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Retinyl palmitate (RP) is recognized as a potential substance for the prevention and treatment of photoaging and skin inflammation. However it is also associated with skin irritations and extreme photo instability. In order to improve its skin delivery, photostability and to avoid undesirable topical side effects the RP was nanoencapsulated using the interfacial deposition of preformed polymer using the grape seed oil (GSO) a potential antioxidant as oil phase. Dynamic light scattering showed droplet size close to 214 nm, polydispersity index close to 0.18 and zeta potential with negative charge. Scanning electron microscopy exhibits spherical shape nanocapsules with a diameter of 205.6 ± 62.2 nm in good agreement with hydrodynamic diameter of nanocapsules in the dispersions. Presence of GSO as oily phase in nanocapsules increases the RP stability as longer than 180 days. It was observed a sustained and controlled RP dermal release by the analysis of RP in the donor and receptor phase by using vertical Franz diffusion cells. Key word: Retinoid, Polymeric nanocapsules, Stability, Skin permeation, Antioxidant.

Cyclic voltammograms and capacitance-potential curves were used to investigate the redox process of poly(3-methylthiophene) films. During the reduction and oxidation of these films the charge transfer and mass transport phenomena are distinguished by the simultaneous analysis of cyclic voltammograms and capacitance data.

The thermal characteristics of electrochemically synthesized poly(3-methyl-thiophene) doped with ClO − 4 have been studied by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), visible spectra and cyclic voltammetry. DSC showed two phase transformations in the polymer. The endothermic process with onset at 60°C was associated with the fusion of the crystalline portion. An exothermic process at 180°C was attributed to degradation of the polymer and is also related to the thermochromic effect.

A new method for the synthesis of Nb[sub 2]O[sub 5] is proposed and thin films are prepared by a dip-coating method. The Nb[sub 2]O[sub 5] films are crystalline and exhibit electrochromic properties changing the optical transmissivity by 52% during the electroreduction. These films may be used for display devices or smart windows.