An electrochemical chiral sensor based on glutamic acid functionalized graphene-gold nanocomposites for chiral recognition of tryptophan enantiomers

A novel chiral sensing platform via the glutamic acid (Glu) functionalized graphene-gold nanoparticles (RGOAu/L-Glu and RGO-Au/D-Glu) synthesized via the one-step hydrothermal method is described for the enantioselective recognition of L-and D-tryptophan (Trp). The SEM, TEM, EDS, AFM, FTIR, and XRD characterization techniques showed that RGO-Au/L-Glu and RGO-Au/D-Glu chiral composite were successfully synthesized. By combining the chiral features of Glu and the excellent electrochemical behaviors of RGO-Au, two electrochemical chiral sensing interfaces constructed by RGO-Au/L-Glu and RGO-Au/D-Glu modified glassy carbon electrode (GCE) were constructed for electrochemical chiral recognition of Trp enantiomers. The results demonstrated that the RGO-Au/L-Glu/GCE showed the highest chiral recognition efficiency, the enantioselectivity coefficient (I-L/I-D) was 2.56. UV-vis absorption spectroscopy and density functional theory (DFT) calculations proved that RGO-Au/L-Glu had a strong binding ability with L-Trp. In addition, the chiral sensing interface had a linear response in the 1 mM to 5 mM Trp concentration range and a 0.28 mM detection limit (at S/N = 3) for L-Trp, and 0.86 mM to D-Trp, also had good stability and reproducibility, which can be used as an efficient chiral sensing interface for the recognition of Trp enantiomers.

Automated summary

A novel chiral sensing platform utilizing glutamic acid-functionalized graphene-gold nanoparticles was developed for enantioselective recognition of tryptophan. The synthesized chiral composites demonstrated successful recognition of enantiomers, with RGO-Au/L-Glu/GCE showing the highest recognition efficiency. The interface exhibited good stability and reproducibility, making it a promising tool for chiral sensing.