Gold nanoparticles-decorated graphene field-effect transistor biosensor for femtomolar MicroRNA detection

Early detection is proven to be the best chance for successful cancer treatment. MiRNAs, as ideal biomarkers, can identify cancer in the early stage. Therefore, development of highly sensitive and selective detection methods for miRNA is still anticipated. Here we report on a gold nanoparticles (AuNPs)-decorated graphene field-effect transistor (FET) biosensor for highly sensitive, selective and label-free detection of miRNA. The AuNPs-decorated graphene FET biosensor was fabricated by drop-casting the reduced graphene oxide (R-GO) suspension onto the sensor surface, and subsequently decorating AuNPs onto the surface of R-GO. After peptide nucleic acid (PNA) probe was immobilized on the AuNPs surface, miRNA detection was carried out via PNA-miRNA hybridization. It was found that the developed FET biosensor was able to achieve a detection limit as low as 10 fM. In addition, the biosensor enabled an accurate distinction of complementary miRNA from one-base mismatched miRNA and noncomplementary miRNA. What's more, this highly sensitive and selective assay was also applied to the detection of miRNA in serum samples, making it a potential method for diagnosis of gene-related diseases.