Changes in denaturation and rheological properties of collagen-hyaluronic acid scaffolds as a result of temperature dependencies

This report describes the effect of temperature on the mechanical viscoelastic properties such as: storage modulus (E?), loss modulus (E?), and loss tangent (tan ?)of the collagen sponges modified with hyaluronic acid (HA). In order to detect collagen-HA copolymer denaturation and to assess its thermal stability, the differential scanning calorimetry (DSC)supplemented by thermogravimetric (TG)measurements was used. The denaturation temperature (Td)of unmodified collagen samples increased from 69 to 86 °C for cross-linked samples, respectively. These temperature dependencies show remarkable changes in E? and E? at selected temperature up to 226 °C for all samples due to the release of loosely and strongly bound water. The influence of HA on the viscoelastic behavior of collagen is manifested by a shift of the tan ? peak associated with the process of decomposition towards higher temperatures resulting in a higher thermo-stability of the modified scaffolds.