Endonuclease Based Hairpin Aptamer Probe for Background Current-eliminated Electrochemical Detection of Thrombin

摘要

In this contribution, Hpa II restriction endonuclease is used for the first time to design endonucleasebased hairpin aptamer probe and develop background current eliminated electrochemical aptasensorfor sensitive signal-on detection of protein biomarker using thrombin as the model target. The hairpinaptamer probe consists of two functional domains: the aptamer sequence for target thrombin and therecognition sequence for Hpa II endonuclease. In the absence of target, the ferrocene labeled aptamerprobe folds into hairpin structure with a palindromic recognition site which can be digested by Hpa IIendonuclease, resulting in thorough removal of electro-active ferrocene from the electrode surface andcomplete elimination of background current for blank sample. While in the presence of target, theaptamer probe changes its conformation when binding with thrombin and dissociates the palindromestructure, resulting in obvious peak current. By eliminating the background current signal instead ofamplifying the detection signal, the proposed electrochemical aptasensor reveals an excellentsensitivity towards target thrombin with a low detection limit of 2.67 pM. The sensing system is costefficient and easy controllable because only one oligonulceotide probe is involved. Moreover, thedesign principle of endonuclease based hairpin aptamer probe is easy adapted to other analytes.