more potentials for investigating the in situ bimolecular reaction pathway.

11

Fundamental and application-driven research on NP dimers should be more evaluated for the

12

specificity, sensitivity and repeatability for potential use in a commercialized format.

13 14

AUTHOR INFORMATION

15

Corresponding Author

16

*E-mail: [email protected]; [email protected]

17 18

Notes

19

The authors declare no competing financial interest.

20 21

Biographies

22 23 24 25 26 27 28 29 30 31 32 33

Yuan Zhao received her Ph.D. degree in 2013 under the direction of Prof. Chuanlai Xu. She was promoted to associate professor at Jiangnan University in 2015. Her research is focused on functional nanomaterials, electrochemical integration and applications. Wei Ma received his B.S. degree and Ph.D. degree under the direction of Prof. Chuanlai Xu at Jiangnan University. He is currently an associate professor at Jiangnan University. His research area is self-assemblies of NPs, optical properties and biosensors. Maozhong Sun received her Ph.D. degree under the direction of Prof. Chuanlai Xu. He is currently a postdoctor under supervisor of Prof. Chuanlai Xu at Jiangnan University. Her research is focused on chiral NP assemblies, biosensors for living cell detection. 11

ACS Paragon Plus Environment

The Journal of Physical Chemistry Letters

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

1 2 3 4 5 6 7

Hua Kuang received her Ph.D. degree at China Agricultural University. She is a full professor with research focused on nanoassemblies, structure properties and instrumental characterizations. Chuanlai Xu received his B.S., M.S. and Ph.D. degrees from Jiangnan University. He is a full professor with research is focused on immunoassays, NPs synthesis, NP-based biodetection, controllable nanoassemblies, optical and theatrical properties of nanostrcutures.

8

ACKNOWLEDGMENTS

9

This work is financially supported by the National Natural Science Foundation of

10

China (21631005, 21673104, 21522102, 21503095).

11 12

12

ACS Paragon Plus Environment

Page 12 of 23

Page 13 of 23

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 Journal of Physical Chemistry Letters

