Fe N C single atom nanozymes with dual enzyme-mimicking activities for colorimetric detection of hydrogen peroxide and glutathione

H2O2 and glutathione (GSH) are critical redox molecules in the organism. Abnormal levels of cellular H2O2 and GSH are closely related to some diseases. Thus, it is imperative to detect H2O2 and GSH efficiently. In this work, FeNC single atom nanozymes (SANs) with both peroxidase and oxidase-mimicking activities were successfully prepared with the help of formamide condensation by one-step hydrothermal method. The FeNC SANs show excellent peroxidase-like activity, which possess a higher affinity for H2O2 and 3,3′,5,5′-tetramethylbenzidine (TMB) than horseradish peroxidase (HRP). Then, based on the chromogenic reaction of TMB, a colorimetric biosensor to detect H2O2 and GSH was developed. This biosensor has the linear ranges of 10–600 μmol/L for H2O2 with a low detection limit of 4.360 μmol/L and 100–400 μmol/L for GSH with a low detection limit of 78.33 μmol/L. Besides, this colorimetric biosensor exhibited a good recovery of H2O2 and GSH in diluted human serum. Finally, the FeNC SANs were encapsulated into agar gel to self-quantitatively detect GSH by naked eyes. This work provides a non-pyrolytic way to prepare SANs, which broadens the synthetic method of SANs and may promote the development of SANs for biosensor application.