Fluorescence life time imaging microscopy tracks nanocarrier penetration into human cell-based non-melanoma skin cancer models

C ZOSCHKE; A. BOREHAM; R. BRODWOLF; P. VOLZ; P. SCHILRREFF; MJ MORILLA; R. HAAG; M. SCHÄFER-KORTING; U. ALEXIEV.

Conferencia; International conference Tight junctions and their proteins.; 2016

Fluorescence Lifetime Imaging Microscopy (FLIM) reveal characteristic fluorescent lifetime signatures of nanocarrier bound dye and provide novel insights into the uptake of different nanocarriers into human skin ex vivo and reconstructed human skin (RHS). FLIM uses excited-state fluorescence decay curves of the fluorescing molecules in each image pixel and thereby allows the identification of unique fluorescence lifetime species, being specific for a certain dye and its environment. Different types of dendritic nanocarriers were fluorescently tagged and topically applied to normal human skin ex vivo, RHS, and organotypic skin cancer models.We found striking interactions between nanocarriers and the stratum corneum of normal tissues due to altered fluorescence lifetime signatures within the stratum corneum compared to the free nanocarrier solution. In normal tissues, nanocarrier penetration stops at the level of the stratum granulosum, whereas impaired skin barrier allows further penetration into the epidermis. This correlates to lost tight junctions within the skin cancer models. In conclusion, FLIM offers a versatile, efficient, and reliable method to unravel fluorophore-tissue interactions and might be useful to study interactions between nanocarriers and tight junctions