Electrochemiluminescence Resonance Energy Transfer Based on Ru

Feb 17, 2013 - •S Supporting Information. ABSTRACT: ... ozone, the ECL of the system is “turned on” because ozone can oxidize ... arthritis.1−...
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Electrochemiluminescence Resonance Energy Transfer Based on Ru(phen)32+-Doped Silica Nanoparticles and Its Application in “Turnon” Detection of Ozone Wenjing Qi,†,‡ Di Wu,§ Jianming Zhao,†,‡ Zhongyuan Liu,† Wei Zhang,† Ling Zhang,†,‡ and Guobao Xu*,† †

State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, PR China ‡ University of the Chinese Academy of Sciences, Chinese Academy of Sciences, No. 19A Yuquanlu, Beijing 100049, China § Department of Chemistry and Chemical Engineering, Sichuan University of Arts and Science, Sichuan Key Laboratory of Characteristic Plant Development Research, Dazhou, Sichuan 635000, PR China S Supporting Information *

ABSTRACT: Both the electrochemiluminescence (ECL) method for sensitive detection of ozone and the ECL resonance energy transfer (ECRET) using ozone have been reported for the first time. It is based on the ECRET of Ru(phen)32+-doped silica nanoparticles (RuSiNPs) to indigo carmine. In the absence of ozone, the ECL of RuSiNPs is quenched as a result of the ECRET of RuSiNPs to indigo carmine. In the presence of ozone, the ECL of the system is “turned on” because ozone can oxidize indigo carmine and interrupt the ECRET from RuSiNPs to indigo carmine. In this way, it provides a simple ECL sensing of ozone via the proposed RuSiNP-based ECRET strategy with a linear range from 0.05−3.0 μM and a limit of detection (LOD) of 30 nM. The detection takes less than 5 min. This method is also successfully applied in the analysis of ozone in human serum samples and atmospheric samples.

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studied owing to their good ECL efficiency and favorable electrochemical properties in aqueous media. Spherical Ru(bpy)32+-doped silica nanoparticles with dye molecules inside the silica matrix can give ultrasensitive electrochemical properties and a much higher ECL efficiency than Ru(bpy)32+.12−18 This method can not only effectively protect the dye from the surrounding environment and increase photostability but also provide signal enhancement due to an increase in the number of dye molecules per nanoparticle. Meanwhile, Ru(bpy)32+-doped silica nanoparticles with the silica shell are less toxic and can easily be modified with other functional groups such as amines and thiols on the surface. All these advantages make Ru(bpy)32+-doped silica nanoparticles attractive. In comparison with Ru(bpy)32+, Ru(phen)32+ has larger molecular scaffolds and better adsorption capability.19−22 Ru(phen)32+-doped silica nanoparticles (RuSiNPs) are excellent alternatives to Ru(bpy)32+-doped silica nanoparticles but have never been reported. In this study, the ECL detection of ozone has been developed for the first time. The proposed ECL detection system is based on ECL resonance energy transfer (ECRET) (Scheme 1). Due to the overlap of the ECL spectrum of

zone exposure is a growing global health problem. Ozone can impair lung function, induce airway inflammation, and promote platelet aggregation. It may be produced endogenously by the immune system. Moreover, ozone therapy has been proposed via autohemotherapy or injection for various diseases, such as cancer, AIDS, heart disease, Alzheimer’s dementia, chronic Hepatitis C, multiple sclerosis, and arthritis.1−3 Up to now, the reported analytical methods for the determination of ozone include fluorescent,1,2 chemiluminescent,4 high-performance liquid chromatography−mass spectrometry (HPLC−MS),5 electrochemical,6 and colorimetric methods.7,8 The fluorescent method requires the use of external light sources. The mass spectrometric method has a relatively high cost. The reported electrochemical method needs the preparation of a multimembrane, a hydrophobic C-18 reactor, a selective sorbent for ozone, and it can detect ozone only at concentrations higher than 60 μM. Colorimetric method based on the decolorization of indigo carmine usually has low sensitivity. Therefore, it is necessary to develop a simple and sensitive method for ozone detection. Electrochemiluminescence (ECL) (also called electrogenerated chemiluminescence) is chemiluminescence triggered by electrochemical methods.9−11 It is a very powerful and sensitive analytical technique for immunoassays, food and water testing, and biowarfare agent detection. Among many ECL systems, ECL based on Ru(bpy)32+ and its derivatives has been most© 2013 American Chemical Society

