Enantioselective Limiting Transport into a Fixed Cavity via Supramolecular Interaction for the Chiral Electroanalysis of Amino Acids Regardless of Electroactive Units

Abstract

Although an increasing number of researchers are developing electroanalytical protocols for the chiral recognition of amino acids, the electroactive units of the tested isomers still need to provide corresponding electrical signals. In this study, a supramolecular system was developed for the chiral electroanalysis of amino acids regardless of electroactive units. As a model system, an enantiopure electroactive molecule Fc-(S,S)-1 that includes a ferrocenyl group was synthesized and acted as a guest. Moreover, hydrophobic cyclobis-(paraquat-p-phenylene) (CBPQT 4+ -2) was used as the host. In the presence of π−π stacking and the attraction of π-electrons, CBPQT 4+ -2 can encapsulate Fc-(S,S)-1 into its cavity. Next, a screen-printed electrode was utilized for electrochemical chiral recognition. The host was fixed on the surface of the working electrode, and the guest was used as the electroactive chiral selector to support electron transfer. Once different configurations of amino acids (threonine, histidine, glutamine, and leucine) were mixed with the guest, regardless of whether they contained electroactive units, differences in the cyclic voltammetry results of the probe enantiomers could be observed, namely, in the peak currents or peak potentials. However, glutamine was an exception because the L-isomer had a stronger binding affinity with Fc-(S,S)-1 + Cu(II), which would limit the transport of the complex into the cavity of CBPQT 4+ -2, thereby resulting in a low peak current. Thus, an inverse phenomenon was observed with glutamine. In summary, we believe that this work can increase the testing scope for the chiral recognition of different kinds of isomers using electrochemical tools.

Chiral voltammetric sensor for tryptophan enantiomers by using a self‐assembled multiwalled carbon nanotubes/polyaniline/sodium alginate composite

“…Alternatively, the electrochemical measurement is of significance due to the advantages of fast detection, low prices, high sensitivity, and anti‐jamming property 6–8 . Many scholars made great effort on the investigation of chiral selectors used for the fabrication of electrochemical sensing interface, such as chiral carbon dots, amino acid, chiral supramolecules, and MOFs 9–12 . In some cases, only modifying the chiral selectors on the electrode will hinder electronic transmission of chiral interface, weakening chiral recognition signal.…”

Recent advances of the ionic chiral selectors for chiral resolution by chromatography, spectroscopy and electrochemistry

“…Therefore, developing new strategies is necessary to address this bottle. In the work of Wu et al [184], a chiral electroactive probe including a ferrocenyl group and carbon chiral F I G U R E 5 Schematic of electrochemical analysis by using (A) β-cyclodextrin-based charged catenane and (B) supramolecular interaction. Reprinted with permission from [177,184] center was prepared as the guest and hydrophobic cyclobis-(paraquat-p-phenylene) was fixed on the electrode surface as the host (Figure 5B).…”

“…In the work of Wu et al [184], a chiral electroactive probe including a ferrocenyl group and carbon chiral F I G U R E 5 Schematic of electrochemical analysis by using (A) β-cyclodextrin-based charged catenane and (B) supramolecular interaction. Reprinted with permission from [177,184] center was prepared as the guest and hydrophobic cyclobis-(paraquat-p-phenylene) was fixed on the electrode surface as the host (Figure 5B). When the guest was mixed with the detecting isomers, the more stable intermolecular interaction between the guest and isomer will prevent it into the cavity of host, generating a different electrochemical signal in the cyclic voltammetry results.…”

A selective electrochemical chiral interface based on a carboxymethyl-β-cyclodextrin/Pd@Au nanoparticles/3D reduced graphene oxide nanocomposite for tyrosine enantiomer recognition

“…18 In recent years, growing attention has been paid to electrochemical chiral recognition methods for amino acids, which possess the properties of effective selectivity, high sensitivity, low cost, fast response and relative simplicity. [19][20][21] Supramolecular chemistry opens up great opportunities for chiral recognition, as the supramolecular host material can demonstrate unique selectivity in combining with the guest molecules. 22 Cyclodextrins (CDs), as a kind of supramolecular host molecule, reveal natural chirality, host-guest interaction and excellent water-solubility, and could include various bioactive compounds in their hydrophobic cavities to form stable host-guest inclusion complexes.…”