Energy Transfer between Semiconducting Polymer Dots and Gold

Mar 12, 2018 - State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Science, School...
0 downloads 9 Views 635KB Size
Subscriber access provided by UNIV OF DURHAM

Energy Transfer between Semiconducting Polymer Dots and Gold Nanoparticles in a Photoelectrochemical System: A Case Application for Cathodic Bioanalysis xiaomei shi, Li-Ping Mei, Qian Wang, Wei-Wei Zhao, Jing-Juan Xu, and Hong-Yuan Chen Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.analchem.8b00839 • Publication Date (Web): 12 Mar 2018 Downloaded from http://pubs.acs.org on March 12, 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 15 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

Energy Transfer between Semiconducting Polymer Dots and Gold Nanoparticles in a Photoelectrochemical System: A Case Application for Cathodic Bioanalysis Xiao-Mei Shi,† Li-Ping Mei,† Qian Wang,† Wei-Wei Zhao,*,†,‡ Jing-Juan Xu† and Hong-Yuan Chen*,† †

State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of

Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China. ‡

Department of Materials Science and Engineering, Stanford University, Stanford, California 94305,

United States

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

ACS Paragon Plus Environment

1

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

Page 2 of 15

Abstract: We report herein the energy transfer (ET) between semiconducting polymer dots (Pdots) and gold nanoparticles (Au NPs) in a photoelectrochemical (PEC) system and its feasibility for cathodic bioanalysis application. Specifically, COOH-capped Pdots were firstly fabricated and then assembled onto the indium-tin oxide (ITO) surface, followed by the modification of single-strand (ss) DNA probe (pDNA). After the DNA hybridization with the Au NP-tethered complementary ssDNA (Au NP-tDNA), the Au NPs were brought into the close proximity of Pdots. Upon light stimulation, photoluminescence (PL) was annihilated, fluorescence was attenuated and the photocurrent intensity was evidently decreased. This ET-based PEC DNA sensor exhibited a linear range from 1 fM to 10 pM with a detection limit of 0.97 fM at a signal-to-noise ratio of 3. The present work first exploited the ET between Pdots and Au NPs, and we believe this phenomenon will spark new interest in the study of various Pdots-based ET-influenced PEC systems and thus catalyze increasing studies for specific bioanalytical purposes.

Keywords: Photoelectrochemical; Bioanalysis; Energy Transfer; Polymer Dots; Au Nanoparticles

ACS Paragon Plus Environment

2

Page 3 of 15 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

We report herein the energy transfer (ET) between semiconducting polymer dots (Pdots) and gold nanoparticles (Au NPs) in a photoelectrochemical (PEC) system and its feasibility for cathodic PEC bioanalysis application.1-18 Different from anodic bioanalysis, the intrinsic electron reduction reaction occurs at the photocathode/electrolyte interface, which makes the absorbed reductive molecules have no influence on the reduction reaction, resulting in good anti-interference to reductive agents in the samples.19 Previously, we have observed the unique interparticle interplay between the photoactivated quantum dots (QDs) and noble metal (Au or Ag) NPs in the PEC nanosystem.13,14 The optical spectral overlap makes possible the simultaneous activation of these particles, and the stimulated surface plasmon resonance (SPR) and local electric fields thereby could regulate the excitonic responses in the QDs.13,14,20 This phenomenon promptly ignited increasing interest among the community and the research on ET-based PEC bioanalysis has since been actively pursued.21-30 For example, enhanced resonance ET between reduced grapheme oxide (RGO)-Au NPs and CdTe QDs enables its use for different target molecules,27 the strong exciton energy transfer (EET) effect of Au NPs and CdSe QDs was applied in the highly sensitive detection of DNA methyltransferase (MTase).28 Recently, our group also utilized the TATA-binding protein to bend the Au NPs capped DNA sequence to affect the interparticle distance and then triggered the transition of the interplay from the CdS QDs-Au NPs to the CdS QDs-Ag NPs systems by a catalytic Ag deposition process.29 Despite these progress, the exploitation in this area is still in its infancy. Typically, the existing reports are all limited in the identical systems consisted of various QDs and noble metal NPs. At current stage, achieving advanced protocols for ET-based PEC bioanalysis remains a challenge. Semiconducting polymer dots (Pdots) is a new family of functional nanomaterials that possess extraordinary properties in terms of readily tailored electrical and optical properties, facile surface functionalization, easy processability of polymers, and excellent photostability.31-34 Especially, as compared to the QDs, Pdots have high biocompatibility and minimal toxicity (no potential leakage of toxic metal ions).33-35 We recently also studied their light-harvesting property and exploited their ACS Paragon Plus Environment

