Ultrasonic-Aided Fabrication of Nanostructured Au ... - ACS Publications

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Ultrasonic-aided Fabrication of Nanostructured Au-ring Microelectrodes for Monitoring Transmitters Released from Single Cells Keqing Wang, Xu Zhao, Bo Li, Kai Wang, Xin Zhang, Lanqun Mao, Andrew G. Ewing, and Yuqing Lin Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.analchem.7b02814 • Publication Date (Web): 08 Aug 2017 Downloaded from http://pubs.acs.org on August 8, 2017

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Analytical Chemistry

Ultrasonic-Aided Fabrication of Nanostructured Au-ring Microelectrodes for Monitoring Transmitters Released from Single Cells Keqing Wang,† Xu Zhao, † Bo Li, † Kai Wang, ‡ Xin Zhang,† Lanqun Mao, ‡ Andrew Ewing, § and Yuqing Lin*†

†

Department of Chemistry, Capital Normal University, Beijing 100048, China

‡

Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, the Chinese

Academy of Sciences (CAS), Beijing 100190, China §

Department of Chemistry and Chemical Engineering Chalmers University of Technology

Kemivägen 10, 41296 Gothenburg, Swede); Department of Chemistry and Molecular Biology University of Gothenburg Kemivägen10, 41296 Gothenburg, Sweden

*Corresponding Author. Fax:+86- 10-68903047; E-mail: [email protected] 1 ACS Paragon Plus Environment


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ABSTRACT: We report a novel ultrasonic-aided fast and straight-forward approach to fabricate Au microelectrodes by electroless deposition of nanostructured gold films on the rigid outer surface of pulled glass capillaries. Microelectrodes with tip diameters ranging from several hundred nanometers to several microns were fabricated in 20 min via three sequential ultrasonication steps. The ultrasonication technique has been validated to be a very effective route in engineering the morphology of Au film surfaces and improves the fabrication efficiency of Au microelectrodes. The nanostructured surfaces of the Au microelectrodes demonstrate excellent sensing activity and antifouling for dopamine oxidation. The microelectrodes were applied for measurement of catecholamines released from exocytosis events from single chromaffin cells and exhibited faster dynamic peak parameters compared to carbon fiber electrodes. This report provides a generally accessible and complementary platform for analyzing catecholamine release events, which should be useful for new electrode designs and neurochemical sensing.

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INTRODUCTION Gold microelectrodes, having excellent physical and chemical properties, could be highly useful for the study of neurochemistry and electrochemistry, and yet it is incredibly difficult to fabricate these electrodes in a simple, fast, and economical way. Methods to fabricate noble-metal microelectrodes including etching,1,

2

laser pulling,3-5 sputtering,6

electrochemical7-9 /chemical10-12 deposition of metal have been reported. Bard and coworkers established some effectively electrochemical etching methods to prepare nanoelectrode for detection of single molecules/nanoparticles13,14 and high-resolution imaging.15,

16

Zhang’s

17

group fabricated individual Pt nanoelectrodes by a laser-assisted pulling method and Au disk nanoelectrodes by electrochemical deposition8 for electrochemical detection of single Au nanoparticles. The Andreescu group sealed 125 µm Pt-wires in glass capillaries for in vivo measurements of glutamic acid, glucose and lactate acid etc.18 On the other hand, many bottom-up wet deposition techniques have also aroused extensive attention to develop micro/nano electrodes for wide applications. Liu et al. recently applied chemical deposition to fabricate individual nanometer Au electrodes on a quartz capillary tip for sensitive detection of cerebral dopamine (DA).10 Chen’s19 and Su’s20 groups reported photo-directed or chemical deposition methods, respectively, to fabricate gold microelectrodes on polymer substrates. Xu et al. developed a more environment-friendly one-step photochemical method for growing an ultrathin gold film using chloroauric acid and ethanol, which took about four hours.12 Lately, our lab described a facile fabrication method of Au-ring microelectrode for in vivo analysis yet taking about 4.5 h for fabrication using non-toxic polydopamine as multifunctional material.11 In this paper, we report a novel ultrasonic-aided rapid approach to fabricate Au-ring microelectrodes (Au-RMEs) in only 20 min, which was then adapted for monitoring catecholamine release from single chromaffin cells. The introduction of ultrasonication into our procedure effectively eliminates the high free energy barrier of the nucleation-dependent reaction to form gold nanoparticles, and thus accelerates gold nanoparticle formation and paves a solid substrate for nanostructured gold film formation.21,

