Ultrashield 600 plus nmr spectrometer

UV-vis spectra of GA–CS sample were recorded using a UV-vis 2450 spectrophotometer (Shimadzu Corporation, Japan) in a range of 200–500 nm. FT-IR spectra were recorded on a Nicolet Nexus 670 infrared spectrophotometer (Thermo Fisher Scientific Inc., USA) with 32 scans at a resolution of 2 cm⁻¹ in a frequency range of 4000–400 cm⁻¹. Solid state ¹³C NMR test was performed on a Bruker UltraShield 600 PLUS NMR spectrometer (Bruker, Germany). Freeze-dried hydrogels were used and operated at a recording frequency of 100.63 MHz and spinning rate of 8 kHz. XRD patterns were obtained with X-ray diffractometer (Bruker AXS, Germany) using Cu as K_α radiation, and the Bragg's angle 2θ was scanned from 5 to 50° at the rate of 0.1° min⁻¹.

The thermal characters of AG, γ-CD, TPGS, physical mixture and AG-CD-TPGS ternary system were recorded using a differential scanning calorimetry system (DSC-60A, Shimadzu, Japan). All the samples (3 mg) were weighed accurately and encapsulated in aluminum pans. The temperature range was set from 30 to 250 °C with a heating rate of 10 °C/min under nitrogen. Aluminum oxide was used as a reference standard. The FTIR spectra of AG, γ-CD, TPGS, formulation physical mixture, and AG-CD-TPGS ternary formulation were recorded with a fourier transform infrared spectrometer (Spectrum 100, PerkinElmer, America) in the scanning range of 4000–400 cm⁻¹ at the resolution of 2 cm⁻¹. NMR spectroscopy has been previously used to establish inclusion modes and stoichiometries [40 (link),41] (link). ¹H NMR spectra of AG, γ-CD and AG-CD-TPGS ternary formulation were recorded at 25 °C with a Bruker ultra-shield 600 plus NMR spectrometer (Bruker, Germany). Deuterium oxide (D₂O) was used as the solvent.