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

Several bioerodible polymers and one hydrogel were studied as potentia l bioadhesive materials. A microbalance-based method was used to measu re bioadhesive interactions between individual polymer microspheres an d rat intestinal tissue. In addition, surface and bulk properties of t hese microspheres were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and contact angle measurement s. Polyanhydride microspheres composed of copolymers of fumaric and se bacic acid, produced bioadhesive fracture strengths greater than 50 mN /cm(2) with rat small intestinal mucosa in vitro. We suggest that bioa dhesion in these bioerodible materials is not attributable to chain en tanglement, but instead to hydrogen bonding between hydrophilic functi onal groups (-COOH) and mucus glycoproteins. We also believe that cont inuous degradation of these materials may enhance their bioadhesive pr operties by changing surface energy, and increasing both carboxylic ac id concentration and surface roughness.