金属纳米粒子超晶格薄膜的可控性构建及其多相高敏检测化合物的研究

Plasmonic superlattice nanomembrane is a conceptually new class of two-dimensional thinnest possible metamaterials, which consists of self-assembled metallic nanocrystals with highly ordered nanoscopic structures and distinctive multi-functionality, enabling great practical significance for optoelectronic devices and ultrasensitive sensors. However, it has been notoriously challenging to manipulate at will for large-scale, ordered assembly of plasmonic nanoparticles due to complex interparticle forces. Also, the structure defects severely limits their tunable plasmonic property, thus restricts their practical applications. To essentially tackle those challenges, this project proposes a generic polymer-ligand-based approach to regulate the pairwise interactions of anisotropic building blocks, and fabricates giant free-standing plasmonic superlattice nanomembranes with nanometers thickness but macroscopic lateral dimensions by using drying-mediated self-assembly at the air-liquid interface. By using both experimental evaluation and theoretical simulation, the optical property and SERS effects will be throughly studied by adjusting the morphology and composition of constituent nanoparticles, varying types or lengths of polymer, and engineering interparticle distances. Finally, this project will develop facile elastomer-assisted technique to transfer free-standing superlattice nanomembranes onto topologically complex surfaces, and study the SERS detecting sensitivity of food contaminants in both air and liquid. Such plasmonic superlattice nanomembrane could serve as a new class of soft-SERS substrate which offers unique capabilities of direct surface attachability and direct spectral acquisition without additional processing steps, enabling its great potential for application in the area of food safety screening and environmental monitoring.

金属纳米粒子超晶格薄膜由二维规则排列的纳米粒子作为基本构成单元，具有微观有序的阵列结构和宏观独特的光学与机械性能，在柔性光电器件和高灵敏检测装置等领域具有重大应用前景。然而，自组装过程中粒子间的复杂相互作用力易导致多层无序性缺陷，影响了超晶格薄膜的大面积有序构筑和性能的可调控性，从而限制了其应用范围。本项目利用基于聚合物的配体修饰方法来调控各向异性纳米粒子间的微观作用力，通过气液界面自组装方法构筑具有宏观大尺度，且微观高度有序的无基底自支撑二维超晶格薄膜。通过实验表征和理论模拟来研究粒子形貌和尺寸、聚合物配体性质、粒子间距离对其光学性能和表面增强拉曼效应的影响因素。开发基于弹性载体的转移技术，将超晶格薄膜转移至复杂形貌表面，研究液相和气相环境下对食品污染物分子的检测灵敏度，构建可在多相环境下对复杂形貌表面进行即时转移并检测的柔性SERS基底，有望在食品安全和环境污染物检测领域得到广泛应用。

本项目聚焦于新型贵金属基二维自组装柔性检测材料的构建，实现了新型二维纳米粒子超晶格薄膜的大面积可控性构筑；通过对两种新型二维超晶格薄膜的结构特征、机械性能和光学性能进行实验表征和理论模拟，研究并揭示了不同纳米粒子形貌和尺寸、聚合物配体性质、粒子间距离对其光学性能、表面增强拉曼效应（SERS）和电磁场增强热点均匀性分布的影响因素；通过优化超晶格薄膜的微观结构提高了其拉曼增强效应和场强热点均匀性；通过实验和计算机模拟从机理层面探讨了表面等离激元共振（SPR）光学性能与拉曼增强效应的关系；研究发现可通过调节纳米粒子的结构参数来调控超晶格薄膜的等离激元共振耦合性能，因此可以控制超晶格薄膜的SPR吸收峰位置，从而调控其光学性能和SERS检测灵敏性。. 通过项目研究，发展出了多层级纳米粒子微纳条纹制备技术，能够结合“自上而下”的柔性模板引导和“自下而上”的柔性配体诱导自组装，实现金-银核壳纳米砖在微纳条纹中组装成为均匀有序的阵列结构，可制备不同宽度的宏观大面积有序阵列，其具有均匀的纳米粒子间距分布特征，具有高的纳米粒子间电磁场耦合增强系数和均匀分布的拉曼增强效应，可对痕量化学分子残留进行高灵敏检测，且检测信号具有均匀性和重复性。. 研究并开发了无基底自支撑超晶格薄膜的转移方法，构建了具有高灵敏和高均匀性检测信号，并且可在多相环境下对复杂形貌表面进行即时转移并检测的柔性SERS检测基底，检测信号均匀性达到了95％以上，解决了传统SERS基底信号差及重复性弱的难题。可将二维超晶格薄膜转移至多种复杂形貌及材质表面，实现靶标待检测分子的实时检测，其液体中最低检测限可低至0.1 nM，气相中可在5秒内捕获待检分子，兼具灵敏度和均匀信号强度，为新型化学气体和药品检测装置的构筑和可控性设计提供了科学依据，推动了二维超晶格薄膜在食品安全和化学毒品检测等领域的应用。