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Colorimetric detection of Hg2+ by Au nanoparticles formed by H2O2 reduction of HAuCl4 using Au nanoclusters as the catalyst
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Colorimetric detection of Hg2+ by Au nanoparticles formed by H2 O2 reduction of HAuCl4 using Au nanoclusters as the catalyst Yuan Zhou, Zhanfang Ma ∗ Department of Chemistry, Capital Normal University, Beijing 100048, China
a r t i c l e
i n f o
Article history: Received 17 June 2016 Received in revised form 6 October 2016 Accepted 8 October 2016 Available online xxx Keywords: Mercury ions Colorimetric detection Gold nanoparticles Gold nanoclusters Catalytic activity
a b s t r a c t Gold nanoclusters (AuNCs), due to their enzyme-like activity, can catalyze the decomposition of hydrogen peroxide (H2 O2 ), which can be used to reduce HAuCl4 into gold nanoparticles (AuNPs). Hg2+ effectively decreases the catalytic ability of AuNCs to decompose H2 O2 by the interactions between Au+ on surface of AuNCs and Hg2+ . In a system containing AuNCs, H2 O2 , and HAuCl4 , increasing the Hg2+ concentration prompts a color change from purple to red of the solution of as-synthesized AuNPs, which results from the increase in residual H2 O2 after decomposition by AuNCs. Based on this principle, a novel colorimetric method for ultrasensitive detection of mercury ions was developed in this work. AuNPs synthesized by a one-step method without modification were used to directly detect mercury ions in lake and river water samples. The detection limit of the present method was determined to be 8:9 pM with a linear response range of 0.1 nM–10 M, which is much lower than the standard value defined by the Environmental Protection Agency (EPA). The method not only possesses advantages of convenience and simplicity, but also is promising for application in real samples. © 2016 Elsevier B.V. All rights reserved.
1. Introduction Mercury ions are recognized as global environmental pollutants that are mainly released from coal combustion, metal mining, and solid waste incineration. Residual Hg0 vapor and Hg2+ remain in the atmosphere and water for long periods of time and can even transport to or deposit in remote places. Moreover, humans’ brains, lungs, and central nervous system can be damaged by mercury through the food chain. [1–3] Therefore, the detection of mercury ions is crucial for monitoring the environment in and around rivers and lakes. Traditional methods for the detection of mercury ions include spectroscopic techniques, [4–6] inductively coupled plasma mass spectrometry (ICP-MS) [7], inductively coupled plasma atomic emission spectroscopy (ICP-AES) [8], yet these often require tedious preparation of materials and timeconsuming, complicated operation. Thus, it is extremely urgent to produce a facile, high sensitive and cost-effective method for detection of mercury ions. Although numerous sensing systems used for determination of heavy metal ions have been reported over the past few years
∗ Corresponding author. E-mail address: [email protected] (Z. Ma).
[9–12], the colorimetric method has attracted the most attention due to its simple readout and obvious color change that occurs in the presence of analyte can be viewed by the naked eye or using a UV–vis spectrophotometer [13–19]. For the colorimetric method, gold nanoparticles (AuNPs) have received extensive interest based on the localized surface plasma resonance (SPR) effect [20–23]. For AuNPs, surface modification by ligand, protein, and aptamers for detecting mercury ions is favorable since the ligand, protein, and aptamers are easily obtained and the resultant modification can be clearly seen [15,24–26]. However, the modification process in the majority of these sensing systems is time-consuming [27]. H2 O2 , as a mild reducing agent, can reduce HAuCl4 to form AuNPs, while 2-morpholinoethanesulfonic acid (MES) induces partial aggregation of AuNPs [28–30]. While addition of 2morpholinoethanesulfonic acid (MES) alters the color of nanoparticle dispersions to purple, the addition of a sufficient amount of H2 O2 enables the solution to maintain a red color [31]. Further, Hg2+ can be introduced to inhibit the catalytic activity of gold nanoclusters (AuNCs) to decompose H2 O2 by interacting with Au+ on the surface of AuNCs [32–36]. Herein, based on these principles, a novel colorimetric strategy for the ultrasensitive detection of Hg2+ was designed. Different from conventional methods [15,37,38], the presented strategy ensures that the color of AuNPs solution changes from purple to
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Please cite this article in press as: Y. Zhou, Z. Ma, Colorimetric detection of Hg2+ by Au nanoparticles formed by H2 O2 reduction of HAuCl4 using Au nanoclusters as the catalyst, Sens. Actuators B: Chem. (2016), http://dx.doi.org/10.1016/j.snb.2016.10.035
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red. Moreover, AuNPs without modification can be directly used to detect Hg2+ . In the absence of Hg2+ , AuNCs were used for the decomposition of added H2 O2 , resulting in the reduction of residual H2 O2 . This slowed the growth of AuNPs and prompted the partial aggregation of AuNPs to display purple color. In the presence of Hg2+ , the catalytic activity of AuNCs was inhibited, decreasing the decomposition of H2 O2 , yet the residual H2 O2 increased. As a consequence, the color of AuNPs solution retained red due to the relatively adequate H2 O2 . An obvious color variation of AuNPs was easily detected by the naked eye, which posed as a simple method for detecting the presence of mercury ions. 2. Experimental 2.1. Materials and reagents Hydrogen Tetrachloroaurate Hydrate (HAuCl4 ·xH2 O) was purchased from Alfa Aesar. 2-Morpholinoethanesulfonic Acid (MES) was obtained from Aladdin Industrial Corporation. Trisodium Citrate (Na3 C6 H5 O7 ·2H2 O), NaOH, HgCl2 were purchased from Beijing Chemical Reagents Company (Beijing, China). AgNO3 , BaCl2 ·2H2 O, Pb(NO3 )2 , FeCl3 ·6H2 O, CuCl2 ·2H2 O, KCl, MgCl2 ·6H2 O, CdCl2 ·5/2H2 O, FeCl2 ·4H2 O and CrCl3 ·6H2 O were obtained from Tianjin Guangfu science and technology development limited company. Bovine Serum Albumin (BSA) was purchased from Beijing xinjingke Biotechnology Co., Ltd. Hydrogen Peroxide 30% (H2 O2 ) was obtained from Xilong Chemical Co., Ltd. Nylon Springe Filter (0.45 m) was purchased from Membrane Solutions Company. Ultra-pure water (resistivity > 18 M cm) was used throughout the experiments. All the reagents were of analytical grade and used as received without further purification. 2.2. Apparatus In all the procedures, the water used was purified by an Olst ultrapure K8 apparatus (Olst, Ltd., resistivity > 18 M cm). Transmission electron microscopy (TEM) was performed with a JEOL-100CX electron microscope under 80 kV accelerating voltage. UV–vis spectra were measured with a 3300 UV–vis–NIR spectrometer (Shimadzu, Japan). High-resolution transmission electron microscope (HRTEM) images were acquired on a JEOL-2100 electron microscope. 2.3. Synthesis of BSA-AuNCs AuNCs were synthesis according to previous method [39]. Briefly, 5 mL aqueous HAuCl4 solution (10 mM) was added to 5 mL BSA solution (50 mg mL−1 ) under vigorous stirring. 0.5 mL NaOH solution (1 M) was added 2 min later, the mixture was incubated at 37 ◦ C for 12 h. The final AuNCs solution was kept at 4 ◦ C before use. 2.4. Detection of Hg2+ 5 L AuNCs solution was added into 35 L 2morpholinoethanesulfonic acid (MES) buffer (1 mM, pH 6.5), 40 L different concentration of HgCl2 solution, 100 L trisodium citrate (4 mM) and 100 L hydrogen peroxide (240 M) in MES buffer was added to each centrifuge tube. After 40 min incubation, 100 L freshly prepared aqueous HAuCl4 solution (2 mM) in MES buffer was added to each well. 50 min later, the absorbance signals were measured by UV-vis-NIR spectroscopy. 2.5. Detection of Hg2+ in real water samples Tap water and river water were collected to evaluate the performance of proposed sensor. Tap water and river water samples
