The hybrids of perylene tetracarboxylic acid functionalized multi-walled carbon nanotubes and chitosan for electrochemical chiral sensing of tryptophan enantiomers

To introduce abundant carboxyl (-COOH) groups to the surface of multi-walled carbon nanotubes (MWCNTs) while maintaining the pristine structure of MWCNTs, 3,4,9,10-perylene tetracarboxylic acid (PTCA) was noncovalently grafted to the sidewalls of MWCNTs. The obtained PTCA functionalized MWCNTs (MWCNTs-PTCA) functioned as a scaffold for the further introduction of chitosan (CS) via electrostatic attractions and hydrogen-bonds. The resultant CS/MWCNTs-PTCA could be used for electrochemical chiral sensing of tryptophan (Trp) enantiomers due to the intrinsic chirality of CS and the high electrocatalytic activity of MWCNTs. Under optimized conditions, the Trp enantiomers could be effectively discriminated at the CS/MWCNTs-PTCA modified electrode by differential pulse voltammetry (DPV), demonstrating that the developed CS/MWCNTs-PTCA might be a potential candidate for the construction of electrochemical chiral sensors.

Automated summary

In this study, abundant carboxyl groups were introduced to the surface of multi-walled carbon nanotubes (MWCNTs) by noncovalent grafting of 3,4,9,10-perylene tetracarboxylic acid (PTCA) to the sidewalls of MWCNTs. Chitosan (CS) was then introduced onto the PTCA functionalized MWCNTs (MWCNTs-PTCA) via electrostatic interactions and hydrogen bonds. The resulting CS/MWCNTs-PTCA composite showed promising potential for electrochemical chiral sensing of tryptophan enantiomers.