BIOADHESIVE MICROSPHERES .2. CHARACTERIZATION AND EVALUATION OF BIOADHESION INVOLVING HARD, BIOERODIBLE POLYMERS AND SOFT-TISSUE

Several bioerodible polymers and one hydrogel were studied as potential bioadhesive materials. A microbalance-based method was used to measure bioadhesive interactions between individual polymer microspheres and rat intestinal tissue. In addition, surface and bulk properties of these microspheres were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and contact angle measurements. Polyanhydride microspheres composed of copolymers of fumaric and sebacic acid, produced bioadhesive fracture strengths greater than 50 mN/cm(2) with rat small intestinal mucosa in vitro. We suggest that bioadhesion in these bioerodible materials is not attributable to chain entanglement, but instead to hydrogen bonding between hydrophilic functional groups (-COOH) and mucus glycoproteins. We also believe that continuous degradation of these materials may enhance their bioadhesive properties by changing surface energy, and increasing both carboxylic acid concentration and surface roughness.