Study of the mechanism of formation of hyaluronan putty at pH 2.5: Part II-Theoretical analysis

A new method was developed for quantitative determination of the viscoelastical characteristics of hyaluronic acid (HA) putty (formed at pH 2.5) using a stress relaxation approach. A concept of entanglement network numbers (ENN) was applied to provide a quantitative measure for the strength of HA putty. Based on the new approach, the relationship between ENN and HA concentration was established. The new approach was successfully applied to evaluate the effect of temperature, urea concentration and pH on putty strength as well as estimate the effects of glucose, β1-3-linked d-glucuronic acid and β1-4 linked d-N-acetylglucosamine, on the ENN of HA solutions quantitatively. The ENN established in the current study can be extended to other non-cross linked hydrogels, i.e. they are formed by hydrogen bonds, ionic interactions or other non-covalent bonds.