4.1. PKH67 Fluorescent Dye

Developed for live cells, PKH linkers are lipophilic molecules that incorporate spontaneously into the lipid bilayer. Their photophysical properties cover the visible and infrared emission spectrum and the molecules are described as nontoxic effects toward cells.^20,22,26 The 1 mM PKH67 solution in ethanol was purchased from Sigma-Aldrich and used as received. The molecule is made of two fluorescent head groups and two aliphatic chains. Its chemical structure as provided by the supplier is shown in Scheme 1. PKH67 fluoresces in the green, its excitation, and emission wavelengths being at 410 and 502 nm, respectively. More information can be found in the website in Supporting Information S5 and S7.