Target-induced silver nanocluster generation for highly sensitive electrochemical aptasensor towards cell-secreted interferon-γ

Interferon-gamma (IFN-γ) is one kind of crucial inflammatory cytokines, and its expression level is closely associated with various disease progressions. This work addresses the development of a sensitive and specific electrochemical assay for detection of IFN-γ by combing the recognition unit of aptamer with the signal reporter of target-induced silver nanoclusters (AgNCs). For biosensor preparation, the gold nanoparticles (AuNPs) immobilized on the amine-terminated electrode surface provided electrochemical interfaces for the self-assembly of C-rich modified aptamers. Then, the aptamer recognized IFN-γ and the free aptamer hybridized with conjugated DNA sequences. After the nuclease-catalyzed cleavage of DNA duplex, in situ-generated AgNCs in the C-rich template was utilized as the electrochemical indicator for IFN-γ detection. The present method demonstrated a good performance for detection of IFN-γ with a low detection limit of 1.7 pg mL-1. This aptasensor was verified to be applied for the evaluation of IFN-γ secreted by cell.