Impedance Spectroscopy-Based Detection of Viral RNA From Clinical Samples

Rapid detection of viruses is necessary for early diagnosis of the disease and initiation of treatment. However, currently popular quantitative polymerase chain reaction (qPCR) techniques involve multistep protocols which consume a lot of time and also use expensive optics for yielding accurate results. Electrochemical biosensors have developed into reliable analytical tools over the past decade for sensitive, specific, and rapid detection of many viruses. Electrochemical impedance spectroscopy (EIS) is being used more frequently in electrochemical sensors and biosensors for both characterizing the sensors throughout the various phases of sensor design, as well as a method for quantitative and qualitative measurements. In this study, a sensitive electronic detection scheme for viral RNA is developed based on nonfaradaic EIS. Impedance measurements corresponding to biomodification on the electrode surface is carried out through an in-house microchip. Sensitivity is included through gold nanoparticle labeling to the DNA primers and a dielectrophoretic (DEP) concentration step. All the tests are conducted with cDNA synthesized from Hepatitis C virus (HCV) RNA samples and the limit of detection (LOD) achieved through the currently developed chip is in the range of 30–35 ng/μL i.e., around 140 nM for a 327-bp cDNA molecule. Further, the device starts detection procedure within 15 min of initiation.