  We apply pulsed-field-gradient NMR (PFG NMR) technique to measure the
translational diffusion for both uncharged and charged polysaccharide
(Ficoll70) in water. Analysis of the data indicate that NMR signal attenuation
above a certain packing fraction can be adequately fitted with a bi-exponential
function. The self-diffusion measurements show also that the Ficoll70, an
often-used compact, spherical polysucrose molecule, is itself non-ideal,
exhibiting signs of both softness and attractive interactions in the form of a
stable suspension consisting of monomers and clusters. Further, we can quantify
the fraction of monomer and cluster. This work strengthens the picture of the
existence of a bound water layer within and around a porous Ficoll70 particle.
