A simple and highly sensitive electrochemical platform for detection of MicroRNAs

MicroRNAs (miRNAs) in blood can act as fingerprints to many diseases including cancer. However, detection of low levels of these miRNAs in blood demands for very sensitive techniques. Despite many reports available for miRNA detection, the available methodologies have drawbacks such as complexity, use of expensive enzymes, etc. We here report a new and simple electrochemical method to detect miRNAs by exploiting the intrinsic charges of the oligonucleotides and a simple amplification method with positively charged gold nanoparticles (AuNPs). Electrochemical impedance spectroscopy (EIS) was used to monitor the changes in capacitance upon miRNA binding without the need for redox markers. miRNA detection was also obtained through measurements of open circuit potential (OCP) variations. We demonstrate a promising cost effective biosensor using both EIS and OCP with a detection limit of 1 fM, which can easily be expanded into miRNA/DNA microarray platforms.