CONICET | Buscador de Institutos y Recursos Humanos

Lipid miniemulsions (ME) are oil in water dispersions stabilized by an interfacial layer of a surfactant and are systems commonly used to encapsulate, maintain and release molecules of pharmacological interest. Since each of those droplets can be regarded as an individual batch reactor, a whole variety of polymerizations reactions can be performed starting from ME to obtaining a polymer based colloidal system, consisting on a liquid-core and a polymeric-shell structure (Liquid Core Capsules, LCC). In this context, Langmuir monomolecular films (LF) at the liquid-liquid interface can be used as experimental models to investigate the dynamic behavior of surfactants at the oil-water interface in ME. Previously, we have used this technique to study the composition and thermodynamic behavior of monomolecular layers of Egg L-α-phosphatidylcholine (EPC) at the Vaseline/water (VAS/W) interface to be further translated to a ME formulation. Based on these previous results, the aim of the present work is to synthetize ME composed of VAS, EPC and a cationic surfactant (CTAB) to use them as a template for silica polymerization allowing the obtention of LCC capable to encapsulate hydrophobic drugs such as Diazepam and Dexamethasone. We found that both compounds have a complex surface behavior and display a favorable penetration into a previously formed EPC monolayer at VAS/W interface, achieving an equilibrium surface pressure πe ≈ 25 mN/m at 20M in the subphase. Furthermore, LCC were characterized by DLS, Z-potential and TEM microscopy. They presented a mean diameter of ≈ 200 nm and were stable at least for one month in suspension. Also, the average encapsulation efficiency for both drugs was determined between 40% and 60%. Their encapsulation in LCC would serve as a method to increase their concentration in aqueous fluids as well as a sustained releasing source.