Dual-stimuli responsive on-demand CO-releasing coating on titanium dental implants for antibacterial,...

Titanium (Ti) implants are widely used in dentistry, but their long-term success is often compromised by peri-implant infection and chronic inflammation. As an endogenous gasotransmitter, carbon monoxide (CO) disrupts biofilm-associated bacteria and modulates dysregulated immune responses, thereby making it a promising mediator against peri-implant complications. Here, we report a photothermal- and inflammation-responsive CO-releasing coating (P/Sr@CO) that enables on-demand CO delivery to achieve synergistic antibacterial and anti-inflammatory effects, while concurrently releasing strontium ions (Sr²⁺) to support osteogenesis. Ti implants were first coated with a polydopamine (PDA), followed by NaOH-assisted co-assembly of poly(allylamine hydrochloride) (PAH) and Sr²⁺ to form a porous P/Sr network that electrostatically loaded the CO donor triiron dodecacarbonyl (Fe₃(CO)₁₂). The P/Sr@CO coating exhibited efficient near-infrared (NIR) photothermal conversion, enabling rapid local heating and controlled CO release to potentiate bactericidal activity. In ROS-enriched inflammatory microenvironments, oxidative activation of Fe₃(CO)₁₂ further triggered CO release, attenuating inflammation, while the sustained release of Sr²⁺ directly promoted osteogenic differentiation. These results suggest that P/Sr@CO is a promising surface-engineering strategy to mitigate implant-associated infection and inflammation and to improve the long-term performance of Ti dental implants.