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

REFERENCES (1) Xu, L.; Sun, M.; Ma, W.; Kuang, H.; Xu, C. Self-assembled nanoparticle dimers with contemporarily relevant properties and emerging applications. Mater. Today 2016, 19, 595-606. (2) Ma, W.; Xu, L.; de Moura, A. F.; Wu, X.; Kuang, H.; Xu, C.; Kotov, N. A. Chiral Inorganic Nanostructures. Chem. Rev. 2017. (3) Kuang, H.; Ma, W.; Xu, L.; Wang, L.; Xu, C. Nanoscale Superstructures Assembled by Polymerase Chain Reaction (PCR): Programmable Construction, Structural Diversity, and Emerging Applications. Acc. Chem. Res. 2013, 46, 2341-2354. (4) Cha, H.; Yoon, J. H.; Yoon, S. Probing Quantum Plasmon Coupling Using Gold Nanoparticle Dimers with Tunable Interparticle Distances Down to the Subnanometer Range. ACS Nano 2014, 8, 8554-8563. (5) Zohar, N.; Chuntonov, L.; Haran, G. The simplest plasmonic molecules: Metal nanoparticle dimers and trimers. J. Photochem. Photobiol., C 2014, 21, 26-39. (6) Ma, W.; Xu, L.; Wang, L.; Kuang, H.; Xu, C. Orientational nanoparticle assemblies and biosensors. Biosens. Bioelectron. 2016, 79, 220-236. (7) Wang, L.; Xu, L.; Kuang, H.; Xu, C.; Kotov, N. A. Dynamic Nanoparticle Assemblies. Acc. Chem. Res. 2012, 45, 1916-1926. (8) Xu, L.; Ma, W.; Wang, L.; Xu, C.; Kuang, H.; Kotov, N. A. Nanoparticle assemblies: dimensional transformation of nanomaterials and scalability. Chem. Soc. Rev. 2013, 42, 3114-3126. (9) Li, Z.; Cheng, E.; Huang, W.; Zhang, T.; Yang, Z.; Liu, D.; Tang, Z. Improving the Yield of Mono-DNA-Functionalized Gold Nanoparticles through Dual Steric Hindrance. J. Am. Chem. Soc. 2011, 133, 15284-15287. (10) Fang, L.; Wang, Y.; Liu, M.; Gong, M.; Xu, A.; Deng, Z. Dry Sintering Meets Wet Silver-Ion "Soldering": Charge-Transfer Plasmon Engineering of Solution-Assembled Gold Nanodimers From Visible to Near-Infrared I and II Regions. Angew. Chem. Int. Ed. 2016, 55, 14296-14300. (11) Guo, L.; Xu, Y.; Ferhan, A. R.; Chen, G.; Kim, D. H. Oriented gold nanoparticle aggregation for colorimetric sensors with surprisingly high analytical figures of merit. J. Am. Chem. Soc. 2013, 135, 12338-12345. (12) Zhao, Y.; Yang, X.; Li, H.; Luo, Y.; Yu, R.; Zhang, L.; Yang, Y.; Song, Q. Au nanoflower-Ag nanoparticle assembled SERS-active substrates for sensitive MC-LR detection. Chem. Commun. 2015, 51, 16908-16911. (13) Hao, C.; Xu, L.; Ma, W.; Wang, L.; Kuang, H.; Xu, C. Assembled Plasmonic Asymmetric Heterodimers with Tailorable Chiroptical Response. Small 2014, 10, 1805-1812. (14) Sun, M.; Ma, W.; Xu, L.; Wang, L.; Kuang, H.; Xu, C. Chirality of self-assembled metal-semiconductor nanostructures. J. Mater. Chem. C 2014, 2, 2702-2706. (15) Xu, X.; Stöttinger, S.; Battagliarin, G.; Hinze, G.; Mugnaioli, E.; Li, C.; Müllen, K.; Basché, T. Assembly and Separation of Semiconductor Quantum Dot Dimers and Trimers. J. Am. Chem. Soc. 2011, 133, 18062-18065. (16) Pal, S.; Deng, Z.; Wang, H.; Zou, S.; Liu, Y.; Yan, H. DNA Directed Self-Assembly of Anisotropic Plasmonic Nanostructures. J. Am. Chem. Soc. 2011, 133, 17606-17609. (17) Lermusiaux, L.; Sereda, A.; Portier, B.; Larquet, E.; Bidault, S. Reversible Switching of the Interparticle Distance in DNA-Templated Gold Nanoparticle Dimers. ACS Nano 2012, 6, 10992-10998. (18) Harimech, P. K.; Gerrard, S. R.; El-Sagheer, A. H.; Brown, T.; Kanaras, A. G. Reversible Ligation of Programmed DNA-Gold Nanoparticle Assemblies. J. Am. Chem. Soc. 2015, 137, 9242-9245. 13

