Voltammetric chiral discrimination of tryptophan using a multilayer nanocomposite with implemented amino-modified β-cyclodextrin as recognition element
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An electrochemical chiral multilayer nanocomposite was prepared by modifying a glassy carbon electrode (GCE) via opposite-charge adsorption of amino-modified β-cyclodextrin (NH2-β-CD), gold-platinum core-shell microspheres (Au@Pts), polyethyleneimine (PEI), and multi-walled carbon nanotubes (MWCNTs). The modified GCE was applied to the enantioselective voltammetric determination of tryprophan (Trp). The Au@Pts enable an effective immobilization of the chiral selector (NH2-β-CD) and enhance the electrochemical performance. Scanning electron microscopy, transmission electron microscopy, UV-vis spectroscopy, FTIR and electrochemical methods were used to characterize the nanocomposite. Trp enantiomers were then determined by differential pulse voltammetry (DPV) (with a peak potential of +0.7 V vs. Ag/AgCl). The recognition efficiency was expressed by an increase in peak height by about 32% for DPV determinations of L-Trp compared to D-Trp in case of a 5 mM Trp solution of pH 7.0. Response was linear in the 10 μM to 5.0 mM concentration range, and the limits of detection were 4.3 μM and 5.6 μM with electrochemical sensitivity of 43.5 μA·μM−1·cm−2 and 34.6 μA·μM−1·cm−2 for L-Trp and D-Trp, respectively (at S/N = 3).
KeywordsElectrochemistry Chiral recognition Tryptophan enantiomers Gold-platinum core-shell microspheres Amino-β-cyclodextrin Multi-walled carbon nanotubes Polyethyleneimine Opposite-charged adsorption Differential pulse voltammetry Glassy carbon electrode
The authors gratefully acknowledge financial support for this study by the National Natural Science Foundation of China (No. 21272188).
Compliance with ethical standards
The authors declare that they have no competing interests.
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