Nanozyme Based Detection of Heavy Metal Ions and its Challenges: A Minireview

Naznozymes have become an important alternative to natural enzymes for many sensing applications, due to their relatively high stability, easy synthesis, and cost-effectiveness. Nanozyme-based assays, especially paper-based assays are portable, and therefore, are convenient for use in field operations, especially in remote parts of the world. Decreasing water levels, depletion of water resources, and large scale mining create the need for rapid detection of heavy metal ions in various water samples. In comparison with traditional methods of heavy metal ion detection, nanozyme-based systems enable rapid and cheap screening on the spot with a very simple instrument such as a UV-Vis absorption spectrophotometer. The sensing mechanism of a nanozyme-based sensor is highly dependent on its surface properties. They often encounter selectivity issues, unlike natural enzyme-based assays. Therefore, different types of target recognition and inhibition/enhancement mechanisms have been reported to achieve high selectivity. In this short review, we mainly focus our discussion on various interaction of the heavy metal ions with the nanozyme, and their responses towards the catalytic activity in the sensing of target metal ions.