Amorphous PtOx-engineered Pt@WO3 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 PtOx 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 PtOx leads to a more positive valence of Pt species within Pt/PtOx@WO3−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/PtOx@WO3−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 PtOx activation in Pt-based NOX mimics and supports the future development of NAD+/NADH-dependent electrochemical biosensors. [ABSTRACT FROM AUTHOR]