3

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

Page 4 of 15

applicability for PEC bioanalysis.36 Notably, these conjugated Pdots also demonstrated ET properties within themselves.37-39 One question is then naturally raised: is there any interplay between adjacent Pdots and noble metal NPs? We assume that Pdots present an ideal element to support analogous interparticle interaction. Unfortunately, such a possibility has not been unveiled. Scheme 1. Schematic Mechanism of the Operating Pdots-Au NPs based PEC System

To verify the hypothesis, we prepared the tetraphenylporphyrin (TPP)-doped conjugated polymer poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1′,3}-thiadazole)]

(PFBT)

Pdots

(TPP-doped

PFBT Pdots, hereafter briefed as Pdots) and constructed the Au NPs-Pdots model system via the doublestranded (ds) DNA bridging on an indium tin oxide (ITO) platform (see Supporting Information for experimental details and the Table S1 for the DNA sequences). ET process in this cathodic PEC system was illustrated in Scheme 1, which will be discussed later. Comparing to previous studies, the major discovery here was that the presence of Au NPs in the proximity of Pdots could cause the reduction of cathodic photocurrent of the Pdots, the phenomenon of which and its bioanalysis application have not been report to our knowledge. More importantly, given the significant advantage of photocathodic bioanalysis as compared to the well-established photoanodic bioanalysis,11,12 this work will present a different perspective for the general development of Pdots and energy-transfer based photocathodic bioanalysis. RESULTS AND DISCUSSION

ACS Paragon Plus Environment

4

Page 5 of 15 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

The synthesis process of the Pdots was shown in Scheme S1. Figure 1a shows typical transmission electron microscopy (TEM) image of the prepared Pdots, the particles were quasi-spherical with the general diameter of ~3 nm, which was beneficial for the formation of uniform photo-responsive film and thus steady signals. Figure 1b shows the normalized absorption and emission spectra of the Pdots. The UV-vis absorption spectrum of the Pdots was measured by optical spectroscopy (black curve). It can be observed that the it had a dominant absorption in the range from 400 to 500 nm. The fluorescence of the Pdots was measured in a clear flat-bottom 96-well plate and was monitored from 500 to 750 nm with excitation of 450 nm (red curve). The red emission at 675 nm and the shoulder peak at 725 nm were attributed to the characteristic emission of the TPP dopants, while the small emission peak at 550 nm was assigned to the emission of the pure PFBT polymer, which was significantly quenched in the presence of TPP dopants due to the dominant exciton ET from the polymer backbone to the doped TPP.40 Figure S1 represents photograph and fluorescence images of the Pdots under a 365 nm UV-lamp excitation. Figure 1c shows the typical image of the Au NPs. The diameter of Au NPs was about 5 nm with a homogeneous distribution. As depicted in Figure 1d, the absorption peak of the Au NPs aroused by the SPR was at 512 nm (blue curve). The target DNA exhibited a typical absorption peak at 260 nm (black curve). Besides, compared to Au NPs, the absorption of Au NP-tDNA exhibited a red-shifted peak at 528 nm (red curve), which was because the covalent connection of tDNA on Au NPs strengthened the trend of aggregation of Au NPs.41

Figure 1. .(a) TEM image of the Pdots. (b) The optical spectra of Pdot, the black and red lines represent the UV-vis absorption and PL spectrum (with excitation wavelength of 450 nm), respectively. (c) TEM ACS Paragon Plus Environment

