Structure-Switching Electrochemical Aptasensor ... - ACS Publications

Article Cite This: J. Agric. Food Chem. 2018, 66, 10106−10112

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Structure-Switching Electrochemical Aptasensor for Single-Step and Specific Detection of Trace Mercury in Dairy Products Xinai Zhang,* Chenyong Huang, Yanjuan Jiang, Yuxiang Jiang, Jianzhong Shen, and En Han School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, People’s Republic of China

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S Supporting Information *

ABSTRACT: A reagentless and single-step electrochemical aptasensor with separation-free fashion and rapid response is developed for the Hg2+ assay in dairy products. Herein, the sensing strategy is established on Hg2+-induced structural transition of the methylene-blue-tagged single-stranded DNA (ssDNA) from a flexible manner to rigid hairpin-shaped double-stranded DNA (dsDNA), generating an improved peak current for the Hg2+ assay with a detection limit of 0.62 fM. Importantly, the best signal-to-noise ratio value can be obtained by exploiting Au flowers as sensing material and the optimal ssDNA concentration. The proposed sensor also exhibits high selectivity as a result of the specific thymine−Hg2+−thymine (T−Hg2+−T) coordination chemistry and can be applied to detect Hg2+ in dairy products. With the use of the electric “signal-on” switch, the electrochemical aptasensor has the advantages of simplicity, ease of operation, and high sensitivity and specificity, offering a promising method to assess the safety of dairy products polluted with Hg2+. KEYWORDS: mercury ions, milk, electrochemical aptasensor, simplicity, structure switching

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INTRODUCTION Dairy products are considered as a highly valuable food as a result of their rich nutritional components, such as minerals, vitamins, and protein. Unfortunately, owing to the increasing content of environmental pollutants with the growth of urban, industrial, and agricultural discharges, dairy products are vulnerable to be polluted with heavy metals in their production.1−3 According to the United States Environmental Protection Agency (U.S. EPA), mercury is one of the most common heavy metals inducing pollution.4 Some investigations show that the presence of mercury even at a low concentration could disorder body mechanisms, such as kidney failure, brain damage, and cardiovascular system destruction.5−8 Therefore, it is essential to develop the analytical techniques for effective monitoring of trace mercury in dairy products. Up to now, some techniques have been reported for the mercury assay in dairy products, such as cold-vapor atomic fluorescence/absorption spectrometry,9 inductively coupled plasma mass spectrometry,10,11 high-performance liquid chromatography,12 and sensing strategy.13−17 In comparison to these analytical techniques, the sensing strategy has received extensive interest because of its rapid detection and tremendous versatility. Consequently, several sensors were developed on the basis of electrochemistry, colorimetry, fluorescence, photoelectrochemistry, etc.18−23 Among them, the electrochemical sensor is well-recognized as a powerful technique for the mercury assay as a result of its inherent simplicity, high sensitivity, and excellent flexibility. Because dairy products are present as a complex matrix, it is an urgent task to enhance the specificity and sensitivity of the electrochemical sensor for trace mercury detection. At present, aptamers, synthetic oligonucleotides (DNA or RNA) that bind to various target molecules (metal ions, small molecules, proteins, cells, etc.) with high affinity,24,25 have drawn © 2018 American Chemical Society

particular interest in sensor design. Owing to their own merits of low cost, specificity, and stability,26−30 some aptasensors have been developed for different types of bioassays of Hg2+ (one of most stable and universal inorganic forms lying in mercury contamination).31 Especially, the formation of thymine−Hg2+−thymine (T−Hg2+−T) coordination between Hg2+ and T-rich DNA strands is a widely used approach for Hg2+ determination with good selectivity.32,33 With regard to sensitivity, many attempts have been made in achieving signal amplification and signal output to improve the detectability of the electrochemical sensing strategy. In this respect, redox labels, including methylene blue (MB) and ferrocene (Fc), are considered as promising tags for signal output as a result of their easy chemical modification and convenient redox potential.34−37 Meanwhile, nanomaterials that are used as a sensing platform for electrode modification play a crucial role in promoting electron transfer for signal amplification.38−41 Recently, various electrochemical sensors have been developed to significantly facilitate Hg2+ analysis based on nanomaterials and T−Hg2+−T base pairs.42,43 Although sensitive and selective, some of the protocols require multiple washing steps and operations, possibly affecting the reproducibility and stability of the sensors. In response to the shortcomings, we report here an electrochemical aptasensor for single-step detection of Hg2+ in dairy products using the T−Hg2+−T complex without multiple operations and labeling combination. The sensing strategy is simply established on Hg2+-induced structural transition of MB-labeled single-stranded DNA (ssDNA) from a flexible manner to rigid hairpin-shaped double-stranded Received: Revised: Accepted: Published: 10106

