Deuterium oxide

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.

In order to evaluate if and how much decellularization affects tissue composition, Fourier transform infrared (FTIR) spectroscopy using a Nicolet iS-50 spectrometer (Thermo Fisher Scientific, Waltham, MA, USA) with an attenuated total reflectance (ATR) accessory was used to process samples from native (n = 3) and decellularized with D2 (n = 3) swine descending aortas. Details about the apparatus were reported in our previous work [25 (link)].
Before the analysis, samples were cut into squares of 10 × 10 mm² and equilibrated for 3–4 h in deuterium oxide (Janssen, Beerse, Belgium) to reduce the interference of water bands in the amide-I region [40 (link),41 (link)]. A Matlab^® script (Mathworks, Natick, MA, USA) was used to analyse the data [42 ].

In order to check if the polycarbonate urethanes coupled with SIS can alter the secondary structure of tissue proteins and if the polymer penetrates it, hybrid materials were analyzed using the Fourier transform infrared spectroscopy (FTIR). Decellularized SIS and hybrid membranes on the SIS side, and polycarbonate urethanes (CF AR and CF AR-LT) flaps (10 × 10 mm²) (n = 3 for each type of material) were equilibrated for 3–4 h. in deuterium oxide (Janssen, Beerse, Belgium). Samples were then processed with a Nicolet iS-50 spectrometer (Thermo Fisher Scientific, Waltham, MA, USA) equipped with the Attenuated Total Reflectance (ATR) accessory. Infrared spectra of the samples and background were recorded using 64 scans in the range of 4000–500 cm⁻¹ at room temperature and analyzed with a Matlab^® script (MathWorks, Natick, MA, USA) [47 ].