ACS Paragon Plus Environment

The Journal of Physical Chemistry Letters

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

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

(19) Simoncelli, S.; Roller, E. M.; Urban, P.; Schreiber, R.; Turberfield, A. J.; Liedl, T.; Lohmuller, T. Quantitative Single-Molecule Surface-Enhanced Raman Scattering by Optothermal Tuning of DNA Origami-Assembled Plasmonic Nanoantennas. ACS Nano 2016, 10, 9809-9815. (20) Chen, Z.; Lan, X.; Chiu, Y.-C.; Lu, X.; Ni, W.; Gao, H.; Wang, Q. Strong Chiroptical Activities in Gold Nanorod Dimers Assembled Using DNA Origami Templates. ACS Photonics 2015, 2, 392-397. (21) Zhao, Y.; Xu, L.; Kuang, H.; Wang, L.; Xu, C. Asymmetric and symmetric PCR of gold nanoparticles: A pathway to scaled-up self-assembly with tunable chirality. J. Mater. Chem. 2012, 22, 5574. (22) Zhao, Y.; Xu, L.; Liz-Marzán, L. M.; Kuang, H.; Ma, W.; Asenjo-Garcı́a, A.; García de Abajo, F. J.; Kotov, N. A.; Wang, L.; Xu, C. Alternating Plasmonic Nanoparticle Heterochains Made by Polymerase Chain Reaction and Their Optical Properties. J. Phy. Chem. Lett. 2013, 4, 641-647. (23) Ma, W.; Kuang, H.; Xu, L.; Ding, L.; Xu, C.; Wang, L.; Kotov, N. A. Attomolar DNA detection with chiral nanorod assemblies. Nat. Commun. 2013, 4, 2689. (24) Chen, W.; Bian, A.; Agarwal, A.; Liu, L.; Shen, H.; Wang, L.; Xu, C.; Kotov, N. A. Nanoparticle Superstructures Made by Polymerase Chain Reaction: Collective Interactions of Nanoparticles and a New Principle for Chiral Materials. Nano Lett. 2009, 9, 2153-2159. (25) Zhao, Y.; Xu, L.; Ma, W.; Wang, L.; Kuang, H.; Xu, C.; Kotov, N. A. Shell-engineered chiroplasmonic assemblies of nanoparticles for zeptomolar DNA detection. Nano Lett 2014, 14, 3908-3913. (26) Wu, X.; Xu, L.; Liu, L.; Ma, W.; Yin, H.; Kuang, H.; Wang, L.; Xu, C.; Kotov, N. A. Unexpected chirality of nanoparticle dimers and ultrasensitive chiroplasmonic bioanalysis. J. Am. Chem. Soc. 2013, 135, 18629-18636. (27) Kuang, H.; Zhao, S.; Chen, W.; Ma, W.; Yong, Q.; Xu, L.; Wang, L.; Xu, C. Rapid DNA detection by interface PCR on nanoparticles. Biosens. Bioelectron. 2011, 26, 2495-2499. (28) Ma, W.; Sun, M.; Xu, L.; Wang, L.; Kuang, H.; Xu, C. A SERS active gold nanostar dimer for mercury ion detection. Chem. Commun. 2013, 49, 4989-4991. (29) Xu, Z.; Xu, L.; Liz-Marzán, L. M.; Ma, W.; Kotov, N. A.; Wang, L.; Kuang, H.; Xu, C. Sensitive Detection of Silver Ions Based on Chiroplasmonic Assemblies of Nanoparticles. Adv. Opt. Mater. 2013, 1, 626-630. (30) Fu, P.; Sun, M.; Xu, L.; Wu, X.; Liu, L.; Kuang, H.; Song, S.; Xu, C. A self-assembled chiral-aptasensor for ATP activity detection. Nanoscale 2016, 8, 15008-15015. (31) Kuang, H.; Yin, H.; Liu, L.; Xu, L.; Ma, W.; Xu, C. Asymmetric Plasmonic Aptasensor for Sensitive Detection of Bisphenol A. ACS Appl. Mater. Interfaces 2014, 6, 364-369. (32) Tang, L.; Li, S.; Xu, L.; Ma, W.; Kuang, H.; Wang, L.; Xu, C. Chirality-based Au@Ag Nanorod Dimers Sensor for Ultrasensitive PSA Detection. ACS Appl. Mater. Interfaces 2015, 7, 12708-12712. (33) Tang, L.; Li, S.; Han, F.; Liu, L.; Xu, L.; Ma, W.; Kuang, H.; Li, A.; Wang, L.; Xu, C. SERS-active Au@Ag nanorod dimers for ultrasensitive dopamine detection. Biosens. Bioelectron. 2015, 71, 7-12. (34) Gao, F.; Liu, L.; Cui, G.; Xu, L.; Wu, X.; Kuang, H.; Xu, C. Regioselective plasmonic nano-assemblies for bimodal sub-femtomolar dopamine detection. Nanoscale 2017, 9, 223-229. (35) Mandl, A.; Filbrun, S. L.; Driskell, J. D. Asymmetrically Functionalized Antibody-Gold Nanoparticle Conjugates to Form Stable Antigen-Assembled Dimers. Bioconjugate Chem. 2017, 28, 14

