INNOVATION CENTER OF NANOMEDICINE Summary Ultra-small nanomedicines of approximately 18 nm were fabricated by dynamic ion-pairing between Y-shaped block copolymers and nucleic acid drugs, such as siRNA and antisense drugs. Chemically modified and double-stranded oligonucleotides dramatically enhanced the stability of the ultra-small nanomedicines in the blood circulation. The ultra-small size allows for high permeability in...