5

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

Page 6 of 15

image of Au NPs. (d) UV-vis absorption spectra of ssDNA sequence (black), Au NPs (blue), and Au NP-tDNA (red). (e) PL spectra of the Pdots/pDNA solution (55 nM Pdots, 60 nM Au NPs in 10 mM Tris-HCl) before (black) and after (red) addition of 1 µM Au NP-tDNA. (f) Fluorescence image of the Pdots/pDNA/MEA electrodes. (g) Fluorescence image of the Pdots/pDNA/Au NP-tDNA. Besides, Figure S2 shows the photoluminescence (PL) spectrum of the Pdots with corresponding discussion. The ET efficiency was also verified by PL spectrum (the concentrations of all the pDNA and tDNA were 1 µM), as shown in Figure 1e. In the absence of Au NP-tDNA, pDNA and Au NP-tDNA are not capable of hybridization in the aqueous solution. In this case, Pdots/pDNA will exhibit higher fluorescence intensity under an excitation laser (black curve). When Au NP-tDNA is present, DNA hybridization will occur. As a result, the Pdots and Au NPs will be brought into close proximity, which enables quenching of the fluorescence emission of the Pdots (red curve). It was validated that the ET between excited Pdots and Au NPs was generated, and it was further verified by fluorescence imaging. The brightness change of the fluorescence during the fabrication process was recorded as shown in Figure 1f and 1g, the fluorescence of Pdots/pDNA/monoethanolamine (MEA) modified substrate was bright. After Au NP-tDNA incubation, the brightness of the Pdots/pDNA/MEA diminished remarkably after the hybridization with Au NP-tDNA, which was attributed to the ET between excited Pdots and Au NPs. Particularly, this quenching of fluorescence could be verified by visual examination. Figure 2a records the signal responses of the fabrication process of the proposed system under the 450 nm intermittent light excitation. After the Pdots were modified onto the electrode, the signal increased significantly (curve I), which was ascribed to fast charge separation in Pdots and the good electrical communication between the electrode and Pdots. The photocurrent intensity decreased in order after the immobilization of pDNA and MEA (curve II), which was attributed to the weak charge-transfer efficiency of DNA sequence and MEA molecules. Compared with bare tDNA (curve IV), the photocurrent intensity exhibited a more evident decrease after the hybridization between pDNA and Au NP-tDNA (curve III), which was resulted from the fully generated electron-hole pair recombination caused by plasmon enhancement and exciton ET.14 The experiment hybridizing pDNA with SiO2 NPstDNA was performed as a contrast, the employed SiO2 NPs (average particle diameter ca. 5 nm) could neither absorb light nor permit electron conduction, but can generate analogous steric effect. The 6 ACS Paragon Plus Environment

Page 7 of 15 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

photocurrent displayed a greater decrease (curve V), which was mainly ascribed to the increased steric hindrance for the mass diffusion to the electrode surface. As reported previously, when the QDs and Au NPs were in close contact, photoexcited electrons were transferred between the two particles, which increased the photocurrent.42 The fabrication of similar close particles was shown in Figure S3. The Au NP-tDNA hybridization exhibited higher photocurrent reduction than SiO2 NPs-tDNA hybridization, which indicated the high decrease should be attributed to the ET rather than other factors. On the basis of the above results, the mechanism is proposed as follows. Once the Pdots were excited (step 1), the electrons will be excited from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) (step 2). Then, some of these LUMO electron will transfer to solution dissolved O2 to generate cathodic signal (step 3), with the simultaneous neutralization of HOMO holes by the electrons supplied by the electrode (step 4). Other LUMO electron will recombine with HOMO holes via either non-irradiative decay route (step 5) or radiative decay route (step 6). Due to the overlap between the emission spectrum of the Pdots and the plasmonic resonance spectrum of Au NPs, the emission of Pdots could induce the surface plasmon resonance (SPR) of the nearby Au NPs, the effect of which could then affect the response of Pdots via promoting the radiative decay (steps 7 and 8). Different from radiative decay, the non-irradiative decay rate due to energy depletion can also be enhanced by proximal Au NPs via the effects of fluorescence resonance ET (step 9) and exciton ET (step 10). In present PEC platform, both steps 5 and 6 will cooperatively compete with step 4. In other words, the final signal intensity was determined by the combined effect against Pdots. In brief, this quenching effect could be attributed to two factors43: i) promotion of the quenching effect by ET within the Pdots and then the rapid internal ET to the sites near the Au NPs. ii) Au NPs could quench the fluorescence efficiently through long-range ET process. Besides, as shown in Figure 2b, the PEC test was conducted repeatedly with 10 fM target DNA and the photocurrent intensity was almost unchanged, indicating the operational stability for signal acquisition. Since the quenching degree was related to the target concentration, a new PEC DNA bioanalysis can be achieved by monitoring the photocurrent signal. Figure 2c shows the variation of the ACS Paragon Plus Environment

