A DNA-functionalized graphene field-effect transistor for quantitation of vascular endothelial growth factor

Graphene field-effect transistor (GFET) is a unique and low-cost device for detection of various analytes. Generally the GFET-based biosensors for protein detection are prepared by immobilizing the recognition elements such as antibody or aptamer on channel interface to capture the target proteins. In this work, a DNA-functionalized GFET was proposed by immobilizing the capture DNA strand on channel interface to recognize another DNA strand containing the sequence complementary to a specific aptamer for quantitation of protein, which endowed the sensing interface with the ability to amplify the detection signal via DNA hybridization. Using vascular endothelial growth factor 165 (VEGF165) as a model analyte, the secondary DNA strand was released from double-stranded DNA-aptamer complex owing to the higher affinity of the aptamer to VEGF165 and then captured on the functionalized channel interface, which triggered the hybridization chain reaction to enhance the n-type doping effect of DNA for signal amplification. Using the shift of Dirac voltage as the detection signal, the designed GFET-based biosensor showed a limit of detection down to 3.24 pg/mL and high selectivity toward VEGF165. The proposed biosensing strategy possessed excellent extensibility for other proteins or even nucleic acids by simply changing the specific aptamer, greatly extending the application of GFET in biosensing and clinical diagnosis.