A chiroptical nanoprobe for highly selective recognition of histidine enantiomers in aqueous media

Histidine is one of the essential amino acids in the human body, and the variation of its concentration in vivo has shown it to align with some liver and kidney diseases. In this work, a series of novel poly(2-oxazoline) derivatives bearing chiral pyrrolidine-triazole moieties in the side chain were designed and synthesized to serve as chemical sensors for histidine. The results demonstrated that the homopolymer HPOx2 is capable of selectively binding optically active histidine through nitrogen/Cu2+ coordination to form complexes exhibiting induced circular dichroism (ICD) signals with signs related to the absolute configuration of the guest compound. Interestingly, the micelle-type nanoparticles assembled from the corresponding amphiphilic copolymer (CPOx2) gave a much stronger CD response, with an intensity five times that of its small molecule- or homopolymer counterparts. The proposed method, based on the chiroptical probe, allows for enantioselective detection of histidine in aqueous media, showing potential application in the field of biomedical assay and chiral drug synthesis.