溶胶浸渗结合电沉积制备氧化镁-磷酸钙复合抗菌涂层

Antibacterial magnesium oxide-calcium phosphate composite coating prepared by combining electrodeposition and sol-gel impregnation

背景:磷酸钙(CaP)涂层被广泛用于改善钛植入物与骨的整合,但存在感染风险,因此有必要赋予CaP涂层抗菌能力。目的:通过氧化镁(MgO)溶胶浸渗制备MgO-CaP复合涂层,评价其体外抗菌能力和细胞相容性。方法:通过滴定法确定CaP电沉积的电解液条件,在钛表面制备CaP涂层(记为Ti-CaP);采用不同质量分数(15%,30%,50%)的MgO溶胶浸渗处理CaP涂层并煅烧成为MgO-CaP复合涂层,分别记为Ti-CaP-15Mg、Ti-CaP-30Mg和Ti-CaP-50Mg,表征涂层的微观形貌、拉伸性能、临界载荷与体外Mg^(2+)释放情况。将金黄色葡萄球菌菌液分别接种于纯钛片及Ti-CaP、Ti-CaP-15Mg、Ti-CaP-30Mg和Ti-CaP-50Mg表面,24,48 h后采用稀释涂布平板法检测抗菌率。将小鼠成骨细胞悬液分别接种于纯钛片及Ti-CaP、Ti-CaP-15Mg、Ti-CaP-30Mg和Ti-CaP-50Mg涂层钛片表面,采用CCK-8法检测细胞增殖,计算细胞存活率;同时观察复合涂层浸泡于DMEM培养基中的微观形貌变化。结果与结论:①电沉积在钛表面制备出由片状磷酸八钙晶体堆积组成的多孔CaP涂层,经浸渗-煅烧处理后,MgO颗粒聚集填充磷酸八钙晶体的间隙,并且填充程度随MgO含量增加而上升;3组复合涂层第1天均出现Mg^(2+)快速释放,从第3天开始Mg^(2+)释放速率明显下降,至第7天仍可检测出少量Mg^(2+)释放;Ti-CaP-30Mg涂层钛片的屈服强度、抗拉强度、断裂生长率与纯钛片比较差异均无显著性意义(P>0.05);Ti-CaP、Ti-CaP-15Mg、Ti-CaP-30Mg和Ti-CaP-50Mg组临界载荷比较差异无显著性意义(P>0.05)。②除纯钛片及Ti-CaP无抗菌性能外,其余样品均具有良好的抗菌性能,并且抗菌率随涂层中MgO含量的增加而增大。③共培养1,3 d,Ti-CaP-15Mg组、Ti-CaP-30Mg组和Ti-CaP-50Mg组细胞存活率低于纯钛组、Ti-CaP组(P<0.05);培养5,7 d,5组间细胞存活率比较差异无显著性意义(P>0.05);随着浸泡于培养基中时间的延长,涂层中MgO的含量逐渐减少。④结果表明,通过MgO浸渗处理赋予CaP涂层抗菌性的同时保持了其生物相容性。

BACKGROUND:Calcium phosphate(CaP)coatings are widely used to improve the integration of titanium implants into bone but these coatings are associated with risks of infection.It is thus desirable to confer antibacterial properties to CaP coatings.OBJECTIVE:To prepare CaP-MgO composite coatings by impregnating magnesium oxide(MgO)sol into CaP coatings and assess the in vitro antibacterial activities and cytocompatibility.METHODS:An electrolyte was determined by titration and used for CaP coating electrodeposition on titanium(referred to as Ti-CaP).MgO was impregnated into the coating by immersing in an MgO sol with different mass fractions(15%,30%,50%)and subsequently calcined to form MgO-CaP composite coatings,which were recorded as Ti-CaP-15Mg,Ti-CaP-30Mg and Ti-CaP-50Mg,respectively.Microstructure,tensile properties,critical load,and Mg^(2+)release of coatings in vitro were characterized.Antibacterial activity was assayed using spread plate method by culturing S.aureus on the pure titanium sheet surface and Ti-CaP,Ti-Cap-15mg,Ti-Cap-30mg and Ti-Cap-50mg surfaces for 24 and 48 hours.Mouse osteoblast suspension was inoculated on pure titanium sheets and Ti-CaP,Ti-CaP-15Mg,Ti-CaP-30Mg and Ti-CaP-50Mg coated titanium sheets,respectively.Cell proliferation was detected by CCK-8 assay,and cell survival rate was calculated.The morphology of composite coating soaked in DMEM was also observed.RESULTS AND CONCLUSION:(1)Homogeneous,microporous CaP coatings consisting of octacaclium phosphate crystal flakes were prepared on titanium by electrodeposition.After sol impregnation-calcination,MgO aggregates were filled into the inter-flake voids.The extent of MgO filling and Mg concentration in the coating increased with the number of sol impregnation procedures.When immersed in phosphate buffered saline,all composite coatings actively released Mg^(2+)within 1 day;subsequently,the Mg^(2+)release slowed down on day 3.A small amount of Mg^(2+)release was still detected on day 7.The yield strength,tensile strength and fracture growth rate of Ti-CaP-30Mg coated titanium were not significantly different from those of pure titanium(P>0.05).There was no significant difference in the critical load of Ti-CaP,Ti-CaP-15Mg,Ti-CaP-30Mg and Ti-CaP-50Mg groups(P>0.05).(2)Except that pure titanium sheet and Ti-CaP had no antibacterial properties,the other samples had good antibacterial properties,and the antibacterial rate increased with the increase of MgO content in the coating.(3)After 1 and 3 days of co-culture,the cell survival rate of Ti-CaP-15Mg,Ti-CaP-30Mg and Ti-CaP-50Mg groups was lower than that of pure titanium group and Ti-CaP group(P<0.05).After 5 and 7 days of culture,there was no significant difference in cell survival rate among five groups(P>0.05).The content of MgO in the coating decreased gradually with the time of immersion in the medium.(4)The MgO sol impregnation added antibacterial properties to the CaP coatings while retained their biocompatibility.