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Sonication‐Induced Formation of Size‐Controlled Self‐Assemblies of Amphiphilic Janus‐Type Polymers as Optical Tumor‐Imaging Agents
Author(s) -
Miki Koji,
Hashimoto Hiroki,
Inoue Tatsuhiro,
Matsuoka Hideki,
Harada Hiroshi,
Hiraoka Masahiro,
Ohe Kouichi
Publication year - 2014
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201400358
Subject(s) - micelle , amphiphile , materials science , sonication , polymer , polymerization , dispersity , romp , ethylene glycol , chemical engineering , nanoparticle , self assembly , polymer chemistry , aqueous solution , nanotechnology , chemistry , copolymer , organic chemistry , metathesis , engineering , composite material
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.