June 21, 2018 September 2, 2018 September 5, 2018 September 5, 2018 DOI: 10.1021/acs.jafc.8b03259 J. Agric. Food Chem. 2018, 66, 10106−10112

Article

Journal of Agricultural and Food Chemistry

Figure 1. Illustration of the single-step and specific detection of Hg2+ using the Au flowers-based electrochemical aptasensor. (Lower left) Conformational change of ssDNA upon binding to Hg2+. 10 min at 10 000 rpm to obtain Au flowers. After centrifugal cleaning 3 times with pure water, the precipitate was dispersed in pure water (1 mL) and kept at 4 °C until use. Preparation of the ssDNA/Au/GCE Aptasensor. The working electrode of GCE was first treated with alumina of different particle sizes (0.3 and 0.05 μm), and then the polished electrode was sonicated in acetone, HNO3 (1:1, v/v), NaOH (50%, w/w), and water. Subsequently, Au flowers (10 μL) were dropped onto a pretreated GCE and then dried under infrared light to achieve Au/ GCE. When the Au/GCE was used to immobilize T-rich ssDNA, it should be kept clean by rinsing with pure water and drying with nitrogen. Additionally, the sensing platform, including PDA−AuNPs/ GCE, AuNPs/GCE, and PDA/GCE, was also prepared to perform the control experiments (PDA, polydopamine; AuNPs, gold nanoparticles). In detail, the bare GCE was immersed in the mixture solution of 20 mM DA and 20 mM HAuCl4, and then 20 cycles of CV measurements were performed between −0.9 and +1.0 V under a scan rate of 20 mV s−1. As a result, the PDA−AuNPs/GCE was fabricated after thoroughly rinsed with water. Using the same method, AuNPs/ GCE and PDA/GCE were also prepared for the following assay. Prior to electrode functionalization, Hg2+-target DNA strands were introduced into TCEP (5 mM) in a centrifuge tube and then reacted for 1 h to reduce the formed disulfide. Subsequently, the mixture was dissolved in Tris−HCl buffer (20 mM, pH 7.0) to obtain a 1.0 μM final concentration. Next, 10 μL of ssDNA (1.0 μM) was placed onto the Au/GCE electrode for 4 h at 4 °C to achieve the ssDNA/Au/ GCE. After the ssDNA-modified Au/GCE was carefully rinsed with Tris−HCl buffer, it was passivated with MCH (10 μL) for 1 h to reduce non-specific binding effects. Electrochemical Measurement. The ssDNA/Au/GCE was incubated with Hg2+ standard solutions or real samples for 1 h at room temperature to form the specific T−Hg2+−T complex. After the obtained electrode was rinsed with Tris−HCl buffer, it was then subjected to SWV measurements with the potential window from −0.50 to 0 V under a step potential of 4 mV, a frequency of 10 Hz, and an amplitude of 25 mV.

DNA (dsDNA), which shortens the distance between MB tags and the electrode surface and, thus, generates an improved peak current.35 Moreover, with the use of the Au flowerssensing platform and the optimal ssDNA concentration, the best signal-to-noise ratio can be achieved to improve the sensor performance. In comparison to other sensors based on Au flowers,44,45 the proposed aptasensor provides a signal enhancement platform to facilitate high sensitivity. On basis of the electric “signal-on” switch and the specific T−Hg2+−T coordination chemistry, the electrochemical aptasensor can achieve a separation-free, simple, selective, and sensitive assay of Hg2+, offering a promising tool for Hg2+ analysis in dairy products.

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MATERIALS AND METHODS

Chemicals and Materials. Mercury nitrate [Hg(NO3)2], 6mercaptohexanol (MCH), Tris(2-carboxyethyl)phosphine hydrochloride (TCEP), and Nafion were obtained from Sigma-Aldrich. The Hg2+-target ssDNA labeled with 5′-SH and 3′-MB was provided by Sangon Biotechnology Co., Ltd. (Shanghai, China). The sequences were given as follows: 5′-SH-(CH2)6-TTCTTTCTTCGCGTTGTTTGTT-MB-3′. Chloroauric acid (HAuCl4·4H2O), dopamine (DA), and other chemical reagents were obtained from Shanghai Sinopharm, Inc. (Shanghai, China). Tris−HCl buffer (20 mM, pH 7.0, containing 140 mM NaCl, 1 mM MgCl2, and 5 mM KCl) was used as buffer solution. Hexaammine ruthenium(III) chloride [Ru(NH3)6Cl3, RuHeX] was supplied by Sinocompound Catalysts Co., Ltd. Fresh milk was obtained from Changjiang Dairy Co., Ltd. (Zhenjiang, China). All chemicals were of analytical reagent grade. Pure water obtained from Millipore (Milli-Q, 18.2 MΩ cm) was used to prepare all solutions. Apparatus. A CHI630D workstation (Shanghai CH Instrument Co., China), consisting of a saturated calomel reference electrode (SCE), the modified glassy carbon working electrode (GCE, 3 mm in diameter), and a platinum wire auxiliary electrode, was used to perform cyclic voltammetry (CV) and square wave voltammetric (SWV) measurements. The morphology of the prepared nanomaterials was characterized by S-4800 scanning electron microscopy (SEM, Hitachi Co., Ltd., Tokyo, Japan). Fabrication of Au Flowers. The preparation of Au flowers were as follows:44 First, 1% HAuCl4 (100 μL) was added to the mixture solution (1 mL) of 20 mM DA and 20 μL of 0.5% Nafion with stirring for 60 min at room temperature until the color became light red. Subsequently, the resulting solution was purified by centrifuging for

