A "signal-on" electrochemical aptasensor for simultaneous detection of two tumor markers

In this paper, we report a "signal-on" electrochemical aptasensor for simultaneous determination of two tumor markers MUC1 and VEGF(165), by using a ferrocene-labeled aptamer-complementary DNA (cDNA) as probe. Since the cDNA immobilized on an electrode surface can hybridize with both MUC1 aptamer and VEGF(165) aptamer to form a long double strand with ferrocene far away from the electrode surface, the probe cannot give electrochemical signal. Nevertheless, the presence of the two tumor markers will inhibit the hybridization of cDNA with the aptamers, thus the distance between ferrocene and the electrode is changed, and a "signal-on" electrochemical method to detect two tumor markers is developed. Experimental results show that the electrochemical signal increases with the addition of either tumor markers, but the biggest electrochemical signal can only be obtained when both tumor markers are present. Therefore, the proposed electrochemical aptasensor can not only detect the two markers but also distinguish their co-existence. It may also display high selectivity and sensitivity towards the detection of the tumor markers, so it might have potential clinical application in the future.