A review on detection of heavy metal ions in water – An electrochemical approach

• Nanomaterial interface helps in developing highly sensitive biosensors.
• Toxicity mechanism of heavy metal ions on cells is highlighted.
• Metal ions inhibit enzymes and induce reactive oxygen species in cells.
• Challenges on sensing various species of metals using nano-interface are discussed.
• Detection of Ag, As, Cd, Cr, Cu, Hg, Pb, and Zn ions in water sources is reported.

Most of the metal ions are carcinogens and lead to serious health concerns by producing free radicals. Hence, fast and accurate detection of metal ions has become a critical issue. Among various metal ions arsenic, cadmium, lead, mercury and chromium are considered to be highly toxic. To detect these metal ions, electrochemical biosensors with interfaces such as microorganisms, enzymes, microspheres, nanomaterials like gold, silver nanoparticles, CNTs, and metal oxides have been developed. Among these, nanomaterials are considered to be most promising, owing to their strong adsorption, fast electron transfer kinetics, and biocompatibility, which are very apt for biosensing applications. The coupling of electrochemical techniques with nanomaterials has enhanced the sensitivity, limit of detection, and robustness of the sensors. In this review, toxicity mechanisms of various metal ions and their relationship towards the induction of oxidative stress have been summarized. Also, electrochemical biosensors employed in the detection of metal ions with various interfaces have been highlighted.

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