A green deep eutectic solvent modified magnetic titanium dioxide nanoparticles for the solid-phase extraction of chymotrypsin.

Magnetic titanium dioxide nanoparticles modified with green deep eutectic solvent (DES) composed of choline chloride (ChCl) and xylitol (Xyl) (FeO@TiO@[ChCl][Xyl]) were synthesized and applied to the solid-phase extraction(MSPE) of chymotrypsin (Chy). The physicochemical properties and morphology of FeO@TiO@[ChCl][Xyl] was characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Zeta potential, X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and transmission electron microscope (TEM). The experiment parameters such as initial concentration of Chy, extraction time, pH value, ionic strength, extraction temperature and sample matrix were effectively optimized. Under the optimal experimental conditions, the extraction capacity of FeO@TiO@[ChCl][Xyl] obtained a significantly improvement after the modification of FeO@TiO nanoparticles by [ChCl][Xyl], and reached up to 347.8 mg g. In the elution experiment, 10% sodium dodecyl sulfate-acetic acid (SDS-HAc) was used as eluent, achieving an elution rate of 85.9% for the Chy on FeO@TiO@[ChCl][Xyl]. And the FeO@TiO@[ChCl][Xyl] still maintained a good extraction capacity for Chy after six times of reuse. The application result in the extraction of Chy from porcine pancreas crude extract showed a good practical application ability for Chy extraction. All the results indicated that the synthesized FeO@TiO@[ChCl][Xyl] has good application potential in the extraction of biomolecular molecules such as protein.