Prussian blue-supported platinum nanoparticles as pH-Universal catalase mimics: enabling robust chemiluminescent immunoassay for VEGF in clinical diagnostics

Introduction Nanozymes have emerged as promising substitutes for natural enzymes in chemiluminescent immunoassays, offering distinct catalytic advantages and superior stability. Despite their potential, many conventional nanozymes are constrained by a strong dependence on pH, which limits their effectiveness in certain assay environments. This highlights the need for nanozymes that maintain robust catalytic activity under alkaline conditions and are compatible with luminol-based detection systems. Methods In this study, we synthesized platinum nanoparticle-modified Prussian blue cubes (PB@Pt) and evaluated their enzyme-mimicking activity. The catalytic performance of PB@Pt was assessed under both weakly acidic and alkaline conditions. Its ability to enhance the luminol-H 2 O 2 chemiluminescence (CL) system was investigated, and the CL signals were compared to those generated by natural horseradish peroxidase (HRP). Based on these properties, a novel CL immunoassay utilizing PB@Pt was developed for the sensitive detection of vascular endothelial growth factor (VEGF). Results and Discussion The synthesized PB@Pt exhibited high catalase (CAT)-like activity across a broad pH range, including alkaline media. Remarkably, in alkaline conditions, PB@Pt catalyzed the luminol-H 2 O 2 reaction, producing CL signals significantly stronger than those achieved with natural HRP. Leveraging this enhanced performance, the established PB@Pt-based CL immunoassay enabled a wide linear detection range, ultra-low detection limits, high specificity, and excellent stability for VEGF quantification. This work introduces a novel strategy for designing CAT-mimicking nanozyme probes, thereby broadening their utility in CL immunoassays and advancing the clinical translation of nanozyme-based diagnostics for applications such as biomarker screening and point-of-care testing (POCT).