22

These microelectrodes

were fabricated by three consecutive ultrasonication steps as shown in Scheme 1. The single Au-RMEs have a smaller tip minimally reaching 500 nm and a controllable gold film thickness of 500 nm to 2 µm. The nanostructured surfaces of the Au microelectrodes demonstrate excellent sensing activity and antifouling for dopamine oxidation. To demonstrate the function of these microelectrodes, they were applied to amperometric



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recording of catecholamine release from single rat adrenal chromaffin cells, exhibiting faster kinetic peak parameters compared to carbon fiber electrodes.

Scheme 1 Schematic illustration of the ultrasonic-aided ultra-fast fabrication steps for an Au microelectrode. (Schematic not drawn to scale)

EXPERIMENTAL SECTION Main Reagents and Instrumentation. Dopamine hydrochloride (DA), ferrocenemethanol (FcCH2OH), chloroauric acid tetrahydrate (HAuCl4•4H2O) and hydroxylamine hydrochloride (NH2OH•HCl) etc. were purchased from Sigma-Aldrich. All aqueous solutions were prepared with doubly distilled water produced by a Milli-Q system. Ultrasound procedures at 300 W were performed in an ultrasonic cleaner (KQ-300DE, Kunshan, China). Powers of 100-200 led to thin films and higher powers of 400-500 W led to too many gold nanoparticles growing in solution but not on the capillary tips. The electrochemical measurements were performed on a computer-controlled electrochemical analyzer (CHI 1030C, Shanghai, China, CHI 600e, Beijing, China). The inverted microscope (IX73, Olympus, Japan) covered with a Faraday cage was used to carry out the single cell experiments. Fabrication of Au-ring Microelectrode. Glass capillaries (OD: 1.5 mm, ID: 0.86 mm) were pulled into two parts with a P-97 puller. Scheme 1 illustrates the three-step process for the fabrication and insulation of Au microelectrode. In the first step, to remove organic chemicals, the rigid tips were exposed in piranha solution (98% H2SO4: 30% H2O2=7:3, v/v) with ultrasonication for 5 min (Scheme 1a-b).23 Then, the tips were dipped into a 10 mL polydopamine (which was prepared by dissolving 5 mg/mL dopamine in 0.05 M Tris (pH=8.5) and keeping in air for 20 min) for 5 min accompanied by ultrasonication (Scheme 1b-c). In this process, the clean tips were covalently or noncovalently aminated.24 After amination, the substrates were immersed into an 8 mL of HAuCl4 (0.1%) and NH2OH•HCl 4 ACS Paragon Plus Environment

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(0.04 M) mixed solution for 10 min, but only sonicating 1 min to accelerate production of a thin layer of gold film (Scheme 1c-d). The fabrication process was reproducible with a success rate over 90% (200 Au-RMEs). Finally, the electrodes were connected to a copper wire at the upper wider region of the tip, the copper wire was covered with a layer of Leit-C, and then the structure was insulated with epoxy. The electrode tips were polished at an angle of 45° on a microelectrode beveller for further characterization and cell experiments.

RESULTS AND DISCUSSION Table 1. Comparison of the method presented here with other approaches for chemically wet deposition of Au films. Electrodes

Grafting hydroxyl

Amination

or carboxyl groups

Seeding gold

Gold film

nanoparticles

growth

Reference

Au-RMEs

10 min

200 min

200 min

50 min

11

Gold-decorated

2h

0h

0h

2h

12

3h

3h

2.5 h, 10 min

30 min

19

12 h

3h

10 min

30min, 3h

20

20 min

12 h

12-18 h

10 min

25

2.5 h

3h

2.5 h, 10 min

45 min

26

3h

3h

2.5 h, 10 min

60 min

27

Au/GCNE

12 h

6h

overnight

30 s

28

Au-ring

5 min

5 min

0 min

10 min

This work

nanopipette Micro gold electrodes Gold microring electrode Glass/APTMS/Au electrode Gold microelectrode Gold film microelectrode

Microelectrode

Preparation of Au-RMEs. Many studies have been carried out to develop new and geometrically well-defined Au microelectrodes by chemical wet deposition, for which the preparation time of each step is presented in Table 1. Our approach provides an advantage in terms of simplicity and shorter preparation time. The method requires less than half an hour to fabricate Au microelectrodes with the assistance of ultrasonication. No toxic organic reagents are involved. Because formation of gold nanoparticles and subsequent film formation are 5 ACS Paragon Plus Environment


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nucleation-dependent processes, the introduction of ultrasonication effectively lowers the free energy barrier needed making nucleation unnecessary or more rapid. This results in immediate formation of gold nanoparticles and nanostructured gold films.

