Light/ultrasound enhance peroxidase activity of BaTiO3/graphdiyne/Au nanozyme for colorimetric detection of E. coli O157:H7

In the past two decades, nanozymes have garnered increasing interest, however, their catalytic activity and efficacy still lag significantly behind that of natural enzymes, posing limitations on their utility in bioanalytical applications. In this study, we introduced a novel BaTiO3/graphdiyne/Au (BGA) nanozyme that leverages surface plasmon resonance and piezoelectric effects to concurrently respond to light and ultrasound (US) stimulation, resulting in a 3.8-fold enhancement in peroxidase-like activity. Theoretical and experimental findings suggest that US stimulation induces lattice distortion in BaTiO3, leading to the reversible conversion of C[tbnd]C bonds to C[dbnd]C bonds in graphdiyne. Consequently, the liberated electrons recombine with the hot holes produced by Au nanoparticles upon light excitation, thereby efficiently inhibiting the recombination of hot electron-hole pairs and substantially augmenting peroxidase-like activity. The BGA nanozyme was further configured as a detection platform for E. coli O157:H7. The sensor exhibited a broad linear range (1–107 CFU mL−1) and a low limit of detection of 7 CFU mL−1. Moreover, the sensor exhibited exceptional applicability in the analysis of various real samples such as milk and lemon juice. This study presents a novel research framework for constructing high-activity nanozyme sensors responsive to external fields, offering significant potential in biological analysis, environmental surveillance, and food safety applications.