(275c) Modulating the Degradation Rate of Fumarate-Based Polymers for Bone Tissue Engineering

Poly(propylene fumerate) (PPF) has been developed and used widely in the field of tissue engineering, specifically bone tissue engineering.  Currently, the rate of degradation of PPF is less than the rate of bone formation.  Due to this limitation, work in our laboratory focuses on new synthetic routes to increase the ester hydrolysis of fumarate-based polymers over PPF.  Poly(butylene fumarate) (PBF), an unsaturated linear polyester which differs from PPF by a methylene group, has been synthesized through a ring opening polycondensation reation from maleic anhydride (MA) and butylene glycol (BG).  Both fumarate polymers, PPF and PBF, were synthesized to have similar molecular weights ( 1301 and 1573, respectively).  Upon synthesis samples were subjected to accelerated degradation conditions (0.1N NaOH, 60⁰C with gentle agitation at 65 rpm), evaluating mass loss as well as change in compressive moduli up to 48 hrs.  PPF and PBF both exhibited mass loss of ~20% in the first 24 hrs, with PPF remaining relatively constant throughout the rest of the incubation and PBF continuing to undergo mass loss.  Compression testing results show a similar trend as the mass loss, with the compressive moduli continuing to decrease for PBF after 24 hrs, as PPF again shows little change after 24 hrs.  These results indicate that with the addition of a methylene in the polymer backbone in turn increases the rate of degradation.  Synthesis, substrate fabrication and degradation of the bulk material will be discussed.  Additionally, fabrication and characterization of three-dimensional non-woven fibrous scaffolds using a novel in situ electrospinning will be presented.