title: Encapsulation and release of molecular cargos via temperature-induced vesicle-to-micelle transitions.
abstract: Temperature-induced vesicle-to-micelle transitions of polystyrene-block-poly acrylic acid (PS(139)-b-PAA(17)) aggregates in tetrahydrofuran (THF)/H(2)O solvent mixtures are studied. For a typical system with an initial concentration of PS(139)-b-PAA(17) of 2 wt% and 50 vol% of H(2)O, the morphology of the aggregates changes from vesicles to micelles upon heating from room temperature to 45 °C. The transition temperature is found to depend on the polymer concentration as well as solvent composition. A higher polymer concentration results in a higher transition temperature. The morphological change is attributed to a change in the solvent-polymer interactions, which results in a reduction in interfacial energy. The corresponding temperature-induced morphological change is employed as a strategy for the reversible release and encapsulation of small molecules. The release of Rhodamine 110 bisamide above the transition temperature is observed as a result of the trypsin-catalyzed hydrolysis of the bisamide into Rhodamine 110. Likewise, the successful encapsulation of Rhodamine 110 below the transition temperature is proven using sodium nitrite as a chemical quencher.
authors.affiliation: Department of Materials Science and Technology of Polymers, University of Twente, MESA+ Institute for Nanotechnology, Postbus 217, 7500 AE Enschede, The Netherlands.
authors.forename: Qi
authors.initials: Q
authors.lastname: Chen
authors.forename: Holger
authors.initials: H
authors.lastname: Schönherr
authors.forename: G Julius
authors.initials: GJ
authors.lastname: Vancso
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D005663:Furans / Q000737:chemistry; D008823:Micelles; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D012235:Rhodamines / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D005663:Furans; D008823:Micelles; D011108:Polymers; D011137:Polystyrenes; D012235:Rhodamines; D014867:Water; C049025:rhodamine 110; C018674:tetrahydrofuran; C006903:carbopol 940