Highly-efficient enantioselective detection of tyrosine enantiomers based on xylose-inulin film

Hydrothermal-assisted assembly of xylose (Xyl) and inulin (Inu) composite was carried out to obtain Xyl-Inu composite. An efficient and enantioselective sensing platform based on Xyl-Inu composite modified glassy carbon electrode (Xyl-Inu/GCE) for tyrosine (Tyr) was constructed. The chiral recognition of Tyr enantiomers at Xyl-Inu/GCE was evaluated via square wave voltammetry (SWV). Under the optimal experimental conditions, the oxidation peak current ratio (I_L/I_D) and peak potential difference (ΔEp = E_D^_ E_L) of Xyl-Inu/GCE for L-Tyr and D-Tyr were 2.22 and 36 mV, respectively. The DFT theoretical calculation revealed that the hydroxyl (-OH) groups of Xyl-Inu/GCE would selectively form hydrogen bonds with the amino/carboxyl/phenolic hydroxyl groups of Tyr enantiomers due to the steric hindrance effects, resulting in difference in peak currents and peak potentials between L-Tyr and D-Tyr is generated. Xyl-Inu/GCE exhibits higher affinity for L-Tyr, and lower oxidation peak potential and higher oxidation peak current would be found. In addition, a good linear relationship between peak current and concentration of Tyr in the range 0.01-1.00 mM could be observed. At the signal-to-noise ratio of 3 (S/N = 3), the limit of detection (LOD) was 0.97 μM for L-Tyr and 2.32 μM for D-Tyr, respectively. More importantly, the chiral sensor could predict the percentage of L-Tyr in Tyr mixtures. Furthermore, the chiral sensor Xyl-Inu/GCE exhibited high anti-interference ability, good repeatability and excellent reproducibility. The developed chiral sensor of Xyl-Inu/GCE has great potential in the practical recognition and determination of Tyr enantiomers.