Fluorescence measurements. Aliquote (250 µL) was collected manually from the outflow of the designed experiment in the presence of the PEM-coated surface (PLL-PSS-PLL FITC). Subsequently, a fluorescence experiment was carried out by exciting the fluorescein isothiocyanate labeled PLL (PLL-FITC) at 488 nm and recording the corresponding emission intensity in the range of 500 to 800 nm. The excitation and emission slit widths were set to 5 and 10 nm, respectively. See Supplementary Information S6.3 for further information.