Use of cyclodextrin-modified gold nanoparticles for enantioseparations of drugs and amino acids based on pseudostationary phase-capillary electrochromatography

The application of chemical-modified gold nanoparticles (GNPs) as chiral selector for the enantioseparation based on pseudostationary phase-CEC (PSP-CEC) is presented. GNPs modified by thiolated β-CD were characterized by NMR and FT-IR. The nanoparticle size was determined to be of 9.5 nm (+2.5 nm) by Transmission Electron Microscopy (TEM) and UV spectra. Four pairs of dinitrophenyl-labeled amino acid enantiomers (DL-Val, Leu, Glu and Asp) and three pairs of drug enantiomers (RS-chlorpheniramine, zopiclone and carvedilol) were analyzed by using modified GNPs as the chiral selector in PSP-CEC. Good theoretical plate number (up to 2.4x10⁵ per meter) and separation resolution (up to 4.7) were obtained even with low concentration of modified GNPs (0.8-1.4 mg/mL). The corresponding concentration of β-CD in the buffer was only 0.30-0.53 mM, which was much lower than the optimum concentration of 15 mM if pure β-CD was used as chiral selector. Our results showed that thiolated β-CD modified GNPs have more sufficient interaction with the analytes, resulting in significant enhancement of enantioseparation. The study shed light on potential usage of chemical modified GNPs as chiral selector for enantioseparation based on PSP-CEC.