A sensing interface for recognition of tryptophan enantiomers based on porous cluster-like nanocomposite films

A sensing interface with porous cluster-like nanocomposite films has been fabricated by electrochemical polymerization of L-cysteine on the surface of multi-walled carbon nanotubes (PLC/MWCNTs), and it was characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The nanocomposite films have been used to interact with tryptophan enantiomers (D- and L-Trp), and an obvious difference was achieved in the oxidation peak currents between D-Trp and L-Trp, suggesting that the PLC/MWCNTs could be used as a chiral selector to discriminate the Trp enantiomers. Under the optimum conditions, D-Trp and L-Trp presented a detection limit of 33 μM (S/N = 3), with a linear range of 1.0 × 10−4 M to 1.0 × 10−3 M. The simple method with rapid recognition, excellent stability and reproducibility provided a new perspective to recognize and determine Trp enantiomers.