Novel nucleic acids nanobiotechnology integrated with materials science

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1. Water soluble polyelectrolyte complex between cationic comb-type copolymer and nucleic acid We have been interested in the soluble interpolyelectrolyte complexes(IPEC)between DNA and the cationic comb-type copolymers, poly(L-lysine)-graft-dextran(PLL-g-Dex), consisting of a polylysine backbone and abundant hydrophilic graft chains of dextran as a model of nucleic acid-binding proteins. The copolymer forms a totally soluble IPEC in which the DNA coil-globule structural transition, i.e. compaction, is suppressed. The soluble nature of the complex enables us to spectroscopically monitor the effect of highly basic polymers on DNA hybridization. We found that an electrostatically equivalent amount of the comb-type copolymers increased stability of a double-stranded (ds)DNA and a triple-stranded DNA under physiological relevant conditions. Furthermore, we found that the copolymers stimulated the strand-exchange reaction between a ds DNA and its complementary single-stranded (ss)DNA, and e … More xhibit nucleic acid chaperoning activity.2. Acceleration of DNA hybridization by cationic comb-type copolymer Nucleic acid hybridization is a pivotal process in gene expression, replication and recombination in vivo. For biotechnology purposes, however, an increase in hybridization rate even at low DNA concentration is particularly important. Poly(L-lysine)-graft-dextran at nanomolar concentration significantly accelerated DNA-hybridization rate over 200-fold under physiologically relevant ionic conditions.3. Cationic comb-type copolymers for boosting DNA-fueled nanomachines For the better applications and developments of DNA nanomachines, their responding kinetics, output, and sequence-selectivity need to be improved. Furthermore, the DNA nanomachines currently have several limitations in operating conditions. In this study, we showed that poly(L-lysine)-graft-dextran produces the robust and quick responses of DNA nanomachines under moderate conditions including physiologically relevant conditions even at very low strand concentrations(nanomoles per liter range)through hybrid stabilization and DNA strand exchange acceleration. Less