ACS Paragon Plus Environment

Page 14 of 23

Page 15 of 23

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 Journal of Physical Chemistry Letters

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

38-42. (36) Han, B.; Zhu, Z.; Li, Z.; Zhang, W.; Tang, Z. Conformation Modulated Optical Activity Enhancement in Chiral Cysteine and Au Nanorod Assemblies. J. Am. Chem. Soc. 2014, 136, 16104-16107. (37) Lu, J.; Chang, Y. X.; Zhang, N. N.; Wei, Y.; Li, A. J.; Tai, J.; Xue, Y.; Wang, Z. Y.; Yang, Y.; Zhao, L.; Lu, Z. Y.; Liu, K. Chiral Plasmonic Nanochains via the Self-Assembly of Gold Nanorods and Helical Glutathione Oligomers Facilitated by Cetyltrimethylammonium Bromide Micelles. ACS Nano 2017, 11, 3463-3475. (38) Xu, L.; Xu, Z.; Ma, W.; Liu, L.; Wang, L.; Kuang, H.; Xu, C. Highly selective recognition and ultrasensitive quantification of enantiomers. J. Mater. Chem. B 2013, 1, 4478-4483. (39) Zhao, Y.; Yang, Y.; Luo, Y.; Yang, X.; Li, M.; Song, Q. Double Detection of Mycotoxins Based on SERS Labels Embedded Ag@Au Core-Shell Nanoparticles. ACS Appl. Mater. Interfaces 2015, 7, 21780-21786. (40) Wu, X.; Chen, X.; Gao, F.; Ma, W.; Xu, L.; Kuang, H.; Li, A.; Xu, C. SERS encoded nanoparticle heterodimers for the ultrasensitive detection of folic acid. Biosens. Bioelectron. 2016, 75, 55-58. (41) Lee, J. H.; You, M. H.; Kim, G. H.; Nam, J. M. Plasmonic nanosnowmen with a conductive junction as highly tunable nanoantenna structures and sensitive, quantitative and multiplexable surface-enhanced Raman scattering probes. Nano Lett. 2014, 14, 6217-6225. (42) Solis, D. M.; Taboada, J. M.; Obelleiro, F.; Liz-Marzan, L. M.; Garcia de Abajo, F. J. Optimization of Nanoparticle-Based SERS Substrates through Large-Scale Realistic Simulations. ACS Photonics 2017, 4, 329-337. (43) Jimenez de Aberasturi, D.; Serrano-Montes, A. B.; Langer, J.; Henriksen-Lacey, M.; Parak, W. J.; Liz-Marzán, L. M. Surface Enhanced Raman Scattering Encoded Gold Nanostars for Multiplexed Cell Discrimination. Chem. Mater. 2016, 28, 6779-6790. (44) Chirumamilla, M.; Toma, A.; Gopalakrishnan, A.; Das, G.; Zaccaria, R. P.; Krahne, R.; Rondanina, E.; Leoncini, M.; Liberale, C.; De Angelis, F.; Di Fabrizio, E. 3D nanostar dimers with a sub-10-nm gap for single-/few-molecule surface-enhanced raman scattering. Adv. Mater. 2014, 26, 2353-2358. (45) Yu, X.; Lei, D. Y.; Amin, F.; Hartmann, R.; Acuna, G. P.; Guerrero-Martínez, A.; Maier, S. A.; Tinnefeld, P.; Carregal-Romero, S.; Parak, W. J. Distance control in-between plasmonic nanoparticles via biological and polymeric spacers. Nano Today 2013, 8, 480-493. (46) Zhao, Y.; Yang, Y.; Sun, Y.; Cui, L.; Zheng, F.; Zhang, J.; Song, Q.; Xu, C. Shell-encoded Au nanoparticles with tunable electroactivity for specific dual disease biomarkers detection. Biosens. Bioelectron. 2018, 99, 193-200. (47) Bordley, J. A.; Hooshmand, N.; El-Sayed, M. A. The Coupling between Gold or Silver Nanocubes in Their Homo-Dimers: A New Coupling Mechanism at Short Separation Distances. Nano Lett. 2015, 15, 3391-3397. (48) Zhou, W.; Li, Q.; Liu, H.; Yang, J.; Liu, D. Building Electromagnetic Hot Spots in Living Cells via Target-Triggered Nanoparticle Dimerization. ACS Nano 2017, 11, 3532-3541. (49) Thacker, V. V.; Herrmann, L. O.; Sigle, D. O.; Zhang, T.; Liedl, T.; Baumberg, J. J.; Keyser, U. F. DNA origami based assembly of gold nanoparticle dimers for surface-enhanced Raman scattering. Nat. Commun. 2014, 5, 3448. (50) Prinz, J.; Matkovic, A.; Pesic, J.; Gajic, R.; Bald, I. Hybrid Structures for Surface-Enhanced 15

