Deep eutectic solvents modified carbon nanotubes as additives for enhanced enantioseparation in capillary electrophoresis

Carbon nanotubes (CNTs) possess many excellent properties; however, their strong hydrophobicity makes it difficult for them to disperse in aqueous solutions, leading to aggregation. Although they are considered to have great potential in capillary electrophoresis (CE) for enantioseparation, this issue still limits their widespread application. In this work, we modified the surface of carboxylated multi-walled CNTs with hydrophilic deep eutectic solvents (DESs) via physical adsorption, preparing DESs@CNTs functional materials as buffer additives in CE. Compared to the single maltodextrin (MD) separation system, the DESs@CNTs modified system exhibited significant advantages in chiral separation. Not only was the resolution of the model drugs increased, but the amount of chiral selectors was reduced. We conducted detailed characterization of DESs@CNTs using several methods such as infrared spectroscopy, nuclear magnetic resonance, X-ray diffraction, and transmission electron microscopy. To achieve better separation, a systematic investigation of several key factors affecting the separation was performed. Additionally, we discussed the potential mechanisms of DESs@CNTs on improving separation by ultraviolet spectroscopy. This study is the first application of DESs@CNTs functional materials in CE chiral separation, laying a solid foundation for the development of novel chiral recognition materials.