【作者】 郭海峰；

【导师】 叶枫；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2009， 博士

【摘要】 本文采用模板法制备了具有介孔结构的磷灰石(HAP)纳米颗粒。通过改变模板剂种类、浓度、反应温度、添加剂等来调控纳米介孔HAP的孔形、孔径及颗粒形貌等,提高纳米HAP的孔体积和比表面积。同时对介孔HAP进行磁性、荧光等功能性掺杂,赋予HAP药物载体磁性靶向和生物标识功能。采用X-射线衍射(XRD/SAXRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅立叶变换红外光谱(FT-IR)、氮气吸附等分析手段研究了各种介孔HAP的显微组织结构。在活性剂自组装的基础上,深入探讨了模板剂引导合成介孔磷灰石的调控机理。并探讨了掺杂纳米介孔HAP的功能性及纳米介孔HAP对模型药物的吸附与体外释放性能。以乙烷基、正戊基、正辛基及十二烷基磷酸酯作原位模板剂,合成了高度有序结构的前躯体。400℃煅烧后,仅乙烷基磷酸酯得到的六方排列纳米结构和非高度有序的介观结构仍然保持,形成磷灰石的六方纳米孔道结构和蠕虫状介孔结构,合成的磷灰石比表面积为42m2/g、孔体积为0.0644cm3/g。加入Tween-60作共模板剂时,得到的片层状磷灰石具有大量孔径约为4nm的蠕虫状介孔,且该介孔结构650℃热处理后仍然存在,具有高的热稳定性。P123和Tween-60混合模板剂引导合成HAP时,通过P123的量、反应温度和添加剂可很好地调控磷灰石的形貌、表面性质及微观结构。这种混合模板对介孔磷灰石的调控机理为:P123的量、反应温度和添加剂等参数影响混和表面活性剂在水溶液中的自组装行为,这些参数发生变化时活性剂自组装体组装方式和形状发生改变,钙和磷沉积在自组装体后得到不同的介孔磷灰石,达到调控合成介孔磷灰石的目的。P123和Tween-60浓度分别为0.04和0.1mol/L及60℃下合成片层状自组装体,热力学上来讲自组装体活性剂分子亲水链排列有利于羟基磷灰石沿着其长度方向生长,最终导致沿c轴定向生长的竹筏状磷灰石的形成。利用P123高温云点完全不溶和低温完全可溶的特性,结合Tween-60高云点性质,将形成的核-壳胶束作为模板合成磷灰石,能够得到球形的磷灰石空心纳米颗粒。加入柠檬酸作为添加时,可调节胶束的形状,得到棒状状的磷灰石空心纳米颗粒。该空心纳米棒内表面被修饰了厚为1.15nm、具有pH感应性的柠檬酸分子层,具有大的比表面积和孔体积,是一种优良的药物载体。利用MDP作模板剂时,能够合成具有层状介孔结构的三斜钙磷石/磷灰石纳米颗粒。MDP加入量、反应温度、乙醇加入量及Ca/P摩尔比调控着合成产物的形状、尺寸、层状介孔结构的层间距。MDP模板合成层状介孔结构的三斜钙磷石/磷灰石调控机理为:温度、乙醇加入量和Ca/P摩尔比使由MDP、钙和磷组合而成的无机-有机复合体的化学位能发生改变,复合体只有通过改变尺寸和层状片晶之间的距离等来改变自身的化学位能,从而与反应体系化学位能的保持平衡。在MDP引导下:Sm3+离子掺杂的HAP具有良好的荧光性能,且发光性随掺入量的增加而增强;掺入的Fe2+形成磁性的Fe3O4或γ-Fe2O3颗粒镶嵌在HAP颗粒中,得到的HAP磁性随Fe2+掺入量的增加而增强;Sm3+和Fe2+复合掺杂合成的介孔磁性-荧光多功能HAP纳米颗粒,同时具有很强的磁性和极好的荧光性,且具有高比表面积(153.52m2/g)、大孔体积(0.3286cm3/g)及双孔径的分布(3.64 and 9.014nm)。Sm3+和Fe3+以固溶和氧化物的形式存在于这种介孔磁性-荧光多功能纳米HAP颗粒中。在药物吸附装载中,空心结构使空心纳米磷灰石载药量大大提高。表面修饰柠檬酸的空心HAP纳米棒万古霉素装载效率达24.14%,加入PDAD后载药效率增加至35.83%;这种空心HAP纳米棒载药后,在缓冲液中释放时具有明显的pH值感应性,中性环境下药物释放速率快,酸性条件下释放速率慢;而加入PDAD后,在中性环境下药物释放缓慢,20小时后累积药物释放率不到28%,但在弱酸环境下前5个小时药物释放率达到89.28%、20个小时后释放率超过98%。此外,得到的磁性-荧光介孔纳米HAP对万古霉素的吸附效率亦可达33.68%。药物吸附和体外释放结果,表明我们制备的中空直径为介观尺寸的空心纳米磷灰石和磁性-荧光介孔纳米HAP,是一种智能型多功能一体化的药物载体,在生物医学领域具有巨大的应用潜力。更多还原

