Thermodynamic data and mechanical measurements are shown for gels prepared
in aqueous binary solvents (water/DMSO, water/DMF, water/methyl formamide a
nd water/formamide). When electrostatic interactions, as opposed to hydroge
n bonding, can be established with the cosolvent (DMSO, DMF, methyl formami
de) we come to the conclusion that ternary complexes are formed (agarose/wa
ter/cosolvent). In the case of chemically-modified agarose (OH groups repla
ced by OCH3 groups) we suggest that these cosolvents are directly involved
in the formation of the gel.