Hydrogen iron oxide from an Acinetobacter strain exhibiting intrinsic peroxidase-like activity and its catalytic mechanism and applications

Biogenic magnetic nano particles (BMNPs) are believed to outperform conventional MNPs; hence, in present study, BMNPs obtained from an Acinetobacter strain isolated from the muddy waters of the Jiangbei River in Harbin, China, were characterized. The BMNP isolated was Fe0.96O0.88(OH)1.12 and had a moderate size of 80 nm, as determined by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The high coercive force of 147.61 Oe and low saturation and residual magnetic strength indicated that Fe0.96O0.88(OH)1.12 exhibits crystal behavior. The experimental results confirmed that the Fe0.96O0.88(OH)1.12 can catalyze the oxidation of the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). Electron spin resonance (ESR) spectroscopy showed that the Fe0.96O0.88(OH)1.12 induced H2O2 to produce hydroxyl radicals (∙OH) in the presence of 5,5-dimethyl-1-pyrroline N-oxide (DMPO). While no reactions occurred with H2O2 alone in the presence DMPO, the addition of Fe0.96O0.88(OH)1.12 to this reaction system led to the production of ∙OH. The isolated Fe0.96O0.88(OH)1.12 was used to detect H2O2 and glucose and could catalyze the degradation of Congo red dye.