Effects of Ultrasound on the Formation of the Gold Film. Previous studies have reported a number of strategies to create metallic-based particles, such as Au, MnO2 and CdS, with ultrasonic synthesis.29, 30 Here, we use ultrasonication to accelerate microelectrode fabrication and control nanostructured surface morphology. To evaluate the importance of ultrasonication, piranha solution and polydopamine solution treatment, we conducted control experiments (see Table S1 and Figure S1). Compared with the static immersion method in our control experiments and the previously reported wet deposition methods10, 11, 20 for preparation of Au microelectrodes, the introduction of ultrasonication makes the fabrication more efficient reducing the time for gold electrode formation from more than 4 h to 20 min. Furthermore, the resultant gold film surfaces display different morphology, i.e. the particle size and shape change significantly with ultrasonication, as shown by SEM images in Figure 1. The surface is more uniform and consistent and the particles become smaller, with the average particle size changing from around 500 nm to 150 nm. These are also more regular with more products exhibiting more cubic shapes following ultrasonication during deposition.

Figure 1. Effect of ultrasonication on preparation of Au microelectrodes. SEM images of Au microelectrode prepared by the static immersion method (a-c) and sonication method (d-f) at different magnifications.


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SEM Characterization of Au-RMEs with a Fine Tapered Tip. The beveled Au-RMEs have fine tapered ends ranging from 500 nm to 2 µm. The comparison of the bare glass capillaries (Figure 2a) and Au-RMEs (Figure 2b) shows that the outer wall of the tapered tip is homogeneously covered with a slightly rough landscape gold film as illustrated in the lateral view (Figure 2 c and d). Figure 2e shows a clear ring in the cross-sectional view, which has been assigned to the gold film structure. The polished electrode tip clearly illustrates the thickness of the ring (Figure 2f) to be 1-2 µm. Moreover, elemental mappings of the tip in Figure S2 shows that the glass capillary contains only Si and O atoms, whereas Au atoms are clearly present in the ring shape outside of the Si mapping region, verifying again the successful deposition of the gold film.

Figure 2. a) Optical image of a bare pulled glass capillary tip, b) gold film-sheathed capillary tip and c) an optical micrograph of a gold film-sheathed tip. SEM images: lateral d) and crosssectional e, f) view of gold film.

Electrochemical Characterization of the Au-RME. The electrochemical behavior of the Au-RMEs in H2SO4 resulted in reproducible voltammograms for Au, shown for 50 consecutive cycles (Figure 3a). In the positive scan, the current increased starting at ~1.18 V while a sharp reduction peak at ~0.85 V was observed on the return scan, corresponding to the reduction of gold oxide on the surface of microelectrode.20 Since the bare tapered tip of glass capillary radius is smaller than the microring thickness in our case, as a first approximation, 7 ACS Paragon Plus Environment


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the performance of the Au-RME was basically the same as a microdisk electrode with the same radius.31, 32 Consequently, the outer radius of the microring was calculated to be 29 µm,33 which is far larger than the actual electrode radius, suggesting the Au-RME is relatively coarse. This result agrees well with the nanostructure observed with SEM images.

Figure 3. Voltammetric responses of Au-RMEs in a) 0.5 M H2SO4 and b) 0.2 M KNO3 solution containing 1 mM FcCH2OH at varied scan rates. The inner and outer radii of the AuRMEs are 2.2 µm and 3.8 µm, respectively, which can be estimated from SEM images.

