Heterogeneous and homogeneous structure dextran-poly(methacrylic acid) interpenetrating network hydrogels: synthesis and an application study

pH-sensitive dextran-poly(methacrylic acid) (Dext-pMeAc) full interpenetrating network hydrogels (INHs) were prepared by simultaneous radical polymerization of methacrylic acid monomer (MeAc) and Dext polymer chains in the presence of N,N-methylenebisacrylamide (MBA) as crosslinker in aqueous solution. These hydrogels were investigated as a drug carrier. The influence of MeAc and MBA contents in the network hydrogels on the swelling behaviour and mechanical strength of prepared Dext-pMeAc INHs was evaluated. Dext-pMeAc INHs were characterized by Fourier transform IR spectroscopy, and kinetic swelling measurements were carried out in deionized water and in simulated gastric fluids (pH 1.1 and pH 7.4). Dext-pMeAc/1-1, Dext-pMeAc/3-1 and Dext-pMeAc/5-1 hydrogels with molar ratios of n(Dext)/n(MeAc) = 10 and n(MBA)/n(Dext) = 10, 30 and 50 respectively showed a core-shell structure when they swelled. This phenomenon was not observed in Dext-pMeAc/5-2, Dext-pMeAc/5-3 and Dext-pMeAc/5-5 hydrogels containing a higher amount of Dext in the gels. The swelling data proved the formation of INHs with pH-sensitive behaviour. A drug release study was performed using Rhodamine 6G fluorescent dye as a model hydrophilic bioactive molecule. The in vitro release rate of Rhodamine 6G from Dext-pMeAc/5-3 hydrogel was dependent on the pH of the release medium. (C) 2012 Society of Chemical Industry