Competitive Self-Assembly Interaction between Ferrocenyl Units and Amino Acids for Entry into the Cavity of β‑Cyclodextrin for Chiral Electroanalysis

• Published in: Analytical chemistry (Washington) Vol. 94; no. 15; pp. 6050 - 6056
• Main Authors: Wu, Datong, Tan, Lilan, Ma, Cong, Pan, Fei, Cai, Wenrong, Li, Junyao, Kong, Yong
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 19.04.2022
• Subjects: Amino Acids; beta-Cyclodextrins - chemistry; Business competition; Chemical sensors; Chemistry; Cyclodextrins; Electroanalysis; Electrochemical analysis; Electrochemical Techniques - methods; Electrochemistry; Electrolytic analysis; Enantiomers; Glutamates; Glutamic acid; Histidine; Isomers; Microspheres; Phenylalanine; Phenylalanine - analysis; Self-assembly; Silica; Silicon Dioxide; Stereoisomerism; Strategy; Threonine; β-Cyclodextrin
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/acs.analchem.2c00777

At present, chiral electroanalysis of nonelectroactive chiral compounds still remains a challenge because they cannot provide an electrochemical signal by themselves. Here, a strategy based on a competitive self-assembly interaction of a ferrocene (Fc) unit and the testing isomers entering into the cavity of β-cyclodextrin (β-CD) was carried out for chiral electroanalysis. First of all, the Fc derivative was directly bridged to silica microspheres, followed by inclusion into the cavity of β-CD. As expected, once it was modified onto the surface of a carbon working electrode as an electrochemical sensor, SiO2@Fc-CD-WE, its differential pulse voltammetry signal would markedly decrease compared with the uncovered Fc. Next, when l- and d-isomers of amino acids that included histidine, threonine, phenylalanine, and glutamic acid were examined using SiO2@Fc-CD-WE, it showed an enantioselective entry of amino acids into the cavity of β-cyclodextrin instead of Fc, resulting in the release of Fc with signal enhancement. For histidine, glutamic acid, and threonine, l-isomers showed a higher peak current response compared with d-isomers. The peak current ratios between l- and d-isomers were 2.88, 1.21, and 1.40, respectively. At the same time, the opposite phenomenon occurred for phenylalanine with a peak current ratio of 3.19 between d- and l-isomers. In summary, we are assured that the recognition strategy based on the supramolecular interaction can enlarge the detection range of chiral compounds by electrochemical analysis.