“…We used poly(ethylene glycol) (PEG) of 400, 1450, 3400 and 4600 Da (Sigma); 600 Da (Riedel de Haën); and 1000, 2000 and 3000 Da (Loba Chemie). In experiments using physiological concentration of electrolytes (0.15 M), the hydrodynamic radii of nonelectrolytes (taken from [17,18,29]) were: 0.26 ± 0.02 glycerol, 0.37 ± 0.02 glucose, 0.47 ± 0.02 sucrose, 0.70 ± 0.04 nm PEG 400, 0.80 ± 0.04 nm PEG 600, 0.94 ± 0.04 nm PEG 1000, 1.05 ± 0.04 nm PEG 1450, 1.22 ± 0.04 nm PEG 2000, 1.44 ± 0.04 nm PEG 3000, 1.65 ± 0.03 nm PEG 3400, and 2.1 ± 0.03 nm PEG 4600. At higher concentration of KCl (0.7 M) used in channel-sizing BLM experiments, the PEG radii were taken as approximately 98% of those noted above, based on an observation (R.R.…”