Uv 2501pc spectrophotometer

The absorption spectra of the pure chitosan and genipin crosslinked chitosan (chitosan-Gp) films were recorded on a Shimadzu UV-2501PC spectrophotometer (Kyoto, Japan) in the spectral region from 190 to 800 nm.

Absorption spectra were recorded using a Shimadzu UV-2501PC spectrophotometer. Steady-state fluorescence spectra were recorded with a Fluorolog Yobin Yvon-SPEX fluorometer. The excitation wavelengths were 300 and 320 nm, and the spectra were automatically corrected using a correction function provided by the manufacturer. Fluorescence quantum yields (Φ_f) in solution were measured following a method using carbazole (Φ_f = 0.367 in DCM) as the ref.^{59 (link)}. Dilute solutions (optical density at λ_ex < 0.1) of A in either THF or DCM was used for the fluorescence spectra recording in 1 cm path length cuvettes. Integrated areas of fluorescence spectra were used for further calculations by using equation (2): $${\varphi }_{f(X)}={\varphi }_{f(R)}\frac{A{\prime }_{(R)}{I}_{(X)}{n}_{(X)}^2}{A{\prime }_{(X)}{I}_{(R)}{n}_{(R)}^2}$$ where subscripts (R) and (X) refer to reference compound and analyte, A’ is an optical density at the excitation wavelength, I is the area under the fluorescence spectrum, n is the refractive index of the medium.

The absorption spectra were recorded on a Shimadzu UV-2501PC spectrophotometer (Japan). Photoluminescence spectra were recorded in 200-700 nm region using a scanning spectrofluorimeter ALS01 M (Russia) with registration in the single photon counting mode at successive time intervals and automatic adjustment of emission intensity. Photoluminescence spectra in the PLA matrix and non-woven coverings were measured in the integrating sphere. The photoluminescence quantum yield of the materials was measured relative to the 2,1,3-benzothiadiazole-based luminophores in the polystyrene matrix (Skorotetcky et al., 2018 (link)).

¹H, ¹³C and ¹⁹F NMR spectra were recorded on Bruker AVANCE 300 or Bruker AVANCE 500 spectrometers. CDCl₃ was use as solvent and tetramethylsilane (TMS) as internal reference. The chemical shifts are expressed in δ (ppm) and the coupling constants (J) in hertz (Hz). UV–Vis spectra were recorded on a Shimadzu UV-2501PC spectrophotometer using toluene or CHCl₃ as solvent. UV−vis absorption spectral wavelengths (λ) are reported in nanometers (nm), and molar absorption coefficients (ε) are reported in M⁻¹ cm⁻¹. Fluorescence emission spectra were recorded on a JASCO FP-8300 spectrofluorometer. Mass spectra were recorded using a MALDI TOF/TOF 4800 Applied Biosystems MDS Sciex mass spectrometer, CHCl₃ as solvent and 3-nitrobenzyl alcohol (NBA) as matrix. High-resolution mass spectra (HRMS) were recorded on a Bruker Apex-Qe FTICR mass spectrometer or on a LTQ Orbitrap XL mass spectrometer using CHCl₃ as solvent. Melting points were measured on a Büchi B-540 apparatus and are uncorrected. Column chromatography was carried out using silica gel (Merck, 35-70 mesh). Analytical TLC was carried out on precoated sheets with silica gel (Merck 60, 0.2 mm thick). Solvents were purified or dried according to the literature procedures [77 ]. Compounds 1 [78 (link)], 2 [78 (link)] and PyC₆₀ [79 (link)] were prepared according to published procedures.

Reductase activity of hPDI and its mutants was determined by monitoring insulin reduction. The reaction was initiated by addition of hPDI proteins to 0.1 M potassium phosphate buffer (pH 7.5) containing 130 µM insulin, 2.5 mM EDTA and 0.1 mM DTT. The absorbance at 650 nm, that represents the light scattering resulted from the aggregation of reduced insulin chains, was immediately recorded on a SHIMADZU UV-2501PC spectrophotometer (Shimadzu) at 25°C. The activity was calculated by the maximal slope of the curve relative to the lag time [24] (link).