Received: December 6, 2012 Accepted: February 15, 2013 Published: February 17, 2013 3207

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mL of 1-hexanol, 3.54 mL of Triton X-100, and 800 μL of water was magnetically stirred for 15 min. Next, 200 μL of TEOS was injected into the solution. After 30 min, 120 μL of ammonium hydroxide was added. The solution was kept stirring for 24 h. Then, 100 μL of APTES was added and kept stirring for another 24 h. Finally, the resultant nanoparticles were collected by centrifugation and washed three times with ethanol and water and then resuspended with 15 mL of water. Ozone Detection Procedure. 100 μL of 0.2 M phosphate buffer solutions, pH 2.0, 15 μL of 1.0 mM IDS, different amounts of ozone solutions, and an appropriate amount of water were pipetted into a 1.0 mL plastic tube, vortex-mixed, and then kept at 4 °C for 10 min because ozone is relatively stable at low temperature. The total volume of the above solution was 500 μL. After that, 10 μL of RuSiNP solution and 290 μL of 50 mM TPA solution, pH 7.4, was added for ECL measurements. Ozone Detection in Indoor Air Samples. Five milliliters of 0.2 M phosphate buffer solution, pH 2.0, containing 0.5 mM IDS was injected into a 10.0 mL plastic centrifugal tube. The plastic centrifugal tube was put in a ventilated photocopy room containing five multifunctional printers and kept there for eight hours. The sample was divided into several parts and diluted with water to keep the final concentration of IDS at 30 μM. One part was used for the ECL measurement of ozone according to the procedures as mentioned above. The other parts were used for the determination of recoveries by adding given amounts of ozone into the sample solutions. ECL measurements were carried out according to the procedures, as mentioned above. The experiment was performed in triplicate. Ozone Detection in Human Serum Samples. Onehundred microliters of 0.2 M phosphate buffer solutions, pH 2.0, 15 μL of 1.0 mM IDS, 50 μL of 10-fold diluted human serum sample, and 335 μL of water were pipetted into two 1.0 mL plastic tubes. Then, 10 μL of RuSiNP solution and 290 μL of 50 mM TPA, pH 7.4, was added for the ECL measurement of ozone in serum. For the determination of recoveries, a given amount of ozone was added into the sample solutions. ECL measurements were carried out according to the procedures as mentioned above. The experiment was performed in triplicate.

Scheme 1. The Schematic Principle of ECRET Detection of Ozone Conjugated with RuSiNPs and IDS

RuSiNPs with the absorption spectrum of indigo carmine (IDS), IDS can quench the ECL of RuSiNPs through the ECRET of RuSiNPs to IDS. Ozone can decompose IDS,1 interrupt ECRET, and increase the ECL intensity, allowing the turn-on ECL detection of ozone.

