Comparative NEXAFS study of the selected icefish hard tissues and hydroxyapatite

The structure of native Champsocephalus gunnari icefish otoliths, scales, teeth, bones and pristine hydroxyapatite (HA) were examined using Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. NEXAFS Cls-absorption spectra of the selected icefish hard tissues indicate that otoliths contain anion [CO3](2-). NEXAFS P2p-spectra clearly indicate the absence of phosphorus atoms only within otoliths and scales samples. However, the icefish teeth and bones P2p-spectra demonstrate identical spectral feature typical for the HA. NEXAFS Ca2p-spectra of the icefish hard tissues studied also shows features, which are in good correspondence with HA spectra. Interestingly, there is a red shift approximate to 0.1 eV of the 2p(1/2,3/2)-> 3d transition energies in NEXAFS Ca2p-spectra of teethes and bones of the C. gunnari in comparison to HA.