Protein release from gelatin matrices.

Gelatin is a denatured, biodegradable protein obtained by acid and alkaline processing of collagen. This processing affects the electrical nature of collagen, yielding gelatin with different isoelectric points (IEPs). When mixed with positively or negatively charged gelatin, an oppositely charged protein will ionically interact to form a polyion complex. This review article describes protein release from charged gelatin matrices on the basis of this polyion complexation. The biodegradable hydrogel matrices are prepared by chemical crosslinking of acidic or basic gelatin and are enzymatically degraded in the body with time. The degradation is controllable by changing the extent of crosslinking, which, in turn, produces hydrogels with different water contents. The time course of protein release is in good accordance with the rate of hydrogel degradation. It is very likely that the protein drug complexed with gelatin hydrogel is released as a result of its biodegradation. This gelatin hydrogel system releases the protein drug under maintenance of biological activity. This article will focus on experimental data that sustained release of growth factor from the gelatin hydrogels is very effective in exerting the biological functions of the growth factor.