were collected from the laboratory of Capital Normal University and Linglong River in Beijing, respectively. Water samples were filtered through a 0.45 m membrane. The different concentrations of Hg2+ were added to prepared water samples, 40 L mixed solution was added to reaction system. 3. Results and discussion 3.1. Design and fabrication of Hg2+ colorimetric detection sensing system The principle of Hg2+ detection is illustrated in Scheme 1. Although AuNPs synthesized by H2 O2 can be partially aggregated by MES to change the solution color to purple, a relatively adequate amount of H2 O2 provokes the AuNPs to stay red. Hg2+ was effective in down-regulating the catalytic activity of AuNCs to decompose H2 O2 . In order to accelerate the reaction rate, trisodium citrate (TSC) was added into the sensing system, which is capable of thermodynamically reducing HAuCl4 into AuNPs. When AuNPs are obtained, they catalyze TSC to reduce HAuCl4 at the surface of AuNPs, leading to the accelerated formation of AuNPs at 37 ◦ C (Fig. S1) [40]. In the absence of Hg2+ , all AuNCs can catalyze the decomposition of H2 O2 , resulting in the decrease in residual H2 O2 . This will accompany the growth of AuNPs at a slow rate and cause partial aggregation of AuNPs, which then display a purple color. In the presence of Hg2+ , however, Hg2+ can decrease the catalytic ability of AuNCs through the interaction of the Au+ on the surface of AuNCs and Hg2+ , which leads to the increase in residual H2 O2 after partial consumption; this relatively adequate amount of H2 O2 can reduce HAuCl4 to form AuNPs that maintain a red color. As a result, the obvious variation of color is determined by the concentration of H2 O2 , which is selectively representative of the concentration of mercury ions. In this case, mercury ions can be detected by the naked eye. 3.2. Optimization of detection conditions It is well known that the reaction temperature and incubation time have a great impact on the analytical performance of a sensing system. In order to achieve optimal conditions, 10 M Hg2+ was used to optimize both reaction temperature and incubation time. The absorbance increased with the increase in Hg2+ , and the absorption peak at 537 nm began to level off at 10 M (Fig. S2). As shown in Fig. 1A, the influence of temperature on the sensing system was investigated. When the temperature was below 37 ◦ C, the absorbance increased with the increase in temperature, since the formation of AuNPs was easier. In contrast, the absorbance decreased with the increase in temperature above 37 ◦ C. Since H2 O2 can be promptly self-decomposed, the residual H2 O2 after decomposition used to reduce HAuCl4 to form AuNPs decreased. As a consequence, 37 ◦ C was selected as the detection temperature. The effect of incubation time on the sensing system at 37 ◦ C was also investigated (Fig. 1B). When the incubation time was less than 40 min, the absorbance increased with the increase in incubation time. After 40 min, the absorbance decreased; thus, the most suitable time for incubation was determined to be 40 min. The reaction time is a significant factor of colorimetric detection performance. The absorbance increased with the increase in reaction time, and the invariant absorbance was obtained after 50 min, as shown in Fig. 1C. Therefore, 50 min was chosen as the reaction time of the sensing system. The concentration of H2 O2 plays a dual role in the catalysis of AuNCs and the formation of AuNPs. For the sake of choosing optimal experimental conditions, the influence of the concentration of H2 O2 was investigated, as shown in Fig. 1D. When the concentra-
Please cite this article in press as: Y. Zhou, Z. Ma, Colorimetric detection of Hg2+ by Au nanoparticles formed by H2 O2 reduction of HAuCl4 using Au nanoclusters as the catalyst, Sens. Actuators B: Chem. (2016), http://dx.doi.org/10.1016/j.snb.2016.10.035
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Scheme 1. Schematic illustration of colorimetric detect Hg2+ .
Fig. 1. The effect of temperature (A), incubation time (B), reaction time (C), and the concentration of H2 O2 on this sensing system.
tion of H2 O2 ranged from 80 to 240 M, the range of A537/A650 gradually increased. The absorbance peaks at 650 nm and 537 nm are related to the aggregated and dispersed AuNPs, respectively. When the concentration of H2 O2 ranged from 240 to 640 M, the range of A537/A650 gradually decreased; thus, 240 M was chosen as the optimal reaction concentration. 3.3. Analytical performance of the Hg2+ detection sensor AuNCs were synthesized according to a previous method [39]. The characterization of AuNCs is shown in Fig. S3 in which it can be clearly seen that the particle diameter of AuNCs is ca. 2.0 nm. In order to determine the sensitivity of the proposed sensing system under the optimized conditions, a linear relation curve was obtained by recording the relationship between the absorbance ratio of Abs537/Abs650 and different concentrations of Hg2+ . The concentration of mercury ions was between 0.1 nM and 10 M. With the increase in concentration of Hg2+ , the color gradually
changed from purple to red, suggesting that the catalytic ability of AuNCs is dependent Hg2+ concentration (Fig. 2A). In this case, Abs537/Abs650 clearly shows the relationship between the concentration of Hg2+ and absorbance of AuNPs. A liner relationship between the absorbance ratio of Abs537/Abs650 and the concentration of Hg2+ was obtained in the range 0.1 nM–10 M (R2 = 0.9965) (Fig. 2B). The limit of detection (LOD) of Hg2+ (S/N = 3) was calculated to be 8:9 pM which is much lower than the maximum permitted level (2.0 ppb = 10 nM) of Hg2+ in drinking water by the United States Environmental Protection Agency (EPA). Fig. 2 In order to evaluate the selectivity of this sensing system, other metal ions, including Fe2+ , Fe3+ , Cu2+ , Cd2+ , Cr3+ , K+ , Ba2+ , Mg2+ , Pb2+ , and Ag+ , were tested respectively under the same conditions as Hg2+ . The concentrations of the aforementioned metal ions were 100 times greater than that of Hg2+ . Fig. 3A shows that no obvious change of Abs537/Abs650 occurred upon adding other metal ions to this sensing system in which the color of the solution remained purple. Conversely, the Abs537/Abs650 sharply
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Table 2 Comparison of different method for metal ions detection. Methods
Selectivity
LOD
Liner range
Colorimetric Colorimetric Colorimetric Colorimetric Fluorescent Colorimetric Fluorescent Fluorescent Colorimetric Colorimetric
Hg2+ Hg2+ Hg2+ Hg2+ Hg2+ Hg2+ MeHg+ Hg2+ Hg2+ Hg2+
53 nM 30 nM 0.05 M 2.9 nM 80 nM 100 nM 5.9 nM 14.5 nM 0.2 nM 8.9 pM
33–300 nM 0.2–60 M 0.2–6 M 1 nM–1 M 0.25–6 M 0–2 M 23–278 nM 0.05–8 M 0.2–3.2 nM 0.1 nM–10 M
Real samples
References
River water River and tap water Tap Water
River, tap and sea water
River and tap water
[13] [41] [26] [15] [42] [24] [43] [44] [45] This work
Fig. 2. (A) UV–vis spectra of the sensing system after the addition of Hg2+ with different concentrations. (B) The corresponding plot of absorption ratio vs. the concentration of Hg2+ . Inset: Calibration plot of Hg2+ . The top image is the colorimetric response to different concentrations of Hg2+ .
Table 1 Result of Hg2+ recovery experiment in water samples.
Fig. 3. The selectivity of the method for Hg2+ (100 nM) against other metal ions with of different metal ions concentration of 10 M. Inset: the corresponding color photographic images of different metal ions.
increased after adding Hg2+ , and the color of the solution became red. Hence, the results indicate that the sensing system has a good selectivity for Hg2+ . This selectivity may be attributed to the combination of Au+ on surface of AuNCs and Hg2+ , which can downregulate the catalytic ability of AuNCs while other ions cannot. 3.4. Detection of Hg2+ in river and tap water samples To validate whether the proposed sensing system can detect Hg2+ from real water samples, tap water and river water sam-
Sample
Added (nM)
Found (nM)
Recovery (%)
River water River water Tap water Tap water
50 100 50 100
49.56 101.25 48.79 99.31
99.12 101.25 97.58 99.31
ples with different spiked concentrations of Hg2+ were performed. Before the experiment, large suspended particles were filtered with 0.45 m membrane, and all samples were measured three times as depicted in Table 1. The relative errors of the measurement were from −2.42% to 1.25%, indicating no obvious differences between the added and measured values. These results suggest that the proposed method has high accuracy and can be applied for the detection of Hg2+ in tap and river water. The obtained results were compared to those produced by other methods (Table 2). Our method has a detection limit of as low as 8:9 pM which is superior to other methods, and a linear response range from 0.1 nM to 10 M, which is wider than other methods. Therefore, the proposed method is an accurate and direct technique to detect mercury ions. 4. Conclusions In summary, we have demonstrated a simple, convenient, and ultrasensitive strategy for the detection of Hg2+ with the naked eye. AuNCs, of which catalytic ability can be inhibited by Hg2+ , can catalyze the decomposition of H2 O2 that reduces HAuCl4 to form AuNPs for readout by the naked eye. One of the most prominent features of this sensing system is that the AuNPs were directly used to detect mercury ions without modification. The second signifi-
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cant feature of this study is that a novel colorimetric method for ultrasensitive detect mercury ions was developed, which induces a color change of the tested solution from purple to red. The method presents good sensitivity and appears to be a promising prospect for practical applications. Acknowledgments This research was financed by Grants from the Beijing Natural Science Foundation (2132008), the Research Base Construction Projects of Beijing Municipal Education Commission. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.snb.2016.10.035. References [1] P.P. Bian, L.W. Xing, Z.M. Liu, Z.F. Ma, Functionalized-tryptophan stabilized fluorescent Ag nanoclusters: synthesis and its application as Hg2+ ions sensor, Sens. Actuators B 203 (2014) 252–257. [2] G.K. Darbha, A. Ray, P.C. Ray, Gold nanoparticle-based miniaturized nanomaterial surface energy transfer probe for rapid and ultrasensitive detection of mercury in soil, water, and fish, ACS Nano 1 (2007) 208–214. [3] P. Li, X.B. Feng, G.L. Qiu, L.H. Shang, Z.G. Li, Mercury pollution in Asia: a review of the contaminated sites, J. Hazard. Mater. 168 (2009) 591–601. [4] J.L. Barriada, A.D. Tappin, E.H. Evans, E.P. Achterberg, Dissolved silver measurements in seawater, TrAC, Trends Anal. Chem. 26 (2007) 809–817. [5] H. Erxleben, J. Ruzicka, Atomic absorption spectroscopy for mercury, automated by sequential injection and miniaturized in lab-on-valve system, Anal. Chem. 77 (2005) 5124–5128. [6] R. Ito, M. Kawaguchi, N. Sakui, H. Honda, N. Okanouchi, K. Saito, et al., Mercury speciation and analysis in drinking water by stir bar sorptive extraction with in situ propyl derivatization and thermal desorption–gas chromatography–mass spectrometry, J. Chromatogr. A 1209 (2008) 267–270. [7] A. Castillo, A.F. Roig-Navarro, O.J. Pozo, Method optimization for the determination of four mercury species by micro-liquid chromatography–inductively coupled plasma mass spectrometry coupling in environmental water samples, Anal. Chim. Acta 577 (2006) 18–25. [8] N. Amiri, M.K. Rofouei, J.B. Ghasemi, Multivariate optimization, preconcentration and determination of mercury ions with (1-(p-acetyl phenyl)-3-(o-methyl benzoate)) triazene in aqueous samples using ICP-AES, Anal. Methods 8 (2016) 1111–1119. [9] X. Chai, L. Zhang, Y. Tian, Ratiometric electrochemical sensor for selective monitoring of cadmium ions using biomolecular recognition, Anal. Chem. 86 (2014) 10668–10673. [10] Y. Chen, Z.-P. Chen, S.-Y. Long, R.-Q. Yu, Generalized ratiometric indicator based surface-enhanced raman spectroscopy for the detection of Cd2+ in environmental water samples, Anal. Chem. 86 (2014) 12236–12242. [11] T.X. Wu, T. Xu, Z.F. Ma, Sensitive electrochemical detection of copper ions based on the copper(ii) ion assisted etching of Au@Ag nanoparticles, Analyst 140 (2015) 8041–8047. [12] Y. Zhou, Z.F. Ma, A novel fluorescence enhanced route to detect copper(ii) by click chemistry-catalyzed connection of Au@SiO2 and carbon dots, Sens. Actuators B 233 (2016) 426–430. [13] M. Annadhasan, T. Muthukumarasamyvel, V.R. Sankar Babu, N. Rajendiran, Green synthesized silver and gold nanoparticles for colorimetric detection of Hg2+ Pb2+ , and Mn2+ in aqueous medium, ACS Sustain. Chem. Eng. 2 (2014) 887–896. [14] F. Chai, C.G. Wang, T.T. Wang, L. Li, Z.M. Su, Colorimetric detection of Pb2+ using glutathione functionalized gold nanoparticles, ACS Appl. Mater. Interfaces 2 (2010) 1466–1470. [15] G. Sener, L. Uzun, A. Denizli, Lysine-promoted colorimetric response of gold nanoparticles: a simple assay for ultrasensitive mercury(ii) detection, Anal. Chem. 86 (2014) 514–520. [16] Z.M. Liu, X.L. Jia, P.P. Bian, Z.F. Ma, A simple and novel system for colorimetric detection of cobalt ions, Analyst 139 (2014) 585–588. [17] E.S. Forzani, D. Lu, M.J. Leright, A.D. Aguilar, F. Tsow, R.A. Iglesias, et al., A hybrid electrochemical-colorimetric sensing platform for detection of explosives, J. Am. Chem. Soc. 131 (2009) 1390–1391. [18] L. Tang, Y. Liu, M.M. Ali, D.K. Kang, W. Zhao, J. Li, Colorimetric and ultrasensitive bioassay based on a dual-amplification system using aptamer and DNAzyme, Anal. Chem. 84 (2012) 4711–4717. [19] Y.-Q. Dang, H.-W. Li, B. Wang, L. Li, Y. Wu, Selective detection of trace Cr3+ in aqueous solution by using 5,5 -Dithiobis (2-nitrobenzoic acid)-modified gold nanoparticles, ACS Appl, Mater. Interfaces 1 (2009) 1533–1538.
