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 bio adhesive interactions between individual polymer microspheres and biol ogical 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: compr essive deformation, peak compressive load, yield point, peak tensile l oad, deformation to peak load, fracture strength, deformation to failu re, compressive work, returned work, and tensile work in a single expe riment. The method has been shown to be statistically reproducible and accurate. Using this technique, several hydrophobic, thermoplastic po lymers and one hydrogel were studied. Go-polymers of fumaric and sebac ic acid, of the polyanhydride family, produced bioadhesive fracture st rengths greater than 50 mN/cm(2) with rat small intestinal mucosa, in vitro. We suggest that bioadhesion in these hard, bioerodible material s is not due to chain entanglement, as required by the diffusion theor y of bioadhesion, but due to numerous hydrogen bonds generated between hydrophilic functional groups (-COOH) and mucus glycoproteins.