The steady-state electrochemical behavior of the Au-RMEs was characterized in 1 mM FcCH2OH, as shown in Figure 3b, a typical sigmoidal voltammogram was recorded for the Au-RME. Moreover, Figure 3b demonstrates the limiting currents are only slightly dependent on the potential sweep rates, benefiting from the fast and radial-type diffusion of redox molecules to the electrode. Szabo’s empirical equation34 can be used for the limiting diffusion current (Ilim) caculation at the micro-ring electrode as follows: Ilim= nFDc * l With l =

π 2 ( r1 + r2 ) 2  32r1 π ln  + exp   r2 - r1  4

(1) (2)   

Here, n is number of electrons transferred, F is the Faraday constant (96485 C mol−1), D is the diffusion coefficient of the FcCH2OH (D = 7.8×10-6 cm2 s-1). This empirical equation (Eq. (1)) fits well for micro-ring electrodes with the inner and outer radius on the micrometer scale or less.34 Figure 3b shows that the limiting diffusion current (Ilim) of FcCH2OH at the microring electrode is ~13 nA at a scan rate of 100 mV/s. Here the limiting diffusion current (Ilim) calculated with Eqs. (1) and (2) was 1.12 nA. The actual measured limiting current is ~13 nA, which is considerably higher than that calculated 1.12 nA. This difference in limiting current might occur from electron transfer at gold nanoparticles on the side of the tip and/or nonshielded diffusion from behind the electrode. 8 ACS Paragon Plus Environment

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The

Sensing Performance and Resistance to Chemical Fouling

of Au-ring

Microelectrodes. The Au-RMEs demonstrated good electrochemical characteristics and showed comparable or slightly higher sensitivity than that obtained at CFMEs. The overall shape of DA voltammetry behavior at Au-RMEs is sigmoidal with a pair of smaller voltammetric peaks, indicating a fast radial-type diffusion to the electrode accompanied by DA molecules adsorbing on the nanostructured Au electrode surface (Figure S6a).9,35 The Auring microelectrode exhibited a linear relationship for the measurement of DA for concentrations ranging from 1.0 to 39.0 µM (Figure S6b) with a detection limit of 200 nM (S/N =3). Furthermore, over a long DA oxidation time using amperometry, as shown in Figure 4, the Au-RME current density decreased by 80% initially, but then remained stable for three hours, whereas that for CFMEs showed an initially slower, but overall continuous signal decrease during the same time by almost 95%. Although DA oxidation products block the electrode surface of both the Au-RMEs and CFMEs initially, the former exhibited a significantly higher long-term stability against chemical fouling (Figure S7). The higher final stability of Au-ring microelectrodes might arise from a decreased binding affinity of the insulating film formed by the products of DA oxidation binding to the electrode surface.36,37

a)

b)

Au-ring microelectrode CF microelectrode

)

Au-ring microelectrode CF microelectrode

(

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Figure 4. a) Amperometric currents obtained from the oxidation of 100 µM DA at 0.78 V vs. Ag/AgCl with a Au-ring microelectrode (black line) and a CF microelectrode (red line) in N2saturated phosphate buffer solution, pH 7.4. Each point represents mean ± SD (n = 3). b) The current density obtained at 5000 s compared to that at 0 s for oxidation of 100 µM DA at AuRMEs (blue column) and a carbon fiber microelectrode (purple column). Continuous experiments repeated 3 times. To calculate the error bar, selected representative points from different i-t curves in Figure 4 were selected. 9 ACS Paragon Plus Environment


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Amperometric Detection of Exocytotic Catecholamines Released from Rat Adrenal Chromaffin Cells (RACCs). Recently, much attention has been paid to developing Au disk nanoelectrodes or goldnanoparticle-network microelectrodes with improved sensitivity and faster response than carbon fiber electrodes for detection of exocytotic DA release from single cells.28,

35

We

measured catecholamines released from single RACCs. The surface area of the cell that is covered with the electrode is considerably larger than a vesicle and nearly all the catecholamines released can be oxidized in subsequent amperometric recordings (Figure 5a, b). The charges calculated by the time integral of current transients from the amperometric traces in Au-RME are 618±16 fQ, which is similar to what has been observed at bovine adrenal cells with CFMEs (Table S2). Thus, electrochemical monitoring of exocytosis is clearly feasible with the Au-RME and, even across species, provides similar numbers of molecules released to that observed with carbon microelectrodes. An interesting aside is that we observe that exocytosis from adrenal cells seems to be similar across species. a)

b)

c)

d)

K+ stim Figure 5. a) Schematic illustration and b) bright-field photomicrograph of an Au-RME positioned on the membrane of a RACC. Amperometric exocytosis recordings from a RACC c) without and d) with high K+ stimulation on a same Au-RME. Insert picture: representative


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current spikes of simple amperometric current traces on an amplified time scale (n=1070 events from 14 cells).

