Nicolet is50 fourier transform infrared spectrophotometer

X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were performed to investigate the crystalline properties of POD in the formulation and possible interaction between POD and the selected excipients [61 (link)]. XRD measurements of POD, a physical mixture of POD and the excipients, blank LCTs, and POD-LCTs were conducted using an X-ray difftometer (D8 ADVANCE, Bruker, Germany) under Cu-Kα radiation at a scan rate of 2° per minute in the 2θ range of 10–80°. The above samples were also analyzed by FTIR, and the FTIR spectra of the samples were recorded by a Nicolet iS50 Fourier transform infrared spectrophotometer (Thermo Fisher Scientific, USA) with a frequency of 400–4000 cm⁻¹.

Effects of processing and nebulization on the aggregation of hLYS was assessed using size exclusion chromatography (SEC) based upon a previously published method [46 (link)]. The effect of processing on the secondary structure of hLYS was determined using a Nicolet iS50 Fourier transform infrared spectrophotometer with attenuated total reflectance (FTIR-ATR) (Thermo Scientific). Spectra were acquired using OMNIC software from a wavelength of 700 cm^-1 to 4000 cm^-1 with 64 acquisitions in total. An atmospheric background scan was collected and subtracted from all powder spectra. Secondary structure analysis was performed in OriginPro (OrginLab Corporation) using the second derivative of the amide I band region (1580–1720 nm) and the peak analyzer function. The region of interest was first baseline-corrected, and the second derivative of the spectra was smoothed using the Savitzky-Golay method with a polynomial order of 2 and 50 points in the smoothing window. Peaks identified from the second derivative minimums were iteratively removed to assess the effect on the model fit.