基于棒状病毒组装而成的胶体膜构建结构化水凝胶的研究

Hydrogels often have a random and dynamic internal structure as determined by thermodynamics and high water content. Imparting regular intrinsic structures into hydrogels to create the so-called structured hydrogels is expected to endow these popular materials with many other unique properties. Such kinds of structured hydrogels have huge potential applications in “naked-eye” colorimetric sensors, display technology induced by mechanical deformations, and soft robotics, etc. Structured hydrogels have been mainly fabricated based on pre-formed templates, among which colloidal crystals, orientationally aligned nanorods or nanodiscs have been exploited so far. These templates suffer from structure inhomogeneity, limited size and also often involved stringent and costly fabrication processes. Therefore, the current challenge in constructing structured hydrogels with rich intrinsic structures and unique functionalities is to develop large-size, homogeneous templates with three dimensional hierarchal structures. In this regards, we noticed that effective depletion attractions can drive lateral association of monodisperse rod-like viruses, leading to the assembly of colloidal monolayer membranes with the thickness of one rodlike virus. The viruses in such membrane are held together by the osmotic pressure of the enveloping polymer suspension. Such intriguing artificial structure has only been a physical wonder but have not attract attentions from other fields, especially the material community, although in many aspects, colloidal membranes with a thickness of single viruses are similar to the star material- graphene. In the current proposal, we intend to exploit the unique colloidal membranes of rodlike viruses as templates for structured hydrogels. The key for such endeavor is to increase the size of the colloidal membrane from decades of micrometer to more than millimeters by circumventing kinetic hindrances during the formation the colloidal membrane. Furthermore, in situ crosslinking chemistry will be developed to permanently crosslink the viruses inside the membrane, in order to remove them from the special physical environments. In this way, chemically crosslinked colloidal membrane with a size more than millimeters can be prepared and manually handled. Superposition of the colloidal membranes can create various kinds of 3D lamellar structures. Introducing precursors of polymeric hydrogels into such templates is expected to produce hybrid hydrogels with internal structure. With vast kinds of possibilities of chemical and generic modifications inherent to viruses, we can tune the internal structure of the hydrogels by varying the thickness and number of the colloidal membrane, the surface properties of the viruses inside each membrane layer. Such lamellar hydrogels fulfill the characteristics of one-dimensional (1-D) polymer-based photonic crystals. In the last part of this proposal, colloidal membrane based structured hydrogels will be exploited as 1D photonic crystal hydrogels in glucose sensing and differentiating infected bacteria by sensing VOC released by bacteria.

在原本无规的水凝胶内部引入规整的内在本征结构有望赋予水凝胶各种独特的性能，作为多重刺激响应性智能材料在裸眼可视化生物传感、机械形变诱导显示技术、软体机器人等新兴领域有着广泛的应用潜能。寻找结构多样化的大尺度规整模板是当前构建结构和功能丰富的结构化水凝胶的核心科学问题。纳米尺度的棒状病毒在排空效应驱使下能组装成厚度为病毒长度的碟状二维胶体膜。本项目拟发展合适的物理化学方法，制备化学交联且可手工操作的大尺度棒状病毒胶体膜。以叠加多层胶体膜构建的三维组装体为模板,引入水凝胶前体，制备具有丰富内在结构特征的高分子结构化水凝胶。从棒状病毒胶体膜的厚度、层数周期、层内棒状病毒表面的物理化学性质等多个方面对水凝胶的结构进行调控。这类水凝胶的周期性结构具备作为光子晶体水凝胶的结构基础，利用棒状病毒丰富的化学和基因可改性，引入特定的识别位点，构建具有多重响应性的一维光子晶体水凝胶并用于化学生物传感。

在原本无规的水凝胶内部引入规整的内在规整结构有望赋予水凝胶各种独特的性能，作为多重刺激响应性智能材料在裸眼可视化生物传感、机械形变诱导显示技术、软体机器人等新兴领域有着广泛的应用潜能。寻找结构多样化的大尺度规整模板是构建结构和功能丰富的结构化水凝胶的核心挑战。纳米尺度的棒状病毒在排空效应驱使下能够组装而成厚度为病毒长度的碟状二维胶体膜。如果能够永久性固化这类独特的组装结构让其脱离于排空效应所需要的特殊条件而存在，胶体膜有望成为构建结构化水凝胶的模板。本项目通过发展合适的策略制备可手动操纵的大尺寸棒状病毒胶体膜，以多层胶体膜叠加构建的三维组装体为模板,制备具有丰富内在结构特征的结构化高分子水凝胶。利用棒状病毒丰富的化学和基因可改性，引入特定的识别位点，构建具有多重响应性的光子晶体水凝胶并用于化学生物传感。本项目在以下几个方面取得了一定的进展: 1) 围绕如何制备基于棒状病毒的低缺陷大尺寸胶体膜这一核心问题，我们深入研究了排空效应的各类物理化学参数对棒状病毒组装行为的影响。通过调控排空效应的物理化学条件如离子种类及强度，排空剂的化学结构及浓度，观察到了多种独特的多级组装结构。2）发展了胶体膜内原位化学改性的方法。通过在病毒表面引入可交联的化学位点如双键基团，在不破坏胶体膜的结构前提下，通过病毒间化学交联将胶体膜固化起来，从而让其可以脱离于排空效应的特定条件而存在。3) 发展了化学改性调控病毒的多级手性性质以降低胶体膜边缘手性结构和通过旋转容器减缓胶体膜沉降等手段，促进了胶体膜间的融合，初步建立了制备低缺陷大尺寸的病毒胶体膜的方法。4）在胶体膜的多极组装和原位凝胶化以构建结构化水凝胶的策略方面进行了有益的尝试。在结余经费的支持下，后续工作中我们将解决大尺寸胶体膜构建方面的一些挑战，推进基于胶体膜叠加构建多重响应性光子晶体水凝胶并用于化学生物传感方面的研究计划，同时加快主要创新性成果的发表。