Biodegradation of hydrophilic-hydrophobic hydrogels and its effect on albumin release

The objective of this study was to examine the effects of composition ratio of a new class of bicomponent biodegradable hydrogels and the molecular weights of the constituents on the hydrolytic degradability of the hydrogels and their release of bovine serum albumin (BSA). Biodegradable hydrogels were prepared from dextran derivative of allyl isocyanate (dex-AI) and poly (D,L) lactide diacrylate macromer (PDLLAM) over a wide range of dex-AI to PDLLAM composition ratio. The results obtained indicated that the hydrolytic degradation of these biodegradable hydrogels could be controlled by adjusting the composition ratio of dex-AI to PDLLAM or by changing their molecular weights. Along with the hydrogel degradation, water content of the hydrogels changed, and 3D porous network structure was observed. Generally, as the PDLLAM composition in the hydrogels increased, the rate of weight loss increased due to the hydrolytic degradation of the PDLLAM. The increase in molecular weights of either dex-AI or PDLLAM would decrease the degradation rate of the dex-AI/PDLLAM hydrogels. BSA release data correlated well with the hydrogel degradation profiles, suggesting that the extent and rate of BSA release would be mainly controled by hydrogel degradation. As the PDLLAM composition in the hydrogel increased, the extent and rate of BSA release also increased. An increase in the molecular weights of the hydrogel constituents, however, led to a decrease in BSA release.