L-Lysine-Functionalized Nickel–Zinc Bis(Dithiolene) Metal–Organic Framework for Electrochemical Chiral Recognition of Tryptophan Enantiomers

l-tryptophan (l-Trp) plays an important role in human and animal metabolism, and an imbalance or deficiency can cause some chronic diseases. While d-tryptophan (d-Trp) is mainly present in microorganisms and green plants and is rarely found in animals. In this work, a simple and efficient electrochemical sensing platform for the simultaneous detection of tryptophan enantiomers based on an l-lysine-functionalized nickel–zinc bis(dithiolene) metal–organic framework and ferrocene-modified multiwalled carbon nanotubes (Fc-MWCNTs) is presented. The identification effect of l-Lys-Ni Zn-MOF/Fc-MWCNTs/GCE on tryptophan (Trp) enantiomers was studied by differential pulse voltammetry. The synthesized materials have been successfully applied to the detection and analysis of Trp enantiomers, and the enantiomer selection coefficient (IL/ID) detected by the sensor is 1.866, indicating that l-Lys-Ni Zn-MOF/Fc-MWCNT composites have good application potential.