Dual-Mode Arginine Assay Based on the Conformation Switch of a Ferrocene-Grafted Polypeptide.

Both controllable regulation of the conformational structure of a polypeptide and specific recognition of an amino acid are still arduous challenges. Here, a novel dual-mode (electrochemical and colorimetric) biosensor was built for arginine (Arg) recognition based on a conformation switch, utilizing controllable and synergistic self-assembly of a ferrocene-grafted hexadecapeptide (PFc) with gold nanoparticles (AuNPs). Benefiting from the flexibility and unique topological structure of PFc formed nanospheres, the assembly and disassembly can undergo a conformation transition induced by Arg through controlling the distance and number of Fc detached from the gold surface, producing on-off electrical signals.