Engineering triple internal electric fields in Ag NWs@BaTiO3 composites for ultrasonic-visible-light driven antibacterial activity

Sono-photodynamic antibacterial therapy (SPDAT) is considered to be one of the most effective biomedical treatments, offering both practical flexibility and excellent performance. However, sono-photosensitizers with good biocompatibility, low cytotoxicity, and high antibacterial efficiency under harsh conditions are lacking nowadays. This paper presented attractive Ag NWs@BaTiO3 core–shell composites, which integrates three elements of piezoelectric effect, twin crystals, and heterojunction to engineer triple internal electric fields. Continuous co-disturbances induced by ultrasound and light disrupted the electrostatic balance and saturation effects of the triple internal electric field on composites, thereby regulating its own electrical properties and increasing its affinity and adhesion to bacterial cells through electrostatic attraction. Remarkably, the antibacterial efficiency of Ag NWs@BaTiO3 against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) reached 92.5% within 60 min and ∼ 100% within 30 min under low-power visible light irradiation and ultrasonic vibration, respectively. Moreover, the composites also exhibited good biocompatibility and low cytotoxicity. Intrinsically, the constructed triple internal electric fields could effectively extend the charges transfer pathway, accelerating the spatial separation of excited-charges pairs and thereby producing sufficient reactive oxygen species (ROSs) to boost the synergistic piezo-photocatalysis activity. Finally, we proposed a combined piezo-photocatalysis mechanism of energy band bending theory and screening charge effect under triple internal electric fields.