Amplification of aptamer sensor signals by four orders of magnitude via interdigitated organic electrochemical transistors.

Electrochemical aptamer receptor/transducer systems are key elements of emerging E-AB sensors (aptasensor) used for the detection of various kinds of targets. However, the performance of these amperometric sensors is often limited by the low density of receptors attached to the sensor surface and high background signals. In the present work, interdigitated organic electrochemical transistors (iOECT) were used as a transducer to enhance the sensitivity and dynamic detection range of aptasensors. Therefore, the electrode of an amperometric sensor was utilized as gate electrode to operate the iOECT. This device was used to detect the low weight target molecule adenosine triphosphate (ATP), a common biomarker, which plays an important role for cardiovascular, neurodegenerative, and immune deficiency diseases. The novel aptasensor can selectively detect ATP with ultrahigh sensitivity down to the concentration of 10 pM, which is four orders of magnitude lower than the detection limit of the same aptasensor using an amperometric transducer principle (limit-of-detection of 106 nM) and most other previously reported electrochemical sensors. Furthermore, sensor regeneration was demonstrated, which facilitates reusability of OECT aptasensors. The small device size in combination with high transconductances paves the way for the development of highly sensitive integrated micro-biosensors for point-of-care applications.