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RESULTS AND DISCUSSION Mechanism of Electrochemical Sensing Strategy. Figure 1 illustrates the structure of the Hg2+-target ssDNA strands and the application of these DNA strands for the single-step electrochemical assay of Hg2+. The T-rich ssDNA strands are composed of the thiol portion (−SH, 5′) and MB portion (3′), in which the thiol part anchors the strands on Au 10107

DOI: 10.1021/acs.jafc.8b03259 J. Agric. Food Chem. 2018, 66, 10106−10112

Article


Figure 2. (A) SEM image of Au flowers. (Inset) Photograph for color change of the mixture of 1% HAuCl4, 20 mM DA, and 0.5% Nafion (a) before and (b) after stirring for 1 h and (c) resulting Au flowers dispersed in deionized water. (B) Comparison of the signal-to-noise ratio (i/i0, where i and i0 correspond to the SWV peak current with the presence and absence of Hg2+, respectively) of the sensor for 1 nM Hg2+ detection based on different sensing platforms: Au/GCE, PDA−AuNPs/GCE, AuNPs/GCE, and PDA/GCE. (C) CV of Au flowers-modified GCE in 5 mM [Fe(CN)6]3−/4− at different scan rates from 10 to 250 mV s−1. Insets show the linear relations of the Au flowers-modified GCE with the anodic and cathodic peak current against the square root of the scan rate.

flowers-modified GCE (Au/GCE) via the Au−S bond, while the MB portion as a redox label is responsible to generate signal output for Hg2+ detection. The ssDNA strands remain in a flexible manner without Hg2+, and MB labeled at the distal end is far away from the underlying electrode. Consequently, the redox MB tags cannot effectively exchange electrons with the electrode, producing low electrochemical signals (off state). When Hg2+ is incubated with the ssDNA/Au/GCE sensor, the target Hg2+ triggers the structural transition of the flexible aptamer to form a rigid dsDNA via chemical coordination of T−Hg2+−T. As a result, the collisions between the MB tags and the sensor surface increase significantly, leading to an enhanced current response of MB (on state). The current increase is related to Hg2+-induced conformational changes of MB-labeled DNA strands and, thus, reflects the target Hg2+ concentration in the samples. Characteristics of Au Flowers as a Sensing Platform. The morphology of Au flowers is characterized using SEM (Figure 2A). As seen, Au flowers present flower-like shapes. The forming reason for the flower-like structure is due to the fact that Nafion acts as the template for AuCl4− reduction and nucleation.44 To evaluate the advantages of Au flowers over other conventional materials, four different modified electrodes containing Au/GCE, PDA−AuNPs/GCE, AuNPs/GCE, and PDA/GCE are applied to the sensor design for 1 nM Hg2+ detection. The evaluation is based on monitoring the signal-tonoise ratio (i/i0, where i and i0 represent the current response with the presence and absence of Hg2+, respectively) of the different sensors. As shown in Figure 2B, Au/GCE exhibits a similar SWV peak current to that of PDA−AuNPs/GCE, AuNPs/GCE, and PDA/GCE in the absence of Hg2+. This is probably due to the ssDNA structure in a flexible manner that inhibits electron exchange between MB tags and different sensing surfaces. However, Au/GCE exhibits the best SWV peak current with the presence of Hg2+, producing the highest i/i0 value. The reason might be due to the fact that Au flowers could provide a large surface area to load more MB-labeled ssDNA and also have good conductivity for the rapid electron transfer rate. The experimental results demonstrate that Au flowers as sensing material can provide obvious superiority over PDA−AuNPs,

AuNPs, or PDA in electrochemical performance and possess the ability to improve sensitivity. To elucidate that, the electroactive surface area of the Au flowers-modified GCE is quantitatively detected by recording CV curves (Figure 2C). The CV measurements are performed using [Fe(CN)6]3−/4− as redox probes under different potential scan rates. The electroactive surface area of Au/GCE is calculated to be 11.602 mm2 according to the Randles−Sevcik equation46−48 i = 2.69 × 105AD1/2n3/2v1/2C

