【作者】 雷波；

【导师】 陈晓峰；

【作者基本信息】 华南理工大学 ， 材料学， 2010， 博士

【摘要】 微纳米生物材料目前已成为生物医用材料领域一个研究热点和难点。大量的研究表明具有微纳米结构特征的生物材料表现出了积极的生物学响应,相对其他生物材料,微纳米材料可以显著促进细胞的粘附、增殖和分化。生物玻璃(BG)与天然的骨及牙齿有着相似的组成,具有较高的生物活性、生物相容性,是一类重要的骨修复材料。然而,目前临床应用的生物玻璃是通过高温熔融法制备,由于高温挥发和坩埚材料等原因易导致生物玻璃组成波动和有害杂质掺杂以及组成不均一等问题,使玻璃结构和性能难以控制。此外,材料的降解性能较差。近年来,通过溶胶-凝胶技术制备的生物玻璃由于其制备条件温和,材料组成和结构可以进行设计,比表面积高,具有纳米孔隙结构,生物活性高,降解性能可调控,使其具有很高的研究及应用价值,可望成为第三代生物材料的重要种类。溶胶-凝胶生物玻璃最大的问题在于颗粒难以分散,其微纳米结构、形态、颗粒尺寸大小难以控制,以至于材料的微纳米效应难以发挥;本论文采用溶胶-凝胶方法结合有机模板合成技术以及胶体化学原理,首次设计制备了具有可控微纳米表面、可调微纳米颗粒形态及尺寸大小的新型溶胶-凝胶生物活性玻璃,并研究了生物玻璃微纳米结构的形成机理、物理化学性质、离子释放动力学行为以及羟基磷灰石矿化活性,详细研究了材料微纳米表面、微纳米形态、微纳米尺寸对骨髓基质干细胞粘附、增殖、分化行为的影响。主要研究工作和结论如下:(1)溶胶-凝胶生物玻璃微纳米表面控制及性能研究采用溶胶-凝胶工艺,利用有机酸分子结构中的羟基、羧基与生物玻璃溶胶胶体颗粒表面羟基发生的氢键相互作用为机理,成功构建了溶胶-凝胶生物玻璃颗粒的微纳米表面结构;调节工艺参数如有机酸浓度和类型精确控制了材料表面性质如比表面积(80-200 m2/g)、孔隙体积(0.1-0.5 cc/g)、介孔直径(2-60 nm);微纳米表面生物玻璃离子释放行为符合一级动力学释放模型,表面结构和性质的变化调控了材料的离子释放速率和降解性,离子释放对环境的pH值影响不大(7.25-7.55);控制离子释放速率可以有效调控材料的羟基磷灰石(HA)形成活性,微纳米表面结构和快的离子释放速率有着高的HA形成能力;培养形式对材料细胞响应能力有影响,对于悬浮颗粒培养的方式,较低的比表面积及较慢的离子释放速率具有较高的促进细胞粘附和增殖的能力;细胞在颗粒表面培养研究发现具有微纳米表面结构和高比表面积有助于细胞的增殖和分化。(2)溶胶-凝胶生物玻璃颗粒的微纳米形态控制及性能研究.以溶胶-凝胶技术为基础,采用表面活性剂-分子模板(聚乙二醇PEG)反应机制,详细调节工艺参数,可以精确控制溶胶-凝胶生物玻璃颗粒的形态;以PEG为模板剂可以制备出规则球形的生物活性玻璃(SBG);通过酸性催化剂的选择可以控制SBG的形态;调整模板剂的浓度可以诱导棒状颗粒的形成(RBG);通过调整模板剂和生物玻璃溶胶的加入顺序,可以诱导空心结构的微球颗粒形成(HSBG);通过煅烧HSBG可以制备多孔的生物玻璃颗粒(PBG);SBG的离子释放行为在起初的24h内严格符合固体溶解一级动力学模型,离子释放速率小于无规则形态生物玻璃(IBG),呈现更稳定均一的释放行为;稳定而均一的离子释放行为使得SBG的HA形成速度慢于IBG,但形成的HA颗粒规则,结晶性弱于IBG,HA晶体沿着(002)晶面生长;细胞相容性研究表明,与IBG相比,规则的形态和稳定的离子释放速率可以促进细胞的粘附和增殖。在溶胶-凝胶模板技术的基础上,结合热致相分离技术和水热工艺可以制备出三维(3D)多孔贯穿的微纳米修复体(3DPBG),3DPBG具有多级孔径分布(10nm-10μm),纳米级孔壁,通过详细工艺参数可以调节孔壁的尺寸,孔径,孔的形态以及修复体的抗压强度;多级贯穿的孔径分布增加了材料的反应面积,大大提高了修复体的HA形成能力和细胞相容性。(3)溶胶-凝胶生物活性玻璃的微纳米尺寸控制以及性能研究通过酸催化溶胶-凝胶技术结合生物分子模板技术和酸催化溶胶碱性沉淀技术成功控制了BG的微纳米尺寸分布,制备了分散性良好的微纳米生物活性玻璃粉体等新型生物活性玻璃材料;酸催化溶胶-凝胶模板法可以控制BG颗粒直径在70 nm-5μm之间变化;酸催化溶胶碱性沉淀法可以制备出直径在40-350nm的纳米生物玻璃颗粒;通过加入分散剂聚乙二醇可以进一步控制颗粒直径在20-100 nm之间,并可诱导颗粒中介孔的形成;酸催化溶胶碱性沉淀法制备的纳米颗粒分散性要好于溶胶-凝胶模板法;SBF中的离子释放动力学行为研究表明,释放初期(6h)NBG具有快速的离子释放速率,符合一级动力学模型,速率常数为同期BG的6倍,此后释放速率小于BG,表现为稳定的缓慢释放;与BG相比,NBG具有快速的HA形成能力,反应6 h即有结晶性良好的致密的HA层覆盖在NBG表面,NBG表面形成的HA呈针片形态,而BG表面形成的HA则呈短棒状形态,NBG表面的HA具有更高的结晶度;与普通BG相比,NBG能更好的诱导细胞的粘附,促进细胞短期内的增殖,表现出良好的细胞相容性。更多还原

