Amorphous PtO x -engineered Pt@WO 3 nanozymes with efficient NAD + generation for an electrochemical cascade biosensor.

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 WO 3 to Pt NPs at the interface, potentially activate and modulate the NOX-like functionality in Pt@WO 3 nanosheets. Incorporating PtO x leads to a more positive valence of Pt species within Pt/PtO x @WO 3- x , where the PtO 2 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@WO 3 . 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.