The Antimicrobial And Osteoinductive Properties Of Silver Nanoparticle/Poly(Dl-Lactic-Co-Glycolic Acid)-Coated Stainless Steel

Objective:Implants are widely used in oral medicine, for example, various metal implants are used in orthodontics-orthognathic surgery for correcting severe osseous dento-maxillofacial deformities; micro-anchorage pins are applying gradually for enhancing intraoral anchorage control and so on. Implant-associated bacterial infections are one of the most serious complications in orthopedic surgery. Treatment of these infections often requires comprehensive means including multiple operations, device removal, long-term systemic antibiotics, and extended rehabilitation and so on, and is frequently ineffective, leading to worse clinical outcomes and increased financial costs of patients. Moreover, osseous destruction of varying degree caused by bacterial infections is also a problem that needs to be resolved. So in this study, we evaluated silver nanoparticle/poly(DL-lactic-co-glycolic acid)(PLGA)-coated stainless steel alloys(SNPSAs) as a potential antimicrobial implant material.Materials and Methods:We carried on in vitro, ex vivo and in vivo experiments, using silver nanoparticle/poly(DL-lactic-coglycolic acid)(PLGA)-coated stainless steel alloys(SNPSAs). We measured surface free energy, antimicrobial activity in vitro and ex vivo and conducted protein adsorption in vitro, in vitro osteoinductivity, then employed rat femoral canal (FC) model to explore the antimicrobial and osteoinductive properties of SNPSAs. Finally, we used X-ray radiograph, micro-computed tomography scanning and histological and immunohistochemical (IHC) evaluation for further confirmation. We employed SPSS18.0statistical software package to process the experimental data.Results:Silver nanoparticle/poly(DL-lactic-co-glycolic acid)(PLGA)-coated layer is a kind of practical material, which is non-toxic, easy accessibility and without silver nanoparticle aggregation by SEM analysis.We found that SNPSAs exhibited strong antibacterial activity in vitro and ex vivo in silver-proportion-dependent manner, and promoted MC3T3-E1preosteoblasts proliferation and maturation in vitro.Furthermore, SNPSAs implants induced osteogenesis while suppressing bacterial survival in contaminated rat femoral canals by imaging analysis and IHC analysis. From characteristic analysis of SNPSAs, its surface free energy, especially its non-dispersive part(or "polarity")rsnA, increases as the silver percentage increases after cultured in bone induction culture medium, moreover, it also represents a silver-proportion-dependent manner in protein adsorption test in vitro.Conclusion:Our results indicate that SNPSAs has simultaneous antimicrobial and osteoinductive properties that make it a promising therapeutic material in implants area of oral medicine, and it has a broad application prospect.