Solute Behavior in Tightly Cross‐linked Dextran Gels

Abstract

The selectivity of neutral, or very weakly charged gels has aroused considerable interest in recent years.',? These gels exhibit various kinds of selectivities of which the molecular sieve properties have attracted most attention particularly in the macromolecular domain. As yet there is no general theory regarding the mechanisms responsible for their selectivity, and it is the purpose of this paper to examine the behaviour of some low molecular nonelectrolytes in tightly crosslinked dextran gels.I n general the molecular sieving range is higher the more water the gel contains. The sieving range now available among different gels is enormous, extending from the smallest molecules up into the range of viruses and sub-cellular particles.",4The distribution of solutes in the tightly crosslinked dextran gels depends on both steric and interactive factors, and the selectivity range makes i t possible t o study solutes which are sufficiently small for analysis of their behaviour in terms of their chemical structure and interactions with the gel and the solvent water.The dextran gels a r e from a biological aspect relatively simple systems, and it seems not unlikely that a study of the distribution of solutes within them may i n addition yield information pertinent to solute behaviour in more complicated living systems. DEXTRAN GELST h e following highly crosslinked dextran gels were used : ( 1 ) Types G-25 (Sephadexo": water regain ( W r ) = 2.5 g water per g d r y gel) and G-10 ( W r = 0.97). These were crosslinked with glyceryl bridges (R-O-CHa-CH (OH) -CHz-O-R).