Figure 1.

sptFM in κ-carrageenan gels. (A) Schematic representation of fluorescent probes (red), embedded in a gel matrix (dotted lines). These probes are capable of diffusion in the gel matrix (arrows). A coarse network (light gray region) allows for obstructed diffusion of the fluorescent probes, while dense network regions (dark gray region) further decrease the mobility of the probes. (B) Typical localization (blue asterisks) and tracking (yellow-red colored lines) overlaid on a raw microscopy image. Shown here is single-particle-tracking of 28 nm diameter polymer probes in a 1% κ-carrageenan gel with 200 mM NaCl, 20 mM KCl. Highlighted regions are enlarged in (C). (C) Examples of obstructed diffusing (top), largely immobile (middle) or transitioning (bottom) particles. Left: the corresponding 2D movement of the single tracks. Middle: jump distance of this track plotted against the time of the track. Right: histogram created from the jump distances found in the track. Revealing network heterogeneity by the multimodal probe self-diffusion behavior.