5
[20] K. Ai, Y. Liu, L. Lu, Hydrogen-bonding recognition-induced color change of gold nanoparticles for visual detection of melamine in raw milk and infant formula, J. Am. Chem. Soc. 131 (2009) 9496–9497. [21] X. Yang, Z. Gao, Gold nanoparticle-based exonuclease III signal amplification for highly sensitive colorimetric detection of folate receptor, Nanoscale 6 (2014) 3055–3058. [22] C. Hua, W.H. Zhang, S.R.M. De Almeida, S. Ciampi, D. Gloria, G. Liu, et al., A novel route to copper(ii) detection using ‘click’ chemistry-induced aggregation of gold nanoparticles, Analyst 137 (2012) 82–86. [23] W. Yun, D. Cai, J. Jiang, P. Zhao, Y. Huang, G. Sang, Enzyme-free and label-free ultra-sensitive colorimetric detection of Pb2+ using molecular beacon and DNAzyme based amplification strategy, Biosens. Bioelectron. 80 (2016) 187–193. [24] J.-S. Lee, M.S. Han, C.A. Mirkin, Colorimetric detection of mercuric ion (Hg2+ ) in aqueous media using DNA-functionalized gold nanoparticles, Angew. Chem. Int. Ed. 119 (2007) 4171–4174. [25] X. Xu, J. Wang, K. Jiao, X. Yang, Colorimetric detection of mercury ion (Hg2+ ) based on DNA oligonucleotides and unmodified gold nanoparticles sensing system with a tunable detection range, Biosens. Bioelectron. 24 (2009) 3153–3158. [26] Y. Xu, L. Deng, H. Wang, X. Ouyang, J. Zheng, J. Li, et al., Metal-induced aggregation of mononucleotides-stabilized gold nanoparticles: an efficient approach for simple and rapid colorimetric detection of Hg(ii), Chem. Commun. 47 (2011) 6039–6041. [27] Y. Zhou, S. Wang, K. Zhang, X. Jiang, Visual detection of copper(II) by azideand alkyne-functionalized gold nanoparticles using click chemistry, Angew. Chem. Int. Ed. 47 (2008) 7454–7456. [28] J. Yan, L. Wang, L. Tang, L. Lin, Y. Liu, J. Li, Enzyme-guided plasmonic biosensor based on dual-functional nanohybrid for sensitive detection of thrombin, Biosens. Bioelectron. 70 (2015) 404–410. [29] J. Hu, Z. Wang, J. Li, Gold nanoparticles with special shapes: controlled synthesis, surface-enhanced raman scattering, and the application in biodetection, Sensors 7 (2007). [30] C. Engelbrekt, K.H. Sorensen, J. Zhang, A.C. Welinder, P.S. Jensen, J. Ulstrup, Green synthesis of gold nanoparticles with starch-glucose and application in bioelectrochemistry, J. Mater. Chem. 19 (2009) 7839–7847. [31] R. de la Rica, M.M. Stevens, Plasmonic ELISA for the ultrasensitive detection of disease biomarkers with the naked eye, Nat. Nanotechnol. 7 (2012) 821–824. [32] F. Jiang, R. Yue, Y. Du, J. Xu, P. Yang, A one-pot ‘green’ synthesis of Pd-decorated PEDOT nanospheres for nonenzymatic hydrogen peroxide sensing, Biosens. Bioelectron. 44 (2013) 127–131. [33] C. Wang, J. Du, H. Wang, C. e. Zou, F. Jiang, P. Yang, et al., A facile electrochemical sensor based on reduced graphene oxide and Au nanoplates modified glassy carbon electrode for simultaneous detection of ascorbic acid, dopamine and uric acid, Sens. Actuators B 204 (2014) 302–309. [34] X. Shan, I. Diez-Perez, L. Wang, P. Wiktor, Y. Gu, L. Zhang, et al., Imaging the electrocatalytic activity of single nanoparticles, Nat. Nanotechnol. 7 (2012) 668–672. [35] L. Zhang, Q. Zhang, X. Lu, J. Li, Direct electrochemistry and electrocatalysis based on film of horseradish peroxidase intercalated into layered titanate nano-sheets, Biosens. Bioelectron. 23 (2007) 102–106. [36] J. Xie, Y. Zheng, J.Y. Ying, Highly selective and ultrasensitive detection of Hg2+ based on fluorescence quenching of Au nanoclusters by Hg2+ -Au+ interactions, Chem. Commun. 46 (2010) 961–963. [37] D. Liu, W. Qu, W. Chen, W. Zhang, Z. Wang, X. Jiang, Highly sensitive, colorimetric detection of mercury(ii) in aqueous media by quaternary ammonium group-capped gold nanoparticles at room temperature, Anal. Chem. 82 (2010) 9606–9610. [38] L. Beqa, A.K. Singh, S.A. Khan, D. Senapati, S.R. Arumugam, P.C. Ray, Gold nanoparticle-based simple colorimetric and ultrasensitive dynamic light scattering assay for the selective detection of Pb(II) from paints plastics, and water samples, ACS Appl. Mater. Interfaces 3 (2011) 668–673. [39] J. Xie, Y. Zheng, J.Y. Ying, Protein-directed synthesis of highly fluorescent gold nanoclusters, J. Am. Chem. Soc. 131 (2009) 888–889. [40] Z.F. Ma, S.-F. Sui, Naked-eye sensitive detection of immunoglubulin g by enlargement of Au nanoparticles in vitro, Angew. Chem. Int. Ed. 41 (2002) 2176–2179. [41] Y.-W. Wang, S. Tang, H.-H. Yang, H. Song, A novel colorimetric assay for rapid detection of cysteine and Hg2+ based on gold clusters, Talanta 146 (2016) 71–74. [42] L. Wang, B. Li, F. Xu, X. Shi, D. Feng, D. Wei, et al., High-yield synthesis of strong photoluminescent N-doped carbon nanodots derived from hydrosoluble chitosan for mercury ion sensing via smartphone APP, Biosens. Bioelectron. 79 (2016) 1–8. [43] I. Costas-Mora, V. Romero, I. Lavilla, C. Bendicho, In situ building of a nanoprobe based on fluorescent carbon dots for methylmercury detection, Anal. Chem. 86 (2014) 4536–4543. [44] L. Zhang, T. Li, B. Li, J. Li, E. Wang, Carbon nanotube-DNA hybrid fluorescent sensor for sensitive and selective detection of mercury(ii) ion, Chem. Commun. 46 (2010) 1476–1478. [45] W. Li, Y. Guo, K. McGill, P. Zhang, A facile synthesis of Ag nanoparticles for mercury ion detection with high sensitivity and selectivity, New J. Chem. 34 (2010) 1148–1152.
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Biographies Yuan Zhou received B.S. degree from Beijing Institute of Fashion Technology in 2014. Now she is a graduate student at Capital Normal University. Her research focused on the heavy metal ion detection.
Zhanfang Ma received a B.S. degree from Northeast Normal University and a Ph.D. in colloid and interface science in Key Laboratory of Colloid, Interface and Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences. He is currently a full professor of physical chemistry in Department of Chemistry of Capital Normal University. His current research interests include nanobiosensor, nanofabrication, and electrochemical biosensors.
