"Nanostructured Injectable Hydrogels with Tunable ""Smart"" Properties"

水凝胶是一种吸水膨胀的聚合物网络，在解决环境(例如土壤修复、农药输送)、消费品(例如保湿剂、洗发水)、食品(例如风味面膜、营养补充剂、安全包装)和药品(药物、医用粘合剂或细胞生长支持的受控输送)方面具有巨大的潜力。由于水凝胶的化学、物理和机械性能可以被设计成模拟肌肉等生物软组织，使得水凝胶能够满足其他类型材料无法满足的应用需求，因此生物应用引起了特别的兴趣。为了在这些应用中有效地应用水凝胶，必须精确控制水凝胶的纳米级和表面性质，以达到所需的药物释放速率、细胞相互作用或粘合强度。拟议的研究旨在开发以微凝胶(即小水凝胶颗粒)和/或工程聚合物为基础的可注射水凝胶，这些聚合物在低粘度前体注射后迅速形成水凝胶，在纳米尺度上具有良好控制的化学和物理性能。我们的方法是开发一系列具有明确性质的化学反应构建块，然后将它们以不同的组合和不同的比例混合；操纵同时的化学反应以形成凝胶，并在所选构建块之间进行物理相互作用，预计将创建定向水凝胶和微凝胶结构，并以编程速度降解。将“智能”材料加入到构建块中，这些构建块的性能会随着某些刺激(如温度、光线或pH)的变化而改变，从而进一步提供对凝胶性能的外部控制。这类材料在设计改进的传感器、实现长期药物治疗(提高疗效同时减少药物治疗的频率)、控制细胞黏附(改善伤口愈合)、在组织之间创建牢固、灵活的粘合(改善湿式黏附)以及为纳米技术创造快速响应的“门”方面具有巨大的潜力。拟议的研究计划还创造了跨学科培训的机会，这是应对当前技术挑战不可或缺的一部分。

Hydrogels, water-swollen polymer networks, have tremendous potential for addressing current challenges in the environment (e.g. soil remediation, pesticide delivery), consumer products (e.g. moisturizers, shampoos), food (e.g. flavour masking, nutritional supplements, safe packaging), and medicine (controlled delivery of drugs, medical adhesives, or cell growth supports). Biological applications have attracted particular interest given that the chemical, physical, and mechanical properties of hydrogels can be designed to mimic biological soft tissues such as muscle, enabling hydrogels to satisfy application needs that other types of materials cannot. To effectively apply hydrogels in these applications, the nano-scale and surface properties of hydrogels must be precisely controlled to achieve the drug release rate, cell interaction, or adhesion strength required. The proposed research aims to develop injectable hydrogels, based on microgels (i.e. small hydrogel particles) and/or engineered polymers that rapidly form hydrogels upon injection from low-viscosity precursors, that have well-controlled chemistries and physical properties on the nano-scale. Our approach is to develop a range of chemically-reactive building blocks with well-defined properties and then mix them in different combinations and different ratios; manipulation of the simultaneous chemical reaction to form a gel and physical interactions between the building blocks selected is anticipated to create oriented hydrogel and microgel structures that degrade at programmed rates. The incorporation of "smart" materials into the building blocks whose properties change upon some stimulus (e.g. temperature, light, or pH) provides further, external control over the gel properties. Such materials have significant potential for designing improved sensors, enabling prolonged duration drug therapies (improving the efficacy while reducing the frequency of drug treatments), controlling cell adhesion (improving wound healing), creating strong, flexible bonds between tissues (improving wet adhesives), and creating fast-responding "gates" for nanotechnology. The proposed research program also creates opportunities for interdisciplinary training integral to address current technology challenges.