Interplay between flow and diffusion in capillary alginate hydrogels
Journal article, 2016

Alginate gels with naturally occurring macroscopic capillaries have been used as a model system to study the interplay between laminar flow and diffusion of nanometer-sized solutes in real time. Calcium alginate gels that contain homogeneously distributed parallel-aligned capillary structures were formed by external addition of crosslinking ions to an alginate sol. The effects of different flow rates (0, 1, 10, 50 and 100 mu l min(-1)) and three different probes (fluorescein, 10 kDa and 500 kDa fluorescein isothiocyanate-dextran) on the diffusion rates of the solutes across the capillary wall and in the bulk gel in between the capillaries were investigated using confocal laser scanning microscopy. The flow in the capillaries was produced using a syringe pump that was connected to the capillaries via a tube. Transmission electron microscopy revealed an open aggregated structure close to the capillary wall, followed by an aligned network layer and the isotropic network of the bulk gel. The most pronounced effect was observed for the 1 nm-diameter fluorescein probe, for which an increase in flow rate increased the mobility of the probe in the gel. Fluorescence recovery after photobleaching confirmed increased mobility close to the channel, with increasing flow rate. Mobility maps derived using raster image correlation spectroscopy showed that the layer with the lowest mobility corresponded to the anisotropic layer of ordered network chains. The combination of microscopy techniques used in the present study elucidates the flow and diffusion behaviors visually, qualitatively and quantitatively, and represents a promising tool for future studies of mass transport in non-equilibrium systems.


Materials Science







membrane dynamics

Polymer Science

correlation spectroscopy


laser-scanning microscope


Erich Schuster

SuMo Biomaterials

SP Sveriges Tekniska Forskningsinstitut AB

Kristin Sott

SuMo Biomaterials

SP Sveriges Tekniska Forskningsinstitut AB

Anna Ström

SuMo Biomaterials

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Annika Altskär

SP Sveriges Tekniska Forskningsinstitut AB

SuMo Biomaterials

N. Smisdom

Universiteit Hasselt

Flemish Institute for Technological Research

Tobias Gebäck

SuMo Biomaterials

Chalmers, Mathematical Sciences, Mathematics

University of Gothenburg

Niklas Lorén

SuMo Biomaterials

SP Sveriges Tekniska Forskningsinstitut AB

Anne-Marie Hermansson

Chalmers, Biology and Biological Engineering, Food and Nutrition Science

SuMo Biomaterials

Soft Matter

1744-683X (ISSN) 1744-6848 (eISSN)

Vol. 12 17 3897-3907

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Polymer Chemistry

Materials Chemistry

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4/5/2022 1