RESUMEN

Here we report the use of ß-cyclodextrin polyurethane nanosponges cross-linked with 1,6-hexamethylene diisocyanate as a template for the preparation of Aun quantum clusters, by the core-etching of glutathione-capped Au nanoparticles. The study of temporal evolution of the core-etching process using different Au concentrations indicated that formation of Aun clusters embedded in the nanosponge is favored by the use of lower Au concentrations, since it began at shorter times and lead to higher cluster loading. An estimation of the number of Au atoms based on the maximum photoluminescence wavelength suggested that, depending on the Au concentration and the core etching time, clusters with 11-15 atoms were formed. After excluding the possibility of an inclusion complex formation, evaluation of the catalytic activity of nanosponge-loaded Aun clusters toward the reduction of 4-nitrophenol has shown that the reaction is catalyzed by the Aun clusters with no induction time, following the Langmuir-Hinshelwood kinetic model.

Asunto(s)

Oro/química , Poliuretanos/química , Puntos Cuánticos/química , beta-Ciclodextrinas/química , Catálisis , Glutatión/química , Isocianatos/química , Modelos Moleculares , Conformación Molecular , Nitrofenoles/química , Oxidación-Reducción

RESUMEN

Nanocapsules containing poly(d,l-lactide) shell and retinyl palmitate core have been prepared by the pre-formed polymer interfacial deposition method. Dynamic light scattering measurements yielded an average hydrodynamic diameter of ∼220nm and a polydispersity index of ∼0.12. Small-angle neutron scattering experiments revealed the presence of two populations of nanocapsules of core diameters ∼192 and 65nm. Freeze fracture transmission electron microscopy showed a polydisperse population of nanocapsules (NC), with a poly(d,l-lactide) shell thickness between 11 and 3nm. For comparison purposes, nanoemulsions (NE, no polymer) and nanospheres (NS, polymer matrix) were also prepared. Each type of nanoparticles exhibited a different morphology (when examined by electron microscopy), in particular NC showed deformability by capillary adhesion. All three types of nanoparticles successfully encapsulated the poorly water-soluble molecules baicalein and benzophenone-3. The thermal behavior of the various nanoparticles was different to a physical mixture of its individual components. Cytotoxicity and phototoxicity assays, performed in human keratinocytes (HaCaT) and murine fibroblasts (BALB/c 3T3), showed that the NC were only cytotoxic at high concentrations. In vitro release studies of benzophenone-3, by the dialysis bag method using NC and NS, showed a sustained release; however, permeation studies using plastic surgery human abdominal skin in Franz diffusion cells showed that a higher amount of benzophenone-3 from NC penetrated into the skin, most probably due to the deformable nature of these nanoparticles.

Asunto(s)

Antioxidantes/administración & dosificación , Nanocápsulas/química , Poliésteres/química , Vitamina A/análogos & derivados , Animales , Antioxidantes/farmacocinética , Células 3T3 BALB , Benzofenonas/administración & dosificación , Benzofenonas/farmacocinética , Línea Celular , Diterpenos , Flavanonas/administración & dosificación , Flavanonas/farmacocinética , Humanos , Ratones , Nanocápsulas/toxicidad , Tamaño de la Partícula , Poliésteres/toxicidad , Ésteres de Retinilo , Piel/citología , Piel/metabolismo , Absorción Cutánea , Protectores Solares/administración & dosificación , Protectores Solares/farmacocinética , Vitamina A/administración & dosificación , Vitamina A/farmacocinética

RESUMEN

Polymeric nanocapsules with elastic characteristics were prepared by the pre-formed polymer interfacial deposition method. The system consists of an oily core of retinyl palmitate with Span 60 and a polymeric wall of poly(D,L-lactide) (PLA). A narrow size distribution (215 nm, P.D.I. 0.10) was showed by dynamic light scattering (DLS) analyses. Particle deformability was observed by transmission electron microscopy (TEM) images and permeation of the particles through two superposed membranes of smaller pore diameters. Permeation studies were achieved using plastic surgery abdominal human skin by Franz diffusion cell. Retinyl palmitate permeates into deep skin layers. Besides, a PLA fluorescent derivative conjugated with Nile blue dye by an amide covalent bound was additionally obtained. Permeation profile of the nanocapsules with the fluorescent polymer was evaluated by confocal laser scanning microscopy (CLSM). The CLSM showed that nanocapsules were distributed uniformly, suggesting that the permeation mechanism through skin is intercellular. Thus, the use of these nanocapsules may be a feasible strategy to enhance the permeation of actives into the skin when delivery to deep layers is aimed.

Asunto(s)

Nanocápsulas/química , Polímeros/química , Vitamina A/análogos & derivados , Cápsulas , Cromatografía Líquida de Alta Presión , Diterpenos , Portadores de Fármacos/química , Elasticidad , Humanos , Microscopía Confocal , Microscopía Electrónica de Transmisión , Nanocápsulas/ultraestructura , Tamaño de la Partícula , Poliésteres/química , Ésteres de Retinilo , Piel/metabolismo , Absorción Cutánea , Vitamina A/química , Vitamina A/farmacocinética , Vitaminas/química , Vitaminas/farmacocinética