Development of fluorescent probe for specific recognition of chiral alanine

Amino acids, the building blocks of life, exhibit significant chirality, whereas L-amino acids predominate in living organisms and play essential roles in protein synthesis and other biochemical processes. Although less abundant, D-amino acids play critical roles in forming bioactive compounds such as peptidoglycans in bacterial cell walls and find applications in the pharmaceutical industry and materials science. This study uses optical detection techniques to develop a chiral fluorescence sensor based on binaphthol (BINOL). We present the design and synthesis of the (R)-5 probe, which exhibits exclusive selectivity for D-alanine (Ala) among the 20 chiral amino acids, with a detection limit of 10.7 nM. The enantioselectivity of the probe was confirmed through fluorescence spectroscopy and visual inspection, demonstrating its potential for detecting and quantifying D-alanine (D-Ala) in biological samples. This work lays the foundation for developing sensitive diagnostic tools that rely on D-amino acid levels.