【作者】 张麟；

【导师】 陈弟虎；

【作者基本信息】 中山大学 ， 凝聚态物理， 2008， 博士

【摘要】 本论文采用脉冲激光沉积技术和射频磁控溅射两种方法制备了具有不同结构(sp3/sp2)和性能的四面体非晶碳膜,以及稀土La不同掺杂量的非晶碳薄膜和稀土La不同掺杂量的TiO2薄膜;通过微观结构、表面形貌、光学性能、电学性能、表面润湿性和动物体外血液相容性实验,系统研究薄膜的抗凝血性能。研究了脉冲重复频率和单脉冲能量对薄膜微结构和表面性质的影响,实现了sp3C成分可调的非晶碳薄膜制备。提出了血液相容性材料的稀土元素掺杂方法,以改善其抗凝血性质,研制出抗凝血性能优异的稀土La掺杂的非晶碳膜,并通过改变稀土元素掺杂量和衬底沉积温度分别讨论了稀土元素及sp2C各自对非晶碳薄膜的表面特性及抗凝血性能的影响。研制出血容性能良好的稀土La掺杂的TiO2薄膜,研究了La掺杂对TiO2薄膜微结构、表面特性及抗凝血性能的影响。采用分子动力学方法模拟计算纤维蛋白原分子在薄膜表面的选择吸附、体系能量和结合能的计算,提出并验证了蛋白质选择性吸附模型,较好地解释了实验结果,并运用生物化学检测方法结合表面及界面分析手段进一步揭示生物材料的抗凝血机制。首先,采用脉冲激光沉积方法,通过改变单脉冲能量和脉冲重复频率制备出不同结构(sp3/sp2)及性能的四面体非晶碳膜,研究了工艺参数对其微结构、光学性能、表面形貌及润湿性的影响,考察了其表面能参数和血液相容性。研究发现与薄膜的表面特性相比,材料的电子结构对其血液相容性起到决定性的影响。其次,采用射频磁控溅射法制备了La2O3不同掺杂量的非晶碳薄膜,研究掺杂对非晶碳薄膜的微结构、光学性能、电学性能、表面形貌和润湿性及抗凝血性能的影响。研究发现:La2O3掺杂使膜中sp2键的含量增加,随La2O3掺杂量由2.52%增加到5.99%,薄膜的石墨化逐渐增强,导致薄膜的带隙由2.1eV下降到约1eV;室温电导激活能由0.55eV下降到0.128eV;La2O3对薄膜晶粒的生长有细化作用,随La2O3掺杂量的增加非晶碳膜表面的亲水性逐渐降低,样品表面能的变化主要受极性成分的影响,掺杂样品的表面对白蛋白分子具有更强的选择吸附性表现出良好的抗凝血性能。再次,固定La3+在薄膜的含量,通过改变沉积时衬底的温度来调节sp2?sp3的相对比率,进一步研究稀土掺杂非晶碳薄膜材料的抗凝血性能。实验结果发现:衬底温度增加,膜中sp2组分也相对增多;受sp2组分影响,薄膜表面的亲水性逐渐增强,表面能变化较小但界面自由能逐渐减小;薄膜对纤维蛋白原分子的选择性能力增强,抗凝血性能逐渐退化,说明稀土元素与sp2含量对薄膜的血浆蛋白分子的选择性吸附的影响是不同的。制备了La2O3掺杂的氧化钛薄膜,研究掺杂对氧化钛薄膜微结构及血液相容性的影响。实验发现:稀土离子La促使TiO2晶粒沿(110)晶面择优生长,能细化TiO2的晶粒;当La3+掺杂量从1.56%增加到3.64%时,TiO2薄膜的光学带隙也从2.85 eV增大到3.3eV;La2O3掺杂促使TiO2薄膜表面的亲水性逐渐增强。血小板粘附实验结果表明:La2O3掺杂的TiO2薄膜表面粘附的血小板的数量和被激活的程度均明显地低于未掺杂样品,具有明显优于未掺杂样品的抗凝血效果。实验还发现La2O3掺杂提高了TiO2薄膜表面与蛋白质界面张力的极性分量。具有对纤维蛋白原和白蛋白更好的选择性吸附能力的表面特性及适宜的电子结构,是La2O3掺杂的氧化钛薄膜表现出良好的血液相容性能的原因。最后,根据本论文的实验结果,运用分子模拟技术模拟计算纤维蛋白原分子在La2O3掺杂的氧化钛薄膜表面的选择吸附、体系能量和结合能,提出并验证了蛋白质选择性吸附模型,较好地解释了实验结果。利用Lifshitz-vander Waals/acid-base法(即酸碱对LW-AB法)进一步揭示生物材料的抗凝血机制,模拟和计算证明:具有Lewis碱性的薄膜表面能抑制纤维蛋白原的吸附并有利于其维持正常的分子构象,进而抑制材料表面血小板的粘附和激活,改善薄膜材料的抗凝血性能。更多还原

