title: Poly(ethylene oxide)-poly(styrene oxide)-poly(ethylene oxide) copolymers: micellization, drug solubilization, and gelling features.
abstract: Two new poly(ethylene oxide)-poly(styrene oxide) triblock copolymers (PEO-PSO-PEO) with optimized block lengths selected on the basis of previous studies were synthesized with the aim of achieving a maximal solubilization ability and a suitable sustained release, while keeping very low material expense and excellent aqueous copolymer solubility. The self-assembling and gelling properties of these copolymers were characterized by means of light scattering, fluorescence spectroscopy, transmission electron microscopy, and rheometry. Both copolymers formed spherical micelles (12-14 nm) at very low concentrations. At larger concentration (>25 wt%), copolymer solutions showed a rich phase behavior, with the appearance of two types of rheologically active (more viscous) fluids and of physical gels depending on solution temperature and concentration. The copolymer behaved notably different despite their relatively similar block lengths. The ability of the polymeric micellar solutions to solubilize the antifungal drug griseofulvin was evaluated and compared to that reported for other structurally-related block copolymers. Drug solubilization values up to 55 mg g(-1) were achieved, which are greater than those obtained by previously analyzed poly(ethylene oxide)-poly(styrene oxide), poly(ethylene oxide)-poly(butylene oxide), and poly(ethylene oxide)-poly(propylene oxide) block copolymers. The results indicate that the selected SO/EO ratio and copolymer block lengths were optimal for simultaneously achieving low critical micelle concentrations (cmc) values and large drug encapsulation ability. The amount of drug released from the polymeric micelles was larger at pH 7.4 than at acidic conditions, although still sustained over 1 day.
authors.affiliation: Grupo de Física de Coloides y Polímeros, Departamento de Física de la Materia Condensada, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors.forename: Adriana
authors.initials: A
authors.lastname: Cambón
authors.forename: Silvia
authors.initials: S
authors.lastname: Barbosa
authors.forename: Ana
authors.initials: A
authors.lastname: Rey-Rico
authors.forename: Edgar B
authors.initials: EB
authors.lastname: Figueroa-Ochoa
authors.forename: José F A
authors.initials: JF
authors.lastname: Soltero
authors.forename: Steven G
authors.initials: SG
authors.lastname: Yeates
authors.forename: Carmen
authors.initials: C
authors.lastname: Alvarez-Lorenzo
authors.forename: Angel
authors.initials: A
authors.lastname: Concheiro
authors.forename: Pablo
authors.initials: P
authors.lastname: Taboada
authors.forename: Víctor
authors.initials: V
authors.lastname: Mosquera
mesh_terms: D000935:Antifungal Agents / Q000008:administration & dosage* / Q000737:chemistry; D003692:Delayed-Action Preparations / Q000737:chemistry*; D005782:Gels / Q000737:chemistry; D006118:Griseofulvin / Q000008:administration & dosage* / Q000737:chemistry; D008823:Micelles; D011092:Polyethylene Glycols / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*; D012212:Rheology; D012995:Solubility
chemical_list: D000935:Antifungal Agents; D003692:Delayed-Action Preparations; D005782:Gels; D008823:Micelles; D011137:Polystyrenes; C541965:polystyrene-b-poly(ethylene oxide); D006118:Griseofulvin; D011092:Polyethylene Glycols