Microporous hydrogels of cellulose ether cross-linked with di- or polyfunctional glycidyl ether made for the delivery of bioactive substances

Abstract

Hydrogels were prepared by the cross-linking reactions of carboxymethyl cellulose with di- or polyfunctional glycidyl ether to investigate the effects of different cross-linker’s chain length and the number of epoxy groups on the properties of the gels. Fourier transform infrared spectra showed a new peak at ν = 1,740 cm−1 assigned to the absorption of carbonyl groups in the new ester structure formed by the cross-linking of –COONa with the epoxy compounds. The interior morphology data indicated microporous network structures which correlated with the swelling of hydrogels. The swelling data in water, urea, sucrose, urine and aspartame showed increases in swelling with an increase in chain length of the cross-linker but decreased with the number of epoxy groups on the cross-linker. Collectively, the gels were ionic strength sensitive. The rheology experiments showed that gel point (tgel) increased with the chain length of the cross-linker but reduced with increase in number of epoxy groups on the cross-linker. Dynamic oscillatory measurements indicated stronger material functions in gels prepared with polyfunctional epoxy cross-linkers. The hydrogels prepared with difunctional epoxy groups had higher loading capacity and faster release of bovine serum albumin compared with hydrogels based on polyfunctional epoxy group cross-linkers.