Abstract
Hydrolytically degradable microspheres were prepared by crosslinkng dextran under alkaline conditions with cyanogen bromide (CNBr). The crosslinking was performed in a water-in-oil type heterophase suspension medium. Dextran Mws of 500,000 and 40,000 were used for the preparations, CNBr:dextran-OH mole ratios ranged from 0.021:1 to 0.21:1. The microspheres absorbed significant quantities of water (20-45 times their own weight), and were shown to degrade in neutral buffer to soluble and non-toxic products. Hydration and degradation behavior varied linearly with the ratios of CNBr to dextran. The physical properties were dependent on the molecular weights of the dextrans used in the preparations. In contrast to epichlorohydrin crosslinked dextran microspheres that are resistant to hydrolysis and only degrade enzymatically, the described microspheres degrade more rapidly by simple hydrolysis of the iminocarbonate bonds that constitute the microspheres. Such degradative properties are ideal in the application of the microspheres as wound filers and as components of wound dressings.
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