Sirish Reddy, Chemical and Biological Engineering, University of Colorado, Boulder, UCB 424, Boulder, CO 80309, Christopher N. Bowman, Chemical and Biological Engineering, University of Colorado, 1111 Engineering Dr. Mail Stop 0424, Boulder, CO 80309, and Kristi S. Anseth, Department of Chemical and Biological Engineering, University of Colorado, Howard Hughes Medical Institute, ECCH 128, Campus Box 424, Boulder, CO 80309-0424.
Tissue engineering utilizes biodegradable materials for providing a suitable environment to regulate cellular growth and differentiation as well as present scaffolds for cell adhesion and proliferation. For successful engineering of tissues, the designed scaffold material should not only be biodegradable and cell responsive, but should also exhibit mechanical properties similar to that of target tissues. Scaffolds based on polylactic acid, polyglycolic acid, and poly(lactic-glycolic) acids are frequently employed for regenerating elastomeric tissue such as heart valves, blood vessels, and lung. However, these biomaterials are limited due to their rigid mechanical properties, high plastic deformation, and fracture under continuous cyclic strain. Recently, novel classes of elastomeric biodegradable scaffolds based on acid-alcohol condensation reactions have been reported. However, formation of these elastomeric scaffolds often involves complex chemical synthetic steps and stringent curing conditions that are on the order of days. In this work, we report development of a novel class of photopolymerizable degradable tough elastomers based on step growth thiol-vinyl polymerizations.
In our polymerization scheme, wherein thiol functionalized ester-containing monomers are reacted with vinyl functionalized monomers, the network properties like elastic modulus and degradation were easily controlled by changing the average functionality of monomers (crosslinking density) and chemistry of thiol and vinyl macromers. The elastic modulus of these materials was varied from 10 Kpa to 11.5 MPa and the degradation was controlled on the order of months to years. Elongations of these materials were as high as 3000% and these elastomers displayed complete recovery after tensile and compressive deformation. These materials also present inherent surface affinity for various cell types. Further, due to the advantageous aspects of photopolymerization scheme, these materials can be formed rapidly (on the order of seconds) under physiological conditions.
The ability of this technique to rapidly form elastomeric degradable materials with wide range of mechanical properties will expand the gamut of currently available biodegradable elastomers and potentially open up new tissue engineering applications.