【作者】 张莹；

【导师】 黄伯云； 刘咏；

【作者基本信息】 中南大学 ， 材料科学与工程， 2012， 博士

【摘要】 羟基磷灰石(HAp)被广泛应用于生物医用材料,同时,其独特的三维网状原子结构表现出优良的电化学传感性能,具有广泛的应用前景。在众多合成方法中,模板辅助下的仿生矿化法不但具有环境友好、工艺简便、成本低廉等优点,而且能够有效地对HAp的形貌及微结构进行调控。本论文针对这一应用领域,开发了多种模板控制-仿生矿化制备HAp纳米晶簇的技术,深入研究了模板对于晶簇形貌和微结构的调控规律,并且进一步考察了HAp晶簇对二价有毒重金属离子、三价砷以及有机分子等物质的电化学传感能力,研究内容包括：1.提出了天然生物模板辅助-仿生矿化制备HAp纳米晶簇的新方法。系统研究了仿生矿化条件下,天然生物膜及天然生物质对于HAp晶簇形核和生长的调控规律。结果表明,天然生物膜(鸡蛋壳内膜和竹内膜)主要通过控制反应离子的扩散来控制晶体生长,膜的物化特性及表面官能团能够影响晶体在其表面形核；较高的温度或较高的pH值能够增大形成HAp的驱动力,有利于HAp的生长；沿c轴方向的晶体生长占主导地位,遵循形核-溶解再结晶-自组装的晶体生长机制。而天然生物质(鸡蛋壳)中的有机基质对于HAp晶簇的生长具有调控作用,在其作用下天然生物质能够更快地转化为HAp,可以形成三维花状HAp晶簇。2.开发了Nafion阳离子交换膜辅助下构建特异形貌HAp纳米结构的技术。在仿生矿化条件下,首次制备出具有海参状形貌和特殊晶体结构的HAp纳米晶簇,遵循底端生长机制。此外,首次采用阳离子交换膜辅助-电沉积技术制备出三维结构纳米HAp晶簇,并发现金属基体的标准电势以及微观结构、电沉积温度和电压等因素均能够显著影响HAp的沉积。其中,阳离子交换膜能够基于空间位阻及分子识别等作用来降低HAp生成的活化能垒,从而加速反应进行。3.发展了具有特异形貌羟基磷灰石晶簇修饰下的电化学传感器的检测技术,并研究了晶簇形貌和微结构对于其电化学传感性能的关系,主要是对于电催化过程动力学的影响。结果表明,具有较高比表面积和吸附能力的海参状HAp晶簇对于二价重金属离子(Pb2+和Cd2+)具有优越的电化学传感性能,其灵敏度比文献报道的HAp电化学传感器高10—100倍；花状形貌HAp晶簇对于痕量重金属离子的电化学传感特性与其晶格大小有关；三维花状HAp晶簇还能够应用于痕量As3+的检测；HAp晶簇对有害类激素分子(双酚A)也具有良好的电化学传感特性。研究对于开发低成本、低能耗、工艺简便的高灵敏度电化学传感器具有重要的实际意义。更多还原

【Abstract】 Hydroxyapatite has been widely used as inorganic biomedical material. The unique3D network structure ensures its excellent electrochemical sensing capability. Among numerous synthesis methods, template-assisted biomineralization provides an effective way for regulating the morphologies and micro structures of HAp with advantages of environmentally friendly, simple process and low cost. Focused on this application area, HAp agglomerates with unique microstructure were fabricated by the template-assisted biomineralization method and the template-controlling mechanisum of morphology and microstructure has been investigated in detail. Furtherly, their electrochemical sensing capabilities towards toxic divaluent heavy metal ions, tervalence arsenic ions and organic molecules were researched respectively. The main contents of the present dissertation are listed as follows:1. A new natural biotemplate-assisted biomineralization method has been proposed to fabricate HAp agglomerates. Wherein, the natural bio-membrane and biomass was used as the templates in the biomineralization process respectively and the influences of them on the morphologies and microstructure of HAp agglomerates have been investigated systematically. It reveals that the biomembranes (egg-shell membranes and bamboo membrane) can regulate the crystal growth mainly by controlling the diffusion of reagent ions. The physical and chemical properties as well as functional groups can affect the nucleation process on the surface. Higher temperature and higher pH value can enhance the driving force for the formation of HAp, favor to its growth towards c-axis, following the "nucleation-dissolution recrystallization-self-assembly" mechanism. The organic matrix in natural eggshell has positive influences on the transformation to3D flower-like HAp agglomerate in a relatively fast way.2. A facile Nafion cathion-exchange membrane assisted strategy has been proposed for constructing multi-dimesional HAp nano-structure. Herein, seacucumber-like HAp agglomerates have been firstly prepared by this method, followed the "grow at the bottom" mechanism. On the other hand, a Nafion-assisted electrodeposition technology has been firstly applied for the fabrication. It was found that the parameters such as standard potential and microstructure of metal substrates, deposition temperature and voltage could obviously affect the deposition process. During this, the Nafion membrane plays important role in lowing the activation energy barrier for HAp and accelerating the formating reaction.3. A new determing technique has been developed via the electrochemical sensor modified by HAp assemblies with unique morphologies. The relationship between microstructure and the electrochemically sensing capability has also been researched, mainly attributes to the effect to the electro-catalytic kinetics. It suggested that the seacucumber-like HAp agglomerate with high surface area and adsorpting ability has excellent electrochemical sensing capability towards the toxic divalent heavy metal ions (Pb2+and Cd2+), with the sensitivity10-100times higher than those previously reported. Then it has been noticed that the crystal lattice structure of flower-like HAp agglomerate is crucial to the detection capabilities. Additionally,3D flower-like HAp agglomerates are explored to be a good candidate for the sensing of trace As3+. Moreover, it shows favourable electrochemical sensing behaviors towards harmful parhormone molecule (bisphenol A). This work is practically significant for the development of new electrochemical sensors with advantages of low cost, less energy consumption, easy preparation and high sensitivity.更多还原