【Abstract】 Amorphous carbon films with different microstructures, La2O3 doped Diamond-like carbon (DLC) films and TiO2 films with La doping different concentration were deposited by using pulse laser ablation and Radio-Frequency magnetron sputtering, respectively. The characters of films, such as microstructure, surface properties, optical & electronic properties and wettability, were investigated and the haemocompatibility of various films was evaluated by in-vitro tests. The influence of pulse repetition rate and pulse energy on the structure and the properties of the ta-C films are investigated and the control of sp3C content in the films is realized. Methods to adulterate biomaterials with rare earth are proposed. La2O3 doped DLC films with good blood compatibility were prepared and the effect of sp2 bonds and La2O3 on the haemocompatibility of DLC films were discussed. La2O3 doped TiO2 films with good blood compatibility were prepared and the effect of La2O3 on the microstructures and haemocompatibility were investigated. The thromboresistance mechanism of biomaterials was studied by means of molecular dynamics simulation methods. The systemic energy and interactive energy of fibrinogen with La2O3-doped TiO2 films were calculated and a selective adsorption model is introduced and applied to explain the result of experimentation. The interaction behavior at the interface between the biomaterial films and the plasma proteins was investigated using the biochemistry examinations.Firstly, the influence of pulse repetition rate and pulse energy in pulse laser ablation on the structures and the properties of the ta-C films have been studied. The wettability and blood-compatibility were investigated. Results show that the electronic structure of ta-C films plays a significant role in haemocompatibility compared with its property of surface.Secondly, La2O3 doped Diamond-like carbon (DLC) films with different concentrations were deposited by using Radio-Frequency magnetron sputtering. The effects of La2O3-dopant on the microstructure, surface properties, optical & electronic properties and wettability of DLC films were investigated. Results show the sp2-bonded C content increases and the band gaps of films decrease from 2.1eV to 1eV with increasing of La2O3 concentration doped. In the same temperature, the carrier concentration increases with increasing La2O3 addition. La2O3 addition has a suppressive effect on the crystal growth of DLC in process of deposition and the hydrophilicity of films decreases with the increase of content of La2O3-doped in the films. The polar component is critical to the change of the surface energy of doped films and the La2O3 doped DLC films have the good blood compatibility.Thirdly, keeping the contents of La3+ in the films and changing the temperature of substrate, the effects of temperature deposited on structure and haemocompatibility of La2O3 doped DLC films were investigated. Results show that the sp2-bonded C content increases with the increase of the temperature of substrate. The surface energy of films change slightly and the interfacial energy decreases with the temperature rising and the films are inclined to adsorb fibrinogen which shows the effect of sp2 bonds and La2O3 on the haemocompatibility of DLC films is different.Fourthly, La2O3 doped TiO2 films with different concentration were deposited by using Radio-Frequency magnetron sputtering. The effects of La2O3-dopant on the microstructure, surface properties, optical properties and wettability of TiO2 films were investigated. Results show La2O3 addition has a suppressive effect on the crystal growth of TiO2 in process of deposition. The band gaps of films increase from 2.85eV to 3.3eV with increasing of La2O3 concentration doped from 1.56% to 3.64% and the hydrophilicity of films increases with the increase of content of La2O3-doped in the films. Doped TiO2 films reveal unique haemocompatibility compared with un-doped films. The selective adsorption of La2O3-doped TiO2 films for the fibrinogen and serum albumin of the blood plasma and suitable electronic structure are believed to the main factor responsible for the good blood compatibility.Finally, according to the result of experimentation, the systemic energy and interactive energy of fibrinogen with La2O3-doped TiO2 films were calculated by means of molecular dynamics simulation methods and a selective adsorption model is introduced and applied to explain the result of experimentation. The thromboresistance mechanism of biomaterials was studied ulteriorly by Lewis acid-base theory about solid surface adsorption. Results also proved that films with the wide band gap structure or Lewis base (electron donor) surface may block the electron transfer through the interface from fibrinogen, retain the conformation of fibrinogen and inhibit the activation of the blood coagulation function.更多还原