An electrochemical aptasensor based on hybridization chain reaction with enzyme-signal amplification for interferon-gamma detection

A novel electrochemical aptasensor based on hybridization chain reaction (HCR) with enzyme-signal amplification was constructed for the detection of interferon-gamma (IFN-γ). In this aptasensor, the recognition probes which contained the sequence of IFN-γ aptamer were initially binded to IFN-γ, and the unbound recognition probes were captured on the electrode as an initiator to trigger the HCR. The two DNA hairpins bio-H1 and bio-H2 were opened by the recognition probe, and bound one by one on the electrode. The biotin was used as a tracer in the hairpins and streptavidin–alkaline phosphatase (SA–ALP) as a reporter molecule. Then, SA–ALP converted its electro-inactive substrate 1-naphthyl phosphate into an electroactive derivative 1-naphthol generating amplified electrochemical signal by differential pulse voltammetry (DPV). The activity of the immobilized enzyme was voltammetrically determined by measuring the amount of 1-naphthol generated for enzymatic dephosphorylation of 1-naphthyl phosphate. The electrochemical signal observed was inversely related to the concentration of IFN-γ. The proposed approach showed a high sensitivity for IFN-γ in a concentration range of 0.5–300 nM with a detection limit of 0.3 nM. The sensing system also provided satisfactory results for the detection of IFN-γ in the cell media.

► The electrochemical sensor used aptamer for target protein recognition. ► This sensor was based on DNA isothermal amplification method (hybridization chain reaction). ► The electrochemical signal was amplified by enzyme. ► This sensing system also performed a satisfactory result in the cell media. ► The assay is high sensitivity, wide response linearity, small volume and rapid readout of IFN-γ.