Determination of the Aptamer Probe Density by Double Layer and Redox Capacitance of CNT-Based Electrochemical DNA-Aptasensors

Electrochemical DNA-Aptasensors are gaining increasing popularity for the recognition of numerous analytes ranging from tiny molecules to entire microorganisms due to their multiple benefits over antibody-based biosensors. However, the reliable determination of aptamer probe density in DNA-Aptasensors is a potential barrier to ensuring their quality and performance. In this regard, an innovative, simple, and reliable electrochemical method has been introduced by exploring the redox capacitance (CR) using [Ru(NH3)6]
^3+/2+
as a model redox species to determine the DNA-Aptamer probe density on a CNT (carbon nanotube) modified gc (glassy carbon) electrode surface. Moreover, the results were compared with the probe density calculated by the existing method using double layer capacitance (CD). Despite a lack of reproducibility caused by the non-specifically adsorbed aptamers on CNT, an excellent coincidence was found between the results obtained following those two methods. Therefore, the new method will accelerate the commercialization of electrochemical DNA-Aptasensors by confirming their quality through assessing the reliable DNA-Aptamer probe density.