Agarose chain conformation in the sol state by neutron scattering

We report on small-angle neutron scattering investigations into the agarose conformation in water. We show that at 70 degrees C in the sol state agarose chains are fairly rigid with a lower limiting value for the persistence length of about 9 nm and a mass per unit length of muL = 360 +/- 36 g/mol x nm. The value of the latter parameter is consistent with single-stranded helices as those proposed recently by Foord and Atkins. Such a high rigidity together with such a low linear mass leads one to wonder how would the chains manage to intertwine should they form double helices in the gel state.