Chiral Nitrogen-Doped Graphene Quantum Dot Electrochemical Sensor for Recognition of Tartaric Acid Isomers

Chirality is a basic attribute of object in three-dimensional space, and the phenomenon of chirality exists widely in nature. By covalently grafting L/D-cysteine to nitrogen-doped graphene quantum dots (NGQDs) through amide reaction, a new type of chiral NGQDs was obtained. Its morphology was characterized by transmission electron microscope, and its structure and composition were determined by X-ray powder diffraction, infrared spectroscopy, raman spectroscopy, ultraviolet spectroscopy and X-ray photoelectron spectroscopy. In the linear cyclic voltammetry test, it is found that chiral NGQDs have different peak current values in different configurations of tartaric acid, and the changes in the peak current intensity can specifically identify L/D-tartaric acid isomers. There are two identical asymmetric carbon atoms in the tartaric acid molecule, which is a by-product of the wine industry. Due to its low price, it is often used to resolve other racemates, such as epinephrine and chloramphenicol. Through the method of molecular simulation and docking calculation, the combination of chiral graphene quantum dots and tartaric acid was studied, and the mechanism of chiral recognition was discussed. This work broadens the application range of graphene quantum dots and provides new ideas for the preparation of chiral inorganic nanomaterials.