A selective electrochemical chiral interface based on a carboxymethyl-β-cyclodextrin/Pd@Au nanoparticles/3D reduced graphene oxide nanocomposite for tyrosine enantiomer recognition.

Palladium@gold nanoparticle modified three-dimensional-reduced graphene oxide (3D-rGO/Pd@Au) was coupled with carboxymethyl-β-cyclodextrin to form a novel nanocomposite (3D-rGO/Pd@Au/CM-β-CD). The 3D-rGO/Pd@Au/CM-β-CD served as a chiral sensing interface for the electrochemical enantiorecognition of tyrosine (Tyr) via a differential pulse voltammetry (DPV) approach. The 3D-rGO/Pd@Au demonstrates good electrical conductivity and efficient catalytic activity as an electrochemical indicator. Simultaneously, the CM-β-CD displays a supramolecular chiral selectivity to reveal a higher binding affinity to the target L-tyrosine (L-Tyr) than to D-tyrosine (D-Tyr). Under the optimized determining conditions, the oxidation peak current ratio of L-Tyr to D-Tyr ( I L / I D ) was 2.12, meanwhile, the peak currents of the two isomers were linearly proportional to the concentration over the range of 0.8-130 μM with LODs of 52 nM and 96 nM for L- and D-Tyr (S/N = 3), respectively. This approach exhibits distinguished sensitivity, excellent selectivity and good reproducibility, as well as great stability, which can accurately determine the relative content of L- or D-Tyr enantiomers in a racemic solution.