7

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

Page 8 of 15

signals with the target concentration from 0 fM to 10 nM. The signal reduction elevated with the increased target concentration, suggesting the quenching effect-influenced responses of Pdots in the proposed system. As shown in Figure 2d, the signal decrease was linear with the target concentration from 1.0 fM to 10 pM and a low detection limit of 0.97 fM. Specifically, the linear range was wider than 1 µM to 100 µM44 and 0.01 pM to 1 nM45 by previous electrochemical reports. The detection limit was also lower than 0.12 pM by the electrochemical method46 and 17.4 nM by the fluorescence method.47 Table S2 lists the comparison of PEC methods for DNA detection. Future work will emphasize the optimization of the experimental conditions with the aim to improve the analytical performance.

Figure 2. (a) Photocurrent responses in 0.1 M Tris-HCl (pH 7.0) of (I) the Pdots/ITO, (II) after pDNA immobilization and MEA blocking, further hybridization with (III) Au NP-tDNA, (IV) bare tDNA and (V) SiO2 NPs-tDNA (b) Photocurrent responses against 10 fM tDNA. (c) Effect of different concentrations of target DNA (0, 0.5, 1, 5, 10, 100, 1000 fM and 5 pM, 10 pM, 1000 pM and 10 nM) on the signal strength. (d) The derived calibration plot (∆I = I0-I, I0 and I are the photocurrents of the Pdots/pDNA/MEA electrode prior to and after hybridization). CONCLUSIONS In summary, we first exploited and confirmed the ET between semiconducting Pdots and Au NPs and applied it for photocathodic bioanalysis application. Since the emission spectra of Pdots overlapped with the plasmonic resonance spectrum of Au NPs, the Au NPs could serve as an efficient energy acceptor in such a system. The efficient quenching of Pdots produced by Au NPs underlies a new and general PEC

ACS Paragon Plus Environment

8

Page 9 of 15 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

bioanalysis format that could be extended for the transduction of various biological recognition events such as in PEC aptasensing or immunoassay. ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.analchem.xxxxxxx. Experimental section; Photograph and fluorescence image of the TPP-doped PFBT Pdots; Standard spectra of TPP-doped PFBT Pdots and Au NPs; Characterization of Au NPs/TPP-doped PFBT Pdots hybrid system via PDDA; Comparison of PEC methods for DNA detection (PDF) AUTHOR INFORMATION Corresponding Authors *E-mail: [email protected]; [email protected] *E-mail: [email protected] Notes The authors declare no competing financial interest. ACKNOWLEDGMENT Financial support from the National Natural Science Foundation of China (Grant nos. 21327902 and 21675080), and the Natural Science Foundation of Jiangsu Province (Grant BK20170073) is appreciated. This work was also supported by a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions. REFERENCES (1) Zhao, W. W.; Xu, J. J.; Chen, H. Y. Photoelectrochemical bioanalysis: the state of the art. Chem. Soc. Rev. 2015, 44, 729-741. (2) Zhao, W. W.; Xu, J. J.; Chen, H. Y. Photoelectrochemical immunoassays. Anal. Chem. 2018, 90, ACS Paragon Plus Environment

