Enhanced peroxidase-like activity of FeO-sodium lignosulfonate loaded copper peroxide composites for colorimetric detection of HO and glutathione.

In this paper, the composites of FeO modified by sodium lignosulfonate and copper peroxide (FeO@CP) were produced by a simple two-step method, and their morphology and composition were featured in Field emission scanning electron microscopy, X-ray powder diffraction, X-ray diffraction and Fourier transform infrared. Then, FeO@CP catalyzed the oxidation of colorless 3,3',5,5'-tetramethylbenzidine to blue oxide in the presence of HO, indicating that it had good catalytic performance. Further, the experimental conditions were optimized, including time, pH, temperature and material concentration. The kinetic analysis results showed that FeO@CP exhibited excellent catalytic performance and its catalytic kinetic plot conformed to the Michaelis-Menten equation and the catalytic mechanism was consistent with the ping-pong mechanism. Finally, a HO colorimetric assay with a linear range of 0.2-300 μM and a detection limit of 0.11 μM was constructed. In addition, due to the decolorization reaction of ox-TMB with glutathione and the scavenging effect of GSH on hydroxyl radicals (·OH), a glutathione colorimetric assay was further constructed with a linear range of 0.2-40 μM and a detection limit of 0.05 μM. It also verified that the assay had excellent selectivity and stability and could be utilized to detect actual samples.