CAREER: Shape Responses of Ultrathin Hydrogel Microcapsules

技术总结：这份职业计划的目标是利用特定形状的pH敏感的中空水凝胶微粒(胶囊)开发一种新型的形状适应性材料，并对pH诱导的胶囊形状变化有一个基本的了解。到目前为止，环境对材料形状的控制仍然是一个主要的挑战，因为实验上的困难阻碍了刺激响应性与形状结构的整合。这项工作的关键任务是了解如何通过改变胶囊的几何形状、尺寸、化学结构和水凝胶壁厚度来控制形状响应。该项目的目标是：(I)利用逐层方法合成各种形状的水凝胶胶囊；(Ii)探索pH触发的成型胶囊中的尺寸和形状变化；以及(Iii)研究pH触发的胶囊机械性能和渗透性的变化。在本项目中，我们将合成一系列含有可交联氨基的pH敏感型阴阳离子共聚物，并将其组装成超薄水凝胶薄膜和形状特定的水凝胶胶囊。将研究水凝胶组成、厚度和硬度以及胶囊几何尺寸和尺寸对pH触发的体积转变以及相关胶囊物理性能的影响，包括壁胀/收缩、胶囊尺寸/形状变化、机械性能和渗透性。我们将综合运用ATR-FTIR、散射技术、椭圆偏振技术、光学和电子显微镜以及纳米压痕等原位技术，探索复杂形状与物理和化学性质之间的基本关联。该方案中所获得的知识可用于控制微凝胶和多层胶囊中的尺寸和形状转变现象。非技术概述：这项关于创造形状可变形的中空颗粒(胶囊)的项目为开发具有新的驱动特性的材料提供了前景，这些材料应用于受控药物输送、组织工程和微流控装置中的pH调节传输。与简单的球体相比，这些结构可能具有独特的性质，包括形状导向相互作用、流动更稳定、形状导向流动行为和细胞摄取。这个项目的教育方面是在阿拉巴马大学伯明翰分校(UAB)开发一个聚合物科学项目，促进从高中到研究生的学习和研究机会。该计划将结合传统聚合物化学的元素，并培养对UAB生物医学研究社区对特殊聚合物的需求的认识。该项目将对东南部这一领域的教育产生强大的影响，可能会产生重大的社会和经济影响。高中、本科生和研究生，包括未被充分代表的少数族裔，将接受聚合物科学的现代方面的培训，包括最先进的合成和分析方法以及在UAB内外的密集多学科合作。教育和外展活动包括在UAB开发新的聚合物科学理科学士和博士课程，并创建“聚合桥”，以加强对聚合物科学中代表性不足的少数群体的影响和增加他们的机会。“PolymerBridge I”将为11-12年级的学生设计，提供教师开发的演示，并包括动手实验室工作，而“PolymerBridge II”将以高中科学和化学教师为目标。

TECHNICAL SUMMARY:The goal of this CAREER proposal is to develop a novel class of shape-adaptable materials using pH-sensitive hollow hydrogel microparticles (capsules) of specific shapes, and to gain a fundamental understanding of pH-induced capsule shape transformations. To date, environmental control over materials shape remains a major challenge due to experimental difficulties that hinder integration of stimuli-responsiveness into shaped structures. The key task in this work is to understand how shape responses can be controlled by varying capsule geometry, dimensions, chemical structure, and thickness of hydrogel wall. The objectives of this project are: (i) to develop synthesis of hydrogel capsules of various shapes using a layer-by-layer approach; (ii) to explore pH-triggered dimensional and shape transformations in the shaped capsules; and (iii) to investigate pH-triggered changes in capsule mechanical properties and permeability. In this project a series of pH-sensitive anionic and cationic copolymers bearing cross-linkable amino groups will be synthesized and assembled into ultrathin hydrogel films and shape-specific hydrogel capsules. The effects of hydrogel composition, thickness, and stiffness as well as capsule geometry and dimensions on pH-triggered volume transitions and on the related capsule physical properties, including wall swelling/shrinkage, capsule size/shape transformations, mechanical properties, and permeability will be studied. Fundamental correlation between complex shapes and physical and chemical properties will be explored using a combination of in situ techniques such as ATR-FTIR, scattering techniques, ellipsometry, optical and electron microscopy, and nanoindentation. The knowledge obtained in the proposal can be used in controlling size- and shape-transition phenomena in microgels and multilayer capsules. NON-TECHNICAL SUMMARY:This project on creation of shape-transformable hollow particles (capsules) offers prospects for developing materials with novel actuation characteristics having applications for controlled drug delivery, tissue engineering, and pH-regulating transport in microfluidic devices. These structures may have unique properties as compared to simple spheres including shape-guided interactions, a greater stability in flow, and shape-directed flow behavior and cellular uptake. The educational aspect of this project is to develop a polymer sciences program at U. Alabama Birmingham (UAB) promoting learning and research opportunities from the high school through the graduate level. The program will combine elements of traditional polymer chemistry with developing awareness of the needs of the UAB biomedical research community for specialized polymers. The program will have a strong influence on education in the field in the Southeast, with potentially significant social and economic impact. High school, undergraduate, and graduate students including underrepresented minorities will be trained in modern aspects of polymer science including state-of-the-art synthetic and analytical methods and intensive multidisciplinary collaborations throughout and beyond UAB. Educational and outreach activities involve developing new B.S. and Ph.D. programs in polymer science at UAB and creating "PolymerBridge" to enhance the impact on and to increase the opportunities for underrepresented minorities in polymer science. "PolymerBridge I" will be designed for 11-12th graders with instructor-developed demonstrations and include hands-on lab work, while "PolymerBridge II" will target high school science and chemistry teachers.