Electrochemical detection of telomerase in cancer cells based on the in-situ formation of streptavidin-biotin-DNA-biotin networks for signal amplification

This work reports on a simple and sensitive electrochemical strategy for the detection of telomerase extracted from HeLa cells. It was based on the signal amplification of in-situ performed streptavidin-biotin-DNA-biotin (SA-biotin-DNA-biotin) networks. Specifically, the DNA primer immobilized on a gold electrode was elongated by telomerase. After the hybridization of biotin-DNA-biotin to the extended primer, the in-situ formation of SA-biotin-DNA-biotin networks was initiated on the electrode surface within 10 min through the SA-biotin interactions. The resulting networks created an insulating layer, thus hampering the electron transfer and causing the significant increase in the electrochemical impedance. Telomerase extracted from 2 HeLa cells can be readily measured. The method showed a linear relationship in the range of 50 ∼ 5000 cells/mL. The signal-amplified strategy can be applied to develop novel sensing platforms for the detection of different biomarkers.