Apparent persistence lengths and diffusion behavior of high molecular weight hyaluronate

Abstract

SYNOPSISHigh purity, high molecular weight hyaluronate from bacteria and rooster comb exhibited clear polyelectrolyte properties, as observed by static and dynamic light scattering. The scattered intensity of hyaluronate solutions increased markedly with ionic strength, while the radii of gyration decreased. Apparent persistence lengths within the wormlike chain model in the coil limit were estimated as a function of ionic strength. The total apparent persistence length varied from about 87 8, in the high ionic strength limit to nearly 400 8, at 1 m M added NaC1. The apparent electrostatic persistence length varied approximately as the inverse square root of the ionic strength. Deviations from the theoretically predicted inverse ionic strength dependence were investigated in terms of excluded volume effects. Dynamic light scattering yielded "ordinary phase" diffusion coefficients whose dependence on polymer and salt concentration agreed reasonably well with hydrodynamic coupled mode theory in the linear limit. Extrapolations to infinite polymer dilution at fixed salts yielded, surprisingly, a constant diffusion coefficient. Thus, there was no evidence of either polyion expansion or electrolyte friction effects in the infinite dilution diffusion coefficients. Since clear evidence for polyion expansion was seen in the static scattering, it is thought that the relative stiffness and consequent openness of the hyaluronate coils lead to partial free draining behavior. There was no evidence for an "extraordinary phase" under no added salt and low added salt conditions. The overall results are contrasted with the very different behavior previously reported for medium purity hyaluronate from animal sources.

The slow relaxation mode: from solutions to gel networks

“…It has been attributed to dynamics of large multichain domains (transient aggregates or clusters) formed due to electrostatic interaction [76][77][78][79][80] or some insoluble chain clusters, or even a trace amount of large particles introduced during the imperfect preparation of solution. [89][90][91][92][93] The transient cluster interpretation was supported by studies of poly(styrenesulfonate) with sodium counterions in aqueous solutions under dialysis. For a long time, this transient cluster has been attributed to the effective interaction between similarly charged segments, namely, the overlapping of the ion clouds of neighboring polyions, so that the more loosely associated small ions are 'shared' by two or more polyions chains, resulting in a fluctuating dipole field that tends to retard the relative motions of those participating polyions.…”

“…The interpretation of the slow mode, especially for those very slow relaxation modes observed in salt-free or low-salt polyelectrolyte solutions, is very controversial. [76][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95] It has been attributed to large multichain domains formed because of electrostatic interaction or some insoluble clusters or even a trace amount of dust particles introduced during the imperfect preparation of polymer solution. Actually, not everyone accepts or recognized such a slow mode, even though it has been repeatedly observed in many dynamic LLS experiments for more than three decades, because of some problems or questions related to previous light-scattering experiments, such as some earlier premature data analysis methods and the preparation of dust-free viscous solutions.…”

Effect of molecular weight distribution on the solution properties of sodium hyaluronate in 0.2M NaCl solution

“…There have been reported a little scattered data for the refractive index increments in NaCl solution. 17,19,21,23,39,40 Viscosity A Zimm-Crothers type low shear rotating viscometer constructed in our laboratory was used for the measurements of viscosity, because of a large shear rate dependence of sodium hyaluronate with the molecular weight larger than 10 6 . Shear rate was 0.10 2 s Ϫ1 for water at 25°C.…”

High osmotic stress behavior of hyaluronate and heparin

“…( 11 ) was obtained by fitting the A2 data presented in Ref. 28 (since those measurements were made in the limit of C, = 0 and u = C,, in the above equations) over the range of 1000 m M down to 10 m M for Hep and 0.5 m M for BHA. When the data from Refs.…”