L-Proline-Stabilized Copper Nanoclusters: Synthesis, Optical Properties, and Testing in Bioanalysis by Fluorimetry and Capillary Electrophoresis

A method for synthesizing copper nanoclusters stabilized by L-proline is optimized by varying the molar ratio of reagents and the holding time of the reaction mixture. The obtained nanoclusters are characterized using absorption and fluorescence spectroscopy, transmission electron microscopy, and high-performance liquid chromatography. L-proline-stabilized copper nanoclusters exhibit intense luminescence in the 450-nm region. Using model drug mixtures, the interaction of copper nanoclusters with a wide range of bioactive molecules is studied using capillary electrophoresis. Milnacipran exhibits a significant change in electrophoretic mobility, which indicates its binding to the nanoclusters. Fluorimetric measurements reveal a linear dependence of the fluorescence quenching coefficient on the concentration of milnacipran, which enables its quantitative detection in the concentration range of 0.4–10 μM.