A sensitive electrochemical probe for the chiral identification of tryptophan isomers with carbon dot/chitosan composites

Reliable chiral recognition of tryptophan (Trp) enantiomers via a portable strategy is extremely important and highly desirable in life science, food science and analytical chemistry. Herein, a sensitive probe for the chiral electrochemical recognition of Trp isomers was designed by combining chiral selectors of carbon dots (CDs), chitosan (CS) and the conductive agent of carbon black (CB). Detailed characterization studies, including SEM, XPS, XRD, CV, EIS and DPV, were carried out to study the chemical structure and electrochemical behaviors of the sensing materials. The proposed sensing platform (CD–CS/CB/GCE) displayed higher affinity for L-Trp, and the enantiomer selection coefficient (I_D/I_L) was 2.18 under the optimized detection conditions, with lower detection limits of 0.655 μM for L-Trp and 0.306 μM for D-Trp. Additionally, the designed sensing platform is suitable for real sample analysis and determines the ratio of isomers of Trp with satisfactory recoveries and reproducibility.