Swelling behavior of a new biocompatible plasmid DNA hydrogel

Chemical plasmid DNA (pDNA) gels were prepared by a cross-linking reaction with ethylene glycol diglycidyl ether (EGDE). Fluorescence microscopy (FM) and scanning electron microscopy (SEM) images of pDNA gels are reported. For the first time, the pDNA gels have been investigated with respect to their swelling in aqueous solution containing different additives, such as metal ions, polyamines, polycations and surfactants. The effect of the cationic surfactant tail length on the volume phase transition of pDNA gels was studied as a function of surfactant concentration; the critical aggregation concentration (cac), is found to decrease with increasing length of the hydrophobic tail. The deswelling appears to be reversible as exemplified by the addition of anionic surfactant subsequent to collapsing the gel by a cationic surfactant. Cell viability assays suggest that the plasmid DNA gels are non-toxic to cells and do not cause any distinct harm to them. This step contributes to the possibility of using these gels, as carriers, in real biological systems.