(1)

in which i refers to the redox peak current, A is the electrode area, D represents the diffusion coefficient (at 25 °C, D = 6.70 × 10−6 cm2 s−1), n is the number of electrons transferred in the redox reaction (n = 1), v is the scan rate of the CV measurement, and C is the concentration of the reactant [5 mM Fe(CN)63−/4−]. This demonstrates that the Au flowersmodified GCE has a larger electroactive surface area in comparison to the bare GCE surface area (7.065 mm2). Optimization of the Immobilization Concentration of ssDNA. The effect of the immobilization concentration of ssDNA on the i/i0 value is evaluated to obtain the best aptasensor performance. With an increasing ssDNA concentration, the background current increases gradually because of the increasing number of ssDNA loading on the Au/GCE (Figure 3A). With the presence of Hg2+, the concentration of ssDNA at 1.0 μM displays the maximum response and produces the highest i/i0 value, which is due to the fact that the combination possibility between the flexible ssDNA and Hg2+ decreases at a lower concentration, while a higher concentration partially inhibits the binding because of the steric hindrance resulting from the immobilized ssDNA with higher surface densities. Therefore, 1.0 μM ssDNA is used to prepare the aptasensor. Additionally, the effects of the pH condition, incubation time, and temperature between ssDNA and Hg2+ on detecting efficiency are also investigated. According to the experimental results (Figure S1 of the Supporting Information), the incubation of the immobilized ssDNA with Hg2+ in pH 7.0 Tris−HCl buffer for 60 min at room temperature is selected for the formation of the specific T−Hg2+−T complex. Meanwhile, the density of ssDNA on the Au/GCE surface is measured by the chronocoulometric method, and the result is shown in Figure 3B. According to the Cottrell equations49,50 10108


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proposed sensor is better or comparable to the other methods reported previously.25,31−33,42,43 Additionally, when compared to the DNA sensors based on Au nanomaterials,51,52 the proposed aptasensor can achieve the improvement of electrochemical performance, which is ascribed to Au flowers as the sensing platform and the “signal-on” format with an increased signal gain. Selectivity, Reproducibility, and Stability. To evaluate the selectivity of the aptasensor, Pb2+, Ca2+, Cu2+, Cd2+, K+, and Na+ are selected as the possible existing metal ions to be analyzed. As seen in Figure 4B, the incubation of the control metal ions (10 nM, 10 times Hg2+ concentration) respectively with the aptasensor has no obvious difference in the current response in comparison to that of the blank assay (without Hg2+). However, the existence of only Hg2+ leads to an obvious increase in the current response relative to other interfering substrates. Besides, the aptasensor is employed for Hg2+ detection in the coexistence of other metals. When other metal ions are introduced into the Hg2+ solution, there is almost no effect on the current response for the Hg2+ assay (Figure 4C). The results demonstrate that the specificity of the present work is acceptable, which is ascribed to the excellent selectivity of the thymine base toward Hg2+ to form the strong T−Hg2+−T complex. Furthermore, the reproducibility of the aptasensor is evaluated using six prepared electrodes to analyze 0.01 nM Hg2+. Under the same conditions, the relative standard deviation (RSD) of the determination is 7.6% (n = 6) with the six electrodes, indicating good reproducibility of the sensor. In addition, the long-term stability of the proposed aptasensor is evaluated on a 20 day period by storing the ssDNA/Au/ GCE-based aptasensor at 4 °C and assessing every 2−3 days. After a longer storage for 10 days, the SWV peak current could remain at 92.6% of the initial value, indicative of good stability. Real Sample Analysis. The developed method is used for the Hg2+ assay in pure fresh milk to investigate the practical application of the aptasensor. The dairy product samples are prepared as follows: 0.10 mL of milk is dissolved in 10 mL of pH 7.0 Tris−HCl buffer, and then 10 fM, 100 fM, 1 pM, 10 pM, and 100 pM concentrations of Hg2+ are respectively spiked into milk under stirring. Subsequently, the as-prepared samples are analyzed using the standard addition method, and the results are exhibited in Table 1. As seen, the obtained

Figure 3. (A) Effects of the immobilization concentration of ssDNA on the signal-to-noise ratio (i/i0, where i and i0 correspond to the SWV peak current with the presence and absence of Hg2+, respectively) of the sensor for 1 nM Hg2+ detection based on Au/ GCE as a sensing platform. (B) Chronocoulometric curves for Au/ GCE modified with (a) MCH/ssDNA and (b) MCH in 20 mM Tris−HCl buffer (pH 7.0) with the presence of 50 μM hexaammine ruthenium(III) chloride (RuHex). Redox charges of RuHex confined near the electrode surface are obtained from chronocoulometric intercepts at t = 0.

listed below, the surface density of the ssDNA on the Au/GCE surface is calculated to be 2.77 × 1012 molecules/cm2 ΓRu =

