葫芦脲基拉曼热点调控方法在药物-靶标作用上的研究

In situ analysis of dynamic drug-target interaction is of paramount importance in drug discovery. Its development and practicability, however, are hampered by the complicated sample preparation process and the lack of universal strategy. Surface-enhanced Raman scattering (SERS) utilizes the gap between nanoparticles in the plasmonic substrate as “hot spots” for efficient and label-free acquisition of analytes’ fingerprint spectra. Detection limit could be trace level or even single molecule. The universal application of any specific plasmonic substrate, however, is limited by the lack of control over the nanostructure of the “hot spots”. Based on the host-guest recognition properties of cucurbituril and its electrostatic interactions with gold nanoparticles, we propose the preparation of hybrid hydrogel-nanoparticle network as SERS substrate. On account of the rheological properties of the hybrid SERS substrate, the nanostructure of the “hot spots” could be dynamically tuned to match the analytes so as to achieve maximum SERS signal intensity. The mechanism of dynamically optimizing SERS signals by manipulating the nanostructure of “hot spots” would be studied in detail in the proposed project, in order to construct a universal SERS substrate for various drug targets and develop a new approach for the analysis of drug-target interactions.

药物分子与靶标相互作用过程的动态、实时监测一直是新药研发的关键环节与瓶颈。现有技术中样品处理步骤阻碍了检测的实时性，标记抗体手段降低了分析的普适性。表面增强拉曼散射（SERS）可利用位于“检测基底”中纳米颗粒间隙的“检测热点”，高效、非标记地获得痕量甚至单分子的指纹图谱。但是，热点结构的不可控性一直限制了SERS基底对不同靶标的普适性。本项目拟通过葫芦脲对客体分子的识别作用及对金纳米颗粒的静电作用，构建水凝胶／金纳米颗粒复合体系作为SERS基底，利用体系的流变特性，根据待检物特征动态调节检测热点微观结构，实现SERS信号的优化；围绕“SERS信号随热点结构调整的动态变化机制”这一关键科学问题，以“基底设计与合成-检测热点动态优化-信号增强机理”研究链条为主线，增强SERS基底对不同药物靶标的普适性，开发基于葫芦脲的药物-靶标作用分析新方法。

原位控制探测热点对于优化SERS的灵敏度至关重要，尤其是可以提高其对动态变化分析物的适用性。本项目利用葫芦脲的主客体相互作用，开发了由硅和金纳米颗粒组成的树莓状复合胶体HRC，并探索了其作为等离子体基质的应用。随着对系统施加越来越大的剪切速率，超分子HRC传感器表现出初期的剪切变稀以及后期的剪切增稠行为。以HRC为基质进行SERS分析，在优化条件下双氯芬酸钠药物的检测灵敏度为10^{−11}M数量级，并且仅在剪切增稠状态下获得。分析其原因，在剪切增稠区HRC在剪切力作用下形成聚集体，此时金纳米颗粒等离子体相互靠近形成SERS检测“热点”，从而大大提高了对于小分子药物双氯芬酸钠的检测灵敏度。