Poly(ethylene oxide)-poly(styrene oxide)-poly(ethylene oxide) copolymers: Micellization, drug solubilization, and gelling features |
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Authors: | Adriana CambónSilvia Barbosa Ana Rey-RicoEdgar B Figueroa-Ochoa José FA SolteroSteven G Yeates Carmen Alvarez-LorenzoAngel Concheiro Pablo Taboada Víctor Mosquera |
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Institution: | a Grupo de Física de Coloides y Polímeros, Departamento de Física de la Materia Condensada, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain b Departamento de Farmacia y Tecnología Farmacéutica, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain c Departamento de Ingeniería Química, Universidad de Guadalajara, Boul. M. García Barragán #1451, Guadalajara, Jalisco 44430, Mexico d Organic Materials Innovation Center, School of Chemistry, University of Manchester, Manchester M13 9PL, United Kingdom |
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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. |
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Keywords: | Block copolymer Polymeric micelle Phase behavior Drug delivery system Release kinetics |
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