G-Quadruplex-Linked Supersandwich DNA Structure for Electrochemical Amplified Detection of Thrombin

In this paper, a novel strategy of electrochemical amplified detection of thrombin based on G-quadruplex-linked supersandwich structure was described. In the presence of K+ and hemin, the original hairpin DNA sequence activated an autonomous cross-opening process to build up hemin/G-quadruplex structure and can hybridize to form supersandwich structure containing multiple signal labels. With the addition of thrombin, it conjugated with its aptamer, leading to a remarkably descended signal. The supersandwich-amplified electrochemical sensor system was highly sensitive in the concentration range from 10−6 to 10−10 M with a detection limit of 10 pM and also demonstrated excellent selectivity. The amplifying supersandwich structure with multiple labels can be implemented as a versatile sensing platform for analyzing other DNA in the presence of the appropriate probe.