Humic acid-based biomass-derived magnetic nanocomposites modified by a deep eutectic solvent for the efficient adsorption of trypsin

Abstract

A novel humic acid-based biomass-derived magnetic nanocomposite (Fe₃O₄-HA@[TEAC][G]), which was modified by a tetraethylammonium chloride/glycerol ([TEAC][G]) deep eutectic solvent, was synthesized. Combined with magnetic solid phase extraction technology, Fe₃O₄-HA@[TEAC][G] was applied to separate trypsin (Tryp) after being systematically characterized. Under optimal adsorption conditions, the adsorption capacity of Fe₃O₄-HA@[TEAC][G] for Tryp was higher than 1300 mg g⁻¹. Simultaneously, the adsorption isotherm fitting test showed that the relationship between Tryp and Fe₃O₄-HA@[TEAC][G] matched well with the Langmuir adsorption model, which belonged to monolayer adsorption. Methodological research verified that the assay work for Tryp separation had good limits of detection (LOD) and quantification (LOQ), which were 0.033 mg mL⁻¹ and 0.11 mg mL⁻¹, respectively. In addition, methodological results showed that the extraction method had excellent stability, instrumental precision and repeatability. SDS-PAGE electrophoresis results proved that the Fe₃O₄-HA@[TEAC][G] extractant could extract Tryp from the actual crude extract of bovine pancreas. In conclusion, the humic acid-based biomass-derived magnetic nanocomposite prepared in this study has an exciting potential application value in the pretreatment of Tryp samples.