The Study Of Antibacterial Activity And Biocompability Of Two Kinds Of Antibacterial Titanium With Nanonetwork Structures

Objective:Titanium is the most extensively applied biomedical implant material worldwide due to its high mechanical resistance,anti-corrosive property,and biocompatibility.However,both postoperative infections adjacent to titanium implants and peri-implantitis remain a significant concern as such infections can eventually lead to implant failure.Hence,endowing titanium implant with antimicrobial activity is a method to prevent the occurrence of peri-implant infection and increase success rate of implant treatment.High concentrations of alkali-treated titanium can produce a surface with nanonetwork structures,termed titanium with nanonetwork structures(TNS)_Although TNS enhances osteogenic activity,it exhibits insufficient resistance to bacterial attachment.UV treatment not only enables more rapid and more complete in vivo osseointegration,but also but also shows capacity to reduce bacterial attachment.In addition,silver nanoparticles(Ag NPs)loaded on titanium by a variety of methods exhibit long term antibacterial activity and good cytocompatibility in vitro.In this study,two kinds of antibacterial TNS that possess different antibacterial duration were fabricated by UV irradiation and loading Ag NPs.Their antibacterial activities and effects to rat bone marrow massenchymal stem cells(rBMMSCs)were evaluated.Methods:Polished pure titanium discs were immersed in 10 M NaOH solution at room temperature for 24 hours.High-intensity and short-duration UV irradiation was applied to produce UV treated TNS(UV-TNS).For loading silver nanoparticles on TNS(Ag-TNS),TNS was immersed in AgNO3 solution and irradiated by UV.Scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS)and contact angle measurement were performed for the surface characteristics analyses of two kinds of antibacterial TNS.Oral initial colonizer Actinomyces oris MG-1 was utilized as a model organism to evaluate the levels of antibacterial activity.Rat bone marrow mesenchymal stem cells(rBMMSCs)were also utilized on two kinds of antibacterial TNS for evaluation of osteogenic activity.Results:1.High-intensity and short-duration UV treatment endowed TNS with a superhydrophilic surface and eliminated surface hydrocarbon contamination.AgN03 solution immersion and UV irradiation successfully fabricated silver nanoparticles loaded TNS.2.UV-TNS effectively resisted initial attachment of Actinomyces oris MG-1,and inhibited biofilm formation for up to 6 hours.3.Ag-TNS not only killed attached bacteria,inhibited biofilm formation,but also maintained antibacterial activity up to 28 days.4.UV-TNS enhanced cell adhesion,proliferation,ALP activity,osteocalcin production and extracellular matrix mineralization of rBMMSCs superior to TNS,and expression levels of osteogenesis-related genes were also up-regulated.5.Compared to TNS,Ag-TNS showed inhibitions of cell adhesion,proliferation and ALP activity of rBMMSCs.Conclusions:UV-TNS possessed a good short-term antibacterial activity up to 6 hours and enhanced osteogenic differentiation of rBMMSCs.Ag-TNS maintained a long-term antibacterial activity up to 28 days but exerted a certain degree of cytotoxicity.Further study will be carried on in attempt to improve biocompatibility of Ag-TNS.