BIOADHESIVE MICROSPHERES .1. A NOVEL ELECTROBALANCE-BASED METHOD TO STUDY ADHESIVE INTERACTIONS BETWEEN INDIVIDUAL MICROSPHERES AND INTESTINAL-MUCOSA

A simple electrobalance-based method has been developed to measure bioadhesive interactions between individual polymer microspheres and biological tissues. Environmental conditions, such as temperature and pH, are easily controlled to mimic physiological parameters. The technique is unique in that it allows the measurement of many parameters: compressive deformation, peak compressive load, yield point, peak tensile load, deformation to peak load, fracture strength, deformation to failure, compressive work, returned work, and tensile work in a single experiment. The method has been shown to be statistically reproducible and accurate. Using this technique, several hydrophobic, thermoplastic polymers and one hydrogel were studied. Go-polymers of fumaric and sebacic acid, of the polyanhydride family, produced bioadhesive fracture strengths greater than 50 mN/cm(2) with rat small intestinal mucosa, in vitro. We suggest that bioadhesion in these hard, bioerodible materials is not due to chain entanglement, as required by the diffusion theory of bioadhesion, but due to numerous hydrogen bonds generated between hydrophilic functional groups (-COOH) and mucus glycoproteins.