Suppression of aggregation in natural-semiflexible/flexible polyanion mixtures, and direct check of the OSF model using SANS

Aggregation and other interactions are suppressed for a biological semi flexible polyelectrolyte, hyaluronan (HA), when it is embedded in a mixture with another negatively charged and flexible polyelectrolyte chain, sodium polystyrene sulfonate. We see directly HA only in the mixture using small-angle neutron scattering (SANS), isotopic labelling and contrast matching. At low ionic strength, for which aggregation is usually seen for pure HA solutions, an unambiguous set of experimental results shows that we neither observe HA aggregation nor a polyelectrolyte peak (observed for solutions of single species); instead we observe a wormlike-chain behaviour characteristic of single chain with a variation of the persistence length with the square of the Debye screening length, L(e) similar to kappa(-2), as formerly predicted by Odijk and not yet observed on a polymer chain. Copyright (C) EPLA, 2008.