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EXPERIMENTAL SECTION Chemical and Materials. IDS was purchased from J&K Scientific Ltd. (Beijing China). Ozone was obtained by an FMC900 ozone generator (BEYOK ozone, Zhejiang, China). The ozone solutions were prepared in ice water, and the concentrations were determined by UV absorption (λmax = 258 nm; ε ≈ 3000 L·mol−1·cm−1).2,23,24 Dichlorotris(1,10phenanthroline)ruthenium(II) hydrate (Ru(phen)3Cl2·H2O) (98%), tripropylamine (TPA), tetraethyl orthosilicate (TEOS), 3-aminopropyltriethoxysilane (APTES), and Triton X-100 were purchased from Sigma-Aldrich. 1-Hexanol was obtained from Beijing Yili Chemical Reagent Factory (Beijing, China). Cyclohexane was purchased from Beijing Chemical Reagent Factory (Beijing, China). Ammonium hydroxide (25%) and sodium oxalate were purchased from Sinopharm Chemical Reagent Company Ltd. (Beijing, China). Phosphate buffer solutions (0.2 M, pH 2.0) were used for the reaction of IDS and ozone,7 while the 0.2 M phosphate buffer solutions, pH 7.4, containing TPA are used for ECL detection. Other chemicals were analytical-reagent grade and used as received. All solutions were prepared with doubly distilled water. Apparatus. Electrochemical experiments were performed with CHI 660C electrochemistry workstation (Shanghai CHI Instruments Company, China) using a glassy carbon working electrode (ϕ = 3 mm), an Ag/AgCl reference electrode (saturated KCl), and a platinum wire counter electrode. ECL intensities were monitored through the bottom of the threeelectrode cell with a BPCL ultraweak luminescence analyzer, which was purchased from the Institute of Biophysics, Chinese Academic of Sciences. Unless otherwise noted, the photomultiplier tube voltage is kept at 1100 V. The glassy carbon working electrode was polished with 0.05 μm alumina and then cleaned by ultrapure water in an ultrasonic bath prior to each use. Ultraviolet−visible (UV−vis) absorption spectra were recorded in a UNICO UV/vis 2802PC spectrophotometer. Scanning electron microscopy (SEM) images were taken using a FEI XL30 ESEM FEG scanning electron microscope operated at 25 kV. A drop of the concentrated RuSiNP solution was deposited on ITO and dried at room temperature for SEM measurements. Synthesis of RuSiNPs. RuSiNPs were prepared with a water/oil (W/O) microemulsion method as previously described with a little modification.12 Typically, 160 μL of 0.1 M Ru(phen)32+ aqueous solution, 15 mL of cyclohexane, 3.2

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RESULTS AND DISCUSSION SEM and Spectral Characterization of RuSiNPs. Figure 1 shows a typical SEM image of the as-prepared RuSiNPs. They have uniform sizes of 55.3 ± 4.3 nm. RuSiNPs have distinct maximum fluorescence emission at 605 nm, and IDS has a

Figure 1. SEM image of RuSiNPs. Inset: typical photograph of RuSiNP solution. c(RuSiNPs), 0.1 mM. 3208

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Figure 2. ECL intensity−potential profiles at the glassy carbon electrode of the RuSiNP solutions in the presence of (a) TPA and (b) oxalate and (c) in the absence of any coreactant. Inset: the magnified ECL intensity−potential profiles of curve b and curve c. c(RuSiNPs), 1.2 μM; c(TPA), 18.1 mM; c(oxalate), 72.5 mM; scan rate, 0.1 V/s; and photomultiplier tube voltage, 1100 V.

Figure 5. The kinetic behavior of RuSiNPs and IDS in the absence (black) and presence (red) of ozone at the glassy carbon electrode at different times (immediately, 2, 5, 10, 15, 20, and 40 min). c(RuSiNPs), 1.2 μM; c(IDS), 30.0 μM; c(TPA), 18.1 mM; c(ozone), 1.5 μM; scan rate, 0.1 V/s; photomultiplier tube voltage, 1100 V.

Figure 3. (A) ECL intensity−potential profiles and (B) cyclic voltammograms at the glassy carbon electrode of the RuSiNPs and TPA mixture in the absence (curve 1) and presence (curve 2) of IDS and the RuSiNPs and TPA mixture in the presence of both IDS and ozone (curve 3). c(RuSiNPs), 1.2 μM; c(IDS), 30.0 μM; c(TPA), 18.1 mM; c(ozone), 1.5 μM; scan rate, 0.1 V/s; photomultiplier tube voltage, 1100 V.

