Externally-Activated Smart Materials and Devices as On-Demand Biomaterials

能够可逆地响应其环境变化的智能材料在开发跨多个领域的一系列新的响应技术和设备方面具有巨大的潜力。 然而，在许多靶向应用中（特别是在体内，环境的细微变化可能导致显著的局部毒性）这些智能反应的有效和安全激活仍然是翻译的障碍。 因此，拟议的Discovery研究的目标是利用我们在设计多个长度尺度上的智能聚合物方面的专业知识，开发可以通过非侵入性刺激（振荡磁场或超声波）外部激活的新材料和设备，从而实现对智能材料的扩散和/或表面相互作用的动态控制。 研究将集中在三个主题，围绕应用聚合物，材料和界面工程的基础知识来设计具有目标应用特性的智能材料：** (1)为了解决当前按需交付车辆的现有问题，将探索使用“硬”聚合物的玻璃化转变而不是水凝胶的体积相变，以减少“关闭”状态释放，而相变材料将与热敏材料相结合，以避免不安全的过热，并即使在短的激活步骤后也能延长“打开”时间。 (2)为了克服旨在局部递送药物或成像疾病部位的纳米颗粒的快速循环清除（以及因此较差的靶向效率），将开发可注射的基于颗粒的递送载体，其可以被外部激活以在超声或磁场激活时按需释放特定浓度的完整纳米颗粒。 (3)为了模拟天然细胞外基质的动态性质，智能多孔水凝胶纳米复合材料支架将被设计，其中我们已经开发了新的方法来控制多个长度尺度上的凝胶孔隙率（反应性电纺和反应性冷冻铸造）将与两种活化剂结合，以实现远程控制的孔隙率变化和可固化的化学物质“锁定”。即使在远程刺激被移除后也能获得新的孔隙结构。 总的来说，这项工作预计将导致新的智能材料的开发，这些材料可以通过非侵入性刺激安全可靠地激活，从而实现脉冲/时间触发的药物递送（治疗癌症和激素不规则的关键），动态细胞环境，更好地模拟天然组织不断演变的性质，以及可以保护脆弱的传感元件直到需要报告事件的传感器。 这种研究将在技术开发以及在具有科学和经济重要性的新兴领域（生物医学设备、纳米技术）的HQP培训方面给加拿大带来重大利益。

Smart materials that can reversibly respond to changes in their environment have significant potential for developing a range of new, responsive technologies and devices across multiple fields. However, the effective and safe activation of these smart responses in many targeted applications (particularly in vivo in which subtle changes in the environment can lead to significant local toxicity) remains a barrier to translation. As such, the objective of the proposed Discovery research is to leverage our expertise in designing smart polymers on multiple length scales to develop new materials and devices that can be externally activated via a non-invasive stimulus (oscillating magnetic fields or ultrasound), enabling dynamic control over diffusion through and/or surface interactions with smart materials. Research will focus on three themes, centred around applying fundamentals of polymer, material, and interfacial engineering to design smart materials with targeted application properties:****** (1) To address existing issues with current on-demand delivery vehicles, the use of the glass transition of “hard” polymers instead of the volume phase transition of hydrogels will be explored to reduce “off” state release, while phase change materials will be combined with thermoresponsive materials to avoid unsafe overheating and enable prolonged “on” times even after short activation steps.****** (2) To overcome the rapid circulation clearance (and thus poor targeting efficiency) of nanoparticles intended to locally deliver drug or image disease sites, injectable particle-based delivery vehicles will be developed that can be externally activated to release specific concentrations of intact nanoparticles on-demand as activated by ultrasound or magnetic fields.****** (3) To mimic the dynamic nature of native extracellular matrices, smart porous hydrogel nanocomposite scaffolds will be designed in which new approaches we have developed to control gel porosity on multiple length scales (reactive electrospinning and reactive freeze casting) will be combined with both activation agents to enable remote-controlled porosity changes and triggerable chemistries to “lock in” the new pore structures achieved even after the remote stimulus is removed.****** Collectively, this work is anticipated to lead to the development of new smart materials that can be safely and reliably activated by non-invasive stimuli, enabling pulsatile/time-triggered drug delivery (key for treating cancer and hormone irregularities), dynamic cell environments that better mimic the constantly-evolving nature of native tissues, and sensors that can protect a fragile sensing element until a reporting event is desired. Such research would have significant benefits to Canada in terms of both technology development as well as HQP training in emerging areas of scientific and economic importance (biomedical devices, nanotechnology).