Synergistic effects of chitosan and DNA self-assembly films on the chiral discrimination of tryptophan enantiomers

The rational design of electrochemical methods for chiral recognition is a focus of research in the detection fields of biomolecules and pharmaceuticals. In this work, electrochemical chiral interface based on chitosan (CS) and deoxyribonucleic acid (DNA) was constructed with self-assembly technology, and then characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), cyclic voltammetry, and electrochemical impedance spectroscopy. The FT-IR and SEM results showed the spatial structure of DNA and CS changed significantly and formed superhelix structure during the self-assembly process. Differential pulse voltammetry (DPV) results showed that the oxidation peak current ratio of D -Trp to L -Trp (I D /I L ) was observed to be 4.02 at 25 °C due to the synergistic effects of CS and DNA, obviously higher than that on any individual CS or DNA modified electrode. In addition, there was a linear relationship between the peak current and Trp enantiomer concentration in the range of 0.005–0.15 mM, and the detection limits of D-Trp and L-Trp were 1.33 and 1.67 µM, respectively. More importantly, the chiral interface can also be used to identify the percentage of D-Trp in non-racemic Trp enantiomers mixture solutions, showing its effectiveness and promising potential in practical applications.