Enhanced peri-implantitis management through purple-LED irradiation coupled with silver ion application and calcium phosphate gene transfection carrier coating

The aim of this study was to investigate the bactericidal effect and recovery of biocompatibility of contaminated titanium surfaces using a combination treatment involving silver, copper, or iron ion application along with 400 nm purple-LED light irradiation. Additionally, the study sought to develop a functional calcium phosphate (CaP) coating treatment on titanium surfaces following disinfection, to promote re-osseointegration. A purple-LED emitting light at 400 nm was utilized to irradiate Staphylococcus aureus suspensions and biofilms in the presence of various concentrations of silver, copper, and iron solutions for 1 min. The bactericidal effect and electron spin resonance (ESR) spectrum were subsequently evaluated. Additionally, the hydrophilicity of the titanium surface and cell viability of MC3T3-E1 cells after combination treatment with silver ion was evaluated. Furthermore, a titanium surface coating with CaP gene transfection carrier containing plasmid DNA was developed using an electric current. The activity of hard tissue formation was then evaluated both in vitro and in vivo post-treatment. The bactericidal effect of the combination treatment with silver ions was attributed to the generation of hydroxyl radicals, whereas the effects from iron and copper treatments were not radical-mediated. The silver treatment significantly restored the hydrophilicity and cell affinity of the titanium surface. Moreover, CaP coating applied via an electric current (30 µA for 5 min) enhanced hard tissue formation activity on the titanium surface in both in vitro and in vivo settings. The combination treatment utilizing silver ions and purple-LED irradiation significantly enhanced bactericidal effects by generating high levels of hydroxyl radicals. Additionally, coating the titanium surface with functionalized CaP promoted early osseointegration, suggesting a promising strategy for improving implant outcomes.