Micro-structural Investigations on Oppositely Charged Mixed Surfactant Gels With Potential Dermal Applications

Dicarboxylic amino acid-based surfactants ( N -dodecyl derivatives of -aminomalonate, -aspartate, and -glutamate) in combination with hexadecyltrimethylammonium bromide (HTAB) form a variety of aggregates. Composition and concentration dependent mixtures may exhibit liquid crystal, gel, precipitate and clear isotropic phases. Liquid crystalline patterns were identified by polarization optical microscopy and fluorescence microscopy. FE-SEM studies reveal porous and flower like morphology. Phase transitions and weight loss depend on composition where thermotropic behaviors were revealed through differential scanning calorimetry and thermogravimetric analyses, respectively. Systems comprising more than 60% HTAB demonstrate shear-thinning behavior. Gels cause insignificant toxicity to human peripheral lymphocytes and irritation to mouse skin; they do not display the symptoms of cutaneous irritation, neutrophilic invasion and inflammation (erythema, edema, and skin thinning). Gels also exhibit antibacterial effect on Staphylococcus aureus , a potent causative agent of skin and soft tissue infections, suggesting its possible application as vehicle for dermatological drug delivery.