Figure 6. (A) ECL intensity−-potential profiles at different concentrations of ozone and (B) ECL intensity−concentration curve at the glassy carbon electrode. Inset: linear calibration curve. c(RuSiNPs), 1.2 μM; c(IDS), 30.0 μM; c(TPA), 18.1 mM; c(ozone, μM): 0, 0.05, 0.2, 0.5, 1.0, 1.5, 3.0, and 4.5; scan rate, 0.1 V/s; photomultiplier tube voltage, 1100 V.

broad absorption band centered at around 605 nm (Figure S1 of the Supporting Information). When IDS is added to the solution of RuSiNPs, the fluorescence emission of RuSiNPs is quenched with a quenching efficiency of 70%, indicating that IDS and RuSiNPs are effective energy transfer acceptors and donors. The high quenching efficiency is attributed to the significant overlap of fluorescence emission spectrum of RuSiNPs with absorption spectrum of IDS.25 After it is oxidized by ozone, its characteristic broad absorption disappears and the fluorescence emission of RuSiNPs is quenched with a low quenching efficiency of only 20%.

Figure 4. ECL intensity of the solutions containing RuSiNPs, TPA, and different concentrations of IDS in the absence (black columns) and presence (green columns) of ozone at the glassy carbon electrode. c(RuSiNPs), 1.2 μM; c(IDS): 10.0, 20.0, 30.0, 50.0, and 80.0 μM (from columns 1 to 5, respectively); c(TPA), 18.1 mM; c(ozone), 1.5 μM; scan rate, 0.1 V/s; and photomultiplier tube voltage, 1100 V.

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Table 1. Comparison of Different Methods for the Detection of Ozone detection time

linear ranges

detection limits

a reagentless alcohol oxidase electrode

10 min

0.06−4.2 mM

22.9 μM

6

indigo carmine nonfluorescent fluorescein derivative

0.2−625 μM 0.05−12.5 μM 0.05−7.0 μM

200 nM 

7 1

near-infrared Trp-Cy fluorescent probe

4 min 10−15 min 30 min

17 nM

2

Eosln Y



4.2 μM

4

Ru(phen)32+-doped silica nanoparticles (RuSiNPs)

5 min

4.2 μM−8.3 mM 0.05−3.0 μM

30 nM

present work

methods electrochemical amperometric biosensor mounted into a flowthrough cell colorimetric sensor by the decolorization of indigo carmine fluorescence sensor based on turn-on fluorescence of a novel nonfluorescent reagent fluorescence sensor based on a twisted intramolecular charge transfer (TICT) chemiluminescence determination using dyes ECL sensor based on resonance energy transfer (ECRET)

probes

ref

Table 2. Analytical Results for ECRET Detection of Ozone in Indoor Air and Human Serum sample

added O3 (μM)

1a 2a 3b 4b

0.5 1.5 0.5 1.5

a

found O3 (μM) 0.48, 1.46, 0.47, 1.42,

0.53, 1.54, 0.49, 1.55,

0.51 1.59 0.54 1.56

RSD (%, n = 3)

recovery (%)

5.0 4.4 7.2 5.2

96.0−106.0 97.3−106.0 94.0−108.0 94.7−104.0

In indoor air samples. bIn human serum samples.

