Nanoassembly of l-Threonine on Helical Carbon Tubes for Electrochemical Chiral Detection of l-Cysteine

Highly efficient recognition and detection of chiral molecules with similar structures are of great significance in the fields of medicine and biochemistry. In this study, strobili fibers of the plane tree were carbonized at high temperatures to prepare hollow chiral helical carbon tubes (HCT). Subsequently, l-threonine (l-Thr) was nanoassembled on the HCT surface (l-Thr@HCT) through hydrogen bonding and electrostatic interactions. Benefiting from the synergistic effect of conductive HCT with inherent chirality and l-Thr with abundant chiral sites, the electrode demonstrates a satisfied recognition efficiency of 3.20 for the cysteine (Cys) enantiomer. The l-Thr@HCT/GCE electrode exhibits a lower affinity toward l-Cys than d-Cys, thereby facilitating the diffusion of l-Cys to the electrode surface and exhibiting excellent selectivity for l-Cys. Under the optimal conditions, the electrode has a high sensitivity of 1.74 μA·mM–1 for l-Cys with a low detection limit of 8.58 μM (S/N = 3). Moreover, the electrode has good repeatability, reproducibility, and stability. This electrode will have a potential clinical application in chiral sensing.