Chiral nanocomposite of sulfobutyl ether-b-cyclodextrin embedded in carbon nanofibers for enantioselective electrochemical discrimination of amlodipine, metoprolol and clenbuterol enantiomers

A highly sensitive and selective electrochemical chiral sensor was developed based on the competitive supramolecular interaction of carbon nanofibers(CNFs)embedded sulfobutyl ether-b-cyclodextrin(SBEb-CD)with optically active cationic drugs at glassy carbon electrode(GCE).The difference in intermolecular hydrogen bonding/stability constant/enantioselectivity coefficient and Gibbs free energy of anionic host SBE-b-CD with enantiomers of amlodipine(R-/S-AML),clenbuterol(R-/S-CBL)and metoprolol(R-/S-MET)as a guest paved the way for efficient discrimination.The proposed sensing platform(CNFs-SBE-b-CD/GCE)could recognize the aforementioned enantiomers based on the discernible difference of peak potential(S/R-AML(△Ep=135 mV),R/S-MET(△Ep=99 mV)and R/S-CBL(△Ep=111 mV).The binding mechanisms and thermodynamic study of the enantiospecific behavior have been investigated using the host-guest chemistry approach inside the nanocavity and results suggest that S-AML,RMET,and R-CBL show stronger stability constants than their antipodes.Formation of the diastereomeric complex was taken as a measure of enantioselectivity and experimental results indicated that anionic SBE-b-CD is a better chiral ligand than neutral cyclodextrins.The fabricated sensor could be a useful lowcost electrochemical tool for molecular recognition of a variety of cationic species not only of drugs but also from other sources.