Figure S8.
Diffusion of eight fluorophores and Na ions in 8-cm glass pipettes in gelatins. All panels are oriented so that gelatin (10 g%) is in the right half of the pipette and the left half is gelatin free. Fluorescence records are given in black, and the first derivatives of fluorescence are given as blue lines. Solutions contained 140 mM KCl, 5 mM HEPES, and 0.5 mM EGTA. (A–C) Fluorescence profiles of three fluorophores 24 h after pipette loading: carboxyfluorescein (CF, 20 μM), sulforhodamine (SR, 20 μM), and ASG2 (5 μM). Sw/g values indicate that CF diffuses 17 times slower, SR 6.3 times slower, and ASG2 8.3 times slower in gelatin than in gelatin-free solution. (D and E) Profiles for Na diffusion after 24 h in pipettes containing ASG2 in both phases. Na (20 mM) was included in the gelatin phase in D and in the gelatin-free phase in E. Gradients are 4.5-fold less steep than for dye in C, as expected for more rapid diffusion. ASG2 accumulates mildly (∼10%) in the gelatin versus gelatin-free solution. Consistent with electrical measurement, Na diffusion is restricted by at most 50% in gelatin. (F–H) Fluorescence profiles of 8 cm pipettes 48 h after initiating diffusion of 2 kD FITC-PEG-COOH (20 μM), 2 kD PEG-NH3 (20 μM), and 10 kD PEG (20 μM). Accumulation in gelatin is very small or negligible, and ratios of fluorescence slopes are 0.08, 0.04, and 0.02, respectively, indicative of strong diffusion restriction in the gelatin phase. (I) Diffusion profile of NADH (M.W. 663, 150 μM) 40 h after initiating diffusion from the gelatin-free phase into gelatin. NADH diffusion is restricted by 11-fold in the gelatin phase. (J) GFP (27 kD) diffuses slowly but significantly into gelatin over 1 wk. It is restricted in the gelatin versus gelatin-free solution by 17-fold. To estimate the diffusion coefficients of free solutes in these experiments, diffusion out of the gelatin phase was restricted by a variable fraction (F) that reconstructed as accurately as possible the rise of fluorescence at the interface to the gelatin. The Sw/g values from these experiments are tabulated in Table S1. The diffusion coefficient in gelatin, plotted in Fig. S12, was calculated as the diffusion coefficient in water times the slope ratio Sw/g and F. AFU, arbitrary fluorescence units.

Diffusion of eight fluorophores and Na ions in 8-cm glass pipettes in gelatins. All panels are oriented so that gelatin (10 g%) is in the right half of the pipette and the left half is gelatin free. Fluorescence records are given in black, and the first derivatives of fluorescence are given as blue lines. Solutions contained 140 mM KCl, 5 mM HEPES, and 0.5 mM EGTA. (A–C) Fluorescence profiles of three fluorophores 24 h after pipette loading: carboxyfluorescein (CF, 20 μM), sulforhodamine (SR, 20 μM), and ASG2 (5 μM). Sw/g values indicate that CF diffuses 17 times slower, SR 6.3 times slower, and ASG2 8.3 times slower in gelatin than in gelatin-free solution. (D and E) Profiles for Na diffusion after 24 h in pipettes containing ASG2 in both phases. Na (20 mM) was included in the gelatin phase in D and in the gelatin-free phase in E. Gradients are 4.5-fold less steep than for dye in C, as expected for more rapid diffusion. ASG2 accumulates mildly (∼10%) in the gelatin versus gelatin-free solution. Consistent with electrical measurement, Na diffusion is restricted by at most 50% in gelatin. (F–H) Fluorescence profiles of 8 cm pipettes 48 h after initiating diffusion of 2 kD FITC-PEG-COOH (20 μM), 2 kD PEG-NH3 (20 μM), and 10 kD PEG (20 μM). Accumulation in gelatin is very small or negligible, and ratios of fluorescence slopes are 0.08, 0.04, and 0.02, respectively, indicative of strong diffusion restriction in the gelatin phase. (I) Diffusion profile of NADH (M.W. 663, 150 μM) 40 h after initiating diffusion from the gelatin-free phase into gelatin. NADH diffusion is restricted by 11-fold in the gelatin phase. (J) GFP (27 kD) diffuses slowly but significantly into gelatin over 1 wk. It is restricted in the gelatin versus gelatin-free solution by 17-fold. To estimate the diffusion coefficients of free solutes in these experiments, diffusion out of the gelatin phase was restricted by a variable fraction (F) that reconstructed as accurately as possible the rise of fluorescence at the interface to the gelatin. The Sw/g values from these experiments are tabulated in Table S1. The diffusion coefficient in gelatin, plotted in Fig. S12, was calculated as the diffusion coefficient in water times the slope ratio Sw/g and F. AFU, arbitrary fluorescence units.

This Feature Is Available To Subscribers Only

or Create an Account

Close Modal
Close Modal