Nicolet is50 spectrometer

Specimens for the FTIR study were analyzed after exposure to 70 Gy radiation (IR group) and the corresponding control treatment (C group). FTIR spectra were acquired using a Nicolet iS50 spectrometer (Thermo Fisher Scientific, Waltham, MA, USA) in a spectral range of 4000–400 cm⁻¹ and a spectral resolution of 4 cm⁻¹. The specimens were dried in a vacuum at room temperature for 7 days and fixed on an attenuated total reflectance (ATR) diamond crystal using a special press. The window of the ATR accessory sampled a circular area (d = 2.5 mm) from the center of each specimen. One spectrum per specimen was acquired by averaging 40 consecutive scans.

The protein secondary structure of native and decellularized samples was studied using Fourier transform infrared spectroscopy (FTIR). NBPs, DBPs, NPPs, and DPPs flaps (10 × 10 mm², n = 3 for each group) were cut and equilibrated for 3–4 h in deuterium oxide (Janssen, Beerse, Belgium) to reduce the contribution of interfering water bands in the amide-I region [42 (link)]. FTIR investigations were performed using the Nicolet iS-50 spectrometer (Thermo Fisher Scientific, Waltham, MA, USA) in the attenuated total reflectance (ATR) mode. The instrument was equipped with a diamond/ZnSe crystal and pressure arm. The transmittance of both samples and background was each measured using 64 scans and infrared spectra were collected within the 4000–500 cm⁻¹ range, at room temperature. Spectra were then overlapped using a Matlab^® script (Mathworks, Natick, MA, USA) [43 ] to compare the composition of the investigated materials. Amide-I and amide-II bonds, respectively at 1630 cm⁻¹ and 1550 cm⁻¹ [40 (link),43 ], were selected to evaluate the integrity of ECM proteins. Peak transmittance ratio (R) was calculated dividing the intensity of the amide-I peak by the intensity of the amide-II peak.

FTIR spectra of the control and obtained samples were recorded using a Nicolet iS50 spectrometer (Thermo Fisher Scientific Co., Hillsboro, OR, USA). Each measurement was performed using a built-in attenuated total reflectance (ATR) accessory. The analysis was carried out in the wavelength range of 4000–400 cm⁻¹.