A novel poly(amidoamine)-modified electrolyte-insulator-semiconductor-based biosensor for label-free detection of ATP

Adenosine triphosphate (ATP) is crucial for cellular activity. The need for ATP detection in the field of biomedicine is rapidly increasing. Several biosensor-based approaches have been developed as a result of the growing demand for ATP detection. An electrolyte-insulator-semiconductor (EIS) sensor is a type of field-effect device that has the ability to detect surface-potential changes with a specific level of sensitivity. In this study, a label-free ATP detection biosensor based on poly(amidoamine)-modified EIS sensors was developed, in which an ATP-sensitive aptamer (Apt) was utilized as the sensitive element and the EIS sensor was used as the transducer. It is possible to monitor the binding of charged molecules, such as aptamers using EIS sensors in a label-free manner with a straightforward setup. To improve the coupling efficiency of Apt with the EIS sensor, a positively charged polyelectrolyte, i.e., poly (amidoamine) (PAMAM) dendrimers, was utilized to modify the surface of the EIS sensors to attach the negatively charged Apt through electrostatic attraction. The adsorptive binding of Apt and ATP results in a change in the capacitance of the EIS sensor. During the process of surface modification, the electrochemical measurements of capacitance-voltage (C-V) curves and constant-capacitance (ConCap) characteristics were utilized as indicators for the corresponding processes of EIS sensor surface modification. The measurement results indicated that this biosensor was able to detect ATP with high sensitivity and good specificity. The detection range of ATP was from 0.1 nM to 100 nM and the detection limit was as low as 0.12 nM. This biosensor has the potential to be utilized in the detection of ATP in the surrounding microenvironment of cells and tissues, with promising prospects for application in the field of biomedicine such as energy and metabolism monitoring of cells and tissues.