DNA terminal mismatch-induced stabilization of polymer micelles from RAFT-generated poly(N-isopropylacrylamide)-DNA block copolymers

Abstract

Temperature-responsive diblock copolymers made of poly(N-isopropylacrylamide) (PNIPAAm) generated by reversible addition-fragmentation chain transfer (RAFT) polymerization and a single-stranded DNA (ssDNA) self-assembled into polymer micelles. The micelles consisted of the PNIPAAm core surrounded by the ssDNA corona with a hydrodynamic diameter up to 300 nm in an aqueous medium above the lower critical solution temperature. In a medium of high ionic strength, the formation of the fully matched duplex with the complementary ssDNA on the surface of the polymer micelles induced rapid and spontaneous aggregation. By contrast, the micelles remained dispersed under the identical conditions when single-base-substituted ssDNA was added to form the corresponding terminal-mismatched duplex on the micellar surface. This highly sequence-selective process took place irrespective of the size of the PNIPAAm core.

Keywords: DNA; block copolymers; colloids; micelles; thermoresponsive polymers.