不同钙磷比对激光熔覆生物陶瓷涂层微观结构性能与细胞活性的影响

Properties and Cell Activity of Bioceramic Coating Fabricated by Laser Cladding with Different Ca∶P Ratios

激光熔覆过程中医用钛合金与混合粉末(CaHPO_4·2H_2O+CaCO_3+La_2O_3)因热膨胀系数相差大而容易产生裂纹、气孔等缺陷,故采用梯度设计方法在医用钛合金表面上制备一层具有生物活性的磷酸钙陶瓷涂层。通过金相显微镜(OM),X射线衍射仪(XRD),显微硬度计,甲基噻唑基四唑(MTT)比色法和倒置荧光显微镜对稀土氧化物La_2O_3添加量相同(0.6%)的不同钙磷比激光熔覆磷酸钙陶瓷涂层结合界面、物相、显微硬度、细胞相对活性和细胞生长状态进行分析。试验结果表明:通过OM观察其横截面积可以看出熔覆试样分为基材、合金化层及陶瓷层3个区域,各区域间呈良好的冶金结合。在2θ在32°~33°附近,当n(Ca)∶n(P)(原子比)=1.40~1.45时,其XRD图谱中羟基磷灰石+β-磷酸三钙(HA+β-TCP)的特征峰较高,表明其生成的生物活性相HA+β-TCP的量最多。显微硬度结果表明n(Ca)∶n(P)值越大,涂层平均硬度越高。MTT比色法和倒置荧光显微镜观察结果表明当涂层n(Ca)∶n(P)=1.40时,吸光度值(OD)最大,生物陶瓷涂层上细胞数量最多且生长状态良好,表明该涂层具有最佳的细胞相容性且有利于细胞的稳定增殖与生长。

Due to the difference of thermal expansion coefficient between medical Ti alloy and mixed powder（ CaHPO4·2H2O ＋ CaCO3＋ La2O3） in the process of laser cladding,it was easy to produce cracks,pores and other defects. Therefore,bioactive calcium phosphate coating was prepared on the surface of medical Ti alloy by using gradient design method. The bonding interface,phases,microhardness,bioactivity and cell growth morphology of different n（ Ca） ∶ n（ P） calcium phosphate ceramic coating doped with the same amount of rare earth oxide La2O3 were characterized by optical microscope（ OM）,X-ray diffraction（ XRD）,microhardness instrument,methyl thiazolyl tetrazolium（ MTT） assay and inverted fluorescence microscope. The experimental results indicated that the cross section of cladding samples observed by OM consisted of substrate,alloying layer and bioceramic coating. There was an excellent metallurgical bonding among layers. When n（ Ca） ∶ n（ P） was 1. 40 - 1. 45,the peak of hydroxyapatite ＋ β-Ca3（ PO4）2（ HA ＋ β-TCP）reached the maximum diffraction intensity at 2θ = 32° - 33° in the XRD pattern,indicating that mostbiologically active phases β-TCP ＋HA were synthesized. The microhardness results showed that the higher the n（ Ca） ∶ n（ P） value,the higher the average hardness of the coating was. MTT assay and inverted fluorescence microscope observation results indicated that when n（ Ca） ∶ n（ P） was 1. 40,OD value reached the maximum and the relative number of cells on the bioceramic coating was the maximum and the cell growth morphologies were in good condition,indicating that this kind of coating has better biocompatibility and was conducive to the stable proliferation and growth of cells.