ACS Paragon Plus Environment

The Journal of Physical Chemistry Letters

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

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

Raman Scattering: DNA Origami/Gold Nanoparticle Dimer/Graphene. Small 2016, 12, 5458-5467. (51) Lim, D.-K.; Jeon, K.-S.; Kim, H. M.; Nam, J.-M.; Suh, Y. D. Nanogap-engineerable Raman-active nanodumbbells for single-molecule detection. Nat. Mater. 2010, 9, 60-67. (52) Prinz, J.; Heck, C.; Ellerik, L.; Merk, V.; Bald, I. DNA origami based Au-Ag-core-shell nanoparticle dimers with single-molecule SERS sensitivity. Nanoscale 2016, 8, 5612-5620. (53) Wang, X.; Li, M.; Meng, L.; Lin, K.; Feng, J.; Huang, T.; Yang, Z.; Ren, B. Probing the Location of Hot Spots by Surface-Enhanced Raman Spectroscopy: Toward Uniform Substrates. ACS Nano 2014, 8, 528-536. (54) Lombardi, A.; Grzelczak, M. P.; Crut, A.; Maioli, P.; Pastoriza-Santos, I.; Liz-Marzán, L. M.; Del Fatti, N.; Vallée, F. Optical Response of Individual Au–Ag@SiO2 Heterodimers. ACS Nano 2013, 7, 2522-2531. (55) Zheng, Y. H.; Thai, T.; Reineck, P.; Qiu, L.; Guo, Y. M.; Bach, U. DNA-Directed Self-Assembly of Core-Satellite Plasmonic Nanostructures: A Highly Sensitive and Reproducible Near-IR SERS Sensor. Adv. Funct. Mater. 2013, 23, 1519-1526. (56) Li, Z.; Zhu, Z.; Liu, W.; Zhou, Y.; Han, B.; Gao, Y.; Tang, Z. Reversible Plasmonic Circular Dichroism of Au Nanorod and DNA Assemblies. J. Am. Chem. Soc. 2012, 134, 3322-3325. (57) Kuzyk, A.; Schreiber, R.; Zhang, H.; Govorov, A. O.; Liedl, T.; Liu, N. Reconfigurable 3D plasmonic metamolecules. Nat. Mater. 2014, 13, 862-866. (58) Lan, X.; Chen, Z.; Dai, G.; Lu, X.; Ni, W.; Wang, Q. Bifacial DNA Origami-Directed Discrete, Three-Dimensional, Anisotropic Plasmonic Nanoarchitectures with Tailored Optical Chirality. J. Am. Chem. Soc. 2013, 135, 11441-11444. (59) Ma, W.; Kuang, H.; Wang, L.; Xu, L.; Chang, W.