Composite nanoparticles based on polymeric deep eutectic solvents modified by carboxymethyl-β-cyclodextrin, as chiral selectors for enantioseparation in capillary electrophoresis

This study is the first to apply polymeric deep eutectic solvents (PDES) for enantioseparation in capillary electrophoresis (CE). We prepared two types of PDESs using poly(diallyldimethylammonium chloride) (PDDA) as the hydrogen bond acceptor and two polyhydroxy compounds as hydrogen bond donors. Due to the stable positive charges of this PDES, it can adsorb negatively charged chiral selectors (carboxymethyl-β-cyclodextrin, CM-β-CD) in the buffer solution, self-assembling to form composite nanoparticles. We characterized the PDES and composite nanoparticles using nuclear magnetic resonance, infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, particle size analysis and the Tyndall effect. The nanoparticles provided a rich platform for chiral separation. We optimized several important separation parameters and successfully separated five chiral drugs. The results indicated that, compared to the single CM-β-CD system, the separation of model drugs was significantly improved in the composite nanoparticles system. Furthermore, we investigated the related chiral recognition mechanism using nuclear magnetic resonance method. The proposed composite nanoparticles exhibit a simple structure, is easy to prepare, and possesses superior separation performance. This research not only broadens the application of DES for enantioseparation in CE but also enriches the variety of chiral functionalized nanomaterials, taking a crucial step towards the development of new chiral recognition materials.