Strong nanozymatic activity of silicene quantum dots: Enhanced sensitivity for the selective detection of H₂O₂ and dopamine in complex media

Nanozymes have recently gained popularity because of their desirable properties such as excellent stability, minimal cytotoxicity, high catalytic activity and enhanced cost-effectiveness. This work reports, for the first time, the nanozymatic nature (peroxidase-like enzyme activity) of silicene quantum dots (SiQDs) using a simple hydrothermal synthesis method. The study utilized the nanozymatic activity of SiQDs to develop a colorimetric biosensor for H₂O₂ and dopamine detection. The developed method was based on the oxidation of the chromogenic substance 3,3′,5,5′-Tetramethylbenzidine (TMB) by the hydroxyl radicals generated from the decomposition of H₂O₂, resulting in a color change that enabled colorimetric detection in the presence of SiQDs. The SiQDs acted as a catalyst for this reaction by supplying more active sites on its surface for the interaction between H₂O₂ and TMB. Various factors affecting the reaction yield were considered and optimized. The proposed method was applied for H₂O₂ and dopamine detection, and the limits of detection (LOD) were found to be 0.0113 mM and 0.5521 µM, respectively, proving the proposed method's high sensitivity. The selectivity of the developed method for dopamine detection was examined by studying the effect of potential interfering substances, the method demonstrated high selectivity for dopamine detection in the presence of other interfering analytes. Additionally, the method was successfully applied for dopamine detection in a simulated blood matrix with a LOD of 1.6982 µM, indicating the superiority of the method for dopamine detection in complex media.