ABSTRACT: Hydrogels have been widely applied in medicine for applications including controlled release drug delivery, tissue engineering, wound healing, and ocular devices. Hydrogels based on “smart” materials that reversibly swell and deswell according to their environment offer additional advantages in terms of providing switchable physical and biological properties under relevant in vivo conditions. However, conventional synthetic “smart” hydrogels suffer from significant limitations in medical applications in terms of their difficulty to non-invasively administer in vivo, their lack of degradability, and their capacity to be triggered on and off via a stimulus safe to apply in the body. From a drug delivery perspective, the highly hydrated hydrogel matrix presents additional challenges with the prolonged release of small molecule and protein drugs as well as hydrophobic drugs, with transparency posing an additional issue in the specific application of ophthalmic biomaterials and weak mechanics posing challenges in other applications. In this talk, I will outline recent progress in my lab toward the development of new chemistries and fabrication techniques to overcome these challenges, focusing on the use of hydrazide-aldehyde chemistry to form hydrazone-crosslinked hydrogels exhibiting precise (and predicable) gel swelling, “smart” environmental responses, transparency, gelation time, mechanical properties, and cell-hydrogel interactions according to the rational selection of the compositions and morphologies of the reactive polymer and/or nanoparticle building blocks used to prepare the hydrogels. Ongoing challenges in applying these hydrogels for biomedical applications will also be highlighted.
Bio-Sketch: Todd Hoare is an Associate Professor in the Department of Chemical Engineering at McMaster University. He received his Ph.D. in Chemical Engineering from McMaster in 2006 and joined the faculty after two-year NSERC-sponsored post-doctoral fellowship in Robert Langer’s laboratory at the Massachusetts Institute of Technology. Hoare specializes in engineering hydrogels and microgels with targeted “smart” properties and was the first to report the fabrication glucose-responsive microgels for diabetes treatment and externally-triggerable, electronics-free magnetically-activated implantable drug delivery devices. Hoare’s work has been profiled by Popular Science, Wired, and BBC for its potential in solving clinical challenges through innovative biomaterials design. He has published over 45 papers, has one granted patent and eight pending patent applications, and won an NSERC Innovation Challenge award recognizing the novelty of his research. Hoare has received an Early Researcher Award and the John Charles Polanyi Prize in Chemistry in recognition of his accomplishments in his early career as a faculty member. He is also an Associate Editor of Chemical Engineering Journal for materials engineering and is a member of the editorial advisory board for Colloid and Polymer Science.