Prestige 21

The chemicals and solvents used in the present study were analytical grade and utilized without further purification; the water employed in the experiment was double distilled. The metal salts of NiSO_4·6H₂O, Ca(OH)₂·4H₂O, Mn(OH₃)₂·4H₂O, ZnSO₄·6H₂O, Cd(SO₄)₂·3H₂O, Cu(SO₄)₂·5H₂O), Co(OH₃)·6H₂O, CrCl₃6H₂O, KNO₃, Hg(NO₃)_2, Pb(NO₃)_2, and Ce(NO₃)₃·6H₂O were purchased from BDH chemical, England. As Ca(OH)₂ was easily available in our laboratory, we utilized it as a source of calcium. Similarly, nitrate and sulphate salts of other metals were used. Sodium hydroxide, 4-methyl cyclohexanone, benzaldehyde, methanol, and acetonitrile were purchased from Sigma Aldrich and Merck. The UV-Visible spectra were obtained using a double-beam UV/VIS spectrophotometer (Shimadzu, Japan) model 1601. The fluorescent measurement was obtained through spectrophotofluorometer model no RF5301 PC (Shimadzu, Japan), containing a Xenon lamp as a source of excitation. The infra-red spectra were obtained through FT-IR spectrophotometer model 1601 (Shimadzu, Japan). The ¹H NMR spectra were obtained on Prestige 21 (Shimadzu, Japan) using a Bruker Advance 400 MHz spectrometer. The spectrum was obtained in CDCl₃ solution using tetramethyl silane (TMS) as an internal standard.

A Prestige 21 Shimadzu (Kyoto, Japan) FTIR instrument equipped with a DTGS detector was used to study the interactions between the different components. In the 400–4000 cm⁻¹ region, with resolution of 4 cm⁻¹ (45 scans) were recorded the spectra of the materials by Fourier transform infrared (FTIR) transmittance. KBr pelletized disks containing 2 mg of each sample and 198 mg of KBr were made. The FTIR spectra were processed by Prestige software (IR solution, software version 1.50, Shimadzu, Kyoto, Japan)

FTIR spectroscopy was necessary in analyzing structure of the scaffolds, in this current study FTIR was performed on wet and dry unprocessed silk fibroin and spidroin fiber as comparison to scaffold with fibroin and spidroin mixed in. FTIR spectroscopy was recorded between 1000 cm⁻¹ and 4000 cm⁻¹ (Shimadzu IR Prestige-21, Japan).

FT-IR analysis was performed in the range of 400–4000 cm⁻¹ using the Prestige21 Shimadzu system, equipped with a DTGS KBr (deuterated triglycine sulfate with potassium bromide windows) detector, resolution of 2 cm⁻¹ (60 scans). The analysis procedure uses KBr disks (2 mg of sample and 198 mg of KBr).

To investigate the chemical reaction between TOCNF and adenine and thymine, the samples were analyzed using Fourier transform infrared spectroscopy (FTIR) and attenuated total reflection (ATR) prestige-21 (Shimadzu, Kyoto, Japan). The FTIR-ATR spectrum was taken from 600 to 4000 cm⁻¹. The morphology of the samples was examined using a scanning electron microscope (SEM) (SU8000, HITACHI, Ichihara, Japan) and an atomic force microscope (AFM) (Dimension Icon, Bruker, Billerica, MA, USA). The acceleration energy of all samples was maintained at 5 kV. The crystal structures of cotton cellulose fibers, TOCNF, and TOCNF-AT were observed by X-ray diffraction (XRD) spectroscopy. The XRD pattern was taken at room temperature (25 ± 3 °C) using a Rotaflex RT300 mA, Shimadzu, Osaka, Japan, with an angle (2θ) range of 5 ≤ 2θ ≤ 60°. The mechanical properties of the prepared TOCNF and TOCNF-AT films were evaluated using a universal testing machine (UTM), Tensilon RTC 250A, A&D Company Ltd., Osaka, Japan. Surface area and pore size distribution are tested by BET (ASAP, Micromeritics, Norcross, GA, USA).

The methodology was conducted according to previous work with minor modifications [20 (link)]. The FTIR spectra of the Ag-HPA salts were obtained from samples dispersed in KBr disks in the range of 4,000-400 cm^-1 in a spectrophotometer model Prestige-21 (Shimadzu, Japan).