Yu Betty, Kim Ki Hean, So Peter T C, Blankschtein Daniel, Langer Robert
Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, U.S.A.
J Invest Dermatol. 2003 Mar;120(3):448-55. doi: 10.1046/j.1523-1747.2003.12061.x.
In a novel application of dual-channel high-speed two-photon fluorescence microscopy, the skin autofluores-cence and the transdermal fluorescent model drug spatial distributions were imaged simultaneously over precisely the same spatial coordinates. The dual channels enable the detection of the fluorescence emission wavelengths characteristic of the endogenous (intrinsic) skin fluorophores, as well as of the rhodamine-based model drug intensity emission at a different wavelength range of the fluorescence emission spectrum. These fluorescent model drugs delineate the oleic acid induced changes in permeant diffusion with respect to the skin structural features over the 0.3 mm by 0.3 mm skin area imaged per skin sample. The dual-channel high-speed two-photon fluorescence microscopy studies presented here provide evidence for the existence of intracorneocyte diffusion in addition to the commonly cited lipid multilamellar transdermal pathway. The image quantification analysis methodology introduced in this paper reveals that intracorneocyte diffusion exists for the hydrophobic (rhodamine B hexyl ester) and for the hydrophilic (sulforhodamine B) model drugs, in the absence of oleic acid chemical enhancer action. The mechanism of oleic acid chemical enhancer action, however, depends on the model drug physicochemical properties, where the oleic acid induces hydrophobic model drug localization to the lipid multilamellar region, while increasing the hydrophilic model drug lipid to corneocyte partitioning.
在双通道高速双光子荧光显微镜的一项新颖应用中，皮肤自身荧光和经皮荧光模型药物的空间分布在完全相同的空间坐标上同时成像。双通道能够检测内源性（固有）皮肤荧光团特有的荧光发射波长，以及在荧光发射光谱不同波长范围内基于罗丹明的模型药物强度发射。这些荧光模型药物描绘了油酸在每个皮肤样本成像的0.3毫米×0.3毫米皮肤区域内，相对于皮肤结构特征引起的渗透剂扩散变化。本文介绍的双通道高速双光子荧光显微镜研究为除了通常提到的脂质多片层经皮途径之外，角质形成细胞内扩散的存在提供了证据。本文引入的图像定量分析方法表明，在没有油酸化学增强剂作用的情况下，疏水性（罗丹明B己酯）和亲水性（磺基罗丹明B）模型药物都存在角质形成细胞内扩散。然而，油酸化学增强剂作用的机制取决于模型药物的物理化学性质，其中油酸诱导疏水性模型药物定位于脂质多片层区域，同时增加亲水性模型药物在脂质与角质形成细胞之间的分配。
