Amorphous PtOx-engineered Pt@WO3 nanozymes with efficient NAD+ generation for an electrochemical cascade biosensor

Abstract

Bioactive NAD⁺ mediated multiple biocatalytic pathways in metabolic networks. Refining the structure of NADH oxidase-like (NOX) mimics to efficiently replenish NAD⁺ has been promising but challenging in NAD⁺-dependent dehydrogenase electrochemical cascade biosensing. Herein, we discovered that PtO_x structures, formed via lattice oxygen translocation from WO₃ to Pt NPs at the interface, potentially activate and modulate the NOX-like functionality in Pt@WO₃ nanosheets. Incorporating PtO_x leads to a more positive valence of Pt species within Pt/PtO_x@WO_3−x, where the PtO₂ species serve as preeminent reaction sites for NADH coordination, activation, and dehydrogenation. Consequently, such nanozymes display enhanced NOX-like activity towards NADH oxidation in comparison to Pt@WO₃. Ultimately, the 650-Pt/PtO_x@WO_3−x nanozyme is employed in an electrochemical cascade biosensor for β-hydroxybutyrate (HB) detection, achieving a calculated detection limit of 25 μM. This study offers insights into PtO_x activation in Pt-based NOX mimics and supports the future development of NAD⁺/NADH-dependent electrochemical biosensors.