表面非均一氧化钛与生物分子相互作用机制及设计

Titania has attracted wide attention in many research fields due to the intrinsic advantages of large specific surface area, structure stability and unique semi-conductive properties. Especially in bio-sensing area, the excellent biocompatibility of titania makes it a promising candidate for the development of nano-biosensing devices. However, it remains a challenge to further enhance the loading and stability of immobilized biomolecule and improve the electrical conductivity. This research is based on the idea that TiO2 surface property can be modified by regulating surface heterogeneity. The major thrusts of this research are to explore the interacting mechanism between TiO2 and biomolecule interface and the mechanism on conductivity enhancement by non-uniform carbide modification. We proposed to regulate the surface heterogeneity by adjusting the geometric structure (porosity, specific surface area and roughness) and surface properties (hydroxyl density, functional group modification, surface polarity) of titania. Based on the surface structure, studies on the adsorption equilibrium and stability in association with biomolecules will be investigated. We will investigate the mechanism for surface heterogeneity regulating the loading and stability of the biomolecular immobilization, and then design experiment to improve the amount of immobilized glucose oxidase and enhance stability, besides, on the basis of retaining the advantages of titania interface properties, we are looking to achieve that improving electrical conductivity and enhancing the biological sensor signals of nano biological sensing composite electrode by surface modification of non-uniform carbide with trace carbon source. Which provides theoretical basis for designing titania based nano biological sensing electrode material with the properties of low detection limit, high detection sensitivity and high selectivity.

氧化钛由于具有高比表面积、结构稳定与半导体特性而成为诸多领域的研究热点，特别是优异的生物相容性使其在纳米生物传感应用中广具前景，但存在生物分子固定化量低、稳定性差及导电性差的难题。本项目基于氧化钛表面非均一性可调控性能的思想，开展表面非均一氧化钛与生物分子间纳米生物界面作用机制及非均一碳化增强导电性微观机制的关键科学问题研究。拟通过氧化钛的几何结构（多孔性、比表面积、粗糙度）与表面性质（羟基密度、功能基团、表面极性）调控表面非均一性，考察非均一表面上生物分子的吸附平衡、吸附稳定性及微观作用力变化，探索调控生物分子平衡吸附量和稳定性的作用机理，提高模型生物分子葡萄糖氧化酶固定化量，增强稳定性；在保留氧化钛优势表面特性的前提下，微量碳源实现非均一碳化修饰，提高导电性，增强复合电极的纳米生物传感信号；为具有低检测限、高检测灵敏度和高选择性的氧化钛基纳米生物传感电极材料的设计提供理论基础。

纳米复合电极是被誉为“迈向21世纪医学检验技术”之一的纳米生物传感技术的心脏。兼具高活性、高稳定性与生物相容性的纳米生物传感电极材料开发成为近十年来研究的热点。氧化钛由于具有高比表面积、结构稳定与半导体特性而成为诸多领域的研究热点，特别是优异的生物相容性使其在纳米生物传感应用中广具前景，但存在生物分子固定化量低、稳定性差及导电性差的难题。本项目基于氧化钛表面非均一性可调控性能的思想，开展表面非均一氧化钛与生物分子间纳米生物界面作用机制及非均一碳化增强导电性微观机制的关键科学问题研究，取得了以下几点突破：1）采用几何结构调控与界面改性的方法，设计调控介孔TiO2的几何结构（孔径、比表面积与形貌等）与界面性质（界面羟基密度、界面基团修饰与亲疏水性等），获得了介孔TiO2的表面非均一性。孔径对吸附量与酶活都有比较明显的影响，最佳孔径为20 nm。2）阐明表面非均一TiO2与生物分子的纳米生物界面作用机制，创新性地实现葡萄糖氧化酶与固定化载体结构和表面性质的匹配，为获得最优化的固定化载体提供理论基础。表面羟基会影响蛋白在介孔TiO2表面的吸附，且随着孔径的增大，表面羟基表现出来的影响会随之增大。介孔TiO2的表面电荷密度和表面化学组成，都会影响生物分子在其上的平衡吸附量以及吸附的难易程度。3）采用表面非均一碳化修饰的方法，在保留TiO2界面特性的基础上，实现纳米生物传感复合电极材料导电性的提高。在0~0.6 mM区间，葡萄糖溶液浓度每次提高0.1 mM，可以看出响应电流随浓度成线性化，电极GOx/ TiO2的灵敏度大小是27.2 μA•mM-1•cm-2，灵敏度性能提升了近10倍。理清提高导电性的微观机制，增强生物传感信号，阐明设计具有低检测限、高检测灵敏度和高选择性的TiO2基纳米生物传感电极材料的理论机制。