CONICET | Buscador de Institutos y Recursos Humanos

Thestratum corneum is a major barrier to drug penetration across the skin in transdermaldelivery. To overcome this barrier, skin penetration enhancers are commonlyused. Lipoaminoacids derived from arginine consist of a family of nontoxicbiodegradable cationic surfactants with antifungal and antimicrobial properties.They meet four crucial requirements for the industrial development of newsurfactants: low toxicity, high biodegradability, multifunctionality and use ofrenewal sources of raw materials for their synthesis. The interaction of anovel arginine-based cationic surfactant, Nα-benzoyl-arginine decyl amide(Bz-Arg-NHC10) with DPPC monolayers was studied at different initial surfacepressures (πo) of the lipid films. For all the πo assayed, the injection of thelipoaminoacid into the subphase bulk produced a rapid increase in π reaching a maximumwithin the first 5 min followed by a decrease in π which stabilized after ~20min. Bz-Arg-NHC10 was able to penetrate into these lipid monolayers up to acritical pressure of 35 mN/m. Differential scanning calorimetry was used to assessthe effect of Bz-Arg-NHC10 upon DPPC membranes. As the concentration ofBz-Arg-NHC10 increased, the main transition temperature of DPPC slightlydecreased. AFM in situ experiments performed on supported DPPC bilayers on micaallowed to follow the changes induced by Bz-Arg-NHC10. DPPC bilayer patcheswere partially removed, mainly in borders and defects for 0.05 mM Bz-Arg-NHC10solution. Increasing the concentration to 0.10 mM resulted in a completedepletion of the supported bilayers. SPR measurements allowed to quantitativelyassess the DPPC removal by Bz-Arg-NHC10. Experiments carried out with fullyDPPC bilayers covered chips showed a net increase of the SPR signal, which canbe assigned to Bz-Arg-NHC10 adsorption. When patchy DPPC bilayers were formedon the substrate, a net decrease of SPR signal was obtained. This is consistentwith the DPPC removal observed in AFM images.