Biomolecules in colloid nanocontainers for drug delivery: Entrapment and properties of the delta sleep-inducing peptide

Nanoemulsions of the water in oil type (w/o) composed of nontoxic components, including low concentrations of AOT (5%) and soy-bean lecithin Lipoid S100 (10%) in eucalyptus oil and limonene, were developed and characterized. These nanoemulsions can be used for the incorporation of biomolecules. As shown, AOT based systems possessed the highest solubilization capacity (12% of an aqueous solution); photon-correlation spectroscopy revealed that the size of nanoemulsions of 5% AOT in eucalyptus oil increased linearly with the growth of the water content. The ability of hydrophilic delta sleep-inducing peptide (DSIP), which is a regulatory neuropeptide, to exist in nanoemulsions of the w/o type in the absence and in the presence of additional biopolymers was demonstrated. DSIP entrapment in a nanoemulsion results in its substantial stabilization (80–90% after 2 months of incubation at 22°C versus 28% in an aqueous solution). The kinetics of peptide srelease was studied in in vitro model experiments; a substantial slowing-down of peptide release in nanoemulsions in comparison to aqueous solutions was revealed. DSIP-containing nanoemulsion systems, which can be used in medicine and cosmetology, can serve as a basis for the development of novel stable pharmaceutical dosage forms of prolonged action peptide preparations.