Carbon Dots Dually Doped with Fe and Co for Visual Detection of H2O2 and Glutathione

Hydrogen peroxide (H2O2) and glutathione (GSH) have been reported to be associated with a variety of diseases. Therefore, the accurate and rapid determination of H2O2 and GSH was very important. The traditional assay was the colorimetric method, which suffered from the bottleneck of single-mode analysis. In this work, we designed a dual-mode fluorescence and colorimetric sensor for detecting H2O2 and GSH based on bifunctional Fe, Co-CDs, which possessed peroxidase (POD)-mimetic activity and fluorescence property. Concretely, the Fe, Co-CDs catalyzed oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue product (oxTMB) with the help of H2O2, which could be inhibited by GSH. Meanwhile, the fluorescence of Fe, Co-CDs weakened with increasing oxTMB, realizing the fluorescence analysis of H2O2 and GSH. In fluorescence and colorimetric sensors, the detection limit (LOD) of H2O2 could reach as low as 0.54 μM and 0.81 μM, as well as the LOD of GSH was 0.39 and 0.61 μM, respectively. Besides, the smartphone-assisted hydrogel sensor was developed for on-site detection of GSH via color change. This study not only designed a dual-mode sensor for dual-target detection but also provided insights for further exploration of multifunctional nanozymes.