Nano-molecular dual-dimensional collaborative sensor for chiral amino acid discrimination and mechanism insights

In this study, nanoscale Fe-N co-doped L/D chiral carbon nanotubes (Fe-N-L/D-CCNTs) were combined with molecular-level L/D histidine adsorbed metal-organic framework (L/D-His-ZIF-8) to construct a highly efficient nano-molecular dual-dimensional chiral recognition biosensor (Fe-N-L/D-CCNTs@L/D-His-ZIF-8), which was used for detecting chiral amino acids (AAs) and providing mechanistic insights. In this biosensor, Fe-N-L/D-CCNTs served as the substrate, and L/D-His-ZIF-8 acted as the chiral recognition molecule. The synergetic effect of both components enhanced chiral recognition performance for tryptophan (Trp), tyrosine (Tyr), and cysteine (Cys) enantiomers. Fe-N-L/D-CCNTs@L/D-His-ZIF-8 identified Tyr enantiomers with detection limits of as low as 10.5 nM and 14.4 nM, with I_D-Tyr/I_L-Tyr and I_L-Tyr/I_D-Tyr ratios up to 2.78 and 2.26, respectively. This performance, which was also observed in Trp and Cys detections, confirmed the excellent chiral recognition performance of Fe-N-L/D-CCNTs@L/D-His-ZIF-8. In addition, density functional theory (DFT) was performed to elucidate the mechanism of the chiral biosensor recognition for L/D-amino acids (AAs). The biosensor realized efficient analysis and detection of actual samples, exhibiting good selectivity, reproducibility, and stability. The findings of this study broaden the scope of chiral amino acid identification, provide an experimental and theoretical basis for the design of novel multi-dimensional chiral recognition biosensors, and carry significant implications in drug screening, clinical diagnosis, and life science.