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

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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).