Drop-coated molybdenum disulfide-ionic liquid for improving the electrochemical chiral recognition ability of chitosan

A faithful strategy to significantly improve the enantiorecognition ability of chitosan (CS) is proposed via drop-coating molybdenum disulfide (MoS₂)-ionic liquid (IL) nanocomposite. The present work describes a novel, simple, and effective chiral interface based on MoS₂-IL/CS nanocomposite which was elaborately integrated to combine the electrical signal amplification and space complexity of MoS₂-IL and vast enantiorecognition sites of CS for the electrochemical enantiorecognition of tryptophan (Trp) enantiomers. Differential pulse voltammetry (DPV) was adopted to evaluate the potential differences (ΔE_P) between the oxidation peaks of L-Trp and D-Trp. MoS₂-IL/CS nanocomposite showed higher chiral recognition ability result from spatial asymmetry of MoS₂-IL/CS. Herein, several parameters, such as drop-coated volume and concentration of MoS₂-IL, electrodeposited viscosity, time and temperature of CS, detection temperature and pH were optimized in order to obtain a large ΔE_P signal between L-Trp and D-Trp, and the ΔE_P value can reach 53.3 mV under optimal conditions. Furthermore, different percentages of Trp mixtures and DPV peaks potential were detected with a good linear relationship even in the real sample, which indicated that MoS₂-IL/CS chiral interface could effectively quantify the enantiomer excess (ee) of Trp enantiomers in Trp mixtures.