Influence of the Membrane Dye R18 and of DMSO on Cell Penetration of Guanidinium-Rich Peptides.

A quantitative analysis by confocal fluorescence microscopy of the entry into HEK293 and MCF-7 cells by fluorescein-labeled octaarginine (1) and by three octa-Adp derivatives (2 - 4, octamers of the ß-Asp-Arg-dipeptide, derived from the biopolymer cyanophycin) is described, including the effects of the membrane dye R18 and of DMSO on cell penetration.