Heparin as a bifunctional biotemplate for Pt nanocluster with exclusively peroxidase mimicking activity at near-neutral pH

Abstract

Heparin serves as both reductant and stabilizer for biogenic synthesis of ultrasmall Pt nanoclusters. The surface remaining heparin enhances the affinity of Pt nanoclusters with the substrate 3,3′,5,5′-tetramethylbenzidine, thereby contributing to outstanding peroxidase mimicking activity in near-neutral media. Heparin-reduced Pt nanoclusters exclusively exhibit peroxidase mimicking activities without oxidase-like characteristics. The most efficient Pt nanozyme was reduced at 80 °C by adopting the [K2PtCl4]/[heparin] of 1, showing the Km of 165 mM for H2O2 and 0.016 mM for TMB. This developed Pt nanozyme displays a marked superior in both peroxidase-like activity and peroxidase specificity under near-neutral environment over previously reported Pt nanozymes. Based on these two considerable features of heparin-Pt nanozyme, a colorimetric test was developed for directly monitoring glucose at pH 6. This work proposes an efficient way to construct peroxidase mimetics at near-physiological pH without the interference of dissolved oxygen.