Synergistic Enhancement of Antibacterial and Osteo‐Immunomodulatory Activities of Titanium Implants via Dual‐Responsive Multifunctional Surfaces

This study presents a “layer by layer” modification strategy to prepare Ti-TA-Sr-PP implants with spatiotemporal regulation patterns. The implants combine the biofunctions of PP (broad-spectrum antibacterial activity) and Sr²⁺ (immunomodulatory and osteogenic effects). It shows promising efficiency in the treatment of infectious bone defects.

Abstract

Bone implant-associated infections and inflammations, primarily caused by bacteria colonization, frequently result in unsuccessful procedures and pose significant health risks to patients. To mitigate these challenges, the development of engineered implants with spatiotemporal regulation capabilities, designed to inhibit bacterial survival and modulate immune responses in the early stage, while promoting bone defect healing in the late stage is proposed. The implants are functionalized with ε-poly-l-lysine-phenylboronic acid (PP) via dynamic boronic ester bonds, which facilitate its release through a reactive oxygen species (ROS) and pH-responsive strategy, thereby establishing an antibacterial microenvironment on and around the implants. Additionally, the dynamic metal coordination interaction facilitates the loading and sustained release of Sr²⁺ under an acidic environment, providing immunomodulatory and osteogenic effects. The ROS/pH-responsive feature, coupled with the implant-bone tissue integration process, affords precise spatiotemporal regulation of the Ti-TA-Sr-PP implants. This strategy represents a promising approach for the preparation of advanced bone implants.