Enhanced peroxidase-like activity of porphyrin functionalized ZnFe2O4 hollow nanospheres for rapid detection of H2O2 and glucose

Abstract

Using a simple one-pot solvothermal method, binary metal oxide, magnetic and hollow ZnFe₂O₄ nanospheres functionalized with 5,10,15,20-tetrakis(4-carboxylphenyl)-porphyrin (Por–ZnFe₂O₄ HSs) were prepared and subsequently applied as a substitute for natural peroxidase. The Por–ZnFe₂O₄ HSs were characterized using powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). In comparison with bare ZnFe₂O₄ HSs, Por–ZnFe₂O₄ HSs exhibit enhanced intrinsic peroxidase-like activity. They demonstrate a fast colorimetric response to H₂O₂ with a detection limit as low as 0.86 μM. The catalytic mechanism of the system was proved to be a hydroxyl radical mechanism using electron spin resonance (ESR). By combining the Por–ZnFe₂O₄ HSs-catalyzed reaction and the enzymatic oxidation of glucose with glucose oxidase, a colorimetric platform for glucose detection was established. The Por–ZnFe₂O₄ HSs/glucose oxidase (GOx)/TMB system shows a good response toward glucose with a detection limit of 5.5 μM. Therefore, such nanocomposites have promising applications in biomimetic catalysis and environmental monitoring.