Electrochemical immunosensors based on the solubility difference of electroactive probe and the dual signal amplification of nanocarrier plus redox cycling.

This work reported a redox cycling system for the design of electrochemical immunosensors by using pyrroloquinoline quinone (PQQ) to promote the oxidation of tris(2-carboxyethyl)phosphine (TCEP). The consumption of TCEP was monitored with ferrocenium (Fc) as the electroactive probe, which was based on the difference in the solubility of Fc with its reduced format (ferrocene, Fc). Metal-organic framework (MOF) was used as the nanocarrier to load biotinylated recognition antibody and PQQ with recombinant streptavidin as the linker.