Photodriven Regeneration of G-Quadruplex Aptasensor for Sensitively Detecting Thrombin

Aptamers have been widely used as recognition elements in electrochemical sensors. However, as the most expensive consumable, the aptasensors regeneration is still a critical challenge for sustainable feasibility and attracting great interest from researchers, due to the high affinity between the aptamers and their targets (the dissociation constant K_d is low to subnanomolar or nanomolar). In this work, we propose a photochromic five-azobenzene-inserted thrombin-aptamer based aptasensor to improve the regenerativity. With ultraviolet light exposure, the trans-structure of azobenzene changes to cis-structure, and open the folded aptamer to realize the aptasensor regeneration. The limit of detection can be sensitive to 3 pM (S/N = 3). The thrombin concentrations were detected to be 2.48 ± 0.02 and 20.26 ± 0.98 nM (n = 3) in duck whole blood and blood serum, respectively. Utilizing surface plasmon resonance, we demonstrated that the certain azobenzene moieties can exactly increase K_d of aptamer-thrombin bounding. The photodriven conversion of thrombin-aptamer from G-quadruplex to loosen structure approaches a convenient regeneration for aptasensor, which will promote its popularization and sustainable feasibility.