Resin-Templated Synthesis of Platinum Nanozymes with Dual Oxidase and Peroxidase Activity for Dopamine Detection

Abstract

A cost-effective and easily implemented approach is reported for the creation of a bifunctional nanozyme for sensitive dopamine (DA) detection. The synthesis centers on a unique platform: the use of an anion exchange resin to effectively immobilize platinum precursors (PtCl₆^2–), and optimizing the subsequent pyrolysis process through urea-assisted calcination. This method leads to the formation of nitrogen-doped carbon-supported platinum nanoparticles (Resin Pt@N) with Pt minimal platinum loading (∼2.29 wt %), the number of platinum atoms accounts for only 0.15%. Comprehensive characterization (SEM, TEM, XRD, XPS, and EDS) confirms the successful generation of Pt nanoparticles encapsulated within a nitrogen-doped carbon matrix. The synthesized nanozyme exhibits robust dual enzyme-like activities (oxidase and peroxidase), promoting the oxidation of chromogenic substrates with favorable reaction kinetics. Based on its peroxidase activity, the colorimetric sensor for DA detection was designed to utilize DA’s ability to inhibit the enzymatic reaction between TMB and H₂O₂. The sensor exhibits a strong linear response for DA within the 1.0–100.0 μM range with a detection limit of 0.123 μM, along with excellent selectivity, and the practical utility substantiated by accurate DA quantification in human serum samples. The straightforward synthetic route and the high performance of the analytical platform pave the way for the use of Resin Pt@N in point-of-care diagnostics and biomedical research applications.