无机纳米粒子凝胶组装体：从界面化学配位到宏观力学性质

Self-assembly of biomacromolecule into hydrogels is one of hot topics in scientific field. Given the similarities in structures and assembly characteristics between inorganic colloidal nanoparticles and many biomacromolecules, the self-assembly of inorganic nanoparticles into suprastructures at nanoscale has been received widely attention. However, the formation of inorganic nanoparticle hydrogels was mainly templated by biomacromolecucle hydrogels. Hydrogels formed by particles with hundreds of nanometer typically ignore the surface chemical coordination of particles. Here, we proposed an idea that inorganic nanoparticle hydrogels can be self-formed from inorganic nanoparticles in the collective non-covalent forces through adjusting the dielectric constant and the weak interaction between amino group and carboxyl group from the ligands. Furthermore, the formation of inorganic nanoparticle hydrogels will be investigated through the analysis of the inherent relationship among macro-mechanical properties, microstructures and the configurable coordination between ligands and nanoparticles in experimental data and simulations. This proposed project could potentially provide new idea for studying inorganic nanoparticle hydrogels and corresponding biological applications.

以生物大分子为基元自组装制备水凝胶是科学界普遍关注的热点问题之一。鉴于无机胶体纳米粒子在结构和组装特性方面同生物大分子具有许多相似之处，以无机胶体纳米粒子为组装基元，构建纳米维尺度的无机纳米超结构已经得到广泛关注。目前无机胶体纳米粒子水凝胶的制备主要为利用生物大分子的凝胶化辅助实现，而纯粒子的凝胶体系主要关注处于亚微米尺度的粒子间弱相互作用形成的凝胶。该体系通常不考虑粒子的表面化学结构。申请者提出从理解无机纳米粒子表面态结构入手，通过调节组装介质的介电常数、组装体基元表面羧基和氨基间的配位与弱相互作用，实现无机纳米粒子自组装凝胶的制备。并建立凝胶宏观力学性质、微观结构、分子水平上的配体与无机核的配位结构之间的关联，为发展功能导向的无机纳米粒子水凝胶自组装体系及其生物学效应研究提供新的思路。

如何利用自组装化学调控组装基元之间的弱相互作用是制备功能组装模块的核心科学问题之一。粒子凝胶的研究是一个古老而又新颖的组装化学课题，科学家已经广泛建立了从微米粒子的分型结构到硬球模型构，从微米粒子基本流变学特性到功能特性的系统性研究。然而，对处于纳米尺度的粒子凝胶各基本基元间相互作用的认识却未受到关注。主要是由于纳米尺度下配体与无机纳米核处于同一尺度，配体-配体，配体-无机核等间的化学相互作用和物理相互作用均需要考虑，并需建立相应的理论模型。本课题系统的以超小尺寸的半导体纳米胶体粒子，贵金属纳米胶体粒子为研究对象，主要研究了粒子尺度、配体结构和构型、组装介质的介电常数等对无机胶体纳米粒子凝胶粘弹性的影响及调控因素。制备了依靠弱相互作用组装的具有超强粘弹性的纳米粒子凝胶。并揭示了该粘弹性受无机纳米粒子“核”与配体间的多种动态配位结构调控。不同种类配体可与纳米无机核存在单点、多点、单层、多层配位形式。且上述配位模式随粒子尺寸变化而呈现不同变化趋势。但较小尺寸的粒子、单层配体配位的粒子、多点配位模式的配体具有更好的粘弹性。本课题也通过设计功能多肽配体、与功能小分子复合，初步探索了其在动态组装、超灵敏检测方面的应用，期待为发展功能复合生物材料奠定基础。