氧化石墨烯/羟基磷灰石复合涂层对RAW264.7巨噬细胞免疫活性的影响

Effect of graphene oxide/hydroxyapatite composite coating on immune activity of RAW264.7 macrophages

背景:纯钛种植体植入机体后存在骨融合失败或者种植体周围感染等问题,因此对钛种植体表面进行改良已成研究的热门话题。巨噬细胞是机体应对外界刺激的一道免疫防线,任何生物材料植入体内后的相关免疫反应均与巨噬细胞相关。目的:采用电化学沉积法在纯钛片表面制备氧化石墨烯/羟基磷灰石复合涂层,分析涂层的表面特征及对RAW264.7巨噬细胞生长、极化的影响。方法:采用电化学沉积法在纯钛片表面分别制备单纯氧化石墨烯涂层、氧化石墨烯/羟基磷灰石复合涂层,表征涂层的物理性能。将纯钛片(空白组)、沉积单纯氧化石墨烯涂层的钛片(对照组)、沉积氧化石墨烯/羟基磷灰石复合涂层的钛片(实验组)分别与RAW264.7巨噬细胞共培养,采用CCK-8法、DAPI染色检测细胞增殖,扫描电镜观察细胞在钛片表面的黏附,流式细胞仪检测细胞极化表型。结果与结论:(1)扫描电镜下可见纯钛片有定向划痕与少量点状凹陷;沉积单纯氧化石墨烯涂层后,钛片表面可见较多裂纹沟壑和大小不均匀的颗粒状物,以及氧化石墨烯特征的褶皱样结构;沉积复合涂层后,钛片表面较光滑,可见团状颗粒,颗粒大小较为均匀。沉积复合涂层钛片的水接触接角小于纯钛片、沉积单纯氧化石墨烯涂层的钛片(P <0.05)。(2)CCK-8检测与DAPI染色显示,相较于空白组、对照组,实验组细胞增殖更快。扫描电镜下可见RAW264.7细胞均黏附于3组钛片表面,随着培养时间的延长细胞形态发生改变,由圆形向梭形转变,至培养7 d时,空白组细胞伸出的伪足短而少,对照组细胞伸出长而多的伪足,实验组细胞伸出短而多的伪足,并且实验组细胞整体饱满度最优。流式细胞仪检测显示,实验组细胞更高比例向抗炎方向M2型极化。(3)结果表明,氧化石墨烯/羟基磷灰石复合涂层具有良好的理化性能及生物学性能。

BACKGROUND:There are some problems such as bone fusion failure or peri-implant infection after implantation of pure titanium implants.Therefore,surface improvement of titanium implants has become a hot topic in research.Macrophages are an immune defense line of the body in response to external stimuli,and the relevant immune response of any biomaterials implanted in the body is related to macrophages.OBJECTIVE:The graphene oxide/hydroxyapatite composite coating on titanium alloy surface was prepared by electrochemical deposition method.The surface characteristics of the coating and the growth and polarization of macrophage RAW264.7 on the surface were analyzed.METHODS:The graphene oxide coating and graphene oxide/hydroxyapatite composite coating on titanium alloy surface was prepared by electrochemical deposition method.The physical properties of the coating were characterized.Pure titanium sheets(blank group),titanium sheets deposited with pure GO coating(control group)and titanium sheets deposited with graphene oxide/hydroxyapatite composite coating(experimental group)were co-cultured with macrophages RAW264.7,respectively.Cell proliferation was detected by CCK-8 assay and DAPI staining.Cell adhesion on the surface of titanium was observed by scanning electron microscopy,and cell polarization phenotype was detected by flow cytometry.RESULTS AND CONCLUSION:(1)Under scanning electron microscope,the pure titanium sheet showed directional scratches and a few punctate pits.After the pure graphene oxide coating was deposited,the surface of titanium sheet showed more cracks,gullies and particles of uneven size,and the wrinkle-like structure characterized by graphene oxide.After the composite coating was deposited,the surface of the titanium sheet was smooth,and the pellet size was more uniform.The water contact angle of composite coated titanium sheet was lower than that of pure titanium sheet and pure graphene oxide coated titanium sheet(P<0.05).(2)CCK-8 assay and DAPI staining showed that compared with the blank group and the control group,the cell proliferation in the experimental group was faster.Scanning electron microscopy showed that RAW264.7 cells all adhered to the surface of the three groups of titanium sheets.With the extension of culture time,cell morphology changed from round to spindle shape.After 7 days of culture,cells in the blank group extended short and few pseudopods;cells in the control group extended long and more pseudopods,and cells in the experimental group extended short and more pseudopods,and the overall cell fullness in the experimental group was the best.Flow cytometry results showed that the cells in the experimental group showed a higher proportion of M2 polarization in the anti-inflammatory direction.(3)These findings conclude that graphene oxide/hydroxyapatite composite coating has good physical,chemical,and biological properties.