Enhanced peroxidase-like activity of Fe3O4-sodium lignosulfonate loaded copper peroxide composites for colorimetric detection of H2O2 and glutathione

In this paper, the composites of Fe 3 O 4 modified by sodium lignosulfonate and copper peroxide (Fe 3 O 4 @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, Fe 3 O 4 @CP catalyzed the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine to blue oxide in the presence of H 2 O 2 , 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 Fe 3 O 4 @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 H 2 O 2 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.