Supramolecular assembly induced chiral interface for electrochemical recognition of tryptophan enantiomers

The beta-CD@PEI-Fc chiral interface was prepared based on the supramolecular host-guest interaction between ferrocene (Fc) grafted polyethyleneimine (PEI-Fc) and chiral beta-cyclodextrin (beta-CD). SEM results show that beta-CD@PEI-Fc interface has a regular spatial structure, which can effectively distinguish tryptophan (Trp) enantiomers. Under the optimal conditions, differential pulse voltammetry shows that the peak current ratio (I-d/I-l) of Trp enantiomers can reach 2.84 at 15 degrees C. More interestingly, the beta-CD@PEI-Fc/GCE exhibited chiral recognition of d-Trp and l-Trp via water contact angle measurements. There was a good linear relationship between the peak current and the concentration of Trp enantiomers in the range from 0.005 mM to 0.10 mM. Finally, the chiral interface can be applied for quick detection of the proportion of isomers in Trp racemic solution, which is very important for chiral recognition in racemic mixture of chiral compounds. Meanwhile, the beta-CD@PEI-Fc/GCE showed good stability and reproducibility.