Q ssDNA − Q MCH nFA

ΓssDNA = ΓRu(z /m)NA

(2) (3)

where ΓRu is the amount of the redox marker restricted near the sensing surface (mol/cm2), QssDNA and QMCH are the surface charges (C), n represents the electron number in the reaction, F refers to the Faraday constant, A is the Au/GCE area (cm2), ΓssDNA is the surface density of DNA, z represents the charge of the redox marker, m is the base number in DNA, and NA represents Avogadro’s number. Hg2+ Analysis. Under the optimized experimental parameters, the proposed aptasensor is used to detect Hg2+ with different concentrations in Tris−HCl buffer. As seen in Figure 4A, the peak current increases gradually with the increasing Hg2+ concentration. The Δi linearly depends upon the logarithm of the Hg2+ concentration ranging from 1 fM to 1 nM (R2 = 0.994; inset). The limit of detection (LOD) corresponding to S/N of 3σ is 0.62 fM. The LOD of the

Figure 4. (A) SWV responses for the sensor toward different concentrations of Hg2+: (a) blank, (b) 1 fM, (c) 10 fM, (d) 100 fM, (e) 1 pM, (f) 10 pM, (g) 100 pM, and (h) 1 nM (inset: corresponding calibration curves). The specificity of the electrochemical sensor toward 1 nM Hg2+ against 10 nM Pb2+, 10 nM Ca2+, 10 nM Cu2+, 10 nM Cd2+ 10 nM K+, and 10 nM Na+: (B) for individual metal ion alone and (C) Hg2+ + coexisting metal ion. 10109


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increased signal gain. Overall, the electrochemical aptasensor gives a useful protocol with simplicity and excellent sensitivity and selectivity and provides a valuable tool for evaluating trace mercury in dairy products.

recoveries range from 88.6 to 115.2%, indicative of the favorable reliability of the electrochemical strategy.

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Table 1. Determination Results and Recoveries of Pure Fresh Milk Samples sample number 1 2 3 4 5

detected (pM)

spiked (pM)

founda (pM) ± SD

not detected not detected not detected not detected not detected

0.01

0.0108 ± 0.0006

0.1

0.0886 ± 0.0030

88.6

1.0

0.9570 ± 0.0560

95.7

9.020 ± 0.5520

90.2

10 100

115.2 ± 5.484

ASSOCIATED CONTENT

S Supporting Information *

recovery (%)

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jafc.8b03259. Optimization of the pH condition, incubation time, and temperature between ssDNA and Hg2+ (Figure S1) (PDF)

108

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115.2

AUTHOR INFORMATION

Corresponding Author

*Telephone: +86-511-88780201. E-mail: [email protected]. edu.cn.

a

The number of samples analyzed was 5.

ORCID

Moreover, in comparison to the SWV current response for the analysis of 10 fM Hg2+ only (panels A and C of Figure 5), there is no obvious difference of the peak current for the 10 fM Hg2+ assay in the sample matrices (containing mineral, protein, fat, vitamins, microorganisms, etc.) of pure fresh milk (panels B and D of Figure 5). The results demonstrate that the exhibiting interferences have no remarkable effect on Hg2+ determination, indicative of the suitability of the aptasensor for the Hg2+ assay in dairy products. In conclusion, in the current study, the electrochemical sensor is proposed for the Hg2+ assay on the basis of the formation of specific T−Hg2+−T coordination chemistry and the structural transition of the MB-labeled ssDNA with a Trich sequence. In comparison to the conventional aptasensors for the Hg2+ assay, the developed strategy could achieve greatly enhanced sensitivity as a result of the use of Au flowers as a sensing platform and the electric “signal-on” switch with an

Xinai Zhang: 0000-0001-9368-7793 Funding

This work was supported by the National Natural Science Foundation of China (21205051) and the project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (1033000006). Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The authors thank the technicians in Yangzhou University for their help in nanomaterial characterization. REFERENCES

(1) Suturović, Z.; Kravić, S.; Milanović, S.; Durović, A.; Brezo, T. Determination of heavy metals in milk and fermented milk products

Figure 5. Electrochemical aptasensor was used for the assay of (A and C) 10 fM Hg2+ only and (B and D) 10 fM Hg2+ in sample matrices of pure fresh milk. 10110


