Flower-like Ag/MgMn2O4 nanozyme detection of GSH and Cu2+ by UV-vis, Raman spectroscopy and smartphone sensing platform.

Although nanozymes have been widely adopted in the field of colorimetric detection of heavy metal contaminants as well as disease markers, it still has development potential to develop a catalyst with high enzyme activity for application in tri-mode: UV-vis, smartphone and Raman. In this study, flower-like Ag/MgMn2O4 microspheres were fabricated via an integrated solvothermal and chemical reduction approach, demonstrating remarkable oxidase-like activity. Leveraging the exceptional oxidase-like activity of Ag/MgMn2O4, we developed a tri-mode (UV-vis-smartphone-Raman) sensing platform with multiplex analytical capability for GSH/Cu2+ detection. The system demonstrated broad linear responses (GSH: 0.5-300 μM; Cu2+: 0.1-300 μM) achieving ultrasensitive detection limits of 0.086 μM (GSH) and 0.062 μM (Cu2+). Furthermore, mechanistic investigations into the target detection revealed that the sulfhydryl groups in glutathione (GSH) readily coordinate with metal sites, thereby suppressing the catalytic activity of the catalyst. This phenomenon demonstrates promising potential for urinary analysis applications in clinical diagnostics. Conversely, the formation of Complex formed by Cu2+ and GSH effectively inhibits the coordination between GSH and metal atoms, which provides great helpful for quantitative detection of Cu2+ in environmental lake water. Therefore, the tri-mode sensor based on Ag/MgMn2O4 oxidase-like activity has a wide application prospect in biomedical fields and environmental detection fields.