생체친화형 바이오계면활성제와 결정성 활성성분의 분자회합 및 나노유화 거동에 대한 연구

Abstract

Ceramide molecules in water-based solutions readily attract each other to form molecular crystals, which seriously hampers to diversify their formulations. This paper describes a facile method that allows fabrication of stable ceramide emulsions through an effective molecular association with a lipid having an asymmetric molecular geometry. The lipid considered in this study is mannosylerythritol lipid (MEL). MEL is specialized in having a unique molecular structure containing sugar alcohol erythritol as a hydrophilic part and two alkyl chains with different number of carbons as hydrophobic moieties. Our particular interest has been focused on experimentally demonstrating how MEL interacts with pseudo-ceramide molecules by observing phase properties, emulsion morphology, and suspension stability. The pseudo-ceramide emulsions prepared with MEL show remarkably improved dispersion stability without either formation of molecular crystals or changes in particle sizes even after storing them for two months. This suggests that MEL readily associates with the pseudo-ceramide due to the hydrophobic interaction, while it makes a break in the continuity of the molecular assembly of the pseudo-ceramide molecules themselves due to the geometric hindrance coming from MEL’s asymmetric molecular structure. Keywords: pseudo-ceramide, crystals, emulsions, lipid, molecular geometry |In this study, we introduce a useful approach to fabricate extremely stable nanoemulsions whose liquid-liquid interface is stabilized by amphiphilic block copolymers, poly (ethylene glycol)-b-poly (ε-caprolactone) block copolymer (PEG-b-PCL). Micron-sized embryo emulsions were produced by using the phase inversion method and they were downsized to hundreds of nanometers by applying strong sonication. The nanoemulsion produced using this method was very stable against drop coalescence and aggregation, which was confirmed from the freeze-thaw test. Also, in our further study on blocking crystal growth of active molecules, we have found that a model crystalline compound, butyl methoxydibenzoylmethane (a UV-A absorbent, 350-365nm), was stably entrapped in the emulsion drops without forming any molecular crystals for a long storage. These results stem from formation of a flexible thin PEG-b-PCL membrane at the oil-water interface.; In this study, we introduce a useful approach to fabricate extremely stable nanoemulsions whose liquid-liquid interface is stabilized by amphiphilic block copolymers, poly (ethylene glycol)-b-poly (ε-caprolactone) block copolymer (PEG-b-PCL). Micron-sized embryo emulsions were produced by using the phase inversion method and they were downsized to hundreds of nanometers by applying strong sonication. The nanoemulsion produced using this method was very stable against drop coalescence and aggregation, which was confirmed from the freeze-thaw test. Also, in our further study on blocking crystal growth of active molecules, we have found that a model crystalline compound, butyl methoxydibenzoylmethane (a UV-A absorbent, 350-365nm), was stably entrapped in the emulsion drops without forming any molecular crystals for a long storage. These results stem from formation of a flexible thin PEG-b-PCL membrane at the oil-water interface.