Dynamic nanostructures showing morphology changes according to external stimuli or environmental changes are of great interest for a broad range of applications. DNA block copolymers, composed of an oligonucleotide strands covalently attached to a hydrophobic polymer, has a number of interesting characters such as high binding ability, efficient cellular uptake, and resistance to nuclease degradation, and efficient delivery for drugs and therapeutic nucleic acids. Herein, we report the self-assembly and programmable shape transition of dual-responsive DNA di- and tri-block copolymers. DNA diblock copolymers, DNA-b-PNIPAM, were synthesized by coupling a thermo-responsive polymer, poly(N-isopropylacrylamide) (PNIPAM) and an oligonucleotide. It shows thermo-responsive properties of PNIPAM as well as molecular recognition properties of oligonucleotide strands. Moreover, functional nanoparticles were simply prepared by hybridization of DNA-b-PNIPAM and DNA-functionalized nanoparticles. These nanoparticles showed the thermally-induced aggregation and disaggregation characters due to the dual responsive nature of DNA-b-PNIPAM. DNA triblock copolymer, DNA-b-PNIPAM-b-PMA, was prepared by introducing a hydrophobic block, poly(methyl acrylate) (PMA) to DNA/PNIPAM block copolymers, which form spherical micelles at room temperature. DNA-b-PNIPAM-b-PMA micelles undergo sphere-to-cylinder shape changes above LCST due to the conformational change of PNIPAM. The shape change is reversible, and fast cylinder-to-sphere transition occurs when the temperature is lowered below LCST. Moreover, shape shifting from cylinder-to-sphere can also be achieved while keeping the temperature above LCST by adding complimentary DNA strands with overhang sequences (Figure 1).

Dual-stimuli induced shape transition of programmable DNA block copolymers

254th National Meeting (2017)

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