Rational design of a thrombin electrochemical aptasensor by conjugating two DNA aptamers with G-quadruplex halves.

A novel strategy for the fabrication of an electrochemical aptasensor is proposed; this strategy has been employed in this work to assay thrombin concentration. Two well-designed oligonucleotides were used as the core element. G-quadruplex–hemin complexes can be formed on the surface of the electrode to give a detectable signal only when thrombin is not bound to the aptamers. The detection limit of the biosensor has been lowered to 10nM. Moreover, since the electroactive probe is not required to be bound to the oligonucleotide, this strategy may integrate the advantages of being both label-free and cost-effective.