多态太赫兹频谱技术及其蛋白质聚集水化层特性研究

Scientific interest in terahertz electromagnetic waves have the response characteristics, rotational and vibrational properties of molecules cluster in terahertz range , unique sensitively related to collective and hydrogen bond vibration energy spectra. In which the strong absorption of water and complex full spectrum interference, like the relationship between the spear and shield, it remains a challenge to obtain terahertz signal effectively and extract comprehensive nature from the spectrum. In this project, to study a kind of new technology and method, it is the polymorphic THz spectroscopy technique and it's applied to water rich, spectrum complex biological sample detection. Aiming at these difficulties above, we are going to focus research, spectrum characteristic response and physical mechanism of water non - state in THz range and relationship between the parameters of hydration layer and the corresponding polymorphic terahertz spectrum during the process of protein aggregation. There are innovatively in the project, a analysis techniques and methods of matching the polymorphic terahertz spectrum information used to explore the dependence between hydrogen bond network fluctuation of water in interfacial layer and the corresponding response characteristics of terahertz wave. Meanwhile, with the help of molecular dynamics simulation of water molecules around the protein, the variation characteristics of dielectric function of hydration layer lied in terahertz frequency are obtained, corresponding to insulin protein aggregation behavior, the ultimate aim of which is to reveal the law of protein aggregation behavior. Mainly solve to these questions, The first one is the technology of polymorphic terahertz spectrum signal acquisition for sample containing water in high sensitivity. Then, molecular dynamics simulation of water molecules in hydration layer bound to protein needs to be established. The third part is extracting the response characteristics and interpreting the physical properties of the hydration layer in the aggregation behavior of protein. Finally, some laws of interaction between hydration layer and protein, and to be revealed and verifier.

太赫兹波(THz Waves)对物质分子间的振动和转动，尤其是对生物组织氢键独特而灵敏的响应特性，成为研究的热点新技术。其中水的强烈吸收和复杂成分频谱干扰，犹如矛与盾的关系，困扰着THz信号的获取和频谱解读。本项目提出一种多态THz光谱技术，应用于含水丰富、频谱复杂生物样品探测。重点研究：THz波段水不同态的频谱特征响应与物理机制，以及与胰岛素蛋白质聚集行为水化层参数的关系。创新地采用水的多态THz频谱信息匹配分析技术与方法，探索微观界面水的氢键网络波动对THz响应特性；利用蛋白质结合水的分子动力学模型，分析胰岛素蛋白质聚集行为水化层微观介质的介电函数变化特性；从THz频谱解读蛋白质的聚集行为规律。主要解决：含水样品的高灵敏度的多态THz频谱信号获取技术；构建蛋白质结合水的分子动力学模型；最终揭示并验证蛋白质水化层行为与蛋白质分子间的相互作用规律。

太赫兹时域光谱（THz-TDS）技术已被证明在研究生物物理特性及结构功能等方面具有突出优势，在获取物质特征集体振动模式信息和分子间相互作用信息的同时，不断向生物传感领域延伸。但是生物体系的高复杂性和水对THz波的强吸收，成为THz技术应用于生物研究中的重要瓶颈问题。本文以THz光子与分子间相互作用的能量匹配作为理论指导，以多肽分子自组装和蛋白聚集体系为研究对象，利用THz-TDS技术研究了固态样品的分子间振动模式、液态样品的水化信息和THz生物传感，获得不同检测条件下THz频谱对结构变化的灵敏度，从THz波谱能量视角揭示并验证蛋白-分子聚集的分子间相互作用规律，完成了以下研究工作：.1. 对固态手性自组装样品的THz频谱研究和分子动力学模拟。以二茂铁-苯丙氨酸二肽（Fc-FF）为原料，在不同溶剂条件下自组装为超分子手性扭带。THz吸收峰频率的相似性来自Fc-FF晶体的集体振动模式，与模拟结果吻合；THz吸收数值的差异性来自Fc-FF分子内氨基酸手性引起的超分子结构对称性破缺。因此THz光谱对固体样品的灵敏度可以拓展到超分子手性和对称性破缺层面。.2. 对不同聚集态胰岛素溶液的THz频谱研究和水化信息定量计算。采用pH值调控法得到稳定的胰岛素单体和二聚体，两者的THz吸收均随浓度增加呈“先增后减”趋势。以拐点浓度为出发点，结合随机分布模型定量计算，得到两者水化分子数存在“1.64倍”关系，与溶剂可及表面积比例一致。对单一位点突变的胰岛素样品研究表明，B24位点在二聚过程结构变化中起到重要作用。因此，THz光谱对溶液样品的灵敏度可以达到不同蛋白聚集体层面。.3. 基于表面等离激元原理的THz微结构传感器设计和在多种溶液样品介电特性表征中的应用。光栅结构传感器用于不同体积分数乙醇-水混合溶液研究，灵敏度约为100 GHz/RIU，谐振峰偏移与乙醇体积分数存在近似线性关系。开口环结构传感器用于不同聚集态胰岛素溶液研究，灵敏度达到200 GHz/RIU，谐振峰偏移量与胰岛素浓度成反比，拐点浓度差异由二聚过程结构变化引起的介电特性差异造成。因此，THz微结构传感器可以发展成为高灵敏度的生物检测工具。