Change of network structure in agarose gels by aging during storage studied by NMR and electrophoresis

Changes of the network structure in agarose gels during storage were studied by measuring diffusion coefficient (D) of probe polymers. PGSTE 1H NMR was used to measure the D of pullulan added as a probe to show an increase with storage suggesting the formation of coarse network with thicker bundles of agarose aggregates. The hydrodynamic mesh size was estimated from the degree of restriction in the diffusion shedding light on the change of microscopic environment in the agarose gel during storage. From the gel electrophoresis, D of DNA was calculated from the friction on the DNA movement under the electric field to show an increase of D with storage suggesting the change of network structure in the aged agarose gels. The results provided a better understanding of the aging mechanism in agarose gels with the conformational changes which should be commonly observed in polysaccharides.