Electrochemical chiral recognition of tryptophan enantiomers based on copper-modified β-cyclodextrin

A novel electrochemical chiral sensor was constructed for the discrimination of Tryptophan (Trp) by the modification of [email protected] bimetallic nanoparticles, poly(cysteine) (PL-Cys), and Cu2+-modified β-cyclodextrin (Cu2-β-CD) on the surface of glassy carbon electrode. The constructed sensor was characterized by transmission electron microscopy, infrared spectroscopy, UV–vis adsorption spectra, and the electrochemical experiments. The modified [email protected] endowed the sensor with high surface area and good conductivity. The electropolymerized PL-Cys facilitated the loading of Cu2-β-CD based on the electrostatic interaction. As a chiral selector, Cu2-β-CD enabled the sensor to effectively identify the Trp enantiomers based on the host–guest interaction with a high the oxidation peak current ratio (IL/ID, IL and ID were the oxidation peak currents of l-Trp and d-Trp measured on the sensor, respectively) of 2.38. Under the optimized conditions, IL/ID increased with the increase of l-Trp in the raceme solution, which was further employed for the detection of Trp in serum samples with satisfactory results. With the good selectivity, stability, and reproducibility, the present electrochemical sensor can be used for the simple, rapid, and efficient chiral recognition and real samples determination.