Authors: G. Harper
Affilation: WetaScience, United Kingdom
Pages: 799 - 801
Keywords: DNA microparticles multilayer layer-by-layer cationic polymers
Alternating multilayers of DNA and polyhydroxylamine [PT] were produced on cationic microbeads [C]. DNA elution on two enclosed layers and a surface layer of DNA, provided 10µg DNA/mg bead/ per layer and yield 54µg/mg bead. Multilayer architecture was probed by dye elution. Cationic sites were lost and gained by DNA and PT addition respectively.<br> <br>INTRODUCTION:<br>Some progress in the development of DNA vectors for possible gene therapy is based on polycation complexation with anionic DNA1, and the adoption of the layer-by-layer approach to build polyelectrolyte multilaminate formulations2,3. Here we investigated the synthesis of polylectrolyte complexes that use alternating layers of DNA and a novel polycation to produce two layers of enclosed DNA and a third outer layer by final DNA adsorption to all types. The approach uses polyhydroxylamine (PT) as the polycation, with the advantage that with its pKa below 9, it can reversibly bind polyanions by modest changes in pH that lie within physiological limits. Cationic and Anionic dye binding can be used to probe the multilaminate structure.<br>CONCLUSION:<br>Multilayered PECs were successfully formulated with alternating layers of polyhydroxylamine (PT) and DNA, on a cationic magnetic microbead support, to enclose upto two layers of DNA and a third surface layer. The polycation PT allows elution of DNA below pH9, and yields 10-15 µg/mg bead, of DNA per layer, and upto 54µg/mg bead. Comparison of elution of bound CR dye between bead types reveals cationic site blocking on DNA adsorption of 34 nM/mg beads, and addition on PT adsorption of 14-18nM/mg beads, indicating a form of layer-by -layer construction.