“…2 Recently, hydrogels have been extensively studied as drug carriers, especially for proteins. Hydrogels have been made from different polymers such as dextran, 3 gelatin, 4-6 amylose, 7-9 cellulose, 10 chitosan, 11 fibrin, 12 collagen, 13,14 alginate, 15,16 poly(vinyl alcohol), 17 poly(hydroxyethyl methacrylate), 18,19 poly(hydroxyethyl acrylate), 20 poly(acrylic acid) (Carbopol), 21 polyasparthydrazide, 22 and poly(ethylene glycol) (PEG). 23,24 Most hydrogel-based drug delivery systems are designed as implants that release drug locally at a predetermined rate.…”