Spectrum one atr ftir spectrometer

The chemical structure of commercial astaxanthin, mPEG-PCL micelles, and astaxanthin-encapsulated mPEG-PCL micelles was characterized by FT-IR. FT-IR spectra were recorded by Spectrum One ATR/FTIR spectrometer (Perkin Elmer, Waltham, MA, USA). The particle size distribution of the mPEG-PCL micelles was determined by dynamic light scattering (DLS) using a Nano ZS Zetasizer (Malvern Panalytical, Westborough, MA, USA). The TEM samples were prepared by adding 10 μL of 1 mg/mL mPEG-PCL micelle solution onto a Formvar grid (Ted Pella, Redding, CA, USA) for 5 min and excess solution was wicked off. The samples were negatively stained with 10 μL phosphotungstic acid solution (2 wt%) for 10 s and excess solution was wicked off. Transmission electron microscopy (TEM) image of mPEG-PCL micelles was taken by JEM-4000FX (JEOL, Tokyo, Japan) at 80 kV.

Optical rotations were determined with a Unipol L1000 Schmidt + Haensch polarimeter at the sodium D line (589.3 nm), at 20 °C, with a 10 cm cell. UV spectra were acquired in spectroscopic grade CHCl₃ or MeOH on a Varian, Cary 100 UV-Vis spectrophotometer. IR spectra were recorded on a Perkin Elmer 400 or a Perkin Elmer Spectrum One ATR FT-IR spectrometer. NMR spectra were acquired using a Jeol 400 MHz, a Varian 500 MHz or an Agilent 600 MHz spectrometer. Chemical shifts are given on the δ (ppm) scale, referenced to the residual solvent signal (CDCl₃: δ_H 7.24, δ_C 77.0 or C₆D₆: δ_H 7.16, δ_C 128.0), and J values in Hz. High-resolution mass spectrometric data were measured on an Agilent QTOF 6540 MS system, with electrospray ionisation (ESI) in the positive ion mode, coupled to an Agilent 1290 Infinity UPLC system, operating on the elution gradient: 50% B for 8 min, increasing to 100% B in 3 min, maintaining 100% B for 5 min (solvent A: H₂O + 0.1% formic acid, solvent B: MeCN + 0.1% formic acid), on a Zorbax Eclipse Plus C18 RRHD (50 × 2.1 mm, 1.8 μm) column, at 0.5 mL/min, with UV detection at 200−600 nm. Thin layer chromatography (TLC) was performed with Kieselgel 60 F254 aluminium support plates (Merck) and spots were detected after spraying with 6% vanillin and 15% H₂SO₄ in MeOH reagent. All solvents were of HPLC or LCMS grade and were purchased from Sigma-Aldrich.