The adsorption of 4-mercaptobenzoic acid (MBA) on Ag(111) and Ag nanoparticles (AgNPs) has been studied by Xray photoelectron spectroscopy (XPS), electrochemical techniques, high-resolution transmission electron microscopy (HRTEM), and density functional theory (DFT) calculations. Results show that MBA molecules adsorb intact on the Ag (111) surface via a thiolate bond, arranged in a (√3 × 4) lattice with coverage θ = 0.25. The phase diagram built using DFT data shows that this lattice is more stable than the dense (√7 × √7)R19.1°MBA lattices on reconstructed Ag(111) surfaces. No significant amounts of sulfide were found neither on the Ag(111) surfaces nor on MBA-protected AgNPs, suggesting that the Ag core@Ag-sulfide shell structure where thiolates could be grafted cannot be applied to the MBAprotected AgNPs. Slow degradation of the MBA protective layer in ambient conditions on the AgNPs results in disulfide formation and AgNP sintering.

Trans-resveratrol (3, 5, 4' trihydroxystilbene, RSV) is a natural compound that shows antioxidant, cardioprotective, anti-inflammatory and anticancer properties. The transdermal, painless application of RSV is an attractive option to other administration routes owing to its several advantages like avoiding gastrointestinal problems and first pass metabolism. However, its therapeutic potential is limited by its low solubility and low stability in water and the reduced permeability of stratum corneum. To overcome these inconveniences the encapsulation of this compound in a drug delivery system is proposed here. In order to find the best carrier for transdermal application of RSV various liposomal nanoparticulate carriers like conventional liposomes (L-RSV), deformable liposomes (LD-RSV), ultradeformable liposomes (LUD-RSV) and ethosomes (Etho-RSV) were assayed. Transmission electron microscopic (TEM) and dynamic light scattering (DLS) studies were performed to analyze the surface morphology of these carriers. Structural characterization for these formulations was performed by confocal Raman spectroscopy. The spectroscopic results were analysed in conjunction with calorimetric data to identify the conformational changes and stability of formulations in the different nanoparticles induced by the presence of RSV. Comparison of the results obtained with the different carrier systems (L-RSV, LD-RSV, LUD-RSV and Etho-RSV) revealed that the best RSV carrier was LD-RSV. The increase in the fluidity of the bilayers in the region of the hydrophobic chains of the phospholipid by ethanol probably facilitates the accommodation of the RSV in the bilayer and contributes to the improved encapsulation of RSV without affecting the mobility of this carrier.