Rapid and label-free electrochemical DNA biosensor for detecting hepatitis A virus

Diagnostic systems that can deliver highly specific and sensitive detection of hepatitis A virus (HAV) in food and water are of particular interest in many fields including food safety, biosecurity and control of outbreaks. Our aim was the development of an electrochemical method based on DNA hybridization to detect HAV. A ssDNA probe specific for HAV (capture probe) was designed and tested on DNAs from various viral and bacterial samples using Nested-Reverse Transcription Polymerase Chain Reaction (nRT-PCR). To develop the electrochemical device, a disposable gold electrode was functionalized with the specific capture probe and tested on complementary ssDNA and on HAV cDNA. The DNA hybridization on the electrode was measured through the monitoring of the oxidative peak potential of the indicator tripropylamine by cyclic voltammetry. To prevent non-specific binding the gold surface was treated with 3% BSA before detection. High resolution atomic force microscopy (AFM) confirmed the efficiency of electrode functionalization and on-electrode hybridization. The proposed device showed a limit of detection of 0.65 pM for the complementary ssDNA and 6.94 fg/mu L, for viral cDNA. For a comparison, nRT-PCR quantified the target HAV cDNA with a limit of detection of 6.4 fg/mu L. The DNA-sensor developed can be adapted to a portable format to be adopted as an easy-to-use and low cost method for screening HAV in contaminated food and water. In addition, it can be useful for rapid control of HAV infections as it takes only a few minutes to provide the results.