Engineering Gold Nanoparticles with DNA Ligands for Selective Catalytic Oxidation of Chiral Substrates

Noble metal nanoparticles are promising materials for heterogeneous enantioselective catalysis because of their high surface-to-volume ratios, large concentrations of highly undercoordinated surface sites, and quantum confinement effects. In this work, we report on the use of DNA as an environment-responsive chiral ligand to engineer the selective catalytic behaviors of glucose oxidase-mimicking gold nanoparticles (AuNPs), with glucose enantiomers as the substrates. DNA can be stimulated externally to switch between random-coiled and multistranded structures (e.g., duplex, i-motif, or G-quadruplex). Random-coiled DNA-capped nanoparticles preferentially catalyze oxidation of l-glucose, and structured DNA-capped nanoparticles show higher activity toward d-glucose. pH-induced selectivity diminishment of DNA-treated AuNPs is also found, further demonstrating the chiral selector effect of DNA ligands. In the end, the selective catalysis of AuNPs allows control of the size enlargement of nanoparticles through self-catalytic Au-0 deposition, in ligand- and substrate chirality-dependent manners. It is found that the effect of substrate chirality on the self-growth rate can be reversed by the hybridization of the capping DNA. The structural and chemical features of DNA grooves in the multistranded structures render binding sites with higher affinity to D-glucose than L-glucose. The results suggest a simple strategy for engineering the responsive enantioselective catalysis of metallic nanoparticles and advance the understanding of chiral interactions between nucleic acids and saccharide.