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A Highly Sensitive Enzymatic Catalysis System for Trace Detection of Arsenic in Water.

ABSTRACT: Arsenic (As) is an extremely toxic element that exists in the environment in different chemical forms. The detection of arsenic in potable water remains a challenging task. This study presents a highly sensitive enzymatic catalysis system for trace sensing of inorganic arsenic in water. This is the first enzyme-catalyzed fluorescence assay capable of detecting arsenic at concentrations below the allowable level adopted by the World Health Organization (10?ppb in drinking water). The enzyme catalytically produces fluorescent NADH in the presence of arsenate, which enables facile detection of arsenate at concentrations in the 0-200?ppb range. Calibration curves made at a set time interval allow accurate determination of unknown arsenic samples. This method holds potential for interfacing with automated analytical sampling systems to allow arsenic determinations in environmental health applications.

SUBMITTER: Liu Y

PROVIDER: S-EPMC5665019 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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A Highly Sensitive Enzymatic Catalysis System for Trace Detection of Arsenic in Water.

Liu Yuanli Y Yu Chuanbai C Cao Zhixin Z Shvarts Daniel D Trogler William C WC

Chemistry (Weinheim an der Bergstrasse, Germany) 20170713 43

Arsenic (As) is an extremely toxic element that exists in the environment in different chemical forms. The detection of arsenic in potable water remains a challenging task. This study presents a highly sensitive enzymatic catalysis system for trace sensing of inorganic arsenic in water. This is the first enzyme-catalyzed fluorescence assay capable of detecting arsenic at concentrations below the allowable level adopted by the World Health Organization (10 ppb in drinking water). The enzyme catal ...[more]

PMID: 28631380

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Project description:Arsenic is considered as a toxic heavy metal which is highly detrimental to ecological systems, and long-term exposure to it is highly dangerous to life as it can cause serious health effects. Timely detection of traces of active arsenic (As3+) is very crucial, and the development of simple, cost-effective methods is imperative to address the presence of arsenic in water and food chain. Herein, we present an extensive study on chemical-free electrogenerated nanotextured gold assemblage for the detection of ultralow levels of As3+ in water up to 0.08 ppb concentration. The gold nanotextured electrode (Au/GNE) is developed on simple Au foil via electrochemical oxidation-reduction sweeps in a metal-ion-free electrolyte solution. The ultrafine nanoscale morphological attributes of Au/GNE substrate are studied by scanning electron microscopy. Square wave anodic stripping voltammetry (ASV) response for different concentrations of arsenites is determined and directly correlated with As3+ detection regarding the type of electrolyte solution, deposition potential, and deposition time. The average of three standard curves are linear from 0.1 ppb up to 9 ppb (n = 15) with a linear regression coefficient R 2 = 0.9932. Under optimized conditions, a superior sensitivity of 39.54 ?A ppb-1 cm-2 is observed with a lower detection limit of 0.1 ppb (1.3 nM) (based on the visual analysis of calibration curve) and 0.08 ppb (1.06 nM) (based on the standard deviation of linear regression). Furthermore, the electrochemical Au/GNE is also applicable for arsenic detection in a complex system containing Cu2+, Ni2+, Fe2+, Pb2+, Hg2+, and other ions for the selective and sensitive analysis. Au/GNE substrate also possesses remarkable reproducibility and high stability for arsenic detection during repeated analysis and thus can be employed for prolonged applications and reiterating analyses. This electrochemically generated nanotextured electrode is also applicable for As3+ detection and analysis in a real water sample under optimized conditions. Therefore, fabrication conditions and analytical and electroanalytical performances justify that because of its low cost, easy preparation method and assembly, high reproducibility, and robustness, nanosensor Au/GNE can be scaled up for further applications.

Project description:Whole-cell biosensors (WCBs) have been designed to detect As(III), but most suffer from poor sensitivity and specificity. In this paper, we developed an arsenic WCB with a positive feedback amplifier in Escherichia coli DH5α. The output signal from the reporter mCherry was significantly enhanced by the positive feedback amplifier. The sensitivity of the WCB with positive feedback is about 1 order of magnitude higher than that without positive feedback when evaluated using a half-saturation As(III) concentration. The minimum detection limit for As(III) was reduced by 1 order of magnitude to 0.1 µM, lower than the World Health Organization standard for the arsenic level in drinking water, 0.01 mg/liter or 0.13 µM. Due to the amplification of the output signal, the WCB was able to give detectable signals within a shorter period, and a fast response is essential for in situ operations. Moreover, the WCB with the positive feedback amplifier showed exceptionally high specificity toward As(III) when compared with other metal ions. Collectively, the designed positive feedback amplifier WCB meets the requirements for As(III) detection with high sensitivity and specificity. This work also demonstrates the importance of genetic circuit engineering in designing WCBs, and the use of genetic positive feedback amplifiers is a good strategy to improve the performance of WCBs.IMPORTANCE Arsenic poisoning is a severe public health issue. Rapid and simple methods for the sensitive and specific monitoring of arsenic concentration in drinking water are needed. In this study, we designed an arsenic WCB with a positive feedback amplifier. It is highly sensitive and able to detect arsenic below the WHO limit level. In addition, it also significantly improves the specificity of the biosensor toward arsenic, giving a signal that is about 10 to 20 times stronger in response to As(III) than to other metals. This work not only provides simple but effective arsenic biosensors but also demonstrates the importance of genetic engineering, particularly the use of positive feedback amplifiers, in designing WCBs.

Dataset Information

A Highly Sensitive Enzymatic Catalysis System for Trace Detection of Arsenic in Water.

Publications

A Highly Sensitive Enzymatic Catalysis System for Trace Detection of Arsenic in Water.

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