SUCROSE DIACRYLATE - A UNIQUE CHEMICALLY AND BIOLOGICALLY DEGRADABLE CROSS-LINKER FOR POLYMERIC HYDROGELS

A series of degradable hydrogels based on different vinyl monomers suc h as acrylamide, sucrose-1'-acrylate, and acrylic acid were synthesize d using sucrose-6,1'-diacrylate (SDA) as a crosslinking agent. SDA was prepared by enzymatic transesterification of vinyl acrylate with sucr ose in pyridine. Base catalyzed hydrolysis of SDA in aqueous solution was studied as a function of pH. As expected, hydrolysis of SDA was fa ster at higher pHs such that poly(acrylamide), poly(sucrose 1'-acrylat e), and poly( acrylic acid) hydrogels underwent substantial degradatio n at and above pH 7, 9, and 13, respectively. The degradation was char acterized by changes in the swelling ratios of the hydrogels indicatin g breakage of the crosslinking agent. Degradation of the hydrogels at their chemically stable pHs was studied in presence of enzymes. Enzyme s, including pepsin and a fungal Lipase, were able to degrade the poly (acrylamide) hydrogel at pH 4 and 5, respectively. Poly(acrylic acid) hydrogel was degraded in presence of a fungal protease at pH 7.8. (C) 1997 John Wiley & Sons, Inc.