Nanosilver/poly (DL-lactic-co-glycolic acid) on titanium implant surfaces for the enhancement of antibacterial properties and osteoinductivity

Background: Despite titanium (Ti) implants have been commonly used in the medical device field due to their superior biocompatibility, implant-associated bacterial infection remains a major clinical complication. Nanosilver, an effective antibacterial agent against a wide spectrum of bacterial strains, with a low-resistance potential, has attracted much interest too. Incorporation of nanosilver on Ti implants may be a promising approach to prevent biofilm formation. Purpose: The objective of the study was to investigate the antibacterial effects and osteoinductive properties of nanosilver/poly (dl-lactic-co-glycolic acid)-coated titanium (NSPTi). Methods: Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and the Gram-negative opportunistic pathogen Pseudomonas aeruginosa (PAO-1) were used to evaluate the antibacterial activity of NSPTi implants through the analysis of bacterial colonization in vitro and in vivo. Furthermore, we examined the osteoinductive potential of NSPTi implants by investigating the proliferation and differentiation of MC3T3-E1 preosteoblast cells. In vivo, the osteoinductive properties of NSPTi implants were assessed by radiographic evaluation, H&E staining, and Masson's trichrome staining. Results: In vitro, bacterial adhesion to the 2% NSPTi was significantly inhibited and <1% of adhered bacteria survived after 24 hours. In vitro, the average colony-forming units (CFU)/g ratios in the 2% NSPTi with 103 CFU MRSA and PAO-1 were 1.50±0.68 and 1.75±0.6, respectively. In the uncoated Ti groups, the ratios were 1.03±0.82×103 and 0.94±0.49×103, respectively. These results demonstrated that NSPTi implants had prominent antibacterial properties. Proliferation of MC3T3-E1 cells on the 2% NSPTi sample was 1.51, 1.78, and 2.22 times that on the uncoated Ti control after 3, 5, and 7 days' incubation, respectively. Furthermore, NSPTi implants promoted the maturation and differentiation of MC3T3-E1 cells. In vivo, NSPTi accelerated the formation of new bone while suppressing bacterial survival. Conclusion: NSPTi implants have simultaneous antibacterial and osteoinductive activities and therefore have the potential in clinical applications.