(
A) Microscopic mobility of particles of ∼1-
μm size with different surface properties in a 0.5 (w/v) mucin hydrogel at pH 3. The background shading indicates the surface properties of the particles changing from negative to positive charge. PEG(a) and PEG(c) particles were created by PEGylation of amine-terminated and carboxy-terminated particles, respectively. Apparent diffusion coefficients
D were determined by single particle tracking for ensembles of ∼50 particles per condition (see ). The error bars denote the error of the mean

, where
σ represents the standard deviation of the obtained distribution and
N denotes the number of particles analyzed per condition. (
B) Spatial heterogeneity in particle diffusion behavior as represented by the relative distribution width

(see and ). Low particle mobilities correlate with higher variances in the diffusion behavior of the particle ensemble. (
C) Zeta-potentials for the test particles investigated in panels
A and
B.