9

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

Page 10 of 15

615-627. (3) Zhao, W. W.; Xu, J. J.; Chen, H. Y. Photoelectrochemical aptasensing. Trends Anal. Chem. 2016, 82, 307-315. (4) Shu, J.; Qiu, Z.; Lin, Z.; Cai, G.; Yang, H. H.; Tang, D. P. Semiautomated support photoelectrochemical immunosensing platform for portable and high-throughput immunoassay based on Au nanocrystal decorated specific crystal facets BiVO4 photoanode. Anal. Chem. 2016, 88, 1253912546. (5) Freeman, R.; Girsh, J.; Willner, I. Nucleic Acid/quantum dots (QDs) hybrid systems for optical and photoelectrochemical sensing. ACS Appl. Mater. Interfaces 2013, 5, 2815-2834. (6) Zhao, W. W.; Xu, J. J.; Chen, H. Y. Photoelectrochemical DNA biosensors. Chem. Rev. 2014, 114, 7421-7441. (7) Zhao, W. W.; Wang, J.; Zhu, Y. C.; Xu, J. J.; Chen, H. Y. Quantum Dots: electrochemiluminescent and photoelectrochemical bioanalysis. Anal. Chem. 2015, 87, 9520-9531. (8) Zhou, H.; Liu, J.; Zhang, S. S. Quantum dot-based photoelectric conversion for biosensing applications. Trends Anal. Chem. 2015, 67, 56-73. (9) Zhang, N.; Zhang, L.; Ruan, Y. F.; Zhao, W.W.; Xu, J. J.; Chen, H. Y. Quantum-dots-based photoelectrochemical bioanalysis highlighted with recent examples. Biosens. Bioelectron. 2017, 94, 207-218. (10) Li, L.; Zhang, Y.; Zhang, L. N.; Ge, S. G.; Liu, H. Y.; Ren, N.; Yan, M.; Yu, J. H. Paper-based device for colorimetric and photoelectrochemical quantification of the Flux of H2O2 releasing from MCF-7 cancer cells. Anal. Chem. 2016, 88, 5369-5377. (11) Yan, K.; Liu, Y.; Yang, Y.; Zhang, J. D. A cathodic “signal-off” photoelectrochemical aptasensor for ultrasensitive and selective detection of oxytetracycline. Anal. Chem. 2015, 87, 12215-12220. (12) Dai, W. X.; Zhang, L.; Zhao, W. W.; Yu, X. D.; Xu, J. J.; Chen, H. Y. Hybrid PbS quantum dot/nanoporous NiO film nanostructure: preparation, characterization, and application for a selfpowered cathodic photoelectrochemical biosensor. Anal. Chem. 2017, 89, 8070-8078. ACS Paragon Plus Environment

10

Page 11 of 15 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

(13) Zhao, W. W.; Wang, J.; Xu, J. J.; Chen, H. Y. Energy transfer between CdS quantum dots and Au nanoparticles in photoelectrochemical detection. Chem. Commun. 2011, 47, 10990-10992. (14) Zhao, W. W.; Yu, P. P.; Shan, Y.; Wang, J.; Xu, J. J.; Chen, H. Y. Exciton-plasmon interactions between CdS quantum dots and Ag nanoparticles in photoelectrochemical system and its biosensing application. Anal. Chem. 2012, 84, 5892-5897. (15) Wang, L. N.; Ma, W. G.; Gan, S. Y.; Han, D. X.; Zhang, Q. X.; Niu, L. Engineered photoelectrochemical platform for rational global antioxidant capacity evaluation based on ultrasensitive sulfonated graphene–TiO2 nanohybrid. Anal. Chem. 2014, 86, 10171-10178. (16) Chen, D.; Zhang, H.; Li, X.; Li, J. H. Biofunctional titania nanotubes for visible-light-activated photoelectrochemical biosensing. Anal. Chem. 2010, 82, 2253-2261. (17) Tang, J.; Li, J.; Da, P. M.; Wang, Y. C.; Zheng, G. F. Solar-energy-driven photoelectrochemical biosensing using TiO2 nanowires. Chem. Eur. J. 2015, 21, 11288-11299. (18) Hao, N.; Zhang, Y.; Zhong, H.; Zhou, Z.; Hua, R.; Qian, J.; Liu, Q.; Li, H. N; Wang, K. Design of a dual channel self-reference photoelectrochemical biosensor. Anal. Chem. 2017, 89, 10133-10136. (19) Fan, G. C.; Shi, X. M.; Zhang, J. R.; Zhu, J. J. Cathode photoelectrochemical immunosensing platform integrating photocathode with photoanode. Anal. Chem. 2016, 88, 10352-10356. (20) Kulakovich, O.; Strekal, N.; Yaroshevich, A.; Maskevich, S.; Gaponenko, S.; Nabiev, I.; Woggon, U.; Artemyev, M. Enhanced luminescence of CdSe quantum dots on gold colloids. Nano Lett. 2002, 2, 1449-1452. (21) Zang, Y.; Lei, J. P.; Hao, Q.; Ju, H. X. “Signal-on” photoelectrochemical sensing strategy based on target-dependent aptamer conformational conversion for selective detection of lead(II) ion. ACS Appl. Mater. Interfaces 2014, 6, 15991-15997. (22) Zhang, X. R.; Xu, Y. P.; Yang, Y. Q.; Jin, X.; Ye, S. J.; Zhang, S. S.; J, L. L. A new signal-on photoelectrochemical biosensor based on a graphene/quantum-dot nanocomposite amplified by the dualquenched effect of bipyridinium relay and AuNPs. Chem. Eur. J. 2012, 18, 16411-16418. (23) Chen, J. J.; Fan, G. C.; Shi, X. M.; Zhu, J. J. Signal-on photoelectrochemical aptasensor amplified ACS Paragon Plus Environment

