Conjugated precursors of isomers to enhance the peroxidase-like activity of carbon dots nanozymes for constructing multi-scenario sensing systems for glutathione and glutathione S-transferase.

Carbon dots (CDs) nanozymes possess remarkable advancements in the fields of catalysis, biosensing and clinical applications. Nevertheless, conventional CDs nanozymes face challenges such as a lack of theoretical guidance in precursor and limited detection scenarios. To resolve these, this study investigated the structure-activity relationship between substituent position from precursor and the peroxidase-like (POD) activity of CDs nanozymes. Through optimization, phthalic acid and o-phenylenediamine were employed as precursors to successfully synthesize a CDs nanozymes with remarkable catalytic activity and stability via the solvothermal strategy. A colorimetric method leveraging POD activity from CDs nanozymes was developed, integrating the spectrophotometer, smartphone and microplate reader into a multi-scenario sensing platform for detecting glutathione (GSH) and glutathione S-transferase (GST) in laboratory, clinical and on site. This method has been successfully implemented for the detection of human serum samples, offering promising applications in the fields of biosensors and clinical diagnosis.