Nitric Oxide-Mediated Dual-Functional Smart Titanium Implant Coating for Antibacterial and Osseointegration Promotion in Implant-Associated Infections

The balance of antibacterial and osseointegration-promoting properties on titanium (Ti) implants in a simple and efficient manner is crucial for the management of implant-associated infections, a condition that has become a significant global health concern. Herein, a nitric oxide (NO)-mediated dual-function smart coating with antibacterial and osseointegration-promoting properties is developed for Ti implants. The coating leverages the distinct properties of NO at high and low concentrations to enable an on-demand functional switch. Specifically, antibacterial function is achieved through a rapid release of high-dose NO in response to the infection microenvironment and near-infrared stimulation. Once the infection is resolved and normal physiological conditions are restored, the coating gradually releases low-dose NO to promote osseointegration. In vitro tests confirm that the coating exhibits antibacterial ratio of 97.84% and 97.18% against methicillin-resistant Staphylococcus aureus and its biofilms, respectively, and demonstrates the ability to activate osteoblasts. The rat femoral implant-associated infection model further certifies that the responsive NO release mechanism of the coating efficiently facilitates the on-demand functional switch between antibacterial and osseointegration-promoting properties. Notably, the use of the dual-functional nonantibiotic agent, NO, significantly mitigates the risk of bacterial resistance.