Ultrathin FeS nanosheets with high chemodynamic activity for sensitive colorimetric detection of H2O2 and glutathione

Iron chalcogenides have attracted great interest as potential substitutes of nature enzymes in the colorimetric biological sensing due to their unique chemodynamic characteristics. Herein, we report the preparation of ultrathin FeS nanosheets (NSs) by a simple one-pot hydrothermal method and the prepared FeS NSs exhibit strong Fenton-reaction activity to catalyze hydrogen peroxide (H2O2) for generation of hydroxyl radical (•OH). Based on the chromogenic reaction of resultant •OH with 3,3′,5,5′-tetramethylbenzidine (TMB), we develop colorimetric biosensors for highly sensitive detection of H2O2 and glutathione (GSH). The fabricated biosensors show wide linear ranges for the detection of H2O2 (5–150 µmol/L) and GSH (5–50 µmol/L). Their detection limits for H2O2 and GSH reach as low as 0.19 µmol/L and 0.14 µmol/L, respectively. The experimental results of sensing intracellular H2O2 and GSH demonstrate that this colorimetric method can realize the accurate detection of H2O2 and GSH in normal cells (L02 and 3T3) and cancer cells (MCF-7 and HeLa). Our results have demonstrated that the synthesized FeS NSs is a promising material to construct colorimetric biosensors for the sensitive detection of H2O2 and GSH, holding great promising for medical diagnosis in cancer therapy.