Polymeric micelle, the self-assembly of block copolymers with core-shell architecture, is a promising nanocarrier for drug and gene delivery. There are several relevant properties in polymeric micelle as nanocarrier systems, such as longevity in blood circulation, tissue-penetrating ability, spatial and temporal controlled drug release, and reduced inherent toxicity of cytotoxic reagents1. Also, engineering of the block copolymer structure allows the preparation of polymeric micelles with integrated smart functions, such as targetability as well as stimuli-sensitivity. This presentation overviews the recent achievements as well as the future perspectives of polymeric micelles as smart nanocarriers for drug and nucleic acid delivery. Notable anti-tumor efficacy against hypovascular cancer, including pancreatic cancer and diffused-type stomach cancer, of the doxorubicin-incorporated polymeric micelles with pH-responding property was demonstrated to emphasize a promising utility of the nanocarrier-modulated chemotherapy for the treatment of intractable cancers. Drug-resistant tumors are well-treated by DACHPt-loaded polymeric micelles revealing to bypass drug inactivating pathway, thereby transporting active Pt compounds sufficiently to perinuclear region. Gene-loaded polymeric micelles were applied as non-viral vectors in the fields of regenerative medicine, particularly bone regeneration. Generation of new bone in experimental animals was successfully achieved by transducting genes encoding differentiation factors using polymeric micellar carriers. Gene therapy by polymeric micelles was also demonstrated for intractable cardiovascular disease, pulmonary hypertension, by intratracheal transfer of therapeutic gene. Further, the supramolecular assebmlies, including polymeric micelles, polymer vesicles, and photosensitive dendrimer assemblies, were utilized as nanodevices directing to the new medical paradigm of smart nanotheranostic systems controlled by external physical stimuli, particularly, photo illumination (nano-photomedicine)2
References

(1)	BAE, Y., KATAOKA, K. Adv. Drug Deliv. Rev. 2009, 61, 768
(2)	NISHIYAMA, N., MORIMOTO, Y., JANG, W.-D., KATAOKA, K. Adv. Drug Deliv. Rev. 2009, 61,327

One of the structural features seen in polyrotaxanes is the absence of any covalent bonds between cyclic compounds and a linear polymeric chain capped both terminals with bulky end-groups. The cyclic compounds can be sliding and/or rotating along the axial polymeric chain, and such structures will be opened if one of the terminal groups is cleaved by any external conditions. Based on such perspectives, we believe that the most striking strategy when initiating the design of biomaterials lies in the fact that polyrotaxanes have a lot of characteristics including the mobility of cyclic compounds threaded onto a linear polymeric chain and the perfect dissociation at specific sites in a living body[1]. One of our studies on polyrotaxane as biomaterials is the design of polyrotaxane surfaces as a platform for dynamic bio-interfaces in order to modulate cellular metabolism through a multivalent ligand–receptor interaction as well as to prevent non-specific interactions with biological molecules[1, 2-4]. Molecular mobility on such surfaces can dominate the fate of cellular response at its interface, and controlling dynamic surfaces is believed to play one of our important strategies. Another important issue will be the design of cytocleavable polyrotaxanes aiming at gene delivery[1, 5, 6]. Complex formation of cationic polyrotaxane with disulfide terminal groups with DNA and its intracellular DNA release ingeniously utilizes the structure of polyrotaxane as a polycation and the subsequent intracellular dissociation to the constituent molecules to achieve effective gene transfection ability and excellent non toxicity. Such supramolecular approaches using polyrotaxanes are extensively expected to exploit a new paradigm of advanced biomaterials for future medicines.