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. 2022 Feb 15;121(6):910–918. doi: 10.1016/j.bpj.2022.02.015

Figure 2.

Figure 2

(A) Viscosity measured at different frequencies at a fixed field strength 8 kV/m increases with frequency. Extrapolating to zero frequency yields the shear surface viscosity. The symbols on the vertical-axis intercept refer to the extrapolated values of 4.11 ± 2.63 nPa·s·m and 9.73 ± 5.80 nPa·s·m for DOPC and SOPC, respectively. The R-squared value of the linear fit is 0.98 and 0.97 for the SOPC and DOPC, respectively. The shaded band represents a 95% confidence interval. (B) Shape relaxation after the field is turned off yields a similar value for the viscosity as the zero-frequency limit obtained from the frequency sweep. Data for SOPC, E0 = 8 kV/m and ω = 1 kHz. Tension obtained from flickering spectroscopy is 5.7 ± 2.6 × 10−9 N/m. Viscosity obtained from initial deformation and relaxation is 164 nPa·s·m and 21.1 ± 29.4 nPa·s·m, respectively. (C) Viscosity of single-component (DOPC) and single-phase multicomponent (DPPC:Chol 1:1) bilayers is independent of field magnitude, in contrast to the viscosity of phase-separated multicomponent (DPPC:DOPC 1:1) bilayers. To see this figure in color, go online.