【作者】 杨春莉；

【导师】 翁文剑； 程逵；

【作者基本信息】 浙江大学 ， 材料学， 2009， 博士

【摘要】 为了满足骨科治疗上提出的新要求,除了设计和制备出综合性能优良的新生物材料外,对传统生物材料进行表面改性也是非常有效的途径,因此表面改性一直都是生物材料研究的热点之一。针对生物活性羟基磷灰石(HA)材料表面呈亲水性难与聚合物形成良好的界面相容性、以及HA表面上缺乏生物信号难以黏附更多细胞等关键问题,本文在HA表面上开展了系统的表面改性、功能化及其材料学和生物学性能的评价研究,主要内容和结果如下:1)基于复合材料的力学性能很大程度上取决于有机相与无机相之间的界面结合程度。本文首次采用十八烷基三氯硅烷(OTS),通过硅烷化反应,在HA颗粒的表面构建出共价键键合改性层。系统地分析了HA上形成OTS改性层的规律,当改性剂OTS的用量是10wt%时,在HA表面接枝上的OTS量达到最大值(此时Si原子含量为2.9at%)。2)采用OTS改性的HA颗粒,与聚乳酸(PLLA)复合形成了多孔材料。与未改性HA形成多孔复合材料相比,其复合材料弹性模量由改性前的2.14MPa提高到了6.44MPa,提高了2倍;抗压强度从改性前的0.556MPa提高到了0.949MPa,提高了近1倍。采用体外细胞培养结果表明:对骨髓间充质干细胞生长无抑制作用,未发生细胞毒性反应,细胞在材料表面均能正常黏附、生长、增殖,均具有良好的细胞附着形态和细胞增殖率,OTS改性前后的PLLA/HA复合材料均是骨细胞相容性良好的骨替代材料。3)采用γ-氨丙基三乙氧基硅烷(APTES)对HA颗粒进行表面改性,随后负载上RGD。Zeta电位和XPS结果都表明APTES改性HA中的APTES是化学键合到HA表面上的。元素分析结果显示了RGD是成功的接枝到HA颗粒上。4)采用RGD表面功能化的HA颗粒与PLLA复合形成了多孔材料。体外细胞培养结果表明:RGD功能化的PLLA/RGD-HA复合多孔材料的细胞黏附率明显提高,从37.21%提高到了69.11%,细胞粘附率提高了近1倍,表明了RGD的生物功能发挥良好。5)本文首次采用APTES对HA涂层进行表面改性,随后负载上RGD。实验结果表明APTES和RGD均是与HA涂层表面形成共价键键合,使RGD能够很稳定的存在于涂层表面。虽然物理吸附法也可使RGD附着在HA涂层表面上,但RGD的存在状态相当不稳定,在超声处理下会从HA涂层表面完全脱离。6)RGD表面功能化的HA涂层的体外细胞培养结果表明:与HA涂层相比,细胞黏附率从功能化前的22.1%提高到了59.3%,提高了近2倍,说明接枝在HA涂层表面的RGD很好地发挥其生物功能,即RGD充分的发挥了其促进更多的细胞的附着的作用。MTT结果显示,RGD功能化HA涂层材料的活细胞增殖能力也明显好于HA涂层材料的,而且两者的活细胞增殖的能力都是随着时间的增加而增长的,表明RGD功能化HA涂层材料的生物性能得到了很好的改善。另外,细胞形态观测表明经过RGD表面功能化后不仅所黏附细胞数量上增多,同时显示出良好的细胞形态,说明这些附着的细胞具有很强的活力状态。更多还原

【Abstract】 More and more researchers focus on the high performance of biomaterials in these years.The surface modification is considered to be an effective way to meet the new demand of bone repair in orthopaedics,besides design and preparation of new biomaterials with good comprehensive properties.In this paper,surface modification on hydroxyapatite(HA) was investigated systematically in order to improve the bonding of HA with polymer matrix and to increase the cytocompatibility of HA.The biocompatibility of the resulting materials was eValuated.In this work,the main following research results have been obtained.1) Since the mechanical performances of inorganic/polymer composites were greatly decided by interfacial boding strength of two phases,octadecyltrichlorosilane (OTS) was used as a coupling agent to modify the surface of HA by a silanization reaction for creating a surface capable of chemical bonding with polymers.The maximum quanlity of OTS modified layer on HA surface was upto 2.9at%Si.2) Using the OTS modified HA powders,porous PLLA/HA composites were prepared.Compared with the composite with unmodified HA,elastic modulus of PLLA/OTS modified HA composite increased 2 times from 2.14MPa to 6.44 MPa; compressive strength increased 1 times from 0.556 MPa to 0.949 MPa.In vitro BMSCs(Bone Mesenchymal Stem Cells) cultivation results showed that BMSCs could adhere and grow normally on PLLA/OTS modified HA composite support,and had good living situation and proliferation.Hnece,PLLA/OTS modified HA composites are a bone substitute material with good cytocompatibility.3)γ-aminopropyltriethoxysilane(γ-APTES) was used to modify HA as a coupling agent,then RGD was immobilized on the modified surface of HA.Zeta potential and XPS analysis results showed APTES was combined with HA by chemical bonding, and element analysis results showed that RGD were successfully immobilized on HA.4) Porous PLLA/RGD immobilized HA composites were prepared.In vitro BMSCs cultivation results showed that BMSCs adhesion ratio of PLLA/RGD immobilized HA cpmosite increased from 37.21%to 69.11%greatly,nearly 2 times of PLLA/HA composite.Hence,RGD in the porous composite functioned well as adhering cells.5) HA coatings were firstly modified by APTES and immobilized by RGD later. The results showed that RGD was combined on the surface of APTES modified HA coating through a covalent bond.Thus,RGD can exist on HA coating surface very stably.Although RGD could appear on HA coating by physical absorption,its existing situation of RGD was rather unstable,all RGD molecules on HA coating by physical absorption were removed away by ultrasonic treatment.6) In vitro BMSCs cultivation showed:the biological performance of RGD immobilized HA coating was greatly improved,BMSCs adhesive ratio increased nearly 2 times from 22.1%to 59.3%,the RGD on the HA coating could play a significant role in enhancing more BMSCs adherence.MTT results showed the proliferation on the RGD immobilized HA coating was much better than that on HA coating..In addition,morphologic analysis results showed that more BMSCs adhered on the RGD immobilized HA coating,they had good cells shape with strong living situation.更多还原