Nanoemulsification of Ceramide-2 by Sodium Dilauramidoglutamide Lysine, a Novel Peptide-Based Gemini Surfactant

A novel peptide-based gemini surfactant, namely, sodium dilauramidoglutamide lysine (DLGL) was employed to fabricate a stable nanoemulsion system for the delivery of hydrophobic bioactive ceramide-2 molecules. The phase properties and morphology and stability of the nanoemulsion were investigated by focusing on the interaction between DLGL and ceramide-2 molecules. The investigation of the phase properties of the mixture of DLGL and ceramide-2 by X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy revealed remarkable reduction in the crystallinity of ceramide-2 due to the presence of DLGL. The spherical shape and nanometer size of nanoemulsions emulsified by DLGL were characterized by scanning electron microscopy and transmission electron microscopy. The nanoemulsions prepared using DLGL exhibited significant improvement in the dispersion stability without any significant changes in the particle sizes even after storing them for a month at 50 °C. The results indicated that DLGL readily associated with ceramide-2 to form a relatively stable structure. The steric hindrance of DLGL and molecular rearrangement of DLGL and ceramide-2 attributed to a break in the continuity of the molecular assembly of ceramide-2, which hampered its crystallinity.