Thermoreversible gelation of a polysaccharide with immunological activity: Rheology and dynamic light scattering

The β — 1.3/1.6 glucan schizophyllan is known to suppress tumor growth. Two different schizophyllan samples have been characterized by static and dynamic light scattering in dilute solution of 0.01M NaOH and dimethyl sulfoxide (DMSO). A thermoreversible, optically transparent gel of schizophyllan was obtained on addition of sorbitol to aqueous solution, and the gelation process was followed by low amplitude oscillatory shear and dynamic light scattering (DLS). Power law behavior of storage modulus G' (ω) and loss modulus G” (ω) with the exponent n=0.5 was found at the gel temperature. In the same temperature range intensity time correlation functions (TCF) were measured and the electric field TCFs were calculated, taking into account the heterodyne contributions. The occurrence of two motions gave evidence for inhomogeneities in the gel. The results of the slow motion from DLS agreed surprisingly well with those, estimated by oscillatory rheology. The viscoelastic properties and the influence of sorbitol and schizophyllan concentrations were investigated regarding the pharmaceutical application in cancer therapy.