In vitro physicochemical evaluation of DNA nanoparticles

We aim to characterise in vitro physiochemical behaviour of DNA nanoparticles that have been developed by our research group based on the biodegradable natural polymers with metal coordination. A polysaccharide, pullulan, was chosen as the vector of plasmid DNA. Diethylenetriamine pentaacetic acid (DTPA) was chemically introduced to the hydroxyl groups of dextran to obtain pullulan-DTPA. When Zn2+ solution was added to the mixture of pullulan-DTPA and a plasmid DNA, DNA nanoparticles were formed. The conjugation of pullulan-DTPA with Zn2+ coordination decreased the apparent size of plasmid DNA. A negative zeta potential of plasmid DNA became almost 0 mV by the Zn2+-coordinated conjugation with the pullulan-DTPA. The stability of DNA nanoparticles formed through metal coordination depended on the percentage of chelate residues introduced, the mixing weight ratio of the plasmid DNA/DTPA residue used for conjugate preparation. We conclude that physicochemical characterisation of non-viral gene vectors is important to enhance gene expression whereas the use of plasmid DNA is not effective.