Self-assembled chitosan-sodium alginate composite material for electrochemical recognition of tyrosine isomers

Chitosan-sodium alginate (CS-SA) chiral composite sensing material was prepared by electrostatic self-assembly method. Scanning electron microscope images show that the morphologies of chitosan (CS) and sodium alginate (SA) have changed after self-assembly, which resulted in a new porous network structure. The structure and composition of the chiral composite sensing material were also identified by infrared spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The self-assembled CS-SA chiral composite sensing material was drip-coated on the glass carbon electrode to construct an electrochemical sensing interface. The tested square wave voltammetry curve in the l-tyrosine (l-Tyr) and d-tyrosine (d-Tyr) solution presented that CS-SA chiral composite sensing material can specifically bind to l-tyrosine, and the binding force is determined as hydrogen bonding by the method of molecular docking calculation. Although chitosan molecules have abundant chiral sites, glassy carbon electrodes modified with pure CS molecules cannot effectively recognize tyrosine isomers. After being combined with sodium alginate by electrostatic self-assembly, the efficiency of chiral recognition is significantly improved. This experiment opens up a new method for the combination of chitosan with other materials, and at the same time, expands its application on chiral recognition.