-S.; Zhang, H.; Sun, M.; Zhu, Y.; Zhao, Y.; Liu, L.; Xu, C.; Link, S.; Kotov, N. A. Chiral plasmonics of self-assembled nanorod dimers. Sci. Rep. 2013, 3, 1934. (60) Kuzyk, A.; Schreiber, R.; Zhang, H.; Govorov, A. O.; Liedl, T.; Liu, N. Reconfigurable 3D plasmonic metamolecules. Nature materials 2014, 13, 862-866. (61) Yan, W.; Ma, W.; Kuang, H.; Liu, L.; Wang, L.; Xu, L.; Xu, C. Plasmonic Chirogenesis from Gold Nanoparticles Superstructures. J. Phy. Chem. C 2013. (62) Bao, Z. Y.; Zhang, W.; Zhang, Y.-L.; He, J.; Dai, J.; Yeung, C.-T.; Law, G.-L.; Lei, D. Y. Interband Absorption Enhanced Optical Activity in Discrete Au@Ag Core–Shell Nanocuboids: Probing Extended Helical Conformation of Chemisorbed Cysteine Molecules. Angew. Chem. Int. Ed. 2017, 56, 1283-1288. (63) Sun, M.; Xu, L.; Fu, P.; Wu, X.; Kuang, H.; Liu, L.; Xu, C. Scissor-Like Chiral Metamolecules for Probing Intracellular Telomerase Activity. Adv. Funct. Mater. 2016, 26, 7352-7358. (64) Zhu, Z.; Guo, J.; Liu, W.; Li, Z.; Han, B.; Zhang, W.; Tang, Z. Controllable Optical Activity of Gold Nanorod and Chiral Quantum Dot Assemblies. Angew. Chem. Int. Ed. 2013, 52, 13571-13575. (65) Kuzyk, A.; Schreiber, R.; Fan, Z.; Pardatscher, G.; Roller, E. M.; Hogele, A.; Simmel, F. C.; Govorov, A. O.; Liedl, T. DNA-based self-assembly of chiral plasmonic nanostructures with tailored optical response. Nature 2012, 483, 311-314. (66) Zhao, Y.; Yang, Y.; Zhao, J.; Weng, P.; Pang, Q.; Song, Q. Dynamic Chiral Nanoparticle Assemblies and Specific Chiroplasmonic Analysis of Cancer Cells. Adv. Mater. 2016, 28, 4877-4883. (67) Zhao, Y.; Xu, L.; Ma, W.; Liu, L.; Wang, L.; Kuang, H.; Xu, C. Shell-Programmed Au Nanoparticle Heterodimers with Customized Chiroptical Activity. Small 2014, 10, 4770-4777. (68) Busson, M. P.; Rolly, B.; Stout, B.; Bonod, N.; Wenger, J.; Bidault, S. Photonic engineering 16

