Cosmetic Science Laboratory, School of Pharmacy and Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Japan.
HOMER ION Laboratory Co., Ltd., Tokyo, Japan.
Int J Cosmet Sci. 2023 Jun;45(3):400-412. doi: 10.1111/ics.12847. Epub 2023 Apr 21.
ε-Poly-l-lysine (PLL) is a cationic polymer consisting of 25-35 l-lysine residues. Our previous study revealed that fluorescently labelled PLL can stain the stratum corneum (SC) via ionic interactions between PLL and SC constituents. In this study, to further clarify the mechanisms underlying the interaction between PLL and the SC, the staining properties of fluorescent PLL were compared with that of fluorescently labelled anionic dextran (aDex), which has approximately the same molecular weight as PLL.
SC samples were collected by non-invasive tape stripping and stained with fluorescent PLL and/or fluorescent aDex. Fluorescence images were acquired using a fluorescence microscope and then analysed.
The SC could be stained with either fluorescent PLL or aDex, both of which were inhibited by the addition of high concentrations of salt solutions. In particular, aDex staining was inhibited at a lower salt concentration than PLL staining. Moreover, PLL staining was inhibited under acidic conditions, while aDex staining was inhibited under neutral to alkaline conditions. Double staining of SC with both fluorescent polymers produced heterogeneous staining patterns: corneocytes stained with both polymers, corneocytes stained with PLL or aDex in a mutually exclusive manner, and unstained corneocytes. Staining of SC samples from the face was more extensive than staining of SC samples from the inside of the upper arm with both polymers. In addition, pretreatment of the SC with ethanol resulted in enhanced staining with both polymers. These results suggest that double staining of SC with both polymers can provide information on the damaged SC.
Staining of SC with fluorescent PLL depends on its properties of a cationic and hydrophobic polymer with appropriate molecular size, which can distinguish the damaged SC. Double staining of SC with fluorescent PLL and aDex is a novel approach to obtain information for the analysis of skin conditions.
ε-聚赖氨酸（PLL）是一种由 25-35 个赖氨酸残基组成的阳离子聚合物。我们之前的研究表明，通过 PLL 与角质层（SC）成分之间的离子相互作用，荧光标记的 PLL 可以染色 SC。在这项研究中，为了进一步阐明 PLL 与 SC 之间相互作用的机制，比较了荧光 PLL 与具有与 PLL 大致相同分子量的荧光标记阴离子葡聚糖（aDex）的染色特性。
通过非侵入性胶带剥离收集 SC 样本，并使用荧光 PLL 和/或荧光 aDex 对其进行染色。使用荧光显微镜获取荧光图像，然后进行分析。
SC 可以用荧光 PLL 或 aDex 染色，这两种聚合物的染色都被高浓度盐溶液的加入所抑制。特别是，aDex 的染色在比 PLL 更低的盐浓度下被抑制。此外，PLL 染色在酸性条件下受到抑制，而 aDex 染色在中性至碱性条件下受到抑制。用两种荧光聚合物对 SC 进行双重染色产生了不均匀的染色模式：两种聚合物都染色的角质细胞、相互排斥地仅被 PLL 或 aDex 染色的角质细胞和未染色的角质细胞。两种聚合物对脸部 SC 样本的染色比上臂内部 SC 样本的染色更广泛。此外，用乙醇预处理 SC 会增强两种聚合物的染色。这些结果表明，用两种荧光聚合物对 SC 进行双重染色可以提供有关受损 SC 的信息。
荧光 PLL 对 SC 的染色取决于其作为具有适当分子大小的阳离子和疏水性聚合物的特性，这可以区分受损的 SC。用荧光 PLL 和 aDex 对 SC 进行双重染色是一种获得用于分析皮肤状况的信息的新方法。
