基于光波导精确重构的生物分子相互作用高通量传感方法基础研究

Although very weak, biomolecular interaction is the base and kernel of many biological processes. It is mainly characterized by binding strength and kinetic parameters (namely association rate and dissociation rate) which imply lots of life information. There exist over thousands types of biomolecules in the life species of a kind. Thus it is needed to simultaneously sense a great number of biomolecular interactions, in the aspects of disclosing life mechanisms and implementing life regulations, biomolecular functions, drug screening and exact diagnosis-therapy etc. However all the existing high-throughput methods of sensing biomolecular interactions are achieved by scanning and reading out the image of biomolecular microarray (bio-microarray) point by point. It is difficult for them to sense kinetic parameters because of their long scanning-time. This project proposed presents a novel high-throughput method of sensing biomolecular interactions with optical waveguide reconstruction that is similar with the CT (computed tomography) technique. In our method, after densely immobilizing many microarrays of different bio-molecules in or on optical waveguide, the biomolecular interactions in all points of the bio-microarrays will vary their refractive indices, and then change the ouput signals of the optical waveguide. By using the output signals and the waveguide reconstruction algorithm based on the Fourier mode coupling (FMC) theory proposed by us, the real-time variations of the refractive indices in all spots of the bio-microarrays are simultaneously, accurately and continually reconstructed on line. Finally, the kinetic parameters and binding strength of the biomolecular interactions are obtained by calculating the rise rate, fall rate and their ratio of the time-dependant variation of the refractive index in each point of the bio-microarrays. In this project, we will research on the principle/mechanism and main performances of the sensing method proposed, the FMC-based reconstruction theory and algorithm, and the readout way of biomolecular interactions, and will also optimize the parameters of the waveguide structure and the reconstruction algorithm.

生物分子相互作用虽微弱却是生命活动的基础和核心，主要用结合强度和动力学参数（结合及解离速率）来表征，含有大量的生命信息。同一物种有成千上万种生物分子，在生命机制及调控研究、分子功能实现、药物筛选和精准诊治中需要同时传感大量的生物分子作用量。但现有方法都是逐点扫读生物分子点阵图像而实现高通量传感，因其扫读时间长而难以传感动力学参数。本项目提出了用类似于CT的波导重构术来高通量传感生物分子作用的新方法：沿光波导密集固化很多不同生物分子的微点阵后，各点的生物分子作用改变其折射率，进而改变波导输出信号；用波导输出信号和基于傅里叶模式耦合（FMC）理论的波导重构算法，在线实时、精确、连续地同时重构出波导上各点的折射率变化，再计算各点折射率变化的升降速率及速率比而得到各点生物分子的动力学参数和结合强度。研究其传感原理/机理和主要特性、FMC重构理论及算法、生物分子作用量的读取法，并优化波导和重构参数。

生物分子的相互作用是生命活动的基础和核心，包含了大量的生命信息。但生物分子的种类繁多，组成千差万别。高通量地获取生物分子间的相互作用参数在生命机制及调控研究、分子功能实现、药物筛选和精准诊治中具有极其重要的作用。此前的高通量传感方法主要是基于荧光标记和表面等离子共振成像的微阵列图像逐点扫读方法，难以快速、高通量地获取生物分子作用的动力学参数。本项目主要研究了基于光波导重构的生物分子相互作用（含动力学参数）高通量传感方法的基础理论和特性，包括：（1）用傅里叶模式耦合理论建立了光波导完全响应（幅值、相位、时延）谱的半解析通解；基于该通解建立了光波导的重构理论和低复杂度重构算法，并用于光波导的分析设计。（2）研究了该传感方法的基本原理，包括生物分子相互作用对光波导折射率微扰及其响应谱的影响，用波导响应谱和重构算法获取折射率微扰的方法，用折射率微扰的时变性获取各微阵列点的生物分子相互作用。（3）研究了可消除光源及光路干扰的、基于共臂双迈克尔逊干涉仪的完全响应谱获取方法及其传感实验系统。（4）根据重构理论、蒙特-卡洛法和对比法，研究了该传感方法的分辨率和误差源，分辨率可优于亚毫米级，误差主要源于量化误差和空间间隔误差且总是呈高斯分布。（5）以灵敏度、效率和精度为目标，研究了引入光栅微扰后的多种光波导结构和算法参数对传感特性的影响及优化，研究表明相移和非对称型结构有助于提高灵敏度，空间采样间隔及长度、变迹处理等与效率、精度密切相关等。（6）研究了高通量光波导生物芯片的多种结构、光波导上固化生物分子的修饰方法。这些研究内容和结果涉及该高通量传感方法的关键核心，为更深入的研究和实际应用、分析设计及制作高通量光波导生物芯片、研制数据读出或传感系统等建立了基础理论及技术，发展了一种新的高通量生物分子传感方法。

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