11

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

Page 12 of 15

by exciton energy transfer and exonuclease-aided target recycling. ChemElectroChem 2017, 4, 927-934. (24) Fan, G. C.; Zhu, H.; Shen, Q. M.; Han, L.; Zhao, M.; Zhang, J. R.; Zhu, J. J. Enhanced photoelectrochemical aptasensing platform based on exciton energy transfer between CdSeTe alloyed quantum dots and SiO2@Au nanocomposites. Chem. Commun. 2015, 51, 7023-7026. (25) Wang, Bin.; Dong, Y. X.; Wang, Y. L.; Cao, J. T.; Ma, S. H.; Liu, Y. M. Quenching effect of exciton energy transfer from CdS:Mn to Au nanoparticles: a highly efficient photoelectrochemical strategy for microRNA-21 detection. Sens, Actuators, B 2018, 254, 159-165. (26) Zhao, M.; Fan, G. C.; Chen, J. J.; Shi, J. J.; Zhu, J. J. Highly sensitive and selective photoelectrochemical biosensor for Hg2+ detection based on dual signal amplification by exciton energy transfer coupled with sensitization effect. Anal. Chem. 2015, 87, 12340-12347. (27) Zeng, X. X.; Ma, S. S.; Bao, J. C.; Tu, W. W.; Dai, Z. H. Using graphene-based plasmonic nanocomposites to quench energy from quantum dots for signal-on photoelectrochemical aptasensing. Anal. Chem. 2013, 85, 11720-11724. (28) Shen, Q. M.; Han, L.; Fan, G. C.; Abdel, E. S.; Jiang, L. P.; Zhu, J. J. Highly sensitive photoelectrochemical assay for DNA methyltransferase activity and inhibitor screening by exciton energy transfer coupled with enzyme cleavage biosensing strategy. Biosens. Bioelectron. 2015, 64, 449455. (29) Ma, Z. Y.; Xu, F.; Qin, Y.; Zhao, W. W.; Xu, J. J.; Chen, H. Y. Invoking direct exciton–plasmon interactions by catalytic Ag deposition on Au nanoparticles: photoelectrochemical bioanalysis with high efficiency. Anal. Chem. 2016, 88, 4183-4187. (30) Dong, Y. X.; Cao, J. T.; Wang, B.; Ma, S. H.; Liu, Y. M. Exciton–plasmon interactions between CdS@g-C3N4 heterojunction and Au@Ag nanoparticles coupled with DNAase-triggered signal amplification: toward highly sensitive photoelectrochemical bioanalysis of MicroRNA. ACS Sustainable Chem. Eng. 2017, 5, 10840-10848.

