Q200 dsc instrument

Conformational analysis was performed on untreated and decellularized patches to test whether sterilization, decellularization, and different storing conditions could affect the SF structure.
Fourier transform-infrared (FTIR) spectroscopy measurements were performed on a NEXUS (Thermo Nicolet) FTIR spectrometer employing an attenuated total reflectance (ATR) accessory model, Smart Performer. All spectra were obtained with a ZnSe crystal cell as the internal reflection element. Spectra were recorded in the 400 to 4,000 cm^-1 wave number range by accumulating 64 scans at a resolution of 4 cm^-1, subjected to data smoothing (15 points with the Savitzky-Golay method) and normalized to the 1,452 cm^-1 peak before any data processing. Each spectrum was the average of at least three spectra measured in different areas of the sample. The crystallinity index was calculated as the intensity ratio between the two amide III components at 1260 cm^-1 and 1230 cm^-1 (C.I. = I₁₂₆₀/I₁₂₃₀) [28 (link)].
Differential scanning calorimetry (DSC) measurements were performed with a DSC Q200 instrument (TA Instruments, Waters, Milan, Italy). The scanned temperature ranged from room temperature to 400°C, at a heating rate of 10°C/minute. The analysis was carried out on samples of about 2 to 3 mg weight, in open aluminum pans of 40 μL volume, under N₂ gas flux.

The thermal analysis includes DSC, DSC-TG, in situ FTIR, and DSC-TG-FTIR-MS quadruple technology experiments. Thermal analysis experiments were carried out with model TG-DSC STA 449C instrument (NETZSCH, Germany) and DSC Q200 instrument (TA, America). Operation conditions: sample mass, 0.5 mg; atmosphere, dynamic nitrogen; aluminum cell. IR spectra were recorded on a Nicolet 60SX FTIR spectrometer with HgCdTe detector. In situ FTIR spectroscopy studies were carried out with Nicolet 60 SXR FTIR spectrometer. Operation conditions: sample mass, 0.5 mg; heating rate, 10 °C/min; resolution, 4 cm⁻¹; spectral acquisition rate, 17.8 file/min, 16 scans/file; temperature range, 20~450 °C. Cautions and experimental condition can be found in Supplementary Materials File S1.

¹H, ¹³C and ¹⁹F NMR spectra of intermediates were recorded on a JEOL resonance ECZ 400S spectrometer (400 MHz) in CDCl₃. Tetramethylsilane (TMS) and CDCl₃ were used as internal standards for ¹H and ¹³C NMR, respectively; CF₃CO₂H was used as an external standard for ¹⁹F NMR. FT-IR spectra were recorded on a Nicolet AVATAR-360 FT-IR spectrophotometer with a resolution of 4 cm⁻¹. Number-average molecular weights (M_n) and molecular weight distributions (M_w/M_n) were obtained on a conventional gel permeation chromatography (GPC) system equipped with a Waters 515 Isocratic HPLC pump, a Waters 2414 refractive index detector, and a set of Waters Styragel columns (HR3 (500–30 000), HR4 (5000–600 000) and HR5 (50 000–4 000 000), 7.8 × 300 mm, particle size: 5 μm). GPC measurement was carried out at 35 °C using tetrahydrofuran (THF) as eluent with a flow rate of 1.0 mL min⁻¹. The system was calibrated with linear polystyrene standards. Differential scanning calorimetry (DSC) was performed on a TA Q200 DSC instrument in N₂ with a heating rate of 10 °C min⁻¹. Thermogravimetry analysis (TGA) was conducted on a TA Discovery TGA 55 thermal analysis system in N₂ with a heating rate of 10 °C min⁻¹. UV/vis spectra were acquired on a Hitachi U-2910 spectrophotometer.