Some representative traces of monitoring exocytosis and analysis of exocytosis from the amperometric recording at chromaffin cells at our Au-RMEs are shown in Figure 5. There were no current spikes in i-t curves before/after stimulation by high concentration of potassium ion without cells (Figure S8). Interestingly, some random small catecholamine release events are observed (Figure 5c) when Au-RMEs are placed on stimulation-free cells. However, the amplitude and frequency of exocytotic of the events increases after K+ stimulation (Figure 5d). Furthermore, amperometric spikes from RACCs, including without and with high K+ stimulation, display typical single events with well-defined rising and decaying phases. Further study will investigate the mechanism of the smaller exocytotic events induced by the nanostructured Au microelectrodes without chemical stimulation.

CONCLUSIONS In summary, we have developed an ultrasonic-aided rapid approach to fabricate nanostructured Au microelectrodes in 20 min. Characterization demonstrates that the ultrasonication technique is an effective route to improve the fabrication efficiency of Au microelectrodes covered with a film or nanoparticles. The nanostructured surface of the Au microelectrode appears to play a role in determining excellent sensing activity and antifouling for DA oxidation. As proof of principle, these nanostructured Au-ring microelectrodes have been applied to amperometric measurements of exocytosis at single chromaffin cells. The simplicity in operation and instrumentation of the present work provides a facile methodology for designing microelectrodes, and this might have implications for the study of the fundamental aspects of electrochemistry. The response of these electrodes when measuring exocytosis release from cells shows some interesting differences from those at carbon microelectrodes. This might allow us to develop a better understanding of the true nature of neuronal communication. Finally, as gold nanoparticles are often used for enzyme-biosensors, these electrodes might be a step in the direction of the quest for biosensors aimed at measuring exocytosis.

ACKNOWLEDGMENTS This work was supported by National Natural Science Foundation (21575090 for Y.Q. Lin; 21321003, 21435007, and 21210007 for L.Q. Mao), Beijing Municipal Natural Science 11 ACS Paragon Plus Environment


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Foundation (2162009 for Y.Q. Lin), Youth Talent Project of the Beijing Municipal Commission of Education (CIT&TCD201504072 for Y.Q. Lin) and Youth Innovative Research Team of Capital Normal University (for Y.Q. Lin). We acknowledge the European Research Council (ERC), the Swedish Vetenskapsrådet and the Knut and Alice Wallenberg Foundation (for A. G. Ewing).

ASSOCIATED CONTENT Supporting Information Available Additional information as noted in the text. This material is available free of charge via the Internet at http://pubs.acs.org. REFERENCES

(1) Zhang, B.; Zhang, Y. H.; White, H. S. Anal. Chem. 2004, 76, 6229-6238. (2) Zhang, B.; Zhang, Y. H.; White, H. S. Anal. Chem. 2006, 78, 477-483. (3) Katemann, B. B.; Schulte, A.; Schuhmann, W. Electroanalysis 2004, 16, 60-65. (4) Sun, P.; Mirkin, M. V. Anal. Chem. 2006, 78, 6526-6534. (5) Meunier, A.; Jouannot, O.; Fulcrand, R.; Fanget, I.; Bretou, M.; Karatekin, E.; Arbault, S.; Guille, M.; Darchen, F.; Lemaître, F.; Amatore, C. Angew. Chem., 2011, 123, 5187-5190. (6) Qiu, W. L.; Xu, M. Z.; Li, R. X.; Liu, X. M.; Zhang, M. N. Anal. Chem. 2016, 88, 1117-1122. (7) Wang, G. L.; Zhang, B.; Wayment, J. R.; Harris, J. M.; White, H. S. J. Am. Chem. Soc. 2006, 128, 7679-7686. (8) Jena, B. K.; Percival, S. J.; Zhang, B. Anal. Chem. 2010, 82, 6737-6743. (9) Zachek, M. K.; Hermans, A.; Wightman, R. M.; McCarty, G. S. J. Electroanal. Chem. 2008, 614, 113-120. (10) Liu, Y. Z.; Yao, Q. Q.; Zhang, X. M.; Li, M. N.; Zhu, A. W.; Shi, G. Y. Biosens. Bioelectron. 2015, 63, 262-268. (11) Lin, Y. Q.; Wang, K. Q.; Xu, Y. N.; Li, L. B.; Luo, J. X.; Wang, C. Biosens. Bioelectron. 2016, 78, 274-280. (12) Xu, X. L.; He, H. L.; Y. D. Jin, Anal. Chem. 2015, 87, 3216-3221. (13) Fan, F.-R. F.; Kwak, J.; Bard, A. J. J. Am. Chem. Soc. 1996, 118, 9669-9675. (14) Xiao, X. Y.; Bard, A. J. J. Am. Chem. Soc. 2007, 129, 9610-9612. (15) Kim, J.; Kim, B. K.; Cho, S. K.; Bard, A. J. J. Am. Chem. Soc. 2014, 136, 81738176. 12 ACS Paragon Plus Environment

