Visual and Colorimetric High-Throughput Analysis of Chiral Carboxylic Acids Based on Enantioselective Charge Shielding of Gold Nanoparticles

Because chiral carboxylic acids (CCAs) are a class of important biological molecules and common functional moieties found in pharmaceutical molecules, the chiral analysis of CCAs has received much attention. Herein, we developed a simple, rapid, and cost-effective method for visual and colorimetric high-throughput analysis of CCAs using chiral di-imine structure-modified gold nanoparticles (C-AuNPs) as the probe. The C-AuNPs are positively charged in the presence of zinc ion, and they can be enantioselectively shielded by the negatively charged CCA enantiomers. Therefore, upon the addition of different concentrations and enantiomeric excess (ee) of CCAs, the C-AuNP-based sensor shows the different levels of aggregation along with the visual changes in solution color, which can achieve simultaneous analysis of the concentration and ee of CCAs. The chiral recognition mechanism based on C-AuNPs was investigated by the determination of binding constants (K) and molecular simulation methods. Our approach is expected to have the wide-ranging applications in the developing region for enantio-sensing of various chiral drugs and biomolecules.