Biologically prepared copper-graphene nanohybrid as the interface of microchips for sensitive detection of crop viruses

Abstract The development of portable and sensitive biosensors for the label-free detection of DNA has influenced fundamental biological research as well as advanced applications. Here, we report the novel microchip-based electronic devices for the efficient and sensitive detection of a crop virus i.e. Cotton leaf curl Khokran virus-Burewala strain (CLCuKoV-Bur), predominant cotton infecting virus worldwide. Three-dimensional copper nanostructures reinforced graphene nanohybrid (Cu Ns@GO) is developed via a biological synthesis approach. The hybrid consists of the typical graphene sheets, embellished with copper nanoparticles of 10–15 nm, to impart conducting and metallic character. This nanohybrid is applied as the active interface of microchips, and the surface charge of +38 mV enables successful anchoring of virus DNA as a probe to the interface. The hybridization events are manipulated as the change in the electron transport between sheets of graphene, leading to a corresponding decrease in conductance of the devices. Termed as Cu Ns@GO-microchip, the devices can detect the presence of viral DNA down to the detection limit of 200 pM. We further investigate specificity patterns and the non-complementary DNAs i.e. Cotton leaf curl Multan betasatellite, Cotton leaf curl Multan alphasatellite, and Maize insect resistance1-cystein protease genes show a negligible response generating only 10–20% of the signal. We apply this strategy to the virus-infected cotton field samples and using the devices, the level of virus infectivity can be discerned. This study suggests the potential of nanotechnology-based microchips for designing benchmark recognition interfaces, for the direct and facile monitoring of agricultural pathogens and other bio-threats.