Light triggered release of solutes from covalent DNA gels

DNA gels were prepared by cross-linking and were examined with respect to the release of DNA as well as macromolecular cosolutes introduced into the gels. In particular the effect of exposure to ultraviolet light was examined for these photodegradable gels. Different cross-linker densities (0.5%, 1%, 3% and 5% ethylene glycol diglycidyl ether) of the DNA gels were used. Network mesh size and the extent of swelling during degradation have been determined to characterize the effect of radiation on hydrogel degradation kinetics and simultaneous changes in gel structure on solute release profile. Modelling release kinetics, using the Weibull function, can describe the DNA release pattern, which is dependent on both radiation wavelength and cross-linker concentration; the mechanism of desorption is found to be complex. The kinetics release of cosolutes (lysozyme, BSA and FITC-dextran), initially loaded on DNA gels, were studied and clear differences on the release pattern were obtained. From the cosolute mechanism release it can be inferred that not only effective size plays an important role, but also interaction with the DNA network.