Ultrasound-Responsive Antibacterial Surfaces on Titanium Alloys: A Narrative Review.

Ultrasound-responsive antibacterial therapies represent a cutting-edge approach to combating implant-associated infections, particularly advantageous because of ultrasound's non-invasive nature, deep penetration, and ability to target infected areas. However, most previous studies have been devoted to ultrasound-responsive nanomaterials, hydrogels, and polymer systems. Research on ultrasound-responsive surfaces on titanium remains in its early stages and is extremely limited. This review primarily focuses on the design principles and construction strategies for ultrasound-responsive antibacterial surfaces on titanium-based implants, key factors affecting acoustic energy conversion efficiency, and the approaches to enhance antibacterial efficiencies. Based on acoustic energy conversion mechanisms and the primary factors responsible for bacterial killing, this review classifies antibacterial surfaces into sonothermal surfaces, sonodynamic surfaces, and multimodal combined surfaces. Moreover, this review discusses perspectives and challenges regarding biocompatibility, long-term antibacterial activity after implantation, and future clinical translation.