Fabrication of an electrochemical chiral sensor via an integrated polysaccharides/3D nitrogen-doped graphene-CNT frame.

We report a novel chiral interface based on polysaccharides that was integrated via an amidation reaction between the COOH of sodium alginate and the NH of chitosan to form a chiral selector (SA-CS) with three dimensional N-doped graphene-CNT (NGC) as the substrate material. This interface was used for chiral discrimination of tryptophan (Trp) enantiomers via electrochemical measurements. The FT-IR, SEM, TEM and XPS characterization showed that the chiral selector and substrate materials were prepared successfully. Compared with individual SA-CS and NGC, the integrated polysaccharides/3D NGC showed higher enantioselectivity for L-Trp than D-Trp due to the smaller steric hindrance for D-Trp during the formation of three-point interactions between the two diastereoisomeric enantiomer-selector complexes, which allowed L-Trp to more easily detach from the electrode modification layer and approach the electrode surface, facilitating its approach and confirming that SA-CS had a higher constant for L-Trp when applied to real samples.