Perylene diimide-modified magnetic γ-Fe2O3/CeO2 nanoparticles as peroxidase mimics for highly sensitive colorimetric detection of Vitamin C

Perylene diimide-modified magnetic gamma-Fe2O3/CeO2 nanoparticles (gamma-Fe2O3/CeO2-PDI) were prepared and exhibited excellent peroxidase-like activity. The samples were characterized by HR-TEM, XRD, Raman, N-2 adsorption, magnetic strength and XPS. The obtained gamma-Fe2O3/CeO2-PDI had size of 1020 nm with high specific surface area of 77 m(2)/g, and could be easily separated from the aqueous solution by using a magnet, which are in favor of its practical application. Due to the decoration of PDI, the gamma-Fe2O3/CeO2-PDI possessed more surface defects (Ce3+) and active oxygen species than that of gamma-Fe2O3/CeO2, resulting in the outstanding catalytic performance. And the composite catalyst also showed highly sensitive and selectivity toward VC with a limit of detection of 0.45 mu M. Based on the fluorescent results, a possible hydroxyl radical (center dot OH) catalytic mechanism was proposed. It is believed that the as-prepared gamma-Fe2O3/CeO2-PDI nanoparticles are promising biosensors applied for biomedical and food analysis.