Event Abstract

Engineering degradable "smart" biomedical hydrogels on multiple length scales

  • 1 McMaster University, Chemical Engineering, Canada

While multiple types of smart, environmentally-responsive materials have been explored for a variety of biomedical applications (e.g. drug delivery, tissue engineering, bioimaging, etc.), their ultimate clinical use has been hampered by their lack of biologically-relevant degradation as well as challenges regarding their non-surgical administration to the body.  These factors have particularly limited the clinical use of temperature-responsive hydrogels, which are either highly labile in diluting environments like the body (e.g. Pluronics formulations) and/or based on functionally non-degradable synthetic polymers with carbon-carbon backbones (e.g. poly(N-isopropylacrylamide) (PNIPAM) or poly(oligoethylene glycol methacrylate) (POEGMA)).  As such, to effectively translate the potential of thermoresponsive hydrogels to the challenges of remote-controlled or metabolism-regulated drug delivery, cell scaffolds with tunable cell-material interactions, theranostic materials with the potential for both imaging and drug delivery, and other such applications, it is necessary to develop hydrogel chemistries that can form gels following administration via minimally-invasive injection procedures and facilitate gel degradation over targeted time intervals such that the degradation products are capable of renal clearance following the required lifetime of the material.

In this presentation, I will outline the recent progress made in my group toward engineering injectable and degradable smart hydrogels on multiple length scales based on in situ gelation of hydrazide and aldehyde-functionalized PNIPAM or POEGMA oligomers with molecular weights below the renal filtration limit.  Specifically, approaches we have developed to fabricate degradable thermoresponsive bulk hydrogels (using a double barrel syringe technique), hydrogel particles (on both the microscale through the use of a microfluidics platform facilitating simultaneous mixing and emulsification of the precursor polymers and the nanoscale through the use of a new thermally-driven self-assembly and cross-linking method), and hydrogel nanofibers (using a reactive electrospinning strategy) will be described.  In each case, hydrogels with temperature-responsive properties similar to those achieved via conventional free radical cross-linking processes can be achieved, but the hydrazone cross-linked network can both enable rapid gelation upon injection and controllable degradation over time to re-form the oligomeric precursor polymers and enable clearance.  Applications of these materials for drug delivery, cell delivery, and tissue engineering will be discussed in conjunction with the various hydrogel morphologies we can generate.  Overall, we anticipate that the tools developed will enable easier translation of synthetic smart materials to clinical applications.  

Keywords: Hydrogel, Drug delivery, Smart material, Intelligent gel

Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016.

Presentation Type: Special Session

Topic: Environmentally sensitive biomaterials

Citation: Hoare T (2016). Engineering degradable "smart" biomedical hydrogels on multiple length scales. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.00250

Received: 28 Mar 2016; Published Online: 30 Mar 2016.

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