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Journal of Agricultural and Food Chemistry by potentiometric stripping analysis with constant inverse current in the analytical step. Food Chem. 2014, 155, 120−125. (2) Zwierzchowski, G.; Ametaj, B. N. Minerals and heavy metals in the whole raw milk of dairy cows under different management systems and country of origin: A meta-analytical study. J. Agric. Food Chem. 2018, 66, 6877−6888. (3) Kazi, T. G.; Jalbani, N.; Baig, J. A.; Kandhro, G. A.; Afridi, H. I.; Arain, M. B.; Jamali, M. K.; Shah, A. Q. Assessment of toxic metals in raw and processed milk samples using electrothermal atomic absorption spectrophotometer. Food Chem. Toxicol. 2009, 47, 2163−2169. (4) Office of Water, United States Environmental Protection Agency (U.S. EPA). Mercury Update, Impact on Fish Advisories; Office of Water, U.S. EPA: Washington, D.C., 2001; EPA Fact Sheet EPA-823F-01-011. (5) Harris, H. H.; Pickering, I. J.; George, G. N. The chemical form of mercury in fish. Science 2003, 301, 1203. (6) Jadán-Piedra, C.; Baquedano, M.; Puig, S.; Vélez, D.; Devesa, V. Use of Saccharomyces cerevisiae to reduce the bioaccessibility of mercury from food. J. Agric. Food Chem. 2017, 65, 2876−2882. (7) Liu, J.; Lu, Y. Rational design of ″turn-on″ allosteric DNAzyme catalytic beacons for aqueous mercury ions with ultrahigh sensitivity and selectivity. Angew. Chem., Int. Ed. 2007, 46, 7587−7590. (8) Onyido, I.; Norris, A. R.; Buncel, E. Biomolecule-mercury interactions: Modalities of DNA base-mercury binding mechanisms. Remediation strategies. Chem. Rev. 2004, 104, 5911−5929. (9) Domínguez, M. A.; Grünhut, M.; Pistonesi, M. F.; Di Nezio, M. S.; Centurión, M. E. Automatic flow-batch system for cold vapor atomic absorption spectroscopy determination of mercury in honey from Argentina using online sample treatment. J. Agric. Food Chem. 2012, 60, 4812−4817. (10) Gao, C.; Huang, X. Voltammetric determination of mercury(II). TrAC, Trends Anal. Chem. 2013, 51, 1−12. (11) Wang, M.; Feng, W.; Shi, J.; Zhang, F.; Wang, B.; Zhu, M.; Li, B.; Zhao, Y.; Chai, Z. Development of a mild mercaptoethanol extraction method for determination of mercury species in biological samples by HPLC-ICP-MS. Talanta 2007, 71, 2034−2039. (12) Kodamatani, H.; Matsuyama, A.; Saito, K.; Kono, Y.; Kanzaki, R.; Tomiyasu, T. Sensitive determination method for mercury ion, methyl-, ethyl-, and phenyl-mercury in water and biological samples using high-performance liquid chromatography with chemiluminescence detection. Anal. Sci. 2012, 28, 959−965. (13) Mor-Piperberg, G.; Tel-Vered, R.; Elbaz, J.; Willner, I. Nanoengineered electrically contacted enzymes on DNA scaffolds: Functional assemblies for the selective analysis of Hg2+ ions. J. Am. Chem. Soc. 2010, 132, 6878−6879. (14) Paramanik, B.; Bhattacharyya, S.; Patra, A. Detection of Hg2+ and F− ions by using fluorescence switching of quantum dots in an Au-cluster-CdTe QD nanocomposite. Chem.Eur. J. 2013, 19, 5980−5987. (15) Zhang, L.; Chang, H.; Hirata, A.; Wu, H.; Xue, Q. K.; Chen, M. Nanoporous gold based optical sensor for sub-ppt detection of mercury ions. ACS Nano 2013, 7, 4595−4600. (16) Tian, R.; Chen, X. J.; Jiang, N.; Hao, N.; Xu, L.; Yao, C. An electrochemical sensing strategy based on a three dimensional ordered macroporous polyaniline-platinum platform and a mercury(II) ionmediated DNAzyme functionalized nanolabel. J. Mater. Chem. B 2015, 3, 4805−4813. (17) Shi, Y.; Chen, N.; Su, Y. Y.; Wang, H. Y.; He, Y. Silicon nanohybrid-based SERS chips armed with an internal standard for broad-range, sensitive and reproducible simultaneous quantification of lead(ii) and mercury(ii) in real systems. Nanoscale 2018, 10, 4010− 4018. (18) Li, M.; Zhou, X. J.; Ding, W. Q.; Guo, S. W.; Wu, N. Q. Fluorescent aptamer-functionalized graphene oxide biosensor for label-free detection of mercury(II). Biosens. Bioelectron. 2013, 41, 889−893.

