Highly selective and efficient recognition of tyrosine enantiomers at Au NPs/D-sorbitol/GCE-based chiral sensor

Electrochemical sensors have been considered as one of the most important methods to determine amino acid (AA) enantiomers. An interesting and highly-efficient electrochemical sensor, gold nanoparticles/D-sorbitol modified glass carbon electrode (Au NPs/D-sorbitol/GCE), was developed for the chiral recognition of Tyrosine (Tyr) enantiomers. Au NPs/D-sorbitol/GCE sensor exhibited excellent chiral recognition efficiency for Tyr enantiomers (I L /I D  = 1.99, ∆Ep = 36 mV) by square wave voltammetry (SWV). The possible recognition mechanism was also proposed by cyclic voltammetry (CV) at different scanning rates, wettability measurements, and density-functional theory (DFT) calculations. The smaller steric hindrance and more suitable molecular distance are beneficial to the selective formation of hydrogen bonds between L-Tyr and the chiral interface of the sensor. The energy difference caused by the formation of hydrogen bonds between the chiral interface and Tyr enantiomers can be expressed as different peak currents to achieve chiral recognition. The redox peak current of Tyr enantiomers at Au NPs/D-sorbitol/GCE showed good linear relationship with their concentration, and the limits of detection (LOD) were calculated to be 4.12 μM and 8.07 μM for L-Tyr and D-Tyr, respectively. Importantly, Au NPs/D-sorbitol/GCE can also predict the mass ratios of L-Tyr in the enantiomeric mixtures. In addition, the sensor has shown good anti-interference ability, high stability, and excellent reproducibility.