Model nicolet is10

FTIR spectra of gelatin, GelMA, and GelMA-HMPs were obtained with Thermo Scientific FTIR spectrometer (Model Nicolet iS10, Madison, WI, USA) in the range between 4000 and 400 cm⁻².

Aqueous solutions containing 1:1 molar ratio (m:n; D_mCD_n where m and n represented the total moles of drug and CD, respectively) of the binary complex, i.e., 1:1 molar ratio of VCZ/SBEβCD, with or without PVA (0.1 mM), were prepared by heating in a sonicator at 60 °C for 30 min. The samples were equilibrated at 30 ± 1 °C for 7 days under constant agitation. After equilibrium was attained, the samples were centrifuged (Thermo Fisher Scientific, Waltham, MA, USA) at 4000 rpm for 30 min. Then, the supernatant was withdrawn, frozen at −80 °C for 2 h and lyophilized at −52 °C for 48 h in a freeze-dryer (Labconco Lyophilizer, Kansas City, MO, USA), yielding a solid complex powder (FD). Identical binary PM was prepared by carefully blending ingredients in a mortar with a pestle. The samples were measured in an FT-IR spectrometer (Thermo Scientific Model Nicolet iS10, Waltham, MA, USA) using the attenuated total reflectance technique at room temperature. The samples comprised the following: intact, PM and FD of binary VCZ/SBEβCD complex and FD of the ternary VCZ/SBEβCD/PVA complex. The data were obtained in a range of 400 to 4000 cm⁻¹.

CPC was mixed with KBr (1:200), ground, and then a total of 200 mg of the mixture powder was pressed into a narrow slice. According to the method of Wang et al. [49 (link)], the Fourier transform infrared (FTIR) spectra were recorded by a FTIR spectrometer (Model Nicolet iS10, Thermo Fisher Scientific, Waltham, MA, USA). The wavelength range was measured from 4000 to 400 cm⁻¹. The obtained FTIR spectra were further processed using Omnic V8.1 (Version V8.1, Thermo Fisher Scientific, USA) and PeakFit 4.12 (Version 4.12, Systat Software, San Jose, CA, USA). Baseline correction, deconvolution, and second-order derivatives were performed on the original data at a fraction of 1600–1700 cm⁻¹. The following ranges were assigned to each secondary structure: β-sheet (1615–1,637 cm⁻¹, 1682–1700 cm⁻¹), random coil (1637–1645 cm⁻¹), α-helix (1646–1664 cm⁻¹), and β-turn (1664–1681 cm⁻¹). The percentages of each secondary structure were calculated to present the relative content of secondary structures in the CPC.