(19) Zhu, X.-J.; Fu, S.-T.; Wong, W.-K.; Guo, J.-P.; Wong, W.-Y. A near-infrared-fluorescent chemodosimeter for mercuric ion based on an expanded porphyrin. Angew. Chem., Int. Ed. 2006, 45, 3150−3154. (20) Knight, A. S.; Kulkarni, R. U.; Zhou, E. Y.; Franke, J. M.; Miller, E. W.; Francis, M. B. A modular platform to develop peptoid-based selective fluorescent metal sensors. Chem. Commun. 2017, 53, 3477− 3480. (21) Chen, G. Q.; Guo, Z.; Zeng, G. M.; Tang, L. Fluorescent and colorimetric sensors for environmental mercury detection. Analyst 2015, 140, 5400−5443. (22) Lustig, W. P.; Mukherjee, S.; Rudd, N. D.; Desai, A. V.; Li, J.; Ghosh, S. K. Metal-organic frameworks: Functional luminescent and photonic materials for sensing applications. Chem. Soc. Rev. 2017, 46, 3242−3285. (23) Shi, L.; Wang, Y.; Chu, Z. Y.; Yin, Y.; Jiang, D. F.; Luo, J. Y.; Ding, S. M.; Jin, W. Q. A highly sensitive and reusable electrochemical mercury biosensor based on tunable vertical single-walled carbon nanotubes and a target recycling strategy. J. Mater. Chem. B 2017, 5, 1073−1080. (24) Zhou, Y.; Tang, L.; Zeng, G.; Zhang, C.; Zhang, Y.; Xie, X. Current progress in biosensors for heavy metal ions based on DNAzymes/DNA molecules functionalized nanostructures: A review. Sens. Actuators, B 2016, 223, 280−294. (25) Liu, S. J.; Nie, H. G.; Jiang, J. H.; Shen, G. L.; Yu, R. Q. Electrochemical sensor for mercury(II) based on conformational switch mediated by interstrand cooperative coordination. Anal. Chem. 2009, 81, 5724−5730. (26) Qiu, Z.; Shu, J.; Tang, D. Near-infrared-to-ultraviolet lightmediated photoelectrochemical aptasensing platform for cancer biomarker based on core-shell NaYF4:Yb,Tm@TiO2 upconversion microrods. Anal. Chem. 2018, 90, 1021−1028. (27) Shu, J.; Qiu, Z.; Lv, S.; Zhang, K.; Tang, D. Plasmonic enhancement coupling with defect-engineered TiO2‑x: A mode for sensitive photoelectrochemical biosensing. Anal. Chem. 2018, 90, 2425−2429. (28) Lv, S.; Zhang, K.; Zeng, Y.; Tang, D. Double photosystemsbased ‘Z-scheme’ Photoelectrochemical sensing mode for ultrasensitive detection of disease biomarker accompanying three-dimensional DNA walker. Anal. Chem. 2018, 90, 7086−7093. (29) Qiu, Z.; Shu, J.; Tang, D. Bioresponsive release system for visual fluorescence detection of carcinoembryonic antigen from mesoporous silica nanocontainers mediated optical color on quantum dot-enzyme-impregnated paper. Anal. Chem. 2017, 89, 5152−5160. (30) Zhou, Q.; Lin, Y.; Zhang, K.; Li, M.; Tang, D. Reduced graphene oxide/BiFeO3 nanohybrids-based signal-on photoelectrochemical sensing system for prostate-specific antigen detection coupling with magnetic microfluidic device. Biosens. Bioelectron. 2018, 101, 146−152. (31) Xu, M. D.; Gao, Z. Q.; Wei, Q. H.; Chen, G. N.; Tang, D. P. Label-free hairpin DNA-scaffolded silver nanoclusters for fluorescent detection of Hg2+ using exonuclease III-assisted target recycling amplification. Biosens. Bioelectron. 2016, 79, 411−415. (32) Zeng, G. M.; Zhang, C.; Huang, D. L.; Lai, C.; Tang, L.; Zhou, Y. Y.; Xu, P.; Wang, H.; Qin, L.; Cheng, M. Practical and regenerable electrochemical aptasensor based on nanoporous gold and thymineHg2+-thymine base pairs for Hg2+ detection. Biosens. Bioelectron. 2017, 90, 542−548. (33) Zhu, Z. Q.; Su, Y. Y.; Li, J.; Li, D.; Zhang, J.; Song, S. P.; Zhao, Y.; Li, G. X.; Fan, C. H. Highly sensitive electrochemical sensor for mercury(II) ions by using a mercury-specific oligonucleotide probe and gold nanoparticle-based amplification. Anal. Chem. 2009, 81, 7660−7666. (34) Vallée-Bélisle, A.; Ricci, F.; Uzawa, T.; Xia, F.; Plaxco, K. W. Bio-electrochemical switches for the quantitative detection of antibodies directly in whole blood. J. Am. Chem. Soc. 2012, 134, 15197−15200. (35) Jiang, B. Y.; Li, F. Z.; Yang, C. Y.; Xie, J. Q.; Xiang, Y.; Yuan, R. Aptamer pseudoknot-functionalized electronic sensor for reagentless 10111


