Spatiotemporal Heterogeneity of ?-Carrageenan Gels Investigated via Single-Particle-Tracking Fluorescence Microscopy.

ABSTRACT: Hydrogels made of the polysaccharide ?-carrageenan are widely used in the food and personal care industry as thickeners or gelling agents. These hydrogels feature dense regions embedded in a coarser bulk network, but the characteristic size and behavior of these regions have remained elusive. Here, we use single-particle-tracking fluorescence microscopy (sptFM) to quantitatively describe ?-carrageenan gels. Infusing fluorescent probes into fully gelated ?-carrageenan hydrogels resulted in two distinct diffusional behaviors. Obstructed self-diffusion of the probes revealed that the coarse network consists of ?-carrageenan strands with a typical diameter of 3.2 ± 0.3 nm leading to a nanoprobe diffusion coefficient of ?1-5 × 10-12 m2/s. In the dense network regions, we found a fraction with a largely decreased diffusion coefficient of ?1 × 10-13 m2/s. We also observed dynamic exchange between these states. The computation of spatial mobility maps from the diffusional data indicated that the dense network regions have a characteristic diameter of ?1 ?m and show mobility on the second-to-minute timescale. sptFM provides an unprecedented view of spatiotemporal heterogeneity of hydrogel networks, which we believe bears general relevance for understanding transport and release of both low- and high-molecular weight solutes.

SUBMITTER: Martens KJA 

PROVIDER: S-EPMC7254830 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature