| An estimated 6.3 million bone fractures occur in the United States during a typical three-year period and about 15% of these are difficult to heal. As of yet there is no effective therapy. Bone fractures are thus a major health concern and an excellent target for biomaterials.; Our research goal was to synthesize an injectable polymer using ring opening metathesis polymerization ROMP approach and photocrosslink the polymer that can fill irregular bone mass by existing arthroscopic procedures, which are therefore far less invasive to implant arthroplasty. We propose a polymerization method in which a soft polymer can be injected as a thick liquid and crosslinked via a light source to a hard polymer. We focus on the use of ring opening metathesis polymerization (ROMP) to construct these new biomaterials.; We initially chose cinnamate ester and coumarin ester bearing [2+2] moieties to provide novel biocompatible, degradable, cross-linking monomers. The carbon-carbon double bond allows the viscous polymer to be crosslinked into a solid, while each ester group allows the polymer to degrade, via ester hydrolysis, into biocompatible fragments. Grubb's ruthenium benzylidene catalyst RuCl 2(=CHPh)(PCy3)2 and Grubb's second generation catalyst promote ring opening metathesis polymerization (ROMP), thus providing a method for the direct synthesis of linear polymers containing cinnamate esters and coumarin esters as functionalized groups.; We have also investigated photocrosslinked poly(diazene) based polymer networks capable of extruding nitrogen, which undergo gel-to-solid transformation upon irradiation as a possible basis for an engineered bone graft. The advantage of incorporating functionality like diazene into polymer was that on photochemical irradiation the polymer will extrude nitrogen and the material characteristic of the polymer would be porous. This porous scaffold was built with our metathesis-based biopolymer method that should permit the flow of water, nutrients, and other biomolecules throughout the new artificial tissue.; This work also describes a different methodology to construct hydrogels as soft tissues based on polyhydroxylated polymer on metathesis support. The purpose of this study was to evaluate the use of photo-cross-linkable poly((vinyl alcohol)2-alt-methylene) (MVOH) scaffolds for tissue engineering applications. To our knowledge, these poly((vinyl alcohol)2-alt-methylene) MVOH copolymers represents the first vinyl alcohol-hydrocarbon materials that can be synthesized in a controlled fashion over a large molecular weight range, are completely regioregular, and contain a desirable high alcohol percentage over poly vinyl alcohol (PVA), which is most widely used as hydrogels in biomedical applications. |
