▎ 摘　　要

To mimic the enantioselectivity of an enzyme in the field of biosensor for a drug molecule is daunting task for chiral selector. Here, we report beta cyclodextrin (beta-CD) as artificial enzyme model for molecular recognition of Clopidogrel (CLP) isomers on chiral carbon paste electrode. The inclusion of CLP enantiomers was initiated by beta-CD and stability constants obtained for 1:1 complex of beta-CD-R-CLP and beta-CD-S-CLP. The stability constants calculated for beta-CD-R-CLP and beta-CD-S-CLP were 6.109 x 10(3)M(-1) and 5.023 x 10(2) M-1, respectively at 25 degrees C. The best enantioselectivity was obtained for R-CLP which was found to be 12 times higher to that of S-CLP. The thermodynamic consideration of the complex formation shows negative values of Gibbs free energy (Delta G)-21.602 kJ K-1 mol(-1) (R-CLP) and - 15.411 kJ K-1 mol(-1) (S-CLP) which indicates inclusion process to be exothermic and spontaneous. The difference in AG values indicates effective enantiomeric recognition of the aforementioned electrode systems for CLP. The synergistic effect of graphene, platinum nanoparticle and beta cyclodextrin in the form of modified carbon paste electrode (GNS-PNP-beta-CD-CPE) were studied by differential pulse voltanunetric techniques. The anodic peak potential difference of 102 mV was able to discriminate isomers of CLP at the surface of GNS-PNP-beta-CD-CPE. Under optimum conditions, R-CLP and S-CLP exhibited good linear response in the range of 2.0 x 10(-6) to 2.0 x 10(-4) M with low detection limit of 4.87 x 10(-7) M and 2.10 x 10(-7) M, respectively. The Michaelis-Menten constants (K-M) calculated for R-CLP and S-CLP were 44.0 mu M and 60.0 mu M employing chronoamperometry. The higher value of K-M for S-CLP suggests weak binding of S-CLP to the beta-CD confirming catalytically different biotransformation rate of each enantiomer towards oxidation. Although the kinetic parameters do not match the level of enzymatic transformations, this study predicts the Michaelis-Menten constants for CLP using beta-CD which may become useful guide for future exploration of enzyme mimics in the area of chiral electrochemical biosensor.