Rheology and drug release properties of bioresorbable hydrogels prepared from polylactide/poly(ethylene glycol) block copolymers

Ring-opening polymerization of L(D)-lactide was realized in the presence of poly(ethylene glycol) (PEG), yielding PLLA/PEG and PDLA/PEG block copolymers. Bioresorbable hydrogels were prepared from aqueous solutions containing both copolymers due to interactions and stereocomplexation between PLLA and PDLA blocks. The theological properties of the hydrogels were investigated under various conditions by changing copolymer concentration, temperature, time and frequency. The hydrogels constitute a dynamic and evolutive system because of continuous formation/destruction of crosslinks and degradation. Drug release studies were performed on hydrogel systems containing bovine serum albumin (BSA). The release profiles appear almost constant with little burst effect. The release rate depends not only on gelation conditions such as time and temperature, but also on factors such as drug load, as well as molar mass and concentration of the copolymers.