2.6.4. ATR-FTIR analysis
Both ASC and PSC were subjected to attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). FTIR spectrometer (Model Equinox 55, Bruker, Ettlingen, Germany) equipped with a horizontal ATR trough plate crystal cell (45 ZnSe; 80 mm long, 10 mm wide and 4 mm thick) (PIKE Technology Inc., Madison, WI, USA) was used. For spectra analysis, the collagen samples were placed onto the crystal cell and the cell was clamped into the mount of the FTIR spectrometer. The spectra in the range of 400–4000 cm1 with automatic signal gain were collected in 32 scans at a resolution of 4 cm1 and were ratioed against a background spectrum recorded from the clean empty cell at 25 C.