Article

Journal of Agricultural and Food Chemistry and single-step detection of immunoglobulin E in human serum. Anal. Chem. 2015, 87, 3094−3098. (36) Hsieh, K. W.; White, R. J.; Ferguson, B. S.; Plaxco, K. W.; Xiao, Y.; Soh, H. T. Polarity-switching electrochemical sensor for specific detection of single-nucleotide mismatches. Angew. Chem., Int. Ed. 2011, 50, 11176−11180. (37) Chen, Z. B.; Guo, J. X.; Zhang, S. G.; Chen, L. A one-step electrochemical sensor for rapid detection of potassium ion based on structure-switching aptamer. Sens. Actuators, B 2013, 188, 1155− 1157. (38) Zhou, H.; Liu, J.; Xu, J. J.; Zhang, S. S.; Chen, H. Y. Optical nano-biosensing interface via nucleic acid amplification strategy: Construction and application. Chem. Soc. Rev. 2018, 47, 1996−2019. (39) Reta, N.; Saint, C. P.; Michelmore, A.; Prieto-Simon, B.; Voelcker, N. H. Nanostructured electrochemical biosensors for labelfree detection of water- and food-borne pathogens. ACS Appl. Mater. Interfaces 2018, 10, 6055−6072. (40) Kumaravel, A.; Chandrasekaran, M. Electrochemical determination of chlorpyrifos on a nano-TiO2/cellulose acetate composite modified glassy carbon electrode. J. Agric. Food Chem. 2015, 63, 6150−6156. (41) Zhang, X.; Jiang, Y.; Huang, C.; Shen, J.; Dong, X.; Chen, G.; Zhang, W. Functionalized nanocomposites with the optimal graphene oxide/Au ratio for amplified immunoassay of E. coli to estimate quality deterioration in dairy product. Biosens. Bioelectron. 2017, 89, 913−918. (42) Zhang, Y.; Zeng, G. M.; Tang, L.; Chen, J.; Zhu, Y.; He, X. X.; He, Y. Electrochemical sensor based on electrodeposited graphene-Au modified electrode and nanoAu carrier amplified signal strategy for attomolar mercury detection. Anal. Chem. 2015, 87, 989−996. (43) Wang, N.; Lin, M.; Dai, H. X.; Ma, H. Y. Functionalized gold nanoparticles/reduced graphene oxide nanocomposites for ultrasensitive electrochemical sensing of mercury ions based on thyminemercury-thymine structure. Biosens. Bioelectron. 2016, 79, 320−326. (44) Shen, W.-J.; Zhuo, Y.; Chai, Y.-Q.; Yuan, R. Cu-based metalorganic frameworks as a catalyst to construct a ratiometric electrochemical aptasensor for sensitive lipopolysaccharide detection. Anal. Chem. 2015, 87, 11345−11352. (45) Shen, W.-J.; Zhuo, Y.; Chai, Y.-Q.; Yang, Z.-H.; Han, J.; Yuan, R. Enzyme-free electrochemical immunosensor based on host-guest nanonets catalyzing amplification for procalcitonin detection. ACS Appl. Mater. Interfaces 2015, 7, 4127−4134. (46) He, Y.; Xie, S. B.; Yang, X.; Yuan, R.; Chai, Y. Q. Electrochemical peptide biosensor based on in situ silver deposition for detection of prostate specific antigen. ACS Appl. Mater. Interfaces 2015, 7, 13360−13366. (47) Bard, A. J.; Faulkner, L. R. Potential Sweep Methods. Electrochemical Methods: Fundamentals and Applications, 2nd ed.; John Wiley & Sons, Inc.: New York, 2001; Chapter 6, pp 228−255. (48) Zanello, P. Voltammetric Techniques. Inorganic Electrochemistry: Theory, Practice and Application, 1st ed.; Royal Society of Chemistry: Cambridge, U.K., 2003; Chapter 2, pp 67−104. (49) Steel, A. B.; Herne, T. M.; Tarlov, M. J. Electrochemical quantitation of DNA immobilized on gold. Anal. Chem. 1998, 70, 4670−4677. (50) Zhang, J.; Song, S. P.; Wang, L. H.; Pan, D.; Fan, C. H. A gold nanoparticle-based chronocoulometric DNA sensor for amplified detection of DNA. Nat. Protoc. 2007, 2, 2888−2895. (51) Zeng, G.; Zhu, Y.; Zhang, Y.; Zhang, C.; Tang, L.; Guo, P.; Zhang, L.; Yuan, Y.; Cheng, M.; Yang, C. Electrochemical DNA sensing strategy based on strengthening electronic conduction and a signal amplifier carrier of nanoAu/MCN composited nanomaterials for sensitive lead detection. Environ. Sci.: Nano 2016, 3, 1504−1509. (52) Zhu, Y.; Zeng, G.; Zhang, Y.; Tang, L.; Chen, J.; Cheng, M.; Zhang, L.; He, L.; Guo, Y.; He, X.; Lai, M.; He, Y. Highly sensitive electrochemical sensor using a MWCNTs/GNPs-modified electrode for lead (II) detection based on Pb2+-induced G-rich DNA conformation. Analyst 2014, 139, 5014−5020.

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