Knowledges

Relationship Between Molecular Weight and Viscosity of HA

It has been confirmed that HA from different sources have the same primary structure but different molecular weight. The order of HA molecular weight (Mw) ranges from 104 to 107 Dalton. For example, HA that is isolated from bovine vitreous have a lower molecular weight in the range of 104-105 Dalton, while HA from umbilical cord and rooster comb have a higher molecular weight around 106~107Dalton.

Relationship between molecular weight and viscosity

HA has an incredible water-retaining capacity that makes HA solutions highly viscous, so the solution can retain moisture in the eyes, joints, and skin tissues. In the clinical setting, HA solutions have been introduced for various medicinal purposes – osteoarthritis, tissue augmentation and ocular surgery, etc. Such clinical applications are strongly dependent on HA’s chain length, that is, the molecular weight. Molecular weight and hydrodynamic volume of HA are closely associated. Intrinsic viscosity has been measured as a parameter of the molecular weight of HA, and the relation between intrinsic viscosity and molecular weight is defined by the Mark-Houwink equation.

[η]=KMα

This equation describes the dependence of the intrinsic viscosity of a polymer on its relative molecular weight. Where [η] is the intrinsic viscosity, K and α are constant the values of which depend on the nature of the polymer and solvent as well as on temperature and M is usually one of the relative molecular mass averages.