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Colorimetric detection of Hg2+ by Au nanoparticles formed by H2 O2 reduction of HAuCl4 using Au nanoclusters as the catalyst Yuan Zhou, Zhanfang Ma ∗ Department of Chemistry, Capital Normal University, Beijing 100048, China
a r t i c l e
i n f o
Article history: Received 17 June 2016 Received in revised form 6 October 2016 Accepted 8 October 2016 Available online xxx Keywords: Mercury ions Colorimetric detection Gold nanoparticles Gold nanoclusters Catalytic activity
a b s t r a c t Gold nanoclusters (AuNCs), due to their enzyme-like activity, can catalyze the decomposition of hydrogen peroxide (H2 O2 ), which can be used to reduce HAuCl4 into gold nanoparticles (AuNPs). Hg2+ effectively decreases the catalytic ability of AuNCs to decompose H2 O2 by the interactions between Au+ on surface of AuNCs and Hg2+ . In a system containing AuNCs, H2 O2 , and HAuCl4 , increasing the Hg2+ concentration prompts a color change from purple to red of the solution of as-synthesized AuNPs, which results from the increase in residual H2 O2 after decomposition by AuNCs. Based on this principle, a novel colorimetric method for ultrasensitive detection of mercury ions was developed in this work. AuNPs synthesized by a one-step method without modification were used to directly detect mercury ions in lake and river water samples. The detection limit of the present method was determined to be 8:9 pM with a linear response range of 0.1 nM–10 M, which is much lower than the standard value defined by the Environmental Protection Agency (EPA). The method not only possesses advantages of convenience and simplicity, but also is promising for application in real samples. © 2016 Elsevier B.V. All rights reserved.
1. Introduction Mercury ions are recognized as global environmental pollutants that are mainly released from coal combustion, metal mining, and solid waste incineration. Residual Hg0 vapor and Hg2+ remain in the atmosphere and water for long periods of time and can even transport to or deposit in remote places. Moreover, humans’ brains, lungs, and central nervous system can be damaged by mercury through the food chain. [1–3] Therefore, the detection of mercury ions is crucial for monitoring the environment in and around rivers and lakes. Traditional methods for the detection of mercury ions include spectroscopic techniques, [4–6] inductively coupled plasma mass spectrometry (ICP-MS) [7], inductively coupled plasma atomic emission spectroscopy (ICP-AES) [8], yet these often require tedious preparation of materials and timeconsuming, complicated operation. Thus, it is extremely urgent to produce a facile, high sensitive and cost-effective method for detection of mercury ions. Although numerous sensing systems used for determination of heavy metal ions have been reported over the past few years
∗ Corresponding author. E-mail address: [email protected] (Z. Ma).
[9–12], the colorimetric method has attracted the most attention due to its simple readout and obvious color change that occurs in the presence of analyte can be viewed by the naked eye or using a UV–vis spectrophotometer [13–19]. For the colorimetric method, gold nanoparticles (AuNPs) have received extensive interest based on the localized surface plasma resonance (SPR) effect [20–23]. For AuNPs, surface modification by ligand, protein, and aptamers for detecting mercury ions is favorable since the ligand, protein, and aptamers are easily obtained and the resultant modification can be clearly seen [15,24–26]. However, the modification process in the majority of these sensing systems is time-consuming [27]. H2 O2 , as a mild reducing agent, can reduce HAuCl4 to form AuNPs, while 2-morpholinoethanesulfonic acid (MES) induces partial aggregation of AuNPs [28–30]. While addition of 2morpholinoethanesulfonic acid (MES) alters the color of nanoparticle dispersions to purple, the addition of a sufficient amount of H2 O2 enables the solution to maintain a red color [31]. Further, Hg2+ can be introduced to inhibit the catalytic activity of gold nanoclusters (AuNCs) to decompose H2 O2 by interacting with Au+ on the surface of AuNCs [32–36]. Herein, based on these principles, a novel colorimetric strategy for the ultrasensitive detection of Hg2+ was designed. Different from conventional methods [15,37,38], the presented strategy ensures that the color of AuNPs solution changes from purple to
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red. Moreover, AuNPs without modification can be directly used to detect Hg2+ . In the absence of Hg2+ , AuNCs were used for the decomposition of added H2 O2 , resulting in the reduction of residual H2 O2 . This slowed the growth of AuNPs and prompted the partial aggregation of AuNPs to display purple color. In the presence of Hg2+ , the catalytic activity of AuNCs was inhibited, decreasing the decomposition of H2 O2 , yet the residual H2 O2 increased. As a consequence, the color of AuNPs solution retained red due to the relatively adequate H2 O2 . An obvious color variation of AuNPs was easily detected by the naked eye, which posed as a simple method for detecting the presence of mercury ions. 2. Experimental 2.1. Materials and reagents Hydrogen Tetrachloroaurate Hydrate (HAuCl4 ·xH2 O) was purchased from Alfa Aesar. 2-Morpholinoethanesulfonic Acid (MES) was obtained from Aladdin Industrial Corporation. Trisodium Citrate (Na3 C6 H5 O7 ·2H2 O), NaOH, HgCl2 were purchased from Beijing Chemical Reagents Company (Beijing, China). AgNO3 , BaCl2 ·2H2 O, Pb(NO3 )2 , FeCl3 ·6H2 O, CuCl2 ·2H2 O, KCl, MgCl2 ·6H2 O, CdCl2 ·5/2H2 O, FeCl2 ·4H2 O and CrCl3 ·6H2 O were obtained from Tianjin Guangfu science and technology development limited company. Bovine Serum Albumin (BSA) was purchased from Beijing xinjingke Biotechnology Co., Ltd. Hydrogen Peroxide 30% (H2 O2 ) was obtained from Xilong Chemical Co., Ltd. Nylon Springe Filter (0.45 m) was purchased from Membrane Solutions Company. Ultra-pure water (resistivity > 18 M cm) was used throughout the experiments. All the reagents were of analytical grade and used as received without further purification. 2.2. Apparatus In all the procedures, the water used was purified by an Olst ultrapure K8 apparatus (Olst, Ltd., resistivity > 18 M cm). Transmission electron microscopy (TEM) was performed with a JEOL-100CX electron microscope under 80 kV accelerating voltage. UV–vis spectra were measured with a 3300 UV–vis–NIR spectrometer (Shimadzu, Japan). High-resolution transmission electron microscope (HRTEM) images were acquired on a JEOL-2100 electron microscope. 2.3. Synthesis of BSA-AuNCs AuNCs were synthesis according to previous method [39]. Briefly, 5 mL aqueous HAuCl4 solution (10 mM) was added to 5 mL BSA solution (50 mg mL−1 ) under vigorous stirring. 0.5 mL NaOH solution (1 M) was added 2 min later, the mixture was incubated at 37 ◦ C for 12 h. The final AuNCs solution was kept at 4 ◦ C before use. 2.4. Detection of Hg2+ 5 L AuNCs solution was added into 35 L 2morpholinoethanesulfonic acid (MES) buffer (1 mM, pH 6.5), 40 L different concentration of HgCl2 solution, 100 L trisodium citrate (4 mM) and 100 L hydrogen peroxide (240 M) in MES buffer was added to each centrifuge tube. After 40 min incubation, 100 L freshly prepared aqueous HAuCl4 solution (2 mM) in MES buffer was added to each well. 50 min later, the absorbance signals were measured by UV-vis-NIR spectroscopy. 2.5. Detection of Hg2+ in real water samples Tap water and river water were collected to evaluate the performance of proposed sensor. Tap water and river water samples
