A general under standing of the inter actions between DNA and oppositely charged agents, and in particular oftheir phase behaviour, has provided a basis for developing novel DNA-based materials, including gels and gel particles. DNA associates strongly with cationic cosolutes, such as surfactants, lipids,polymers and proteins; all these systems are characterized by a strong associative phase separation.
The binding patterns for several systems are presented, illustrating the consequences of this binding insolution, in terms of phase behaviour, compaction/decompaction and microstructure.
Plasmid DNA gels have been prepared and investigated with respect to their swelling/deswelling in aqueoussolution containing different additives, such as metal ions, surfactants, polyamines, proteins and drugs. It was found that covalent gels offer novel opportunities for monitoring DNA-cosolute interactions. The photodisruption of pDNA gels was used as a strategy to promote controlled pDNA release. Cell viability assays also suggest that the pDNA gels are biocompatible.
Based on the associative phase separation and interfacial diffusion, we have also developed a way to prepare DNA gel particles without adding any kind of cross-linker or organic solvent;and the preparation of DNA particles, by just mixing DNA with surfactant,polycation and protein solutions, has been achieved. Surface morphology,degree of DNA entrapment, swelling/deswelling behaviour and kinetics of DNA/protein release are also described. The stronger interaction of ssDNA, as compared with dsDNA, suggests the important role of the amphiphilicity of DNA on the interactions. These DNA gel particles were also assessed for haemolysis.
It is our belief that these findings may increase the potential of these systems as delivery and co-delivery systems.
mgmiguel@ci.uc.pt
