钛表面接枝聚乙二醇-精氨酸-甘氨酸-天冬氨酸聚合物分子刷对细菌和成骨细胞黏附的影响

Effect of modification of titanium surfaces to graft poly（ethylene glycol） methacrylate-arginine-glycine-aspartic polymer brushes on bacterial adhesion and osteoblast cell attachment

目的研究钛表面接枝聚乙二醇[poly（ethylene glycol） methacrylate, PEG]-精氨酸-甘氨酸-天冬氨酸（arginine-glycine- aspartic, RGD ）多肽聚合物分子刷对细菌和成骨细胞黏附的影响，探讨使种植体具有抗感染和加速骨结合功能的表面处理方法。方法采用原子转移自由基聚合反应在固定有引发剂2-溴异丁酰溴的钛表面（Ti-Br）接枝PEG（Ti-PEG），在PEG分子末端接枝RGD多肽（Ti-PEG-RGD）。用接触角测量仪和X射线光电子能谱仪对纯钛、Ti-Br、Ti-PEG和Ti-PEG-RGD进行表征；分别在纯钛组、Ti-PEG组、Ti-PEG-RGD组试件表面进行变形链球菌（Streptococcus mutans，Sm）、内氏放线菌（Actinomyces naeslundii，An）和成骨细胞MC3T3培养，行荧光显微镜和扫描电镜观测。结果纯钛、Ti-Br、Ti-PEG、Ti-PEG-RGD表面接触角分别为〈10°、80°、45°、55°；X射线光电子能谱显示聚合物分子刷被成功接枝于钛表面。荧光显微镜和扫描电镜显示：纯钛培养Sm和An24h后表面黏附大量细菌，而Ti-PEG、Ti-PEG-RGD组细菌黏附较少，且散在分布；成骨细胞在纯钛和Ti-PEG组表面黏附较少，Ti-PEG-RGD组则黏附大量成骨细胞。结论钛表面接枝PEG能抑制细菌及成骨细胞黏附，而接枝PEG-RGD不仅能抑制细菌黏附还能促进成骨细胞黏附。

Objective To study the effect of poly（ethylene glycol） methacrylate（PEG）-arginine- glycine-aspartie（RGD） polymer brushes graft on bacterial adhesion and MC3T3 osteoblast cell attachment on titanium, and to investigate if the modification of titanium will enable the implant to be anti-fouling and promot osteointegration. Methods PEG was tethered on titanium surface modified with 2-bromoisobutyryl bromide（denoted as Ti-Br） to form Ti-PEG brushes. Functionalization of the Ti-PEG surface with RGD was performed to form Ti-PEG-RGD brushes. The chemical composition of modified titanium surfaces was characterized by X-ray photoelectron spectroscopy（XPS）. Changes in surface hydrophilicity and hydrophobicity were characterized by static water contact angle measurements. Streptococcus mutans（Sm）, Actinomyces naeslundii（An） and osteoblast cell were cultured on pure titanium（Ti）, Ti-PEG, Ti-PEG-RGDsurfaces respectively. There were ten samples in each group. The bacterial adhesion ability and cell attachment were confirmed by fluorescence microscopy and scanning electron microscopy（SEM）. Results The static water contact angle of Ti, Ti-Br, Ti-PEG, Ti-PEG-RGD was less than 10°, 80°, 45°, 55° respectively. XPS confirmed that PEG-RGD brushes were successfully tethered on titanium surfaces. Anti- bacterial test showed that on the pure-Ti, there were large amount of bacteria from both groups, however, in the Ti-PEG, Ti-PEG-RGD surfaces, both kind of bacteria were rare and distributed diffusely. Cell culture test showed that on the Ti-PEG-RGD surfaces, the number of cells was significantly more than that on the Ti and the Ti-PEG surfaces. Conclusions PEG can inhibit both kind of bacteria adhesion and osteoblast cell attachment, and PEG-RGD brushes can not only inhibit bacterial adhesion but also promote osteoblast cell attachment.