基于表面等离子体波调幅的单细胞折射率空间分布高分辨研究

Real-time, nondestructive, time and space observation of high resolution analysis for the interactions between single living cells and dope, between biological macromolecules in the cell, which is an important content of cellular physiology behavior and mechanism research. Surface plasmon resonance (SPR) sensing technology has characteristics such as label-free, high sensitivity, nondestructive, and non-intrusive, but for cell analysis the main problem is that the low axial depth of detecting and incapable of high spatial resolution. This project presents a new concept, which is effective depth of interaction of the surface plasma wave (SPW), it can accurately reflect the SPR sensing space scale; And put forward the SPR sensing of wavelength scanning - angle modulation, to achieve SPW amplitude modulation in medium, effective depth of interaction is increasing with tens of nanometer level with scanning at 10 nm wavelength resolution, and the effective depth of interaction of about 5μm when the excitation light wavelength scanning to 1.7μm. Space characteristics, penetration mechanism and depth of interaction of the interaction between SPW and micron scale complex medium will be studied, then establish a medium refraction tomographic method with high spatial resolution; Set up the corresponding SPR sensing system, through the living cell experiments, monitoring the the spatial distribution and dynamic process of refractive index of the mouse brain cells under the influence of different drugs, verify the function of ion channels, provides a new analysis method for cell physiology research.

活体单细胞与外加物之间、细胞内生物大分子之间的相互作用的实时、无损、时间和空间上高分辨的观测分析是细胞生理学行为及其机理研究的重要内容。表面等离子体共振（SPR）传感技术具备免标记、高灵敏、无损非侵入等特点，但用于细胞分析的主要的问题是轴向探测深度低和无法高空间分辨。本项目提出表面等离子体波（SPW）作用深度新概念，能准确反映SPR传感的空间尺度；并提出波长扫描-角度调制SPR传感方式实现介质中SPW调幅，当以波长分辨率10nm进行扫描，作用深度呈数十纳米量级递增，当激发光波长扫描至1.7μm时，作用深度约5μm。研究SPW与微米尺度复杂介质相互作用下的空间特性、穿透机制和作用深度，建立高空间分辨的介质折射率层析测量方法；搭建相应的SPR传感系统，通过活体单细胞实验，在不同药物作用下，监测鼠脑细胞的折射率空间分布及动态过程，验证离子通道功能，为细胞生理学等研究提供一种新分析手段。

表面等离子体共振（Surface Plasmon Resonance，SPR）传感技术因其免标记，高灵敏度和非侵入性等特点，被广泛应用于生物传感器领域。但是，SPR技术仍然仅限于二维表面的传感分析，轴向深度探测作为SPR在三维介质空间分析中的应用关键，尚未得到很好的研究和解决。在本项目研究中，我们研究了在多个波长下，倏逝波-电介质相互作用的空间特性，并分析了影响表面等离子体共振的空间分布的因素。提出了一种基于粒子群优化（PSO）算法的多波长角度调制结构的轴向空间分辨方法，通过分析特征SPR信号确定轴向空间的折射率分布。此外，我们还开展了适用波长范围的计算和分析。在入射光波长为600-900 nm的光谱工作范围内，轴向折射率空间分辨率的平均误差会随着轴向层数的增加而从10-5 RIU增加到10-4 RIU。本项目提出的基于PSO算法的多波长角度调制结构分析方法，将SPR检测范围从二维表面扩展到三维空间，为分子生物学提供了一种崭新而有前景的分析模型。

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