were collected from the laboratory of Capital Normal University and Linglong River in Beijing, respectively. Water samples were filtered through a 0.45 m membrane. The different concentrations of Hg2+ were added to prepared water samples, 40 L mixed solution was added to reaction system. 3. Results and discussion 3.1. Design and fabrication of Hg2+ colorimetric detection sensing system The principle of Hg2+ detection is illustrated in Scheme 1. Although AuNPs synthesized by H2 O2 can be partially aggregated by MES to change the solution color to purple, a relatively adequate amount of H2 O2 provokes the AuNPs to stay red. Hg2+ was effective in down-regulating the catalytic activity of AuNCs to decompose H2 O2 . In order to accelerate the reaction rate, trisodium citrate (TSC) was added into the sensing system, which is capable of thermodynamically reducing HAuCl4 into AuNPs. When AuNPs are obtained, they catalyze TSC to reduce HAuCl4 at the surface of AuNPs, leading to the accelerated formation of AuNPs at 37 ◦ C (Fig. S1) [40]. In the absence of Hg2+ , all AuNCs can catalyze the decomposition of H2 O2 , resulting in the decrease in residual H2 O2 . This will accompany the growth of AuNPs at a slow rate and cause partial aggregation of AuNPs, which then display a purple color. In the presence of Hg2+ , however, Hg2+ can decrease the catalytic ability of AuNCs through the interaction of the Au+ on the surface of AuNCs and Hg2+ , which leads to the increase in residual H2 O2 after partial consumption; this relatively adequate amount of H2 O2 can reduce HAuCl4 to form AuNPs that maintain a red color. As a result, the obvious variation of color is determined by the concentration of H2 O2 , which is selectively representative of the concentration of mercury ions. In this case, mercury ions can be detected by the naked eye. 3.2. Optimization of detection conditions It is well known that the reaction temperature and incubation time have a great impact on the analytical performance of a sensing system. In order to achieve optimal conditions, 10 M Hg2+ was used to optimize both reaction temperature and incubation time. The absorbance increased with the increase in Hg2+ , and the absorption peak at 537 nm began to level off at 10 M (Fig. S2). As shown in Fig. 1A, the influence of temperature on the sensing system was investigated. When the temperature was below 37 ◦ C, the absorbance increased with the increase in temperature, since the formation of AuNPs was easier. In contrast, the absorbance decreased with the increase in temperature above 37 ◦ C. Since H2 O2 can be promptly self-decomposed, the residual H2 O2 after decomposition used to reduce HAuCl4 to form AuNPs decreased. As a consequence, 37 ◦ C was selected as the detection temperature. The effect of incubation time on the sensing system at 37 ◦ C was also investigated (Fig. 1B). When the incubation time was less than 40 min, the absorbance increased with the increase in incubation time. After 40 min, the absorbance decreased; thus, the most suitable time for incubation was determined to be 40 min. The reaction time is a significant factor of colorimetric detection performance. The absorbance increased with the increase in reaction time, and the invariant absorbance was obtained after 50 min, as shown in Fig. 1C. Therefore, 50 min was chosen as the reaction time of the sensing system. The concentration of H2 O2 plays a dual role in the catalysis of AuNCs and the formation of AuNPs. For the sake of choosing optimal experimental conditions, the influence of the concentration of H2 O2 was investigated, as shown in Fig. 1D. When the concentra-
Please cite this article in press as: Y. Zhou, Z. Ma, Colorimetric detection of Hg2+ by Au nanoparticles formed by H2 O2 reduction of HAuCl4 using Au nanoclusters as the catalyst, Sens. Actuators B: Chem. (2016), http://dx.doi.org/10.1016/j.snb.2016.10.035
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Scheme 1. Schematic illustration of colorimetric detect Hg2+ .
Fig. 1. The effect of temperature (A), incubation time (B), reaction time (C), and the concentration of H2 O2 on this sensing system.
tion of H2 O2 ranged from 80 to 240 M, the range of A537/A650 gradually increased. The absorbance peaks at 650 nm and 537 nm are related to the aggregated and dispersed AuNPs, respectively. When the concentration of H2 O2 ranged from 240 to 640 M, the range of A537/A650 gradually decreased; thus, 240 M was chosen as the optimal reaction concentration. 3.3. Analytical performance of the Hg2+ detection sensor AuNCs were synthesized according to a previous method [39]. The characterization of AuNCs is shown in Fig. S3 in which it can be clearly seen that the particle diameter of AuNCs is ca. 2.0 nm. In order to determine the sensitivity of the proposed sensing system under the optimized conditions, a linear relation curve was obtained by recording the relationship between the absorbance ratio of Abs537/Abs650 and different concentrations of Hg2+ . The concentration of mercury ions was between 0.1 nM and 10 M. With the increase in concentration of Hg2+ , the color gradually
changed from purple to red, suggesting that the catalytic ability of AuNCs is dependent Hg2+ concentration (Fig. 2A). In this case, Abs537/Abs650 clearly shows the relationship between the concentration of Hg2+ and absorbance of AuNPs. A liner relationship between the absorbance ratio of Abs537/Abs650 and the concentration of Hg2+ was obtained in the range 0.1 nM–10 M (R2 = 0.9965) (Fig. 2B). The limit of detection (LOD) of Hg2+ (S/N = 3) was calculated to be 8:9 pM which is much lower than the maximum permitted level (2.0 ppb = 10 nM) of Hg2+ in drinking water by the United States Environmental Protection Agency (EPA). Fig. 2 In order to evaluate the selectivity of this sensing system, other metal ions, including Fe2+ , Fe3+ , Cu2+ , Cd2+ , Cr3+ , K+ , Ba2+ , Mg2+ , Pb2+ , and Ag+ , were tested respectively under the same conditions as Hg2+ . The concentrations of the aforementioned metal ions were 100 times greater than that of Hg2+ . Fig. 3A shows that no obvious change of Abs537/Abs650 occurred upon adding other metal ions to this sensing system in which the color of the solution remained purple. Conversely, the Abs537/Abs650 sharply
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Table 2 Comparison of different method for metal ions detection. Methods
Selectivity
LOD
Liner range
Colorimetric Colorimetric Colorimetric Colorimetric Fluorescent Colorimetric Fluorescent Fluorescent Colorimetric Colorimetric
Hg2+ Hg2+ Hg2+ Hg2+ Hg2+ Hg2+ MeHg+ Hg2+ Hg2+ Hg2+
53 nM 30 nM 0.05 M 2.9 nM 80 nM 100 nM 5.9 nM 14.5 nM 0.2 nM 8.9 pM
33–300 nM 0.2–60 M 0.2–6 M 1 nM–1 M 0.25–6 M 0–2 M 23–278 nM 0.05–8 M 0.2–3.2 nM 0.1 nM–10 M
Real samples
References
River water River and tap water Tap Water
River, tap and sea water
River and tap water
[13] [41] [26] [15] [42] [24] [43] [44] [45] This work
Fig. 2. (A) UV–vis spectra of the sensing system after the addition of Hg2+ with different concentrations. (B) The corresponding plot of absorption ratio vs. the concentration of Hg2+ . Inset: Calibration plot of Hg2+ . The top image is the colorimetric response to different concentrations of Hg2+ .
