Electrochemical Analysis of Target-Induced Hairpin-Mediated Aptamer Sensors.

The state of probe DNA on the biosensing interface greatly affect the detection performance of electrochemical DNA biosensors. Herein, we constructed a target-induced hairpin-mediated biosensing interface to study the effect of probe DNA on the analytical performance of adenosine triphosphate aptamer (ATPA) and adenosine triphosphate (ATP) detection. Moreover, we also explored the electrochemical contribution of co-existed hairpin and double-strand DNA (dsDNA) on this sensing interface. Experimental results suggested that the molecular recognition ability and detection performance of biosensing interface were majorly dependent on the surface density of methylene blue (MB)-labelled probe hairpin DNA and partly affect by the spatial state of the formed dsDNA. When the surface density of hairpin DNA was moderate (5.72 pmol•cm-2), this sensing interface determine as low as 0.74 fM ATPA and 5.04 pM ATP with high selectivity and excellent regeneration, respectively. Furthermore, we calculated that the formed dsDNA had 31.87% contribution in total electrochemical signal for 10 pM ATPA detection. Based on above results, we designed a XOR logic gate based on the biosensing interface for ATPA and ATP detection.