BIOCHEMICAL ASSAY ON INTERACTION BETWEEN HIGH MOLECULAR WEIGHT (HMWC), AND LOW MOLECULAR WEIGHT (LMWC) POLYMERS WITH PLASMID DNA

Polymer based non-viral gene delivery systems depend on the electrostatic interaction between cationic polymers and nucleic acids which yields inter-polyelectrolyte complexes (ipec). Such behaviour of interaction between polycations (cationic polymers) and polyanions (dna/sirna) can be well explained well by polyelectrolyte theory. Further addition of polycations, portion of negatively charged n-pec decreases until over all concentration of polycations and polyanions become equal and all dna/sirna charges are neutralized. Therefore when the portion of the insoluble complex (s-pec) grows the phase separation of complex species takes place and complex solubility decreases. High and low molecule chitosan were selected for this work. Physicochemical characterization of polyplexes formed due to the interaction of high molecular weight (hmwc) and low molecular weight (lmwc) chitosan with plasmid dna and sirna were performed. Gel retardation assay of polyplexes formed due to the interaction of high molecular weight (hmwc) with plasmid dna were done. Gel retardation assay of polyplexes formed due to the interaction of low molecular weight (lmwc) with plasmid dna were also performed. In (hmwc) gel image lane 1 contains polymer only and lane 10 contains plasmid dna only as controls while lane 2-9 contains complexes of polymer and dna with polymer to dna ratios of (0.25:1, 0.5:1, 0.75:1, 1.5:1, 3:1, 6:1, 8:1, and 10:1) respectively. In (lmwc) gel image lane 1 contains polymer only and lane 10 contains plasmid dna only as controls while lane 2-9 contains complexes of polymer and dna (w/w) with polymer to dna ratios of (0.25:1, 0.5:1, 0.75:1, 1.5:1, 3:1, 6:1, 8:1, and 10:1) respectively