Nakamura Erika, Iwase Hiroki, Arima-Osonoi Hiroshi, Sakuragi Mina
Faculty of Engineering, Department of Nanoscience, Sojo University 4-22-1 Ikeda, Nishi-ku Kumamoto City 860-0082 Japan
Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society Tokai Ibaraki 319-1106 Japan.
RSC Adv. 2023 Jun 12;13(26):17742-17749. doi: 10.1039/d3ra02546b. eCollection 2023 Jun 9.
The stratum corneum (SC) consists of a lipid layer that forms two types of lamellar structures: short lamellar (S-La) and long lamellar (L-La). It has been reported that S-La contains water phases in the hydrophilic region of the lipids, and that it may play an important role in regulating the water content of the SC. The amount of water in the SC can affect how a drug carrier permeates through the intercellular lipid pathway. To better understand the impact of SC water content on the skin penetration mechanism of a microemulsion (ME), we conducted a study using small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), and small-angle neutron scattering (SANS). Our results showed that MEs can enhance skin permeation under humid conditions because the lipid packing structures of the hydrated SC are more disrupted than those of the dry SC. The results also showed that the inner water of MEs was released to the SC when applying MEs to the dry SC, resulting in an increase in the repeat distance of S-La. Conversely, when MEs are applied to hydrated SC, the MEs absorb the water from the SC into their inner phases, causing a decrease in the repeat distance of S-La over time.
角质层（SC）由形成两种类型层状结构的脂质层组成：短层状（S-La）和长层状（L-La）。据报道，S-La在脂质的亲水区含有水相，并且可能在调节SC的含水量中起重要作用。SC中的水量会影响药物载体如何通过细胞间脂质途径渗透。为了更好地理解SC含水量对微乳液（ME）皮肤渗透机制的影响，我们使用小角X射线散射（SAXS）、广角X射线散射（WAXS）和小角中子散射（SANS）进行了一项研究。我们的结果表明，MEs在潮湿条件下可以增强皮肤渗透，因为水合SC的脂质堆积结构比干燥SC的脂质堆积结构更易被破坏。结果还表明，当将MEs应用于干燥的SC时，MEs的内部水分释放到SC中，导致S-La的重复距离增加。相反，当将MEs应用于水合SC时，MEs会将SC中的水分吸收到其内部相中，导致S-La的重复距离随时间减少。
