摘要
Oxidative stress, resulting from an imbalance between free radicals and antioxidants, is widely recognized as a critical factor in numerous human disorders, including neurodegenerative disorders and cancers. Evaluating total antioxidant capacity (TAC) in bodily fluids is a vital bioanalytical parameter for assessing oxidative stress and redox status. However, current methods for TAC evaluation are significantly limited by their inability to detect a wide range of antioxidant molecules, their lack of sensitivity to important thiol antioxidants, and their high cost and complexity. In this study, we develop bimetallic gold-silver nanoclusters (AuAgNCs) as a photocatalyst for the evaluation of TAC. The reported nanozyme exhibits strong oxidase-like activity and precise, stable photocatalytic performance under LED irradiation. Upon light exposure, the bimetallic nanoclusters generate reactive oxygen species (ROS) by utilizing dissolved oxygen. These generated ROS then oxidize a non-fluorescent substrate, thiamine, to its fluorescent form, thiochrome. In the presence of antioxidants, ROS scavenging inhibits this conversion resulting in a lower fluorescence signal. This capability enables the detection of all physiologically relevant antioxidant species by responding to both single electron transfer (SET) and hydrogen atom transfer (HAT) reactions, allowing for the detection of a broad range of antioxidants present in saliva. This approach highlights the potential of innovative nanostructures like bimetallic photonanozymes in advancing future diagnostic and therapeutic strategies for oxidative stress-related disorders.