ACS Paragon Plus Environment

12

Page 13 of 15 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

(31) Wang, L.; Fernandez-Teran, R.; Zhang, L.; Fernandes, D. L.; Tian, L.; Chen, H.; Tian, H. Organic polymer dots as photocatalysts for visible light-driven hydrogen generation. Angew. Chem., Int. Ed. 2016, 55, 12306-12310. (32) Liu, H. Y.; Wu, P. J.; Kuo, S. Y.; Chen, C. P.; Chang, E. H.; Wu, C. Y.; Chan, Y. H. Quinoxalinebased polymer dots with ultrabright red to near-infrared fluorescence for in vivo biological imaging. J. Am. Chem. Soc. 2015, 137, 10420-10429. (33) Wu, C.; Chiu, D. T. Highly fluorescent semiconducting polymer dots for biology and medicine. Angew. Chem., Int. Ed. 2013, 52, 3086-3109. (34) Koner, A. L.; Krndija, D.; Hou, Q.; Sherratt, D. J.; Howarth, M. Hydroxy-terminated conjugated polymer nanoparticles have near-unity bright fraction and reveal cholesterol-dependence of IGF1R nanodomains. ACS Nano 2013, 7, 1137-1144. (35) Zhang, X. J.; Yu, J. B.; Wu, C. F.; Jin, Y. H.; Rong, Y.; Ye, F. M.; Chiu, D. T. Importance of having low-density functional groups for generating high-performance semiconducting polymer dots. ACS Nano 2012, 6, 5429-5439. (36) Li, Y.; Zhang, N.; Zhao, W. W.; Jiang, D. C.; Xu, J. J.; Chen, H. Y. Polymer dots for photoelectrochemical bioanalysis. Anal. Chem. 2017, 89, 4945-4950. (37) Wu, P. J.; Kuo, S. Y.; Huang, Y. C.; Chen, C. P.; Chan, Y. H. Polydiacetylene-enclosed nearinfrared fluorescent semiconducting polymer dots for bioimaging and sensing. Anal. Chem. 2014, 86, 4831-4839. (38) Tian, Z.; Yu, J.; Wu, C.; Szymanski, C.; McNeill, J. Amplified energy transfer in conjugated polymer nanoparticle tags and sensors. Nanoscale 2010, 2, 1999-2011. (39) Sun, J.; Wang, S.; Gao, F. Covalent surface functionalization of semiconducting polymer dots with β-cyclodextrin for fluorescent ratiometric assay of cholesterol through host–guest inclusion and FRET. Langmuir. 2016, 32, 12725-12731.

ACS Paragon Plus Environment

13

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

Page 14 of 15

(40) Li, S.; Chang, K.; Sun, K.; Tang, Y.; Cui, N.; Wang, Y.; Qin, W.; Xu, H.; Wu, C. Amplified singlet oxygen generation in semiconductor polymer dots for photodynamic cancer therapy. ACS Appl. Mater. Interfaces 2016, 8, 3624-3634. (41) Haiss, W.; Thanh, N. T. K.; Aveyard, J.; Fernig, D. G. Determination of size and concentration of gold nanoparticles from UV−Vis spectra. Anal. Chem. 2007, 79, 4215-4221. (42) Sheeney-Haj-Ichia, L.; Pogorelova, S.; Gofer, Y.; Willner, I. Enhanced photoelectrochemistry in CdS/Au nanoparticle bilayers. Adv. Funct. Mater. 2004, 14, 416-424. (43) Fan, C. H.; Wang, S.; Hong, J. W.; Bazan, G. C.; Plaxco, K. W.; Heeger, A. J. Beyond superquenching: hyper-efficient energy transfer from conjugated polymers to gold nanoparticles. Proc. Natl. Acad. Sci. U.S.A. 2003, 100, 6297-6301. (44) Singhal, C.; Pundir, C. S.; Narang, J. A genosensor for detection of consensus DNA sequence of dengue virus using ZnO/Pt-Pd nanocomposites. Biosens. Bioelectron. 2017, 97, 75-82. (45) Hui, N.; Sun, X. T.; Niu, S. Y.; Luo, X. L. PEGylated polyaniline nanofibers: antifouling and conducting biomaterial for electrochemical DNA sensing. ACS Appl. Mater. Interfaces 2017, 9, 29142923. (46) Ruiz-Valdepeñas Montiel, V.; Gutiérrez, M. L.; Torrente-Rodríguez, R. M.; Povedano, E.; Vargas, E.; Reviejo, Á. J.; Linacero, R.; Gallego, F. J.; Campuzano, S.; Pingarrón, J. M. Disposable amperometric polymerase chain reaction-free biosensor for direct detection of adulteration with horsemeat in raw lysates targeting mitochondrial DNA. Anal. Chem. 2017, 89, 9474-9482. (47) Loo, A. H.; Sofer, Z.; Bousa, D.; Ulbrich, P.; Bonanni, A.; Pumera, M. Carboxylic carbon quantum dots as a fluorescent sensing platform for DNA detection. ACS Appl. Mater. Interfaces 2016, 8, 19511957.

For ToC only.

ACS Paragon Plus Environment

14

Page 15 of 15 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

ACS Paragon Plus Environment

15