DNA chemical and physical networks have been investigated with respect to their stability and swelling, and rheological properties. Chemical networks were prepared by cross-linking DNA with ethylene glycol diglycidyl ether (EGDE), and physical networks by association with cationic polymers. Both types of gels display strong elastic properties and have a shear thinning behaviour. Addition of cationic surfactants effectively collapses the chemical gels, de-swelling starting from a critical aggregation concentration (cac) much lower than the critical micelle concentration (cmc) but similar to that for binding of surfactant to DNA in solution. The swelling-deswelling process appears to be reversible; thus the addition of an anionic surfactant to a gel collapsed by cationic surfactant gives a gel volume close to that of the original gel. Physical networks prepared by mixing DNA (either single- or double-stranded) with cationic polyelectrolytes, both derivatives of hydroxyethyl cellulose, one of them carrying hydrophobic groups, show an intriguing asymmetric phase separation and a very different rheological response from that of the polymers alone. Phase maps of the mixtures show three distinctive regions, a two-phase region, a bluish one-phase region and a transparent one-phase region. Effects due to hydrophobic groups on the polymers are relatively minor.
|Publication status||Published - 2006|
Subject classification (UKÄ)
- Physical Chemistry
- physical gels
- chemical gels