Ft ir tensor 2 spectrometer

Fourier-transform infrared (FT-IR) spectra of CS, mPEG-CS, mPEG-CS-CHO, and mPEG-CS(SH)-CHO were recorded by an FT-IR Tensor II spectrometer (Bruker, Zurich, Switzerland) to confirm the formation of mPEG-CS(SH)-CHO. Moreover, the proton nuclear magnetic resonance (¹H NMR) study was also performed on a Bruker AV-400 spectrometer (Bruker, Zurich, Switzerland) using DMSO-d6 as the solvent. The critical micelle concentration (CMC) of mPEG-CS(SH)-CHO and the substitution degree of mPEG, CHO, and NAC were determined according to the previous report [26 (link)].

Infrared spectra of the TOCN-x and TS-TOCN were measured using Fourier-transform infrared spectroscopy (Bruker, karlsruhe, Germany, FT-IR TENSOR II spectrometer) with a resolution of 4 cm⁻¹. The dried samples (powder form) were mixed well with KBr powder and pressed into an ultra-thin pellet with a ratio of 1:10 (w/w). The spectra were collected at ambient conditions in the transmittance mode over the regions of 4000–400 cm⁻¹.

An FTIR Tensor II spectrometer was used to determine the secondary
structure of the materials (Bruker Optics Inc., Billerica, MA, USA).
Lyophilized materials at room temperature were used to determine the
spectra as absorbance at wavelengths between 400 and 4000 cm^–1 in every four scans. After baseline correction, the amide I region
(1600–1700 cm^–1) was smoothed by the Savitzky–-Golay
algorithm. The peak was deconvoluted using a Gaussian peak-fit model,
and the limit of error (R²) was converged
between 0.99 and 1 by using Origin Pro 2022b software (Origin Lab
Corporation, USA). Relative percentages of the peaks corresponding
to β-sheet (1610–1645 and 1680–1700 cm^–1), random coil (1648 ± 2 cm^–1), α-helix
(1652 ± 2 cm^–1), and β-turn (1660–1680
cm^–1) were calculated by the area of the deconvoluted
peaks.^{5 (link)}