Kinetics of in vitro release of a model nucleoside deoxyuridine from crosslinked insoluble collagen and collagen-gelatin microspheres.

The objective of this research is to investigate the effect of highly crosslinked insoluble collagen and collagen-gelatin hybrid matrices as platforms for controlled release of a highly water soluble model nucleoside, deoxyuridine as well as a high molecular weight model compound fluoroscienisothoicyanate (FITC)-dextran. Collagen and gelatin can be considered as biodegradable proteinous materials. Microspheres of deoxyuridine and FITC-dextran were prepared by emulsification solvent evaporation technique using collagen alone and collagen-gelatin combination. The microencapsulation efficiency, particle size and in vitro release profiles were compared. Microencapsulation efficiency of approximately 10% was obtained with collagen while 20% encapsulation efficiency was obtained when collagen was used in combination with gelatin. Particle size range became wider when only collagen was used as compared to collagen-gelatin combination. A slower release profile was observed for crosslinked as compared to noncrosslinked microspheres. This study demonstrated diffusion controlled release of both compounds from the two polymers used. A good correlation was obtained between theoretically predicted and experimentally obtained in vitro release rates for both deoxyuridine and FITC-dextran using Higuchi's square root model.