Chiral discrimination of ofloxacin enantiomers using DNA double helix regulated by metal ions.

DNA-based chiral selectors are constructed to discriminate ofloxacin enantiomers through metal-ion anchoring on a special DNA double helix that contains successive GC pairs. The effects of metal ions involving Mg(2+), Ni(2+), Cu(2+), Ag(+), and Pt(2+) were studied on the regulation of DNA chiral discrimination towards ofloxacin enantiomers. It is shown that DNA-Cu(II) complexes exhibit the highest enantioselectivities at the [Cu(2+)]/base ratio of 0.1. The enantiomeric excess can reach 59% in R-enantiomer after being adsorbed by the RET-Cu(II) complex. Stereoselective recognition of ofloxacin enantiomers on the double helix is tunable via external stimulus, providing a programmable desorption process to regenerate DNA. This DNA-based chiral selector exhibits excellent reusability without apparent loss of enantioselectivity after three cycles of adsorption and desorption.