Zinc oxide/vancomycin-based electrochemical chiral sensor for the recognition of penicillamine enantiomers

Abstract

In this study, an electrochemical chiral sensor based on Zinc oxide/vancomycin-modified indium tin oxide glass substrate (ZnO/Van/ITO) was successfully fabricated and used in the chiral recognition of penicillamine (Pen) enantiomers. The preparation of the modified electrode was a two-step procedure in which electrodeposition of ZnO was conducted first on the ITO glass substrate. The deposition parameters were conducted at-0.9 V, in a buffer solution of pH 7 at 60 °C for 900 s. The second part of the procedure involved drop casting Van on the surface of the ZnO/ITO modified electrode. Different oxidation peak current, Ip of L-and D-Pen were observed in the differential pulse voltammograms (DPV). Under optimal condition, the chiral sensor exhibited good linear response to Pen enantiomers in a linear range of 5 mM to 30 mM with a detection limit of 23.56 mM and 14.73 mM (S/N=3) for the D-Pen and L-Pen, respectively. The modified electrode fabricated possessed exceptional performance of having low detention limit and good enantioselectivity for Pen enantiomers. The association constant from the experiment, KD and KL obtained were 2.314 x 103 L/mol and 1.076 x103 L/mol for the D and L-Pen, respectively. The value of KD was larger compared to KL indicating that the binding effect is higher between ZnO/Van with D-Pen. The findings suggested that this proposed chiral sensor has the ability to discriminate Pen enantiomers which can bring good use in the pharmaceutical industries.