effective ECL coreactant in the following ECRET experiment. In order to know where exactly the ECL comes from, we have studied the effect of centrifugation of the RuSiNP solution on ECL intensity. The ECL intensity of the supernatant obtained by centrifugation of the RuSiNP solution at 10000 rpm for 10 min is much lower than that of the RuSiNP solution, suggesting that ECL results from RuSiNPs. It has been reported that the oxidation of TPA can generate some intermediate. The generated TPA intermediate is stable enough to cause the excitation of Ru(bpy)32+ that is several micrometers away from the electrode surface.26 So, ECL may result from Ru(phen)32+ on the silica surfaces and inside the silica nanoparticles. Figure 3A shows that RuSiNPs and TPA display strong ECL emissions in the absence of IDS (curve 1). The ECL spectrum of RuSiNPs is similar to its fluorescent spectrum (Figure S2 of the Supporting Information). In contrast, ECL emission is quenched with a high quenching efficiency up to 84% (curve 2) in the presence of IDS, which indicates that the donor− acceptor interaction between RuSiNPs and IDS works well, as shown in Scheme 1. The cyclic voltammogram (Figure S3 of the Supporting Information) of IDS shows that IDS can be electrochemically oxidized under the present ECL condition. The strong quenching effect of IDS on ECL indicates that IDS can suppress ECL effectively, even if it is electrochemically oxidized. When ozone is added, ECL emission is quenched with a low quenching efficiency of only 40% (curve 3). To investigate the quenching mechanism, electrochemistry of RuSiNPs and TPA under different conditions was studied. As shown in Figure 3B, IDS dramatically suppresses the oxidation current as a result of the adsorption of IDS on the glassy carbon electrode (Figure S3 of the Supporting Information). In contrast, IDS has little effect on the oxidation current in the presence of ozone because the oxidation product of IDS by ozone cannot adsorb onto the electrode surface. It indicates that IDS can not only quench ECL through energy transfer but also suppress ECL through the inhibition of the oxidation of TPA. When IDS is oxidized by ozone, its product can neither quench the ECL through energy transfer nor suppress the

Figure 7. The selectivity of the ECRET detection of ozone. (A) c (from left to right): 20.0, 20.0, 20.0, 18.0, 10.0, 0.1, 0.1, 10.0, and 1.5 μM. (B) The concentrations of all the metal ions are 0.5 mM and the concentration of ozone is 1.5 μM. Black column of ozone represent the ECL intensity in the absence of ozone; other black columns represent the ECL intensity in the presence of one of the reactive oxygen species, reactive nitrogen, biological antioxidants, oxidants, or metallic ions. The green column of ozone represents the ECL intensity in the presence of ozone; other green columns represent the ECL intensity in the presence of both ozone and one of the reactive oxygen species, reactive nitrogen, biological antioxidants, oxidants, or metal ions. c(RuSiNPs), 1.2 μM; c(TPA), 18.1 mM; c(IDS), 30.0 μM; scan rate, 0.1 V/s; photomultiplier tube voltage, 1100 V.

Therefore, a turn-on fluorescence emission of the system is observed. ECRET in the Presence of Ozone. Since IDS has a high fluorescence quenching efficiency and ozone can decompose IDS to inhibit quenching, the energy transfer motif is tested for the ECL detection of ozone. ECL efficiency of RuSiNPs is an important factor in the ECRET system. Figure 2 shows ECL efficiency of RuSiNPs in the presence of two common ECL coreactants, TPA and oxalate. RuSiNPs exhibit much stronger ECL in the presence of TPA. Therefore, TPA is chosen as the 3210

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practical samples analysis. When 0.5 and 1.5 μM ozone are added, respectively, the obtained recoveries range from 94.0% to 108.0% and 94.7% to 104.0%. All the results obviously indicate that the ECRET probe is supposed to be useful for the detection of ozone in environmental science and biology.

