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

Abstract

An electrochemical chiral sensing platform was fabricated by successive modification of Au@Pt bimetallic nanoparticles, poly(cysteine), and Cu 2 -β-CD on the surface of glassy carbon electrode. Good conductivity and high surface area of Au@Pt endowed the sensor with high sensitivity. Cu 2 -β-CD enabled the sensor to effectively identify tryptophan (Trp) enantiomers upon the host–guest interaction with a high the oxidation peak current ratio (I L /I D ) of 2.38. Thus, the simple and efficient sensor can be used for the discrimination of Trp enantiomers. • Cu 2 -β-CD can discriminate Trp enantiomers based on the host–guest interaction. • Au@Pt bimetallic nanoparticles improved the sensitivity of the sensor. • Sensor showed excellent enantioselectivity toward Trp enantiomers. • Facile preparation facilitates the present approach promising. A novel electrochemical chiral sensor was constructed for the discrimination of Tryptophan (Trp) by the modification of Au@Pt bimetallic nanoparticles, poly(cysteine) (PL-Cys), and Cu 2+ -modified β-cyclodextrin (Cu 2 -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 Au@Pt endowed the sensor with high surface area and good conductivity. The electropolymerized PL-Cys facilitated the loading of Cu 2 -β-CD based on the electrostatic interaction. As a chiral selector, Cu 2 -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 (I L /I D, I L and I D were the oxidation peak currents of l -Trp and d -Trp measured on the sensor, respectively) of 2.38. Under the optimized conditions, I L /I D 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.