A Tanshinone IIA-Loaded Nanorod Coating on Titanium Abutments for Antibacterial and Antibiofilm Activity

Ensuring stable soft tissue sealing at the transgingival zone of titanium (Ti) abutments is critical for long-term implant success, yet conventional Ti abutment surfaces lack intrinsic antibacterial functionality. Here, a multifunctional antibacterial coating was developed by immobilizing pH-responsive nanorods (NRs) composed of tanshinone IIA (TA), lactoferrin (LF), and sodium alginate (SA) onto a polydopamine-modified (PDA) Ti surface. The resulting Ti&PDA@NRs coating achieved a high TA loading capacity through synergistic electrostatic adsorption and covalent crosslinking. The coating exhibited pH-modulated release behavior, characterized by accelerated TA release under acidic conditions and sustained release at physiological pH. Antibacterial evaluations using representative oral bacterial species demonstrated effective inhibition of bacterial adhesion and biofilm formation via surface-mediated contact killing, while released TA further suppressed free bacteria, confirming a dual-mode antibacterial mechanism. Mechanistic studies indicated that antibacterial activity was associated with bacterial membrane disruption accompanied by elevated intracellular reactive oxygen species (ROS) generation. Cytocompatibility assessments using human gingival fibroblasts and NIH/3T3 cells under both normal and inflammatory conditions confirmed low cytotoxicity. Moreover, the coating maintained good stability and sustained TA retention under simulated oral conditions. Collectively, this work presents a clinically relevant antibacterial surface strategy for mitigating implant-associated bacterial challenges in the transgingival region.