Table 1 Result of Hg2+ recovery experiment in water samples.
Fig. 3. The selectivity of the method for Hg2+ (100 nM) against other metal ions with of different metal ions concentration of 10 M. Inset: the corresponding color photographic images of different metal ions.
increased after adding Hg2+ , and the color of the solution became red. Hence, the results indicate that the sensing system has a good selectivity for Hg2+ . This selectivity may be attributed to the combination of Au+ on surface of AuNCs and Hg2+ , which can downregulate the catalytic ability of AuNCs while other ions cannot. 3.4. Detection of Hg2+ in river and tap water samples To validate whether the proposed sensing system can detect Hg2+ from real water samples, tap water and river water sam-
Sample
Added (nM)
Found (nM)
Recovery (%)
River water River water Tap water Tap water
50 100 50 100
49.56 101.25 48.79 99.31
99.12 101.25 97.58 99.31
ples with different spiked concentrations of Hg2+ were performed. Before the experiment, large suspended particles were filtered with 0.45 m membrane, and all samples were measured three times as depicted in Table 1. The relative errors of the measurement were from −2.42% to 1.25%, indicating no obvious differences between the added and measured values. These results suggest that the proposed method has high accuracy and can be applied for the detection of Hg2+ in tap and river water. The obtained results were compared to those produced by other methods (Table 2). Our method has a detection limit of as low as 8:9 pM which is superior to other methods, and a linear response range from 0.1 nM to 10 M, which is wider than other methods. Therefore, the proposed method is an accurate and direct technique to detect mercury ions. 4. Conclusions In summary, we have demonstrated a simple, convenient, and ultrasensitive strategy for the detection of Hg2+ with the naked eye. AuNCs, of which catalytic ability can be inhibited by Hg2+ , can catalyze the decomposition of H2 O2 that reduces HAuCl4 to form AuNPs for readout by the naked eye. One of the most prominent features of this sensing system is that the AuNPs were directly used to detect mercury ions without modification. The second signifi-
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cant feature of this study is that a novel colorimetric method for ultrasensitive detect mercury ions was developed, which induces a color change of the tested solution from purple to red. The method presents good sensitivity and appears to be a promising prospect for practical applications. Acknowledgments This research was financed by Grants from the Beijing Natural Science Foundation (2132008), the Research Base Construction Projects of Beijing Municipal Education Commission. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.snb.2016.10.035. References [1] P.P. Bian, L.W. Xing, Z.M. Liu, Z.F. Ma, Functionalized-tryptophan stabilized fluorescent Ag nanoclusters: synthesis and its application as Hg2+ ions sensor, Sens. Actuators B 203 (2014) 252–257. [2] G.K. Darbha, A. Ray, P.C. Ray, Gold nanoparticle-based miniaturized nanomaterial surface energy transfer probe for rapid and ultrasensitive detection of mercury in soil, water, and fish, ACS Nano 1 (2007) 208–214. [3] P. Li, X.B. Feng, G.L. Qiu, L.H. Shang, Z.G. Li, Mercury pollution in Asia: a review of the contaminated sites, J. Hazard. Mater. 168 (2009) 591–601. [4] J.L. Barriada, A.D. Tappin, E.H. Evans, E.P. Achterberg, Dissolved silver measurements in seawater, TrAC, Trends Anal. Chem. 26 (2007) 809–817. [5] H. Erxleben, J. Ruzicka, Atomic absorption spectroscopy for mercury, automated by sequential injection and miniaturized in lab-on-valve system, Anal. Chem. 77 (2005) 5124–5128. [6] R. Ito, M. Kawaguchi, N. Sakui, H. Honda, N. Okanouchi, K. Saito, et al., Mercury speciation and analysis in drinking water by stir bar sorptive extraction with in situ propyl derivatization and thermal desorption–gas chromatography–mass spectrometry, J. Chromatogr. A 1209 (2008) 267–270. [7] A. Castillo, A.F. Roig-Navarro, O.J. Pozo, Method optimization for the determination of four mercury species by micro-liquid chromatography–inductively coupled plasma mass spectrometry coupling in environmental water samples, Anal. Chim. Acta 577 (2006) 18–25. [8] N. Amiri, M.K. Rofouei, J.B. Ghasemi, Multivariate optimization, preconcentration and determination of mercury ions with (1-(p-acetyl phenyl)-3-(o-methyl benzoate)) triazene in aqueous samples using ICP-AES, Anal. Methods 8 (2016) 1111–1119. [9] X. Chai, L. Zhang, Y. Tian, Ratiometric electrochemical sensor for selective monitoring of cadmium ions using biomolecular recognition, Anal. Chem. 86 (2014) 10668–10673. [10] Y. Chen, Z.-P. Chen, S.-Y. Long, R.-Q. Yu, Generalized ratiometric indicator based surface-enhanced raman spectroscopy for the detection of Cd2+ in environmental water samples, Anal. Chem. 86 (2014) 12236–12242. [11] T.X. Wu, T. Xu, Z.F. Ma, Sensitive electrochemical detection of copper ions based on the copper(ii) ion assisted etching of Au@Ag nanoparticles, Analyst 140 (2015) 8041–8047. [12] Y. Zhou, Z.F. Ma, A novel fluorescence enhanced route to detect copper(ii) by click chemistry-catalyzed connection of Au@SiO2 and carbon dots, Sens. Actuators B 233 (2016) 426–430. [13] M. Annadhasan, T. Muthukumarasamyvel, V.R. Sankar Babu, N. Rajendiran, Green synthesized silver and gold nanoparticles for colorimetric detection of Hg2+ Pb2+ , and Mn2+ in aqueous medium, ACS Sustain. Chem. Eng. 2 (2014) 887–896. [14] F. Chai, C.G. Wang, T.T. Wang, L. Li, Z.M. Su, Colorimetric detection of Pb2+ using glutathione functionalized gold nanoparticles, ACS Appl. Mater. Interfaces 2 (2010) 1466–1470. [15] G. Sener, L. Uzun, A. Denizli, Lysine-promoted colorimetric response of gold nanoparticles: a simple assay for ultrasensitive mercury(ii) detection, Anal. Chem. 86 (2014) 514–520. [16] Z.M. Liu, X.L. Jia, P.P. Bian, Z.F. Ma, A simple and novel system for colorimetric detection of cobalt ions, Analyst 139 (2014) 585–588. [17] E.S. Forzani, D. Lu, M.J. Leright, A.D. Aguilar, F. Tsow, R.A. Iglesias, et al., A hybrid electrochemical-colorimetric sensing platform for detection of explosives, J. Am. Chem. Soc. 131 (2009) 1390–1391. [18] L. Tang, Y. Liu, M.M. Ali, D.K. Kang, W. Zhao, J. Li, Colorimetric and ultrasensitive bioassay based on a dual-amplification system using aptamer and DNAzyme, Anal. Chem. 84 (2012) 4711–4717. [19] Y.-Q. Dang, H.-W. Li, B. Wang, L. Li, Y. Wu, Selective detection of trace Cr3+ in aqueous solution by using 5,5 -Dithiobis (2-nitrobenzoic acid)-modified gold nanoparticles, ACS Appl, Mater. Interfaces 1 (2009) 1533–1538.
