A rapid and sensitive method for chiroptical sensing of α-amino acids via click-like labeling with o-phthalaldehyde and p-toluenethiol

A highly practical method for comprehensive chiroptical sensing of free alpha amino acids with streamlined operation and high sensitivity via dual CD/UV measurements is developed. The assay takes advantage of an efficient and selective three-component labeling reaction of primary amines with o-phthalaldehyde and p-toluenethiol reagents to derivatize the NH2 group of analytes into an isoindole. The covalent labeling generates sensitive UV and CD readouts, both of which show an excellent linear relationship with the concentration of analytes. The high reactivity and the novel optical reporting mechanism allow fast and accurate measurement without background interference. The sensing assay works well for a remarkably broad range of analyte concentrations, with an unprecedented lower limit of 10 micromolar concentration.

Automated summary

A practical method for chiroptical sensing of free alpha amino acids has been developed, utilizing a three-component labeling reaction to derivatize analytes into an isoindole for sensitive CD and UV readouts. The assay shows high selectivity and accuracy across a wide range of concentrations, with a unprecedented lower limit of 10 micromolar concentration.