Antibacterial Activity and Biocompatibility of Magnesium Oxide Coating Prepared on Micro-arc Oxidized Titanium by Electrophoretic Deposition
Owing to their mechanical properties and biosafety,titanium(Ti)implants are widely used to replace missing teeth;however,their non-antimicrobial properties can lead to infection.The main reasons underlying the failure of oral implant repair are the biofilms and surrounding inflammation caused by bacterial adhesion to the surface of the implants.Implant-related infections considerably influence the effect of surgery and increase the pain and cost incurred by patients;the main pathogen is Porphyromonas gingivalis(Pg).Therefore,endowing the surface of implants with antibacterial ability to reduce the adhesion and colonization of bacteria on the surface of implants,thus reducing the incidence of infection,is necessary.Microarc oxidation(MAO)is currently one of the primary technologies used for implant surface modification.It can form porous titanium dioxide coatings on Ti with strong adhesion under high voltages.Moreover,the introduction of elements(such as calcium and phosphorus.)can promote bone healing and improve the osseointegration properties of the implant.However,owing to the rough and porous surface of micro-arc oxidation Ti(MAO-Ti),bacteria can easily attach and reproduce;therefore,infection will still occur.Magnesium and its compound[magnesium oxide(MgO)]have been found to have excellent antibacterial ability and biocompatibility.Therefore,in this study,MAO and electrophoretic deposition(EPD)were combined to deposit nano-magnesium oxide(nano-MgO)coatings on MAO-Ti for 0,15,30,45,or 60 s,while maintaining its biosafety.The MAO-Ti surface was endowed with antibacterial properties to reduce the incidence of infection.In this study,the in vitro antibacterial properties and biocompatibility of the samples were evaluated,the surface morphology and element composition of the samples were observed by scanning electron microscope(SEM),X-ray diffractometer(XRD),and energy dispersive spectrometer(EDS),the in vitro antibacterial properties of the samples against P.g were evaluated by dilution plate counting,bacterial live/dead staining,and SEM observation,and the in vitro biocompatibilities of human gingival fibroblasts(HGF)were evaluated using the CCK-8 method,cell live/dead staining,and cytoskeleton staining after co-culture with the samples.The results showed that the nano-MgO particles were uniformly agglomerated on the MAO-Ti porous surface,and the coverage rates increased with EPD time.The in vitro antibacterial activity of each sample against P.g was 5％,26％,31％,and 54％at 24 h,39％,69％,72％,and 79％at 72 h,and microscopic observation(live/dead staining and SEM)showed that the proportion of live bacterial cells on the surface of the samples decreased with increasing deposition time.After co-culture with HGF cells for 1 d,the relative survival rate of cells was 79％,76％,72％,70％,and 67％,93％,92％,90％,87％,and 85％after co-culture with HGF cells for 5 d.Only the samples deposited for 60 s had low cytotoxicity on the day 1(relative cell survival rate=67％),while,on days 3 and 5,no samples had cell cytotoxicity(all cell relative survival rates ≥70％).Fluorescence microscopy showed that there were almost no dead cells on the surface of MAO-Ti samples,and the proportion of dead cells on the surface of the other four groups increased with EPD time.The morphology of cells on the surface of each group was intact and there was no significant difference among the groups.Therefore,the EPD nano-MgO coatings on the surface of MAO-Ti have excellent in vitro antibacterial properties and biocompatibility,providing a new method for reducing the incidence of infection and pain suffered by patients as well as the cost of operation.
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