5
[20] K. Ai, Y. Liu, L. Lu, Hydrogen-bonding recognition-induced color change of gold nanoparticles for visual detection of melamine in raw milk and infant formula, J. Am. Chem. Soc. 131 (2009) 9496–9497. [21] X. Yang, Z. Gao, Gold nanoparticle-based exonuclease III signal amplification for highly sensitive colorimetric detection of folate receptor, Nanoscale 6 (2014) 3055–3058. [22] C. Hua, W.H. Zhang, S.R.M. De Almeida, S. Ciampi, D. Gloria, G. Liu, et al., A novel route to copper(ii) detection using ‘click’ chemistry-induced aggregation of gold nanoparticles, Analyst 137 (2012) 82–86. [23] W. Yun, D. Cai, J. Jiang, P. Zhao, Y. Huang, G. Sang, Enzyme-free and label-free ultra-sensitive colorimetric detection of Pb2+ using molecular beacon and DNAzyme based amplification strategy, Biosens. Bioelectron. 80 (2016) 187–193. [24] J.-S. Lee, M.S. Han, C.A. Mirkin, Colorimetric detection of mercuric ion (Hg2+ ) in aqueous media using DNA-functionalized gold nanoparticles, Angew. Chem. Int. Ed. 119 (2007) 4171–4174. [25] X. Xu, J. Wang, K. Jiao, X. Yang, Colorimetric detection of mercury ion (Hg2+ ) based on DNA oligonucleotides and unmodified gold nanoparticles sensing system with a tunable detection range, Biosens. Bioelectron. 24 (2009) 3153–3158. [26] Y. Xu, L. Deng, H. Wang, X. Ouyang, J. Zheng, J. Li, et al., Metal-induced aggregation of mononucleotides-stabilized gold nanoparticles: an efficient approach for simple and rapid colorimetric detection of Hg(ii), Chem. Commun. 47 (2011) 6039–6041. [27] Y. Zhou, S. Wang, K. Zhang, X. Jiang, Visual detection of copper(II) by azideand alkyne-functionalized gold nanoparticles using click chemistry, Angew. Chem. Int. Ed. 47 (2008) 7454–7456. [28] J. Yan, L. Wang, L. Tang, L. Lin, Y. Liu, J. Li, Enzyme-guided plasmonic biosensor based on dual-functional nanohybrid for sensitive detection of thrombin, Biosens. Bioelectron. 70 (2015) 404–410. [29] J. Hu, Z. Wang, J. Li, Gold nanoparticles with special shapes: controlled synthesis, surface-enhanced raman scattering, and the application in biodetection, Sensors 7 (2007). [30] C. Engelbrekt, K.H. Sorensen, J. Zhang, A.C. Welinder, P.S. Jensen, J. Ulstrup, Green synthesis of gold nanoparticles with starch-glucose and application in bioelectrochemistry, J. Mater. Chem. 19 (2009) 7839–7847. [31] R. de la Rica, M.M. Stevens, Plasmonic ELISA for the ultrasensitive detection of disease biomarkers with the naked eye, Nat. Nanotechnol. 7 (2012) 821–824. [32] F. Jiang, R. Yue, Y. Du, J. Xu, P. Yang, A one-pot ‘green’ synthesis of Pd-decorated PEDOT nanospheres for nonenzymatic hydrogen peroxide sensing, Biosens. Bioelectron. 44 (2013) 127–131. [33] C. Wang, J. Du, H. Wang, C. e. Zou, F. Jiang, P. Yang, et al., A facile electrochemical sensor based on reduced graphene oxide and Au nanoplates modified glassy carbon electrode for simultaneous detection of ascorbic acid, dopamine and uric acid, Sens. Actuators B 204 (2014) 302–309. [34] X. Shan, I. Diez-Perez, L. Wang, P. Wiktor, Y. Gu, L. Zhang, et al., Imaging the electrocatalytic activity of single nanoparticles, Nat. Nanotechnol. 7 (2012) 668–672. [35] L. Zhang, Q. Zhang, X. Lu, J. Li, Direct electrochemistry and electrocatalysis based on film of horseradish peroxidase intercalated into layered titanate nano-sheets, Biosens. Bioelectron. 23 (2007) 102–106. [36] J. Xie, Y. Zheng, J.Y. Ying, Highly selective and ultrasensitive detection of Hg2+ based on fluorescence quenching of Au nanoclusters by Hg2+ -Au+ interactions, Chem. Commun. 46 (2010) 961–963. [37] D. Liu, W. Qu, W. Chen, W. Zhang, Z. Wang, X. Jiang, Highly sensitive, colorimetric detection of mercury(ii) in aqueous media by quaternary ammonium group-capped gold nanoparticles at room temperature, Anal. Chem. 82 (2010) 9606–9610. [38] L. Beqa, A.K. Singh, S.A. Khan, D. Senapati, S.R. Arumugam, P.C. Ray, Gold nanoparticle-based simple colorimetric and ultrasensitive dynamic light scattering assay for the selective detection of Pb(II) from paints plastics, and water samples, ACS Appl. Mater. Interfaces 3 (2011) 668–673. [39] J. Xie, Y. Zheng, J.Y. Ying, Protein-directed synthesis of highly fluorescent gold nanoclusters, J. Am. Chem. Soc. 131 (2009) 888–889. [40] Z.F. Ma, S.-F. Sui, Naked-eye sensitive detection of immunoglubulin g by enlargement of Au nanoparticles in vitro, Angew. Chem. Int. Ed. 41 (2002) 2176–2179. [41] Y.-W. Wang, S. Tang, H.-H. Yang, H. Song, A novel colorimetric assay for rapid detection of cysteine and Hg2+ based on gold clusters, Talanta 146 (2016) 71–74. [42] L. Wang, B. Li, F. Xu, X. Shi, D. Feng, D. Wei, et al., High-yield synthesis of strong photoluminescent N-doped carbon nanodots derived from hydrosoluble chitosan for mercury ion sensing via smartphone APP, Biosens. Bioelectron. 79 (2016) 1–8. [43] I. Costas-Mora, V. Romero, I. Lavilla, C. Bendicho, In situ building of a nanoprobe based on fluorescent carbon dots for methylmercury detection, Anal. Chem. 86 (2014) 4536–4543. [44] L. Zhang, T. Li, B. Li, J. Li, E. Wang, Carbon nanotube-DNA hybrid fluorescent sensor for sensitive and selective detection of mercury(ii) ion, Chem. Commun. 46 (2010) 1476–1478. [45] W. Li, Y. Guo, K. McGill, P. Zhang, A facile synthesis of Ag nanoparticles for mercury ion detection with high sensitivity and selectivity, New J. Chem. 34 (2010) 1148–1152.
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Biographies Yuan Zhou received B.S. degree from Beijing Institute of Fashion Technology in 2014. Now she is a graduate student at Capital Normal University. Her research focused on the heavy metal ion detection.
Zhanfang Ma received a B.S. degree from Northeast Normal University and a Ph.D. in colloid and interface science in Key Laboratory of Colloid, Interface and Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences. He is currently a full professor of physical chemistry in Department of Chemistry of Capital Normal University. His current research interests include nanobiosensor, nanofabrication, and electrochemical biosensors.
Please cite this article in press as: Y. Zhou, Z. Ma, Colorimetric detection of Hg2+ by Au nanoparticles formed by H2 O2 reduction of HAuCl4 using Au nanoclusters as the catalyst, Sens. Actuators B: Chem. (2016), http://dx.doi.org/10.1016/j.snb.2016.10.035