oxidation of TPA. Consequently, ozone can effectively enhance the ECL of RuSiNPs and TPA in the presence of IDS. Factors Concerning ECRET Detection of Ozone. Figure 4 shows the effect of IDS concentrations on the ECL quenching efficiency. The ECL background signals gradually decrease with the increasing concentration of IDS because IDS can not only quench ECL but also suppress the generation of ECL. The turn-on intensity difference value increases with the addition of ozone. Excess IDS may surround RuSiNPs and make the ECL of the system not so easily emitted. Therefore, the optimal concentration of IDS is 30.0 μM. Figure 5 shows the kinetic behaviors of the ECRET system. The proposed ECRET system for the detection of ozone is a time-dependent process. ECL signals of the system in the absence of ozone decrease rapidly in the first 5 min and then change slightly later. It results from the fact that IDS adsorbs onto the electrode surface and suppresses ECL through the inhibition of the oxidation of TPA. While, in the presence of ozone, ECL signals of the system increase rapidly at the beginning and then later change slightly. It is because the product of IDS oxidized by ozone cannot suppress the oxidation of TPA and induces enhanced ECL signals. These results suggest that the proposed ECRET system can reach a maximum signal-to-background ratio for the detection of ozone in a short time. In other words, the oxidation process by ozone can occur in a short time and the ECRET detection for ozone is a fast process. To make the detection of ozone stable and reliable, 5 min is used for analytical purposes in the following experiments. Detection of Ozone. Figure 6A shows ECL intensity of the sensing system in the presence of different concentrations of ozone. The plot of the relative ECL intensity versus the concentration of ozone is shown in Figure 6B. A good linear relationship is obtained under the optimal conditions. The linear range is 0.05−3.0 μM with the linear equation of I = 699.8 + 834.3c, where I is the relative ECL intensity and c is the concentration of ozone (r = 0.9947). The limit of detection (LOD) for the target ozone is calculated to be 30 nM. Compared with other methods (Table 1), the proposed ECRET method is a very fast and sensitive method for the detection of ozone. Figure 7A shows the effect of some reactive oxygen species, reactive nitrogen, and biological antioxidants, such as ascorbic acid (Vc) and glutathione (GSH), on ECL intensity.1,2 None show similar ECL turn-on effects like ozone. It suggests that they cannot cleave the carbon−carbon double bond of IDS as effectively as ozone. However, when the same concentration of ozone is continually added into the samples used in the former step, ECL intensity is turned on again. Furthermore, another experimental verification is conducted using a certain amount of coexistent metal ions such as Cd2+, Co2+, Cu2+, Zn2+, Ni2+, K+, Na+, and Mg2+ (Figure 7B). No notable inhibiting effects on the ECL signals are noted. The tolerance level is defined as a relative error not exceeding ±5% in the determination of ozone. All these results suggest that this ECRET sensor is potentially appropriate for sensitive detection of ozone. Then, the detection of ozone both in biological and in atmospheric samples is investigated in Table 2. Real samples containing IDS and RuSiNPs are prepared in a ventilated photocopy room containing five multifunctional printers for ozone detection.1 When 0.5 and 1.5 μM ozone are added respectively, the recoveries from 96.0% to 106.0% and 97.3% to 106.0% are obtained. Diluted human serums are applied in

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CONCLUSIONS In conclusion, the ECL spectrum of RuSiNPs overlaps with the absorption spectrum of IDS at around 605 nm. In this way, a novel ozone-dependent ECRET platform conjugated RuSiNPs and IDS has been developed successfully for the first time. This simple and cost-effective ECRET sensor exhibits excellent sensitivity. This ECRET turn-on strategy for the detection of ozone is also successfully applied in biological and atmospheric samples. It also provides a new model of ECRET using ozone.

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ASSOCIATED CONTENT

S Supporting Information *

Normalized UV−vis absorption and fluorescence spectra of IDS reacting with ozone. This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*Address: State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street Changchun, Jilin 130022, China. Tel: +86-431-85262747. Fax: +86-431-85262747. Email: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This project was supported by the National Natural Science Foundation of China (Grant 21175126) and the Chinese Academy of Sciences (CAS).

