Binding of the water of primary hydration to the sodium and cesium salts of deoxyribonucleic acid and potassium hyaluronate

Differential scanning calorimetry (DSC) has been used to evaluate the average enthalpy of desorption of the water of primary hydration bound to wet-spun films of potassium hyaluronate (KHA) and CsDNA. The enthalpies were measured to be $0.24\pm 0.08$ ${\mathrm{e}\mathrm{V}/\mathrm{H}}_2\mathrm{O}$ molecule for KHA and $0.32\pm 0.10$ ${\mathrm{e}\mathrm{V}/\mathrm{H}}_2\mathrm{O}$ molecule for CsDNA. A Kissinger analysis was used to extract the net activation energy $(0.61\mathrm{}\pm 0.04$ eV) for the desorption of this water from KHA by analyzing DSC data acquired at different heating rates. The average effective force constants at 295 K of this water bound to KHA $(63\mathrm{}\pm 3\hspace{0.5em}\mu \mathrm{d}\mathrm{y}\mathrm{n}/\mathrm{\AA })$ and NaDNA $(17\mathrm{}\pm 4$ $\mu \mathrm{d}\mathrm{y}\mathrm{n}/\mathrm{\AA })$ are determined from Rayleigh scattering of Mossbauer radiation data [G. Albanese, A. Deriu, F. Cavatorta, and A. Rupprecht, Hyperfine Interact. 95, 97 (1995)] via a harmonic approximation.