ACS Paragon Plus Environment

Page 16 of 23

Page 17 of 23

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 Journal of Physical Chemistry Letters

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

of hybrid metal-organic chromophores. Angew. Chem. Int. Ed. 2012, 51, 11083-11087. (69) Acuna, G. P.; Moller, F. M.; Holzmeister, P.; Beater, S.; Lalkens, B.; Tinnefeld, P. Fluorescence enhancement at docking sites of DNA-directed self-assembled nanoantennas. Science 2012, 338, 506-510. (70) Bidault, S.; Devilez, A.; Maillard, V.; Lermusiaux, L.; Guigner, J. M.; Bonod, N.; Wenger, J. Picosecond Lifetimes with High Quantum Yields from Single-Photon-Emitting Colloidal Nanostructures at Room Temperature. ACS Nano 2016, 10, 4806-4815. (71) Vietz, C.; Kaminska, I.; Sanz Paz, M.; Tinnefeld, P.; Acuna, G. P. Broadband Fluorescence Enhancement with Self-Assembled Silver Nanoparticle Optical Antennas. ACS Nano 2017, 11, 4969-4975. (72) Li, G.-C.; Zhang, Y.-L.; Jiang, J.; Luo, Y.; Lei, D. Y. Metal-Substrate-Mediated Plasmon Hybridization in a Nanoparticle Dimer for Photoluminescence Line-Width Shrinking and Intensity Enhancement. ACS Nano 2017, 11, 3067-3080. (73) Li, G.-C.; Zhang, Y.-L.; Lei, D. Y. Hybrid plasmonic gap modes in metal film-coupled dimers and their physical origins revealed by polarization resolved dark field spectroscopy. Nanoscale 2016, 8, 7119-7126. (74) Wang, D.; Li, Y.; Lin, Z.; Qiu, B.; Guo, L. Surface-Enhanced Electrochemiluminescence of Ru@SiO2 for Ultrasensitive Detection of Carcinoembryonic Antigen. Anal. Chem. 2015, 87, 5966-5972. (75) Wang, D.; Guo, L.; Huang, R.; Qiu, B.; Lin, Z.; Chen, G. Surface enhanced electrochemiluminescence of Ru(bpy)3(2+). Sci. Rep. 2015, 5, 7954. (76) Zhou, H.; Han, T.; Wei, Q.; Zhang, S. Efficient Enhancement of Electrochemiluminescence from Cadmium Sulfide Quantum Dots by Glucose Oxidase Mimicking Gold Nanoparticles for Highly Sensitive Assay of Methyltransferase Activity. Anal. Chem. 2016, 88, 2976-2983. (77) Wang, J.; Shan, Y.; Zhao, W. W.; Xu, J. J.; Chen, H. Y. Gold nanoparticle enhanced electrochemiluminescence of CdS thin films for ultrasensitive thrombin detection. Anal. Chem. 2011, 83, 4004-4011. (78) Li, M. X.; Zhao, W.; Qian, G. S.; Feng, Q. M.; Xu, J. J.; Chen, H. Y. Distance mediated electrochemiluminescence enhancement of CdS thin films induced by the plasmon coupling of gold nanoparticle dimers. Chem. Commun. 2016, 52, 14230-14233.

17

ACS Paragon Plus Environment

The Journal of Physical Chemistry Letters

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

1

Captions:

2 3 4 5 6 7 8 9

Figure 1. (a) Y-shaped DNA duplex driven Au NP homodimers.11 (b) Scheme of DNA-directed assembly of Au

NR-NP heterodimers.13 (c) Schematics of DNA-driven self-assembled QD dimers, Au NP-QD dimers, and Ag NP-QD dimers.14 (d) TEM image and schematic representation of the experimental procedure of DNA origami driven Au NP homodimers.19 (e) Schematic illustration and TEM images of Au NR dimers assembled by quasi-2D DNA origami.20 (f-g) Schematic illustration of PCR-assembled Au NP heterodimers and the corresponding TEM image.25 (h-i) Schematic illustration of PCR-assembled Au NR dimers and the corresponding TEM image.59

10

18

ACS Paragon Plus Environment

Page 18 of 23

Page 19 of 23

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 Journal of Physical Chemistry Letters

1 2 3 4 5 6 7

Figure 2. (a) Self-assembled Au nanostar dimers based on the Hg2+ mediated T-T base pair of ssDNA.28

(b) ATP

aptamer driven Au NP heterodimers.30 (c) Illustration of antibody-antigen mediated Au NP dimers.35 (d) Schematic illustration of antibody-antigen driven Au NP-Ag NP dimers depending on competitive immunorecognition and sandwich immunoassay modes.26 (e) Self-assembly of Au NRs induced by GSH.37 (f) Schematic representation of cysteine driven Au NP heterodimers.38

19

ACS Paragon Plus Environment

The Journal of Physical Chemistry Letters

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

1 2 3 4 5 6 7

Figure 3. (a) Schematic, calculated EM field views and TEM images of various Au-Ag dimers with various neck

junction morphologies.41 (b) Schematic representation of the target-programmed NP dimerization and thus Raman enhancement in situ.48 (c) SERS measurements of a thin layer of Rhodamine 6G adsorbed onto Au NP dimers.49 (d) DNA origami based Au-Ag core-shell NP dimers with single-molecule SERS sensitivity.52 (e) SERS signal of NP dimers dispersed on a dielectric support and Au support.53