【Abstract】 Micro/nano biological material has become the research hotspot and difficulty in the field of biomedical materials. A number of studies have shown that micro/nano structure of biological material can show a positive biological response such as greatly promoting cell adhesion, proliferation and differentiation, comparing with other biological materials. Bioactive glass (BG) possesses the similar chemical composition with the bone and teeth, and has the high apatite-forming bioactivity, biocompatibility, bone conductivity and inductivity. BG is the ideal biomaterial for bone tissue regeneration. However, for the traditional BG preparing by high temperature melting conditions it is difficult to control the structure and this material has the low biological activity and poor degradation. Sol-gel derived bioactive glass possesses lot of advantages such as mild conditions, controlled composition and design, high bioactivity and degradation. The problems for sol-gel BG are that it is difficult to control the dispersion, micro/nano structure, shape and size of BG particle. This study will use sol-gel method combining biological organic templates and colloidal chemistry, to control and design micro/nano structure of bioactive glasses, to study forming mechanism of micro/nano structure and their physical and chemical properties, apatite-forming bioactivity. The biological evaluation of material was carried out using marrow stem cell (MSCs) as a model. Main research work and conclusions are as follows:(1) Micro-nanoscale surface control and properties of sol-gel bioactive glass particlesIn sol-gel preparation process, by the hydroxyl bone interactions between hydroxyl-carboxyl acids and bioactive glass sol particles, we successfully controlled the formation of micro/nano surface structure of sol-gel bioactive glass particles.By changing concentrations of organic acids, the surface area, pore volume and mesoporous size can be controlled in between 80-200 m2 / g, 0.1-0.5 cc/g and 2-60 nm, respectively. The ions release behavior are according to the first order kinetic model. Ions release has little effect on the pH of environment. The ions release ratios and HA forming are controlled by surface properties of particles. The micro-nanoscale surface and high ions release can induce the fast HA forming ability. For cell culture of dispersive particles, lower surface area and slow ion release rate of materials are helpful to promote cell proliferation. For the cells culture of bulk particle surface, materials with the micro/nano surface structure and high surface area can enhance cells proliferation and differentiation.(2) Micro-nanoscale morphological control and properties of sol-gel bioactive glass particles For this study, through sol-gel co-organic template technology and optimizing process parameters, we successfully controlled the morphology of sol-gel bioactive glass particles. Regularly spherical bioactive glasses (SBG) can be prepared using PEG as templates (mean size 4.5μm). Tuning the adding of templates and sintering temperature can induce the formation of hollowly spherical bioactive glasses (HSBG) and porous sol-gel bioactive glasses particles (PBG). RBG can be prepared by increasing the template concentration.The study of short-term ion release behavior showed that SBG greatly reduces the ion release speed of BG and makes the whole ion release speed more uniform; SBG possesses the slower HA forming rate than irregular BG; SBG can induce the formation of uniform nanometer fiber sheets of apatite crystals; The apatite crystals grow along the direction (002); SBG (regular morphology) can significantly improve cell proliferation and adhesion.In this study, by sol-gel method and template hydro-thermal process, a three dimensional porous bioactive glass bulk (3D-PBG) with strength was synthesized. 3DPBG has the multi-level pore distributions(10nm-10μm) and nanoscale pore wall. The size of pore wall, pore size, pore morphology and the compressive strength can be controlled by tuning the parameters in detail. Because of the 3D connected pore distributions, 3DPBG presents the high HA forming ability and cellular compatibility.(3)Micro-nanoscale size control and properties of sol-gel bioactive glass particlesIn this study, controlled micro-nanoscale bioactive glass particles (NBG) can be prepared successfully by template-acids-catalyzed sol-gel technology and sols-basic precipitation method. The forming mechanism of nanoscale particles can be explained by sol-gel-template interaction. By sol-gel co-template method, the particle size of NBG can be controlled at 70 nm-5μm; Adjusting the volume ratio of water and TEOS can control the particles size of 500 nm-2μm; By sol-basic precipitation method, NBG sizes are about 40-350 nm by adjusting basic concentration and about 20-100 nm by regulating the PEG weight.Two stages of ions release can be found for NBG: higher release speed than BG at early time (6h) and stable release at middle or later time; NBG possesses the fast HA-forming ability and well crystalline dense HA layer formed after reaction for 6 h; Better cells attachment on NBG than BG can be found at early time and NBG promoted the cells proliferation.更多还原