Electrochemical DNA Biosensor Based on Partially Reduced Graphene Oxide Modified Carbon Ionic Liquid Electrode for the Detection of Transgenic Soybean A2704-12 Gene Sequence

In this work a partially reduced graphene oxide (p-RGO) modified carbon ionic liquid electrode (CILE) was prepared as the platform to fabricate an electrochemical DNA sensor, which was used for the sensitive detection of target ssDNA sequence related to transgenic soybean A2704-12 sequence. The CILE was fabricated by using 1-butylpyridinium hexafluorophosphate as the binder and then p-RGO was deposited on the surface of CILE by controlling the electroreduction conditions. NH2 modified ssDNA probe sequences were immobilized on the electrode surface via covalent bonds between the unreduced oxygen groups on the p-RGO surface and the amine group at the 5-end of ssDNA, which was denoted as ssDNA/p-RGO/CILE and further used to hybridize with the target ssDNA sequence. Methylene blue (MB) was used as electrochemical indicator to monitor the DNA hybridization. The reduction peak current of MB after hybridization was proportional to the concentration of target A2704-12 ssDNA sequences in the range from 1.0x10-12 to 1.0x10-6mol/L with a detection limit of