title: Sonication-induced formation of size-controlled self-assemblies of amphiphilic Janus-type polymers as optical tumor-imaging agents.
abstract: In this study, amphiphilic Janus-type polymers were synthesized via ring-opening metathesis polymerization (ROMP), multiple vicinal diol formation, and grafting of poly(ethylene glycol) monomethyl ether (mPEG). These amphiphilic polymers formed self-assemblies, which were a mixture of micelles and multimicellar aggregates, in water. By choosing suitable Janus-type polymers and irradiating an aqueous solution of polymers using a sonicator, either small micelles or large multimicellar aggregates were obtained selectively. Hydrophobic substituents controlled the aggregation-disaggregation behavior, leading to the formation of metastable self-assemblies by sonication. The formation of self-assemblies with a uniform size was affected by ultrasonic frequency, rather than power. In vivo optical tumor imaging revealed that the large-size multimicellar aggregates persisting for a long time in blood circulation slowly accumulated in tumor tissues. In contrast, the tumor site was rapidly, clearly visualized using the small-size micelles.
authors.affiliation: Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto, 615-8510, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Miki
authors.forename: Hiroki
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Tatsuhiro
authors.initials: T
authors.lastname: Inoue
authors.forename: Hideki
authors.initials: H
authors.lastname: Matsuoka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Harada
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hiraoka
authors.forename: Kouichi
authors.initials: K
authors.lastname: Ohe
mesh_terms: D045744:Cell Line, Tumor; D003460:Crystallization / Q000379:methods; D005456:Fluorescent Dyes / Q000138:chemical synthesis*; D019220:High-Energy Shock Waves; D006801:Humans; D008856:Microscopy, Fluorescence / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry* / Q000528:radiation effects; D009374:Neoplasms, Experimental / Q000473:pathology*; D010316:Particle Size; D011108:Polymers / Q000737:chemistry; D013010:Sonication / Q000379:methods*; D013501:Surface-Active Agents / Q000138:chemical synthesis / Q000528:radiation effects
chemical_list: D005456:Fluorescent Dyes; D011108:Polymers; D013501:Surface-Active Agents
keywords: janus-type polymer; self-assembly; size-control; sonication; tumor imaging