Light-driven sp-C bond interconversion in black phosphorus/graphdiyne nanozyme for enhanced peroxidase-like activity and dual-mode detection of Vibrio vulnificus.

The development of high-performance nanozymes is often hindered by intrinsic activity limitations that restrict biosensing sensitivity. In this study, a black phosphorus/graphdiyne (BP/GDY) heterostructure nanozyme was engineered to overcome these challenges, exhibiting significantly enhanced peroxidase (POD)-like activity under light irradiation. Compared to pristine GDY and BP, the BP/GDY nanozyme demonstrated 11.8-fold and 7.7-fold higher catalytic efficiency, respectively. Mechanistic analysis revealed that this enhancement stems from a light-induced structural transformation in GDY (CC → CC transition), which facilitates electron release and optimizes interfacial charge transfer, thus further amplifying POD-like activity. Leveraging this photo-enhanced catalysis and combining the advantages of enzyme-linked immunosorbent assay (ELISA), a high-specificity nanoprobe (BP/GDY-Ab2) was constructed and integrated with a capture antibody to develop a dual-mode biosensing platform for the detection of Vibrio vulnificus (V. Vulnificus). This platform incorporates both colorimetric (LOD = 4.7 CFU mL, linear range: 10-10 CFU mL) and photothermal (LOD = 9.4 CFU mL, linear range: 10-10 CFU mL) signals. The sensor demonstrated high accuracy in detecting V. vulnificus in spiked seafood samples, achieving a rapid response time of 5 min and effectively distinguishing the target pathogen from six interfering bacterial species through spatial charge distribution matching. This study introduces a novel photo-enhanced nanozyme activation strategy, establishing a versatile and scalable platform for on-site food safety monitoring and precision diagnostics, particularly in resource-limited settings.