Novel N-Doped Carbon Dots/β-Cyclodextrin Nanocomposites for Enantioselective Recognition of Tryptophan Enantiomers

Based on N-doped carbon dots/beta-cyclodextrin nanocomposites modified glassy carbon electrodes (N-CDs/beta-CD/GCE), an effective electrochemical sensor for enantioselective recognition of tryptophan (Trp) enantiomers was developed by differential pulse voltammograms (DPVs). Fluorescent N-CDs were synthesized through a hydrothermal method and characterized by spectroscopic approaches. The N-CDs/beta-CD nanocomposites were efficiently electrodeposited on the surface of GCE through C-N bond formation between N-CDs and electrode. The obtained N-CDs/beta-CD/GCE was characterized by multispectroscopic and electrochemical methods. Such N-CDs/beta-CD/GCE generated a significantly lower Ip and more negative Ep in the presence of L-Trp in DPVs, which was used for the enantioselective recognition of Trp enantiomers. The N-CDs/beta-CD nanocomposites showed different binding constants for tryptophan enantiomers, and they further selectively bonded with L-Trp to form inclusion complexes. This N-CDs/beta-CD/GCE combined advantages of N-CDs with strong C-N binding ability and beta-CD with specific recognition of Trp enantiomers to fabricate a novel sensing platform for enantioselective recognition of Trp enantiomers. This strategy provided the possibility of using a nanostructured sensor to discriminate the chiral molecules in bio-electroanalytical applications.