Polyelectrolyte complexes based on an outer layer of cationic polyhydroxylamine (PT) were prepared on carboxylated microparticles pretreated with polyamine (A) and a middle layer of Polyacrylic Acid (PA). A synergistic effect between PT and PA layers provides greater binding with release of DNA (11.5 µg/mg, 0.36se) on pH change compared to PT adsorbed without a supporting polyanion (7.95 µg/mg, 0.38se). Historically polyelectrolyte complexes formed in solution between polyions of opposite charge, polycations and polyanions, were considered to be largely stoichiometric in structure1. More recent evidence suggests that non-stoichiometry occurs within PECs according to formulation conditions2. The formation of PEC multilayers or nanolayers on substrates is now receiving attention3. Our development of a polycationic polyhydroxylamine with a pKa below 9 allows the synthesis of alternating polyion layers on a magnetic bead substrate . These beads have the capability to bind polyanionic DNA at low pH (4) and elution at a moderate pH(8), with obvious utility in isolation and purification of DNA in aqueous media.
pH dependent DNA binding and elution from polyhydroxylamine [PT] containing PECs is described. Significantly greater binding and subsequent release of DNA is achieved by PT, as a PEC, than as a simply adsorbed polycation (Fig 6.). Synergism exists between anionic PA, as a supporting layer, and cationic PT providing a significant increase in DNA binding and elution (11.6 (0.4se) vs 7.9 (0.4se) µgDNA/mg beads) . Polyanion and polycation layer presence is confirmed by both zeta potential and dye binding results. NR dye recovery from PA with PT present (C/AF/PA/PT) provides evidence that the electrosteric architecture of each polyion layer is largely conserved between adjacent polyion layers.
Journal: TechConnect Briefs
Volume: 2, Technical Proceedings of the 2006 NSTI Nanotechnology Conference and Trade Show, Volume 2
Published: May 7, 2006
Pages: 381 - 383
Industry sector: Medical & Biotech
Topicss: Biomaterials, Materials for Drug & Gene Delivery