Construction of a Dual-Mode Biosensor with Ferrocene as Both a Signal Enhancer and a Signal Tracer for Electrochemiluminescent and Electrochemical Enantioselective Recognition
Chenyu Zhu, Maoding Zuo, Yuncong Yang, Ning-ning Zhao, Xiaolei Wang, Lin Cui, Chun‐yang Zhang
Abstract
We demonstrate for the first time the construction of a dual-mode biosensor for electrochemiluminescent (ECL) and electrochemical chiral recognition of l - and d -isomers of amino acids, with ferrocene (Fc) as both a signal enhancer and a signal tracer. With the dissolved oxygen as a coreactant, ZnIn 2 S 4 acts as the ECL emitter to generate a weak cathodic ECL signal. Fc can enter into the β-cyclodextrin (β-CD) cavity on ZnIn 2 S 4 -modified electrode as a result of host–guest interaction. Since Fc can promote H 2 O and O 2 to produce abundant reactive oxygen species (ROS) (e.g., O 2 · – and · OH), the ECL signal of ZnIn 2 S 4 can be further amplified with Fc as a coreaction accelerator. Meanwhile, Fc molecules on the β-CD/ZnIn 2 S 4 -modified electrode can be electrochemically oxidized to Fc + to produce a remarkable oxidation peak current. When l -histidine ( l -His) is present, the matching of the l -His configuration with the β-CD cavity leads to the entrance of more l -His into the cavity of β-CD than d -histidine ( d -His), and the subsequent competence of l -His with Fc on the Fc/β-CD/ZnIn 2 S 4 -modified electrode induces the decrease in both Fc peak current and ZnIn 2 S 4 -induced ECL intensity. This dual-mode biosensor can efficiently discriminate l -His from d -His, and it can sensitively monitor l -His with a detection limit of 7.60 pM for ECL mode and 3.70 pM for electrochemical mode. Moreover, this dual-mode biosensor can selectively discriminate l -His from other l - and d -isomers (e.g., threonine, phenylalanine, and glutamic acid), with potential applications in the chiral recognition of nonelectroactive chiral compounds, bioanalysis, and disease diagnosis.