4.4.2. FTIR

The infrared spectrum of the samples was obtained by using a Bruker FTIR spectrophotometer (VERTEX 70, Bruker, Karlsruhe, Germany) at room temperature. The samples (lyophilized collagen) were mixed with KBr by grinding at the ratio of 1:100 ( *w*/*w*). The wavelength range was 4000–400 cm<sup>−</sup>1, with a resolution of 4 cm<sup>−</sup>1. The signals were collected automatically in 32 scans and ratioed against a background spectrum recorded from KBr.
