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

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 [K 2 PtCl 4 ]/[heparin] of 1, showing the K m of 165 mM for H 2 O 2 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.