Peroxidase-mimetic activity of FeOCl nanosheets for the colorimetric determination of glutathione and cysteine

For the first time the enzyme mimic activity of iron oxychloride (FeOCl) nanosheets has been studied. The intrinsic peroxidase-mimetic activity of the nanosheets in the presence of H2O2 was approved by the efficient oxidation of tetramethylbenzidine (TMB). The Michaelis-Menten constant of the nanosheets toward TMB was about six times lower than that of natural horseradish peroxidase. The superiority of the nanosheets' catalytic property ascribes to their H2O2 activation ability. Based on the inhibition of the nanozymes' catalytic reaction, an assay was developed for the quantitative measurement of glutathione (GSH) and cysteine (Cys). The linear range for both biomolecules was over the range of 3-33 mu M. The LOD values (3 sigma/slope) for GSH and Cys were 2.23 mu M and 2.76 mu M, respectively. Importantly, we succeeded in colorimetric discrimination of GSH and Cys kinetically. We achieved high selectivity toward GSH and Cys. This work extends the feasibility of using FeOCl as nanozymes to construct biosensors, colorimetric probes for medical diagnosis, and nanozyme-based cancer therapy.

Automated summary

FeOCl nanosheets exhibit enzyme mimic activity with superior H2O2 activation ability. A new method for quantitatively measuring GSH and Cys was developed by inhibiting the catalytic reaction of nanozymes. The FeOCl nanosheets show high selectivity and potential applications in biosensors, medical diagnostics, and cancer therapy.