Evolution 300 uv vis spectrophotometer

The in vitro dissolution of the coated tablets was evaluated in a gastrointestinal simulation system (GISS) previously described by Schellekens et al., with the modification that half of the volumes were used [27 (link)]. In GISS, tablets are exposed to four different phases of different pHs, similar to the passage in the in vivo gastrointestinal tract. These phases are shown in Table 1. The GISS was prepared by adding four different media sequentially, as presented in Table 2. Approximately 5–10 min before reaching the next phase time point, the subsequent media were added using a peristaltic pump. The composition of each medium is provided in Table 2. Tablet dissolution testing was carried out in a USP dissolution apparatus type 2 (Sotax AT 7, Sotax, Basel, Switzerland) at 37 °C and a paddle speed of 50 rpm. The release of tablet content was determined by measuring the concentration of methylene blue using an in-line UV-spectrophotometer set to measure at 664.5 nm (Evolution 300 UV–VIS spectrophotometer, Thermo Fisher Scientific, Madison, WI, USA). Samples were taken every 5 min for 8 h, and all experiments were performed in triplicate.

The UV absorbance at a wavelength of 280 nm was recorded on the Evolution 300 UV–Vis spectrophotometer (Thermo, USA). Infrared spectra were obtained using a Fourier transform infrared spectrometer (Nicolet iS 50, Thermo, USA). Fluorescence measurements were performed on an F-7100 fluorescence spectrophotometer (Techcomp, Shanghai, China) equipped with a 980 nm external exciter (2 W, Shanghai Feibo Laser Technology Co., China) as the light source. Transmission and scanning electron microscopy (TEM and SEM) images were obtained from a Talos G2 200X and Apreo electronic microscope (Thermo, USA), respectively. X-ray powder diffraction (XRD) patterns were recorded on a Malvern Panalytical apparatus at a scanning rate of 1° min⁻¹ in the 2θ range from 5° to 80° (Shanghai, China). Energy dispersive X-ray photoelectron spectroscopy (XPS) patterns were measured on ARL QUANT'X Energy dispersive X-ray spectrometer (Thermo, USA). Nitrogen adsorption/desorption analysis was performed on a 3H-2000PS apparatus (Beijing, China) with a bath temperature of 77 K. Millipore ultrafine filters from Merck Company (Germany) and a centrifuge machine from Eppendorf (Germany) were used in the pre-treatment of milk products. A HPLC system equipped an SPD-20A detector from Shimadzu Corporation (Japan) was applied to verify the results of β-LG measurement in milk products.

Two yeast strains, asn1(A6E)::GFP (asn2Δ) and ASN1(WT)::GFP (asn2Δ), were diluted in fresh YPD to give the starting OD₆₀₀ ~ 0.1 and continuously cultured at 30 °C with shaking for 5 days. An aliquot was taken out from each culture to measure OD₆₀₀ using an Evolution™ 300 UV-Vis Spectrophotometer (Thermo Fisher Scientific, Waltham, MA, USA) at the following time points; 4.5, 24, 48, 72, 96, and 120 h, respectively. The data were used to plot their growth curve and statistically analyzed (paired t-test) using GraphPad Prism Version 9.0.2 (161) (GraphPad, San Diego, CA, USA).