An aptamer-based biosensor for detection of doxorubicin by electrochemical impedance spectroscopy

An aptamer-based biosensor was developed for the detection of doxorubicin using electrochemical impedance spectroscopy. Doxorubicin and its 14-dehydroxylated version daunorubicin are anthracyclines often used in cancer treatment. Due to their mutagenic and cardiotoxic effects, detection in groundwater is desirable. We developed a biosensor using the daunorubicin-binding aptamer as biological recognition element. The aptamer was successfully co-immobilized with mercaptohexanol on gold and a density of 1.3*1013 ± 2.4*1012 aptamer molecules per cm2 was achieved. The binding of doxorubicin to the immobilized aptamer was detected by electrochemical impedance spectroscopy. The principle is based on the inhibition of electron transfer between electrode and ferro-/ferricyanide in solution caused by the binding of doxorubicin to the immobilized aptamer. A linear relationship between the charge transfer resistance (R ct ) and the doxorubicin concentration was obtained over the range of 31 nM to 125 nM doxorubicin, with an apparent binding constant of 64 nM and a detection limit of 28 nM. With the advantages of high sensitivity, selectivity, and simple sensor construction, this method shows a high potential of impedimetric aptasensors in environmental monitoring.