微弧氧化钛电泳沉积制备氧化镁涂层及其抗菌性与生物相容性

口腔种植修复术失败的主要原因是术后细菌在种植体表面黏附形成生物膜并导致周围炎症，主要致病菌为牙龈卟啉单胞菌（P. gingivalis，P.g），植入物相关感染严重影响手术效果及增加患者痛苦与费用，因此须赋予植体表面抗菌能力以降低感染发生率。微弧氧化（Micro-arc oxidation, MAO）技术是通过高电压形成牢固结合且具备良好骨整合性能的氧化涂层，同时已有研究发现镁及其化合物（氧化镁）具有良好抗菌性和生物相容性。将 MAO 与电泳沉积（Electrophoretic deposition, EPD） 技术结合，在多微孔的二氧化钛表面沉积纳米氧化镁（nano-MgO）涂层，并评价其体外抗菌性能及生物相容性。通过 SEM、 XRD、EDS 观察样品表面形貌结构、测定元素组成。通过稀释涂板计数法、细菌活死染色及 SEM 观察评价 nano-MgO 涂层对 P.g 的体外抗菌性能。通过将人牙龈成纤维细胞（HGF）与 nano-MgO 涂层共培养后 CCK-8 法、细胞活死染色及骨架染色观察评价 nano-MgO 涂层体外生物相容性。研究结果发现，nano-MgO 颗粒在二氧化钛多微孔表面均匀-团聚沉积且覆盖率随沉积时间增加。各组样品对 P.g 的体外抗菌性能在 24 h 为 6%~54%，在 72 h 为 39%~79%。显微观察（活死及 SEM）样品表面活菌比例随沉积时间而减少。各组样品与 HGF 共培养 1 d 后细胞相对存活率为 79%–67%，5 d 后为 93–85%。荧光显微观察发现 MAO 钛样品表面几乎无死细胞，其余 4 组表面死细胞比例随沉积时间增加，各组样品表面细胞形态完整且各组间无明显差异。MAO 钛表面 EPD nano-MgO 涂层具备良好体外抗菌性能及生物相容性，研究成果可为降低口腔种植修复术的感染发生率、减少患者痛苦及手术费用提供一种新方法。

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 (P.g). 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.