Volz Pierre, Schilrreff Priscila, Brodwolf Robert, Wolff Christopher, Stellmacher Johannes, Balke Jens, Morilla Maria J, Zoschke Christian, Schäfer-Korting Monika, Alexiev Ulrike
Institute of Experimental Physics, Freie Universität Berlin, Berlin, Germany.
Nanomedicine Research Program (Departamento de Ciencia y Tecnologia), Universidad Nacional de Quilmes, Buenos Aires, Argentina.
Ann N Y Acad Sci. 2017 Oct;1405(1):202-214. doi: 10.1111/nyas.13473.
Targeted topical application promises high drug concentrations in the skin and low systemic adverse effects. To locate drugs and drug-delivery systems like nanocarriers, fluorescent dyes are commonly used as drug surrogates or nanocarrier labels in micrographs of tissue sections. Here, we investigate how labeling degree, concentration of fluorophore, and nanocarrier may affect the interpretation of these micrographs. False-negative penetration results due to inter- and intramolecular quenching effects are likely. Using tecto-dendrimers as an example, we present a detailed analysis of pitfalls in the (semi-)quantitative evaluation of skin nanocarrier penetration. Fluorescence lifetime imaging microscopy (FLIM) allows distinguishing the target fluorescence of dye-tagged nanocarriers from skin autofluorescence, providing a highly sensitive tool for clear-cut localization of the nanocarriers. Cluster-FLIM images reveal that FITC-labeled tecto-dendrimers penetrate the stratum corneum of human skin ex vivo and reconstructed human skin but do not cross the tight junction barrier.
靶向局部应用有望在皮肤中实现高药物浓度并降低全身不良反应。为了定位药物和纳米载体等药物递送系统，荧光染料通常用作组织切片显微照片中的药物替代物或纳米载体标记物。在此，我们研究标记程度、荧光团浓度和纳米载体如何影响这些显微照片的解读。由于分子间和分子内猝灭效应，可能会出现假阴性渗透结果。以tecto-树枝状大分子为例，我们对皮肤纳米载体渗透的（半）定量评估中的陷阱进行了详细分析。荧光寿命成像显微镜（FLIM）能够区分染料标记的纳米载体的目标荧光与皮肤自发荧光，为纳米载体的清晰定位提供了一种高灵敏度工具。聚类FLIM图像显示，异硫氰酸荧光素（FITC）标记的tecto-树枝状大分子能够穿透离体人皮肤和重建人皮肤的角质层，但不会穿过紧密连接屏障。
