Urease combined with CdSe quantum dots as an enzyme sensor for quantitative detection of some metals in water

This investigation illustrates the potential role of urease as an enzymatic sensor in conjunction with CdSe quantum dots (QDs) for the detection of various metals present in aqueous environments. The enzyme urease catalyzes the hydrolysis of urea, resulting to the production of carbon dioxide and ammonia. The formation of ammonia leads to an increase in the pH of the solution, which in turn enhances the fluorescence of the CdSe quantum dots. In contrast, the presence of different metal can inhibit enzyme activity, thereby reducing ammonia production, which results in less pronounced pH changes and a subsequent increase in the fluorescence of the QDs. These variations are dependent on the concentration of the metals, allowing for the detection of several metals in water. This method enables the identification of metals such as Cu, Co, Mg, Fe, Cr, Zn, and Ni, with a detection limit of 0.2 μM. This level of sensitivity is adequate for evaluating the safety of water intended for various food products.