Page 13 of 14

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


(16) Zu, Y. B.; Ding, Z. F.; Zhou, J. F.; Lee, Y.; Bard, A. J. Anal. Chem. 2001, 73, 2153-2156. (17) Li, Y. X.; Cox, J. T.; Zhang, B. J. Am. Chem. Soc. 2010, 132, 3047-3054. (18)

özel,

R. E.; Ispas, C.; Ganesana, M.; Leiter, J. C.; Andreescu, S. Biosens.

Bioelectron. 2014, 52, 397-402. (19) Hu, X. Q.; He, Q. H.; Lu, H.; Chen, H. W. J. Electroanal. Chem. 2010, 638, 21-27. (20) Wu, S. Z.; Su, B. J. Electroanal. Chem. 2013, 694, 12-16. (21) Caruso, R. A.; Ashokkumar, M.; Grieser, F. Langmuir 2002, 18, 7831-7836. (22) Radziuk, D.; Grigoriev, D.; Zhang, W.; Su, D. S.; Möhwald, H.; Shchukin, D. J. Phys. Chem. C 2010, 114, 1835-1843.

(23) Sfez, R.; De-Zhong, L.; Turyan, I.; Mandler, D.; Yitzchaik, S. Langmuir 2001, 17, 2556-2559.

(24) Liu, Y. L.; Ai, K. L.; Lu, L. H. Chem. Rev. 2014, 114, 5057-5115. (25) Jin, Y. D.; Kang, X. F.; Song, Y. H.; Zhang, B. L.; Cheng, G. J.; Dong, S. J. Anal. Chem. 2001, 73, 2843-2849. (26) Kong, Y.; Chen, H. W.; Wang, Y. R.; Soper, S. A.; Electrophoresis 2006, 27, 2940-2950. (27) Wang, Y.; Luo, J.; Chen, H. W.; He, Q. H.; Gan, N.; Li, T. H. Anal. Chim. Acta. 2008, 625, 180-187. (28) Liu, Y. Z.; Li, M. N.; Zhang, F.; Zhu, A. W.; Shi, G. Y. Anal. Chem. 2015, 87, 5531-5538. (29) Caruso, R. A.; Ashokkumar, M.; Grieser, F. Langmuir 2002, 18, 7831-7836. (30) Radziuk, D.; Grigoriev, D.; Zhang, W.; Su, D. S.; Möhwald, H.; Shchukin, D. J. Phys. Chem. C 2010, 114, 1835-1843. (31) Kim, Y. T.; Scarnulis, D. M.; Ewing, A. G. Anal. Chem. 1986, 58, 1782-1786. (32) Szunerits, S.; Walt, D. R. Anal. Chem. 2002, 74, 1718-1723. (33) Rand, D. A. J.; Woods, R. J. Electroanal. Chem. 1971, 31, 29-38. (34) Szabo, A. J. Phys. Chem. 1987, 91, 3108-3111. (35) Adams, K. L.; Jena, B. K.; Percival, S. J.; Zhang, B. Anal. Chem. 2011, 83, 920927. (36) Burke, L. D.; Nugent, P. F. Gold Bull. 1998, 31, 39-50. (37) Zhang, L.; Jiang, X. E. J. Electroanal. Chem. 2005, 583, 292-299.



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