Amorphous PtO-engineered Pt@WO 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 structures, formed lattice oxygen translocation from WO to Pt NPs at the interface, potentially activate and modulate the NOX-like functionality in Pt@WO nanosheets. Incorporating PtO leads to a more positive valence of Pt species within Pt/PtO@WO, where the PtO 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. Ultimately, the 650-Pt/PtO@WO 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 activation in Pt-based NOX mimics and supports the future development of NAD/NADH-dependent electrochemical biosensors.