%0 Journal Article %A Ramona Birke %A Julia Ast %A Dorien A. Roosen %A Bettina Mathes %A Kilian Roßmann %A Christiane Huhn %A Ben Jones %A Martin Lehmann %A Volker Haucke %A David J. Hodson %A Johannes Broichhagen %T Sulfonated rhodamines as impermeable labelling substrates for cell surface protein visualization %D 2021 %R 10.1101/2021.03.16.435698 %J bioRxiv %P 2021.03.16.435698 %X Sulfonated rhodamines that endow xanthene dyes with cellular impermeability are presented. We fuse charged sulfonates to red and far-red dyes to obtain Sulfo549 and Sulfo646, respectively, and further link these to SNAP- and Halo-tag substrates for protein self-labelling. Cellular impermeability is validated in live cell imaging experiments in transfected HEK cells and neurons derived from induced pluripotent stem cells (iPSCs). Lastly, we show that Sulfo646 is amenable to STED nanoscopy by recording membranes of SNAP/Halo-surface-labelled human iPSC-derived neuronal axons. We therefore provide an avenue for rendering dyes impermeable for exclusive extracellular visualization via self-labelling protein tags.Competing Interest StatementThe authors have declared no competing interest. %U https://www.biorxiv.org/content/biorxiv/early/2021/03/16/2021.03.16.435698.full.pdf