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≈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.