An electrochemical sensor for Oct4 detection in human tissue based on target-induced steric hindrance effect on a tetrahedral DNA nanostructure.

Here, we report an electrochemical sensor for rapid and sensitive detection of octamer-binding transcription factor 4 (Oct4) in human tissue samples by utilizing a designed tetrahedral DNA nanostructure (TDN). In the design, the TDN is also extended with two additional strands from two vertices. When Oct4 is absent, the strands are linked together by complementary pairing bases. Owing to the rigid structure of TDN, contact of the redox labels on the signal strand and electrode surface is greatly prohibited, resulting in a lower electrochemical signal. However, the specific binding of Oct4 to the edge of the tetrahedron will liberate the signal strand and increase the redox current dramatically. Experimental results reveal that the proposed sensor shows a linear range of 0.5-1000 ng/mL with a detection limit of 60 pg/mL. Moreover, it can be directly applied to clinical sample detection. This sensor can also achieve one-step detection of Oct4 in less than 30 min. Furthermore, through replacing the binding site, this sensor can be easily extended to a wide application range of DNA binding proteins.