One-pot synthesis of porphyrin functionalized γ-Fe2O3 nanocomposites as peroxidase mimics for H2O2 and glucose detection

Abstract

Meso-tetrakis(4-carboxyphenyl)-porphyrin-functionalized γ-Fe2O3 nanoparticles (H2TCPP-γ-Fe2O3) were successfully prepared by one-pot method under hydrothermal conditions and were found to possess intrinsic peroxidase-like activity. The H2TCPP-γ-Fe2O3 nanocomposites can catalytically oxidize peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 to produce a blue color reaction, which can be easily observed by the naked eye. Furthermore, kinetic studies indicate that the H2TCPP-γ-Fe2O3 nanocomposites have an even higher affinity to TMB than that of the natural enzyme, horseradish peroxidase (HRP). On the basis of the high activity, the reaction provides a simple, sensitive and selective method for colorimetric detection of H2O2 over a range of 10-100 μM with a minimum detection limit of 1.73 μM. Moreover, H2TCPP-γ-Fe2O3/glucose oxidase (GOx)/TMB system provides a novel colorimetric sensor for glucose and shows good response toward glucose detection over a range of 5-25 μM with a minimum detection limit of 2.54 μM. The results indicated that it is a simple, cheap, convenient, highly selective, sensitive and easy handling colorimetric assay. Results of a fluorescent probe suggest that the catalase-mimic activity of the H2TCPP-γ-Fe2O3 nanocomposites effectively catalyze the decomposition of H2O2 into H2O and O2.