Detection of BRCA1 gene on partially reduced graphene oxide biosensors

A biosensor based on reduced graphene oxide (rGO) and simple silver paint contacts assembled on a functionalized silicon oxide (SiO2) substrate is presented. To fabricate the sensor, graphene oxide is reduced after a relatively low temperature (180 °C) treatment which restores its sp2 lattice, but leaves several functional groups on its surface, thus allowing for the immobilization of probe biomolecules. The biosensor is applied in the detection of biotinylated 157 bp DNA amplicons, containing the exon 20 of BRCA1 gene, which is linked to breast and ovarian cancer. The amplicons are obtained after Polymerase Chain Reaction (PCR) amplification of purified human DNA containing the target template. First, the adhesion of graphene oxide (GO) on the SiO2 and the immobilization of streptavidin (SA) probes on the rGO are studied. Then, the constructed sensor is placed in a reaction cell and tested against different concentrations of DNA. Concentrations down to 0.2 nM were successfully detected indicating that the sensor is sensitive enough to detect the amplified DNA coming out of the PCR. This scheme has been devised so that the two processes (PCR amplification and detection) are executed sequentially, while both the PCR stage and the rGO biosensors are amenable to integration into a single Lab-on-Chip device incorporating both functions.