Intramolecular Coreaction Accelerated Electrochemiluminescence of Polypeptide-Biomineralized Gold Nanoclusters for Targeted Detection of Biomarkers

The development of label-free electrochemiluminescence (ECL)-based sensing technology for biomarkers detection has a congenital defect compared to noncompetitive sandwich-type biosensors due to the lack of detection antibody conjugated with a signal label. Nevertheless, it is still not difficult to realize the ultrasensitive analysis benefit from the exploration of efficient sensing substrates and signal transducers. In this work, an innovative sensing system is purposed utilizing Fe₂O₃ nanoarrays (Fe₂O₃ NAs) as a well-ordered coreaction accelerator and polypeptide-biomineralized gold nanoclusters (Au NCs) as a signal transducer. Bifunctional peptide ligands of H₂N-MMYYHFRRHL-COOH (MYH-10) are self-designed; it cannot only play a role of reductant and coupling reagent for cluster formation using the MMYY sequence root in the N-terminal but also act as a connection for coupling carriers and immune molecules via the HFRRHL region of the C-terminal. In addition to intramolecular ECL emission between Au NCs and tris­(3-aminoethyl)­amine (TAEA), all strategies undoubtedly reduce the spatial hindrance of the sensing interface and increase the effectiveness of the electron transfer and immune recognition. With CYFRA21-1 as a target, the biosensor exhibits a linear ECL response in a wide range (10 fg mL^–1 to ∼100 ng mL^–1) and an ultralow detection limit of 1.33 fg mL^–1 (S/N = 3). With convincing experimental data, these innovative strategies will be more eye-catching in peptide-based nanocluster synthesis and expansion of a more novel thought for sensing platform fabrication.