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

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.