Cyclotriphosphazenes grafted with equimolar amounts of a hydrophilic polyethylene glycol and a hydrophobic oligopeptide in cis-nongeminal way form a new class of tripodal amphiphiles allowing both intra- and intermolecular hydrophobic interactions that differ from linear block copolymer amphiphiles. It has been found in this study that the tripodal amphiphiles can be tuned for self-assembly from micelles to bilayered polymersomes by controlling the hydrophobicity of the oligopeptide grafted. For instance, the tripodal amphiphiles with an intermediate hydrophobicity (0<log P<1) (P=[solute]n-octanol/[solute]water) reassemble from initially formed micelles into polymersomes, whereas the trimers bearing highly hydrophobic oligopeptides (log P>1) remain as stable micelles in aqueous solution. These biodegradable polymersomes exhibit outstanding physicochemical properties required for practical drug delivery and other biomedical applications. In particular, the cyclic phosphazene trimer platinated with a hydrophobic cis-bis(cyclohexylamine)Pt-moiety forms very stable polymersomes with excellent tumor selectivity by EPR effect and seems to be a promising candidate for preclinical studies.
Bibliographical noteFunding Information:
This work was supported by the SRC program of the Korea Science and Engineering Foundation through the Center for Intelligent Nano-Bio Materials at Ewha Womans University (Grant R11-2005-008-01002-0 ), by a Korea Research Foundation Grant ( KRF-2004-005-C00090 ), by Seoul R & BD Program ( 10816 ), and by Nanohybrid Co. Ltd .