Recognizing chiral amino acids with a dual-optical-response system

Chiral amino acids are crucial for humans, and their recognition can provide information for pharmaceutical quality and clinical diagnosis. Histidine (His) and tryptophan (Trp), for example, have a close association with nephropathy and are extensively utilized in the pharmaceutical field. However, efficiently distinguishing these two amino acids and their configurations is still in its infancy, requiring the development of a practical, cost-effective, and reliable detection method. Herein, we disclose a dual-optical-response recognition system, composed of 9-aminoacridine and cellulose nanocrystals, that can stepwise recognize His/Trp and their enantiomers based on photoluminescence and circular dichroism (CD) analysis. Amino acids cause variation in the fluorescence intensity of the DOR system, while their enantiomers give distinctive shifts in CD spectra. This study achieves a stepwise recognition of chiral amino acids, paving a new way for drug screening and clinical diagnosis.