Engineering Chiral Confinement Environment in Polyoxometalate Intercalated Graphene Oxide Sensor for Electrochemical Enantioselective Recognition

Abstract

The electrochemistry recognition of enantiomeric chiral molecules holds great significance for the pharmaceutical industry and scientific research. However, enhancing sensitivity and selectivity simultaneously, and elucidating chiral recognition mechanism, are two primary challenges. Here, an electrochemical chiral sensor L-C₄-PMoV/GO is developed by confining chiral imidazole cations (L-C₄) and [PMo₁₀V₂]⁵⁻ (PMoV) signal anions within the interlayer of graphene oxide (GO). The L-C₄-PMoV/GO is highly sensitive to recognition towards the chiral drug Levodopa (L-DOPA), which exhibits 16 times higher than the L-C₄/GO. In addition, the enantioselectivity of ΔS = 19.92 is achieved. Mechanism studies suggest that the chiral confinement effect plays a crucial role in the synergism between the signal site PMoV and the enantioselectivity L-C₄. In the chiral-confined microenvironment, the chiral induction from L-C₄ to PMoV is facilitated, which results in the distortion of Mo (V)─O bonds. The hydrogen-bonding networks among the L-C₄, Mo (V)─O, and DOPA generate the adsorption energy difference between the L/D-DOPA, as revealed by the in situ Raman spectroscopy and theoretical calculation. Compared to the conventional techniques, the electrochemical sensor shows comparable enantiomer excess (ee) value determination, low limits of detection (LOD) (6.7 nm for L-DOPA, 50.6 nm for D-DOPA), and portability, enabling practical chiral recognition.