20

ACS Paragon Plus Environment

Page 20 of 23

Page 21 of 23

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 Journal of Physical Chemistry Letters

1 2 3 4 5 6 7 8 9

Figure 4. (a) Schematic illustration and CD spectra of DNA origami template driven Au NR dimers.57 (b) CD

spectra of the bifacial DNA origami-directed 3D plasmonic Au NR dimers.58 (c) CD spectra of PCR-based Au NR dimers assembled by side-by-side and end-to-end patterns.23 (d) CD and UV-vis spectra of Au NP heterodimers triggered by DNA with different interparticle distance and sizes of NPs.61 (e) CD and UV-vis spectra of Au NR-Au NP heterodimers with different sizes of Au NPs and aspect ratio of Au NRs.13 (f) CD and UV-vis spectra of Au NP-Ag NP heterodimers bridged by antibody-antigen complex.26 (g) CD and UV-vis spectra of QD dimers, Au NP-QD dimers and Ag NP-QD dimers.14

21

ACS Paragon Plus Environment

The Journal of Physical Chemistry Letters

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

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Figure 5. (a) Tuning of CD spectra of self-assembled Au NP helices by metal composition.65 (b) Dynamic CD and

UV-vis spectra of Ag NP assemblies after Au shell deposition.66 (c-d) Tailored CD and UV-vis spectra of Au NP heterodimers after Ag shell and Au shell deposition. Samples 1-8: Au NP heterodimers made by addition of 0, 5, 10, 20, 30, 50, 70, and 100 µL solution of 1 mM AgNO3. Samples 9-13: Au NP heterodimers made by addition of 5, 10, 20, 30, and 50 µL solution of 5 mM HAuCl4. (e-f) Scanning TEM-EDX elemental map, and CD and UV-vis spectra of double shell heterodimers. Samples 1-5: double shell Au NP heterodimers made by addition of 5, 30, 50, 70, and 100 µL of solution of 1 mM AgNO3 and then 0.8, 3, 5, 6, and 8 µL of solution of 5 mM HAuCl4. Samples 6-10, double shell Au NP heterodimers made by addition of 5, 10, 20, 30, and 50 µL solution of 5 mM HAuCl4 and then 5, 10, 30, 40, and 50 µL solution of 1 mM AgNO3.25 (g) CD spectra of Au@Ag core-shell NP heterodimers with the same interparticle gaps and increasing shell thickness. Sample 1-8, heterodimers assembled from Au NPs deposited with a Ag shell from 70, 100, 150, 200, 250, 300, 400, and 500 µL AgNO3 solution.67 (h) Au@Ag NR dimers with different Ag shell thickness by adding various concentrations of AgNO3 in the range of 0 to 10 mM.32

22

ACS Paragon Plus Environment

Page 22 of 23

Page 23 of 23

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 Journal of Physical Chemistry Letters

1 2 3 4 5 6 7 8 9

Figure 6. (a) Sketch of the DNA origami pillar with two Au NPs forming a dimer, and the numerical simulation of

electric field intensity for 80 nm Au NP and dimers with interparticle spacing of 23 nm.69 (b) Schematic representation and the fluorescence enhancement of the three considered DNA-templated Au NP dimers featuring one fluorescent emitter.70 (c) Sketch of the dimer consisting of two 80 nm Ag NPs (spherical structures in gray) attached to a DNA origami pillar, and the numerical simulations of the absorption and scattering cross sections for 100 nm Au NP dimers and 80 nm Ag NP dimers.71 (d) ECL aptamer sensing platform based on energy transfer between CdS QDs and Au NPs.77 (e) Schematic illustration of the plasmonic Au NPs and Au NP dimers enhanced ECL platform.78

10

23

ACS Paragon Plus Environment