Highly selective tryptophan enantiomers electrochemical chiral sensor based on poly-lysine and functionalized multi-walled carbon nanotubes

A novel electrochemical chiral sensor was reported for recognizing tryptophan enantiomers based on multi-walled carbon nanotubes functionalized by 3,4,9,10-perylenetetracarboxylic acid binding with the l-lysine (MWCNTs-PTCA-PLL) via electropolymerization. The electrochemical behaviors of the proposed sensors were then characterized by cyclic voltammetry (CV). Differential pulse voltammetries (DPVs) were applied to investigate the stereoselective recognition of tryptophan (Trp) enantiomers. d-Trp and l-Trp showed different responses in DPVs, and a larger selectivity was obtained from d-Trp. pH level and the effect of the incubation time on the chiral recognition were also investigated for optimizing experimental parameters. In addition, the results of analyzing percentage composition revealed this sensor was able to determine the enantiomeric mixtures. The novel strategy with high stability, good sensitivity, and selective characteristics had opened up a new avenue to recognize Trp enantiomers.