Spectrum gx system

X-ray diffraction data were acquired with a Rigaku/Dmax2100 equipment equipped with Cu radiation (K_α1 = 1.5406 Å). Infrared spectra were measured with a Spectrum GX system/Perkin Elmer using a resolution of 4 cm⁻¹ and averaging over 64 scans. Spectra from the cuticle of C. Chrysargyrea and crab chitin were measured in attenuated total reflection mode and for uric acid the KBr pellet technique was employed. For transmission electron microscopy the sample was first fixed in 3% glutaraldehyde for 2 h, then rinsed in sodium cacodylate buffer, immersed in osmium tetroxide for 1 h, rinsed in deionized water, immersed in 1% uranyl acetate for 1 h, rinsed again in deionized water, followed by a dehydration series starting with 30% ethanol and ending with 100% ethanol, and embedding in a resin. The sample was imaged in JEOL 100 S TEM instrument.

Physicochemical characterization was conducted by infrared spectroscopy, coupled to an attenuated total reflectance accessory (IR-ATR) in a Spectrum GX System (Perkin Elmer-DuraSamplIR II, USA), 16 scans were taken in a range of 650–4000 cm⁻¹. Thermogravimetric analysis was performed in a PerkinElmer Pyris 1 TGA system, in a nitrogen atmosphere at 20.0 mL/min flowrate. A heating ramp from 30.00 °C to 600.00 °C at 10.00 °C/min was used.
Crystallinity of the scaffolds was tested by X-ray diffractometry in a BRUKER D8 ADVANCE ECO X-ray diffractometer. The degree of crystallinity was calculated using the ratio of the area under the peaks to the total area (A_T) under the XRD pattern [48 (link),49 (link)], which is the sum of the crystalline diffraction peak area (Ac) and the amorphous diffraction component (Aa) of the pattern (A_T = Ac + Aa).
Differential scanning calorimetry (DSC) tests were carried out in a TA Instruments DSC-2920 system. Between 6–8 mg of each sample were scanned at a rate of 10 °C/min, using a heating/cooling/heating program, from 30 to 230 °C. The first heating was used to erase the thermal history, and the thermal properties were obtained from the second heating.
The wettability of the fabricated scaffolds was evaluated by measuring the contact angle of a 20 µL drop of distilled water on each sample (n = 6).

Fourier-transform infrared–attenuated total reflectance (FTIR–ATR) was used to identify the structural properties of the CS/Gel/PVA hydrogels. Freeze-dried hydrogels were lyophilized, ground with a grinder, and placed on the ATR surface of the Spectrum GX system (Perkin Elmer, Branford, CT, USA). Spectra were obtained with a resolution of 1 cm⁻¹ over 24 scans, ranging from 4000 to 650 cm⁻¹.