Dynamics during thermoreversible gelation of the polysaccharide schizophyllan

The beta-1.3/1.6 glucan schizophyllan is a fungal polysaccharid that is kno wn to suppress tumor growth. Addition of sorbitol to aqueous solutions of s chizophyllan led to a thermoreversible formation of optically transparent g els. The gelation process was followed by low amplitude oscillatory shear a s well as by static and dynamic light scattering. Power law behavior of sto rage modulus G'(omega) and loss modulus G "(omega) was found at the gel tem perature with an exponent n=0.5. However, no power law was found for the ti me correlation functions as measured by dynamic light scattering. Two separ ated relaxation modes were found above and below the gel transition. The sl ow mode diverged below the gel temperature indicating a second critical poi nt related to heterogeneities in the gel.