Synthesis and Characterization of Molecular Building Blocks for Responsive Materials

响应性材料可以在其体积上表现出大的变化，并且在小的环境变化（例如温度、pH、光或其他溶液性质）下产生力。这些材料已被用作生物材料、药物递送装置和微流体装置。目前使用的最常见的材料是无规交联聚合物水凝胶。它们的主要局限性是响应时间慢、方向性差和体积变化小。限制可能是缓慢的扩散和聚合物的聚集和水的扩散。这项合作的目标是通过开发分子尺度的响应亚基来克服这些限制。它们可以在没有聚合物扩散的情况下操作，并允许形成稀释的凝胶，这使得聚合物和水的扩散不再受到限制。因此，与传统的响应性水凝胶相比，这些材料的响应速度更快，尺寸更小。在一项综合努力中，分子构建模块是使用各种天然蛋白质的结构设计的。在克利夫兰州立大学Holland教授的实验室中，人工蛋白质在DNA中编码，并在细菌表达系统中产生。Hugel教授（慕尼黑工业大学）的实验室通过基于AFM的单聚合物力测量来表征这些新材料的行为。作为一个团队，这些小组将说明材料的各种应用，包括光学驱动分子马达，用于控制释放的快速响应水凝胶，以及用于大型和快速定向致动器的定向响应纤维。

Responsive materials can exhibit large changes in their volume and generate force with small environmental changes (e.g. temperature, pH, light, or other solution property). These materials have found applications as biomaterials, drug delivery devices, and in microfluidic devices. The most common materials currently used are randomly crosslinked polymer hydrogels. Their major limitation is their slow response time, poor directionality and the small volume changes. The limitations probably being slow diffusion and aggregation of polymers and also water diffusion.The objective of this collaboration is to overcome these limitations by developing molecular scale responsive subunits. They can operate without polymer diffusion and allow to form dilute gels, which make the polymer and water diffusion not limiting anymore. Therefore, these materials will respond much more quickly and exhibit a greater size reduction than the traditional responsive hydrogels.In a combined effort, the molecular building blocks were designed using structures from various natural proteins. In the lab of Prof. Holland (Cleveland State University) the artificial proteins are encoded in DNA and produced in bacterial expression systems. The lab of Prof. Hugel (Technische Universität München) characterizes the behavior of these new materials with AFM-based single polymer force measurements. As a team, the groups will illustrate various applications of the materials including optically driven molecular motors, fast response hydrogels for controlled release, and oriented responsive fibres for large and fast directional actuators.