Our laboratory has developed an emulsion templating method that generates high porosity scaffolds that are both biodegradable and injectable. The biodegradable macromers used in these high internal phase emulsions (HIPEs) were designed to polymerize at body temperature and have a low viscosity prior to cure, eliminating the use of toxic solvents common in fabricating biodegradable polyHIPEs. New methodology was developed to permit the rational selection of these macromers based on prediction of molecular hydrophobicity and structural analysis of surfactant chemical structure in contrast to the traditional trial-and-error approach. As proof-of-concept, we demonstrated that a biodegradable HIPE injected into a porcine bone defect cured to a rigid foam at body temperature with microscale integration with the tissue. Subsequent studies generated a library of polyHIPE grafts with tunable pore sizes (5 �m to 1 mm) and mechanical properties (modulus = 50 kPa-50 MPa). Modulation of polymer chemistry was also used to generate a range of degradation rates based on the inclusion of thioether bonds proximal to the methacrylate esters. Finally, redox initiation was studied as a means to decrease cure times from hours to minutes, comparable to bone cements used currently in the clinic. This new initiation method also improved mechanical properties with minimal effects on pore structure. The use of a double-barrel syringe permitted storage of the emulsions for up to 6 months prior to cure with no negative effects on pore structure. In summary, this emulsion templating platform can be used to generate injectable porous materials with clinically relevant properties that can be used to improve tissue regeneration.

Injectable polyHIPE bone grafts with tunable degradation rate, porosity, and cure time

248th National Meeting (2014)

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