Sensitive electrochemical sensor for selective detection of chiral amino acids based on covalent organic framework–cyclodextrin–gold nanocomposite

Background Development of chiral sensors for determining amino acid enantiomers is an important topic in the biosensing field. However, the inherent non-electroactivity or weak electroactivity of many chiral amino acids poses a fundamental challenge for direct electrochemical detection, necessitating alternative transduction strategies. In this work we developed a sensitive electrochemical sensor for selective detection of chiral amino acids based on covalent organic framework–cyclodextrin–gold nanocomposite. Results In this work, a novel electrochemical chiral sensor was designed for the discrimination of both electroactive and non-electroactive enantiomers. The COF-V framework, synthesized from 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 2,5-divinylterephthalaldehyde (DVA), served as the sensor substrate to enhance electrode stability and effective surface area. The chiral gold nanoparticle complex of 6-mercapto-6-deoxyβ-cyclodextrin (6-SH-β-CD) and 4-aminothiophenol (4-ATP) formed via Au–S bonds was electropolymerized on the surface of the COF-V-modified electrode by cyclic voltammetry, and then coated with a chitosan solution to provide a stable chiral microenvironment. The enantioselectivity of the sensor was evaluated by monitoring methylene blue redox signals, enabling chiral discrimination of phenylalanine, tryptophan, tyrosine, histidine, propranolol, and naproxen. This platform demonstrated excellent enantiomeric recognition for both electroactive and non-electroactive amino acids, exhibiting remarkable stability and reproducibility. Furthermore, successful quantitative detection of phenylalanine in real samples was achieved. Significance and novelty Chiral sensor work well for both electroactive and non-electroactive amino acids via MB competitive host-guest. COF-V substrate enhanced electrode surface area and stability. Synergy of AuNPs-cyclodextrin and chitosan for improving chiral recognition.