MESOSCOPIC GELS AT LOW AGAROSE CONCENTRATION - PERTURBATION EFFECTS OF ETHANOL

Aqueous agarose solutions at low concentrations (0.5 g/liter) were tem perature quenched below the spinodal line to form mutually disconnecte d mesoscopic gels. In the presence of 6% ethanol, these solutions, obt ained by quenching at the same temperature depth as in pure water, app ear much more fluid, as determined by probe diffusion experiments. We show by static and dynamic light scattering that this can be explained by the solvent-mediated effects of ethanol, leading to a globular sha pe of mesoscopic agarose gels, rather than to an extended rodlike stru cture observed in pure water. Our findings show the significant effect s of solvent perturbations on particle condensation and, therefore, ma y be useful in understanding the role of the solvent in the folding of biomolecules.