Highly dispersed Pt nanoparticles on ultrasmall EMT zeolite: A peroxidase-mimic nanoenzyme for detection of H2O2 or glucose

Abstract

In past decade, Pt-based nanomaterials as peroxidase mimics have attracted much attention for H2O2 and glucose detection. However, easy aggregation of Pt nanoparticles (Pt NPs) greatly decreases their peroxidase-like activity. In this work, novel Pt/EMT nanocomposites were prepared by uniformly loading Pt NPs (5–8 nm) onto the support of ultrasmall EMT zeolite (15–20 nm), a kind of low-silica microporous aluminosilicate material. The hybrid Pt/EMT nanomaterials could be well dispersed in water to form a homogeneous suspension, and were then utilized as a superior peroxidase-like catalyst for oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). The optimal catalyst of 2.6Pt/EMT nanocomposite exhibited excellent catalytic performance toward H2O2 and TMB than natural enzyme of horseradish peroxidase (HRP) by using a steady-state kinetic analysis based on the typical Michaelis-Menten kinetics theory. The peroxidase-like catalyst showed a promising activity in a wide pH and temperature range as well as the long-term stability. A facile and reliable colorimetric assay based on the peroxidase mimic of Pt/EMT nanocomposite was constructed for precise detection of H2O2 and glucose in a wide linear range, with low limits of detection of 1.1 μM and 13.2 μM, respectively. Due to high selectivity to glucose against other sugars on the catalyst, the method was demonstrated to accurately measure the concentration of glucose in real samples including human blood serum and fruit juices, indicating a potential application of the Pt/EMT nanocomposites as a robust peroxidase mimic and a reliable biosensor in the fields of clinical diagnosis, pharmaceutical, food research and so on.