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REFERENCES

(1) Garner, A. L.; Croix, C. M. S.; Pitt, B. R.; Leikauf, G. D.; Ando, S.; Koide, K. Nat. Chem. 2009, 1, 316−321. (2) Xu, K.; Sun, S.; Li, J.; Li, L.; Qiang, M.; Tang, B. ChemComm 2012, 48, 684−686. (3) Zhang, Q.; Powers, E. T.; Nieva, J.; Huff, M. E.; Dendle, M. A.; Bieschke, J.; Glabe, C. G.; Eschenmoser, A.; Wentworth, P., Jr; Lerner, R. A.; Kelly, J. W. Proc. Natl. Acad. Sci. U.S.A. 2004, 101, 4752−4757. (4) Ray, J. D.; Stedman, D. H.; Wendel, G. J. Anal. Chem. 1986, 58, 598−600. (5) Wentworth, P., Jr.; Nieva, J.; Takeuchi, C.; Galve, R.; Wentworth, A. D.; Dilley, R. B.; Delaria, G. A.; Saven, A.; Babior, B. M.; Janda, K. D.; Eschenmoser, A.; Lerner, R. A. Science 2003, 302, 1053−1056. (6) Stergiou, D. V.; Prodromidis, M. I.; Veltsistas, P. G.; Evmiridis, N. P. Anal. Chem. 2006, 78, 4676−4682. (7) Bader, H.; Hoigné, J. Water Res. 1981, 15, 449−456. (8) Maruo, Y. Y. Sens. Actuators, B 2006, 79, 485−491. (9) Richter, M. M. Chem. Rev. 2004, 104, 3003−3036. (10) Miao, W. Chem. Rev. 2008, 108, 2506−2553. (11) Bertoncello, P.; Forster, R. J. Biosens. Bioelectron. 2009, 24, 3191−200. (12) Zhang, L.; Dong, S. Anal. Chem. 2006, 78, 5119−5123. (13) Gorman, B. A.; Francis, P. S.; Barnett, N. W. Analyst 2006, 131, 616−639. (14) Omer, K. M.; Bard, A. J. J. Phys. Chem. C 2009, 113, 11575− 11578. 3211

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Analytical Chemistry

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(15) Ma, D.; Kell, A. J.; Tan, S.; Jakubek, Z. J.; Simard, B. J. Phys. Chem. C 2009, 113, 15974−15981. (16) Nakamura, M.; Shono, M.; Ishimura, K. Anal. Chem. 2007, 79, 6507−6514. (17) Kurita, R.; Arai, K.; Nakamoto, K.; Kato, D.; Niwa, O. Anal. Chem. 2012, 84, 1799−1803. (18) Sentic, M.; Loget, G.; Manojlovic, D.; Kuhn, A.; Sojic, N. Angew. Chem., Int. Ed. 2012, 51, 11284−11288. (19) Kuwabara, T.; Noda, T.; Ohtake, H.; Ohtake, T.; Toyama, S.; Ikariyama, Y. Anal. Biochem. 2003, 314, 30−37. (20) Liu, Z.; Zhang, W.; Hu, L.; Li, H.; Zhu, S.; Xu, G. Chem.Eur. J. 2010, 16, 13356−13359. (21) Yuan, T.; Liu, Z.; Hu, L.; Zhang, L.; Xu, G. ChemComm 2011, 47, 11951−11953. (22) Parveen, S.; Zhang, W.; Yuan, Y.; Hu, L.; Gilani, M. R. H. S.; Rehman, A. U.; Xu, G. J. Electroanal. Chem. 2012, DOI: 10.1016/ j.jelechem.2012.05.014. (23) Prasse, C.; Wagner, M.; Schulz, R.; Ternes, T. A. Environ. Sci. Technol. 2012, 46, 2169−2178. (24) Panich, N. M.; Ershov, B. G.; Seliverstov, A. F.; Basiev, A. G. Russ. J. Appl. Chem. 2007, 80, 1812−1815. (25) Tokel-Takvoryan, N. E.; Hemingway, R. E.; Bard, A. J. J. Am. Chem. Soc. 1973, 95, 6582−6589. (26) Miao, W.; Choi, J.-P.; Bard, A. J. J. Am. Chem. Soc. 2002, 124, 14478−14485.

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