摘要
目的 赋予医用钛表面pH响应性的抗菌功能.方法 采用阳极氧化首先在纯钛表面制备二氧化钛纳米管(TNTs),随后超声沉积聚多巴胺层(PDA),再通过化学接枝法将没食子酸和银离子的络合物装载在纳米管表面,制备纯钛表面载银二氧化钛纳米管.通过SEM、XRD、FTIR、XPS对涂层的形貌及成分进行分析,并对涂层在不同pH条件下银离子的释放行为及抗菌能力进行评价.结果 TNTs-PDA-Ag样品具有良好的多孔结构,管径缩小至60nm,实现了银离子的有效装载,表面Ag的原子数分数约为2.9％,C的原子数分数(69.13％)相对于TNTs-PDA的原子数分数(37.09％)明显增加.经体外矿化,TNTs-PDA-Ag表面形成了 HA(羟基磷灰石).涂层在不同pH的磷酸盐缓冲溶液中表现出差异性的Ag+释放速率,在pH为4.5的环境中浸泡至7 d时,银离子释放速度和释放比例(97.65％)相对于中性条件下均得到明显提高.在抗菌实验中,Ag+的释放浓度在5.56～13 μmol/L之间,对大肠杆菌具有明显的抑菌作用.结论 制备的载银二氧化钛纳米管涂层可以有效提高材料的骨生物相容性,具有一定的pH响应性抗菌功能,在医用钛表面有较大的应用潜力.
Abstract
Titanium and titanium alloys have a wide range of clinical applications in dental implants,bone screws,and artificial hip joints.However,due to their biological inertia and lack of antibacterial properties,excellent osseointegration cannot be achieved after surgery,they are prone to bacterial infection,inflammation,and implant failure.Surface modification can effectively endow it with biological functions such as promoting bone growth,antibacterial and anti-inflammatory.In view of the bacterial infection of the implant,according to the low pH value of the surrounding environment of the infected tissue,the construction of pH-responsive antibacterial function on the surface of the implant has become a research hotspot.In this study,metal-polyphenol network(MPN)was used to graft silver ions in TiO2(titanium dioxide)nanotubes,and the responsive release of silver ions was achieved by the pH responsiveness of MPN.In order to endow the surface of medical titanium with pH-responsive antibacterial function,TiO2 nanotubes(TNTs)were prepared on the surface of pure titanium by anodic oxidation,followed by ultrasonic deposition of a polydopamine layer(PDA)and then the complex of gallic acid and silver ion was loaded into the nanotubes by chemical grafting.Silver ions had good antibacterial ability.Gallic acid,as a polyphenol compound,had anti-inflammatory,anti-oxidation and other biological functions.It could cooperate with metal ions to enhance antibacterial activity.The complexation of gallic acid and silver ions could form pH-responsive MPN.The preparation of silver-loaded titanium dioxide nanotubes on the surface of pure titanium was realized.The morphology and composition of the coating were analyzed by SEM,XRD,FTIR and XPS,and the release behavior of silver ions and antibacterial ability of coatings at different pH were evaluated.SEM and XRD results showed that the prepared TNTs were mainly anatase titanium dioxide.The TNTs-PDA-Ag sample had a porous surface,the diameter of the tube was reduced to 60 nm,and the effective loading of silver ions was realized.FTIR and XPS results showed that the crosslinking of PDA and GA occurred on the surface of TNTs-PDA-Ag,and silver ions were successfully loaded by phenolic hydroxyl groups.The atomic percentage of Ag on the surface was about 2.9％,and the percentage of C(69.13％)was significantly increased compared with that of TNTs-PDA(37.09％).After in vitro mineralization,HA(hydroxyapatite)was formed on the surface of TNTs-PDA-Ag.The Ag+release rate of the coating was heterogeneous in different pH phosphate buffer solution.When the coating was immersed in pH 4.5 environment for 7 days,the silver ion release rate and release ratio(97.65％)of silver ions were significantly higher than those under neutral conditions.In the antibacterial experiment,the release concentration of Ag+was between 5.56-13 μmol/L,which had obvious antibacterial effect on Escherichia coli.The prepared silver-loaded titanium dioxide nanotube coating can effectively improve the bone biocompatibility of the material,and has pH-responsive antibacterial function,which has great application potential on the surface of medical titanium.
维普
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