Hydrogel delivery systems

Water-soluble polymers (see Appendix A.3) can be cross-linked to create materials, called hydrogels, that swell, but do not dissolve, in water. In these hydrogels, the rate of drug diffusion through the bulk material depends on the extent of cross-finking. Cross-links, or interconnections between polymer chains, con- 

Diffusion of albumin in PVA hydrogels with different cross-linking density. The diffusion coefficient for bovine serum albumin at 37 °C was measured in poly(vinyl alcohol) hydrogels prepared with different cross-linking densities. Adapted from [56]. 

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SH Gehrke, LH Uhden, JF McBride. Enhanced loading and activity retention in hydrogel delivery systems. J Controlled Release. 21-33 (1998). 

Knuth, K., M. Amiji, and J.R. Robinson. 1993. Hydrogel delivery systems for vaginal and oral applications. Adv Drug Deliv Rev 11 137. 

Kissel T, Li YX, Unger E. ABA-triblock copolymers from biodegradable polyester A-blocks and hydrophilic poly (ethylene oxide) B-blocks as a candidate for in situ forming hydrogel delivery systems for proteins. Adv. Drug Deliv. Rev. 2002 54 99-134. 

Knuth, K. Amiji, M. Robinson, J. Hydrogel delivery systems for vaginal and oral apphcations, formulation and biological considerations. Adv. Drug Delivery Rev. 1993,... 

Durand-Cavagna G, Delort P, Duprat P, et al. Corneal toxicity studies in rabbits and dogs with hydroxyethyl cellulose and benzalkonium chloride. Fundam Appl Toxicol 1989 13 500-508. Li J, Xu Z. Physical characterization of a chitosan-based hydrogel delivery system. ] Pharm Sci 2002 91(7) 1669-1677. 

Hydrogels formed by PEO block copolymers have previously been proposed as sustained release matrix [85,86], The a-CD-PEO hydrogel delivery system differs in that the gelation relies on the formation of a polymer inclusion complex induced by the PEO-threaded CDs. The properties of the supramolecular hydrogel can be fine-tuned with the composition, molecular weight and chemical structure of the polymer or copolymers. 

H.T. Ta, C.R. Dass, I. Larson, P.E Choong, and D.E. Dunstan, A chitosan hydrogel delivery system for osteosarcoma gene therapy with pigment epithelium-derived factor combined with chemotherapy, Biomaterials, 30 (27), 4815-4823,2009. 

Gehrke SH, Uhden LH, McBride IF (1998) Enhanced loading and activity retention of bioactive proteins in hydrogel delivery systems. J Control Release 55 21 Gekko K, Ito H (1990) Competing solvent effects of polyols and guanidine hydrochloride on protein stabihty. J Biochem 107 572... 

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