Synthesis and application of amino triazolium-modified lactobionic acid as chiral selector in capillary electrophoresis

Amino acids-based deep eutectic solvents as additives for improved enantioseparation in capillary electrophoresis

In this study, several amino acids deep eutectic solvents were prepared using L-valine and L-leucine as hydrogen bond acceptors, and L-lactic acid and glycerol as hydrogen bond donors. These amino acids' deep eutectic solvents were first used as buffer additives to construct several synergistic systems along with maltodextrin in capillary electrophoresis for the enantioseparations of four racemic drugs. Compared with single maltodextrin system, the separations of model drugs in the synergistic systems were significantly improved. Some key parameters affecting chiral separation such as maltodextrin concentration, deep eutectic solvent concentration, buffer pH, and applied voltage were optimized. In order to further understand the specific mechanism of the amino acids deep eutectic solvents in improving chiral separation, we first calculated the binding constants of maltodextrin with enantiomers using the capillary electrophoresis method in the two separation modes, respectively. We also used molecular simulation to calculate the binding free energy of maltodextrin with enantiomers. It is the first time that amino acids deep eutectic solvents were used for enantioseparation in capillary electrophoresis, which will greatly promote the development of deep eutectic solvents in the field of chiral separation.

Revelation of the Electrochemical Chiral Recognition of l-Proline-Tuned Zr-MOFs

Chirality plays an extremely important role in nature. In this work, a highly ordered and non-clustered crystalline material UiO-88-LP was synthesized by using l-proline (l-Pro)-tuning Zr-MOF and the solvothermal method, which was then modified on the glassy carbon electrode (GCE) to construct an electrochemical chiral interface for the recognition of tryptophan (Trp) configuration. UiO-88-LP composites were characterized by scanning electron microscopy, X-ray transmission diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy. After optimization of the experimental conditions, redox peaks for l-Trp and d-Trp were clearly observed at the UiO-88-LP/GCE electrochemical sensing interface with a peak-to-current ratio (IL/ID) of 2.47. The peak current was positively correlated with the concentration of Trp. The electrochemical recognition behavior of l-Trp and d-Trp was investigated by differential pulse voltammetry. The electrochemical characterization showed that UiO-88-LP/GCE had an enantiomeric resolution of amino acids. The recognition mechanism showed that l-Pro entering the UiO-66 molecular cage provided a site for the system to be recognized, so the purpose of recognition was achieved. The relevant data provide theoretical support for the practical application of UiO-88-LP in electrochemical sensors.

Evaluation of kasugamycin as a chiral selector in capillary electrophoresis

The discovery of novel chiral selectors always fascinates us. This work describes the chiral separation performances of a new chiral selector (kasugamycin, KAS) in capillary electrophoresis (CE) for six pairs of stereoisomers, including ephedrine and pseudoephedrine, quinine and quinidine, cinchonine and cinchonidine, and amlodipine, promethazine and ofloxacin enantiomers. Kasugamycin, an aminoglycoside antibiotic in agriculture, shows significant biological activity against rice blast with low toxicity. As it turns out, this new chiral selector possesses good CE compatibility and stereoselectivity towards model analytes. In this work, we systematically investigated several separation parameters including kasugamycin concentration, buffer pH, separation voltage and the composition of the buffer solution. A detailed discussion about the chiral recognition mechanism was made based on Statistical Product and Service Solution (SPSS) analysis, NMR experiments (1D and 2D) and molecular modeling. This is the first time that kasugamycin is utilized as a chiral selector in CE, and the development of new chiral selectors from agricultural or veterinary antibiotics deserves more attention.

Chiral Recognition for Chromatography and Membrane-Based Separations: Recent Developments and Future Prospects

With the rapid development of global industry and increasingly frequent product circulation, the separation and detection of chiral drugs/pesticides are becoming increasingly important. The chiral nature of substances can result in harm to the human body, and the selective endocrine-disrupting effect of drug enantiomers is caused by differential enantiospecific binding to receptors. This review is devoted to the specific recognition and resolution of chiral molecules by chromatography and membrane-based enantioseparation techniques. Chromatographic enantiomer separations with chiral stationary phase (CSP)-based columns and membrane-based enantiomer filtration are detailed. In addition, the unique properties of these chiral resolution methods have been summarized for practical applications in the chemistry, environment, biology, medicine, and food industries. We further discussed the recognition mechanism in analytical enantioseparations and analyzed recent developments and future prospects of chromatographic and membrane-based enantioseparations.

Advances of capillary electrophoresis enantioseparations in pharmaceutical analysis (2017-2020)

Capillary electrophoresis is a powerful technique for the analysis of polar chiral compounds and has been widely accepted for analytical enantioseparations of drug compounds in pharmaceuticals and biological media. In addition, many mechanistic studies have been conducted in an attempt to rationalize enantioseparations in combination with spectroscopic and computational techniques. The present review will focus on recent examples of mechanistic aspects and summarize recent applications of stereoselective pharmaceutical and biomedical analysis published between January 2017 and November 2020. Various separation modes including electrokinetic chromatography in combination with several detection modes including laser-induced fluorescence, mass spectrometry and contactless conductivity detection will be discussed. A general trend also observed in other analytical techniques is the application of quality by design principles in method development and optimization.

Enantioseparation of amino alcohol drugs by nonaqueous capillary electrophoresis with a maltobionic acid-based ionic liquid as the chiral selector

This study deals with the nonaqueous capillary electrophoretic enantioseparation of twenty-two amino alcohol drugs with a maltobionic acid (MA)-based ionic liquid (tetramethylammonium maltobionic acid, TMA-MA) as the novel chiral selector.