Magnetic nanoparticles composed of Fe3(PO4) 2 ·8H2O by Burkholderia cepacia CG-1：A study of peroxidase-like activity and its application in H2O2 and glucose detection

In this study, magnetic nanoparticles were successfully separated from the strain Burkholderia cepacia CG-1. The composition, structure and morphology of the magnetic nanoparticles were characterized. The results indicated that the magnetic nanoparticles were indicated as Fe 3 (PO 4 ) 2 ·8H 2 O clusters with an average size of 69 nm. The values of magnetic parameters such as coercivity, saturation remanence and saturation magnetization were 150.93 Oe, 1.9333 emu/g and 15.844 emu/g, respectively. We have confirmed that the Fe 3 (PO 4 ) 2 ·8H 2 O magnetic nanoparticles exhibitted an intrinsic peroxidase-like activity which could catalyze the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) in the presence of H 2 O 2 . Comparing with HRP, the peroxidase mimic was more stable under different physiochemical conditions. The mechanisms of the peroxidase-like catalysis with Fe 3 (PO 4 ) 2 ·8H 2 O were investigated by the fluorescence spectroscopy and Electron spin resonance (ESR) analysis. The results showed that the peroxidase-like activity of Fe 3 (PO 4 ) 2 ·8H 2 O originated from the generation of hydroxyl radical (•OH). In addition, we have established a platform for colorimetic detection H 2 O 2 and glucose. As low as 1.0×10 − 3 mmol L − 1 H 2 O 2 and 5.0×10 − 3 mmol L − 1 glucose could be dectected via our method. Moreover, this sensitive method was successfully applied for the determination of glucose in human serum.