title: Size-controlled self-assembly of superparamagnetic polymersomes.
abstract: We report the size-controlled self-assembly of polymersomes through the cooperative self-assembly of nanoparticles and amphiphilic polymers. Polymersomes densely packed with magnetic nanoparticles in the polymersome membrane (magneto-polymersome) were fabricated with a series of different sized iron oxide nanoparticles. The distribution of nanoparticles in a polymersome membrane was size-dependent; while small nanoparticles were dispersed in a polymer bilayer, large particles formed a well-ordered superstructure at the interface between the inner and outer layer of a bilayer membrane. The yield of magneto-polymersomes increased with increasing the diameter of incorporated nanoparticles. Moreover, the size of the polymersomes was effectively controlled by varying the size of incorporated nanoparticles. This size-dependent self-assembly was attributed to the polymer chain entropy effect and the size-dependent localization of nanoparticles in polymersome bilayers. The transverse relaxation rates (r2) of magneto-polymersomes increased with increasing the nanoparticle diameter and decreasing the size of polymersomes, reaching 555 ± 24 s(-1) mM(-1) for 241 ± 16 nm polymersomes, which is the highest value reported to date for superparamagnetic iron oxide nanoparticles.
authors.affiliation: Department of Chemistry, University of Pennsylvania , 231 S. South 34th Street, Philadelphia, Pennsylvania 19104, United States.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Hickey
authors.forename: Jason
authors.initials: J
authors.lastname: Koski
authors.forename: Xin
authors.initials: X
authors.lastname: Meng
authors.forename: Robert A
authors.initials: RA
authors.lastname: Riggleman
authors.forename: Peijun
authors.initials: P
authors.lastname: Zhang
authors.forename: So-Jung
authors.initials: SJ
authors.lastname: Park
mesh_terms: D008280:Magnetics; D046529:Microscopy, Electron, Transmission / Q000379:methods; D053758:Nanoparticles; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*
chemical_list: D011108:Polymers