Vancomycin-Stabilized Copper Nanoclusters: Isolation by Solid-Phase Extraction and Application in Chiral Capillary Electrophoresis

Utilizing state-of-the-art nanomaterials for chiral discrimination is an emerging area of analytical research. Herein, we explored for the first time, metal nanoclusters as a chiral selector in capillary electrophoresis. Vancomycin-stabilized copper nanoclusters (CuVanc NCs) were intentionally synthesized, purified and characterized by UV-Vis and fluorescence spectroscopy, transmission electron microscopy, dynamic light scattering, and X-ray photoelectron spectroscopy. The 5-step sequential protocol of solid-phase extraction was designed to isolate CuVanc NCs from the as-synthesized solution before electrophoretic experiments. The recovery was found to be over 90%. The purified CuVanc NCs were utilized as a chiral discriminator for enantioselective recognition of model drugs. The effects of key parameters, including the pH value of the running buffer and concentration of CuVanc NCs, were assessed. Chiral separation was successfully achieved for both positively and negatively charged analytes, with the better enantioselectivity observed for amlodipine (α = 1.017) and acenocoumarol (α = 1.015), respectively. The separation behavior was strongly influenced by the background electrolyte pH and nanocluster concentration, balancing electrostatic interactions and electrophoretic mobility. Overall, the study highlights a high potential of metal nanoclusters as effective chiral selectors in capillary electrophoresis, opening up new opportunities for chiral analysis and pharmaceutical quality control.