【Abstract】 Mesostructured hydroxyapatite (HAP) nanoparticles (NPs) were prepared using various templates. The reaction temperature, the additive, the variety and the concentration of templates were proposed to regulate the pore shape, the pore size and the morphology of the mesostructured HAP, and meanwhile to improve the the specific surface area and the pore volume. And the mesostructured HAP NPs were further fuctionalized with magnetism and luminescence, to endow them with biotargeting and biomarking functions when applied in drug carriers. The morpgolies and microstructures of the obtained mesostrured HAP were analysed by X-ray diffraction (XRD), small angle X-ray diffraction (SAXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and nitrogen absorption, etc. The regulation mechanmisms of mesostrutured HAP by various templates were fully disscussed based on the self-assemly behaviors of surfactants. Furthermore, the functions of the doped mesostructured HAP NPs, drug adsorption property and in-vitro release kinetics for mesostructured HAP NPs were also investigated.All the as-prepared precursors in-situ templated by dodecyl, n-octyl, n-pentyl, and ethyl phosphates had ordered nanostructures. But only the ethyl phosphate templated HAP sustained with an orderly hexagonal nanostructure at 400°C, possessing a specific surface area of 42m2/g and a pore volume of 0.0644cm3/g. With Tween-60 as the cosurfactant, the ethyl phosphate in-situ templated HAP had a large amount of 4nm worm-like mesopores which still thermally stable at 650oC.The aqueous behavios of Pluronic P123 regulated by the addition of P123, the reaction temperature and the additive were utilized to mediate the biomimetic synthesis of hydroxyapatite (HAP) with controllable morphology, microstructure and surface property in the presence of Tween-60. The thermodynamic calculations proved the demanded energy of HAP nucleation upon lamellar PEO aggregates is less than one twentieth of that on HAP surface, and the nucleation upon lamellar PEO aggregates favors in the longitudinal direction of the lamellar aggregates resulting in the oriented crystal growth along the [001] or c-direction of HAP and forming the oriented raft-like HAP. The characteristic of P123, i.e. insoluble at CP and totally soluble below CMT, was used to prepare mesoscaled hollow HAP nanoparticles in the help of Tween-60 which possesses a much higher CP than P123 does. The resultant hollow HAP has a sphere-like morphology, and it can be transformed to rod-like shape with the addition of polar citric acid. The citrate added HAP hollow nanorods have a layer of citrate molecules with a thickness of 1.15nm coupled upon the inner surfaces, which are pH-responsive and have great potential in smart drug delivery system.Monetite/HAP nanoparticles with lamellar mesostructures were prepared using monododecyl phosphate (MDP) as the directing template. The morphology and layer space of the lamellar mesostructured products could be controlled by different Ca/P mol ratio, reaction temperature, addition of MDP and ethanol. These factors changed the chemical potential of the product. Therefore the product had to regulate its morphology and microstructure to keep the potential in banlance.In the mediation of MDP: the Sm3+ doped HAP had a excellent luminescence, which increased with the addition of Sm3+; the Fe2+ doped HAP nanoparticles were embeded with Fe3O4 orγ-Fe2O3, and had an increased magnetism with the addition of Fe2+; and multifunctional magnetic and luminescent mesoporous HAP nanoparticles were prepared by doping with Sm3+ and Fe2+, the doped Sm3+ and Fe2+ were found dispersedly embeded and solid-soluted in HAP, and the resultant magnetic and luminescent mesoporous HAP NPs possessed both good magtism and excellent luminescence, a high specific surface area (153.52m2/g) and a large pore volume (0.3286cm3/g) with a bimodal pore size distribution (3.64 and 9.014nm).In the drug loading process, the hollow property made all the hollow HAP NPs have a much higher drug payload than the traditional HAP NPs did. The citrate coupled hollow rod-like HAP had a relatively high drug payload of 24.14%, and it was further increased to be 35.83% with the addition of cationic polyelectrolyte poly (dimethyldiallyl ammonium) chloride (PDAD). In in-intro release, the loaded vancomycin was stored inside the citrate chelate hollow rod-like HAP when the pH was at acidity, and released in a neutral environment. Reversely, with the addition of PDAD, the drug was steadily stored at a neutral pH (7.4), the cumulative release was less than 28% for 20h. But the drug linearly released when the pH was at weak acidity, the cumulative release was more than 89% for 5h and 98% for 20h. In addition, the magnetic and luminescent mesoporous HAP NPs also had a high payload ratio of vancomycin, over 33%. The drug loading and in-intro releasing results indicated that the prepared hollow HAP with a mesoscaled hollow diameter and the magnetic and luminescent mesoporous HAP NPs, were smart and multifunction integrated drug carriers, having a great potential in biomedical applications.更多还原