TABLE 2.

Vesicle diffusion near planar membranes as a function of pH and planar membrane mol % POPS content

POPS composition in planar membrane (mol %)	Measured D (× 10−8 cm2/s)	Calculated D (× 10−8 cm2/s)*	Calculated effective mol % of charged lipids*
pH 7.4
0 (n = 23)	5.1 ± 0.2	5.1†	1.2‡
5 (n = 38)	5.2 ± 0.1	5.5	1.7
10 (n = 29)	5.4 ± 0.1	5.5	3.3
15 (n = 38)	5.5 ± 0.1	5.6	15§
20 (n = 30)	5.5 ± 0.2	5.6	20§
pH 4
0 (n = 23)	4.8 ± 0.1¶	—‖	2.4
5 (n = 38)	4.9 ± 0.1¶	—‖	2.8
10 (n = 29)	4.9 ± 0.1¶	—‖	2.8
15 (n = 38)	4.9 ± 0.1¶	—‖	2.8
20 (n = 30)	4.8 ± 0.2¶	—‖	2.5

^*Values calculated from Eqs. 5–14.

^†Value is calculated from ^‡ value.

^‡Value indicates the surface charge density represented in Table 1.

^§Values are taken from initial experimental conditions of the prepared supported bilayers.

^¶P < 0.05, indicates a statistically significant difference in the diffusion coefficients between paired samples at pH 7.4 and pH 4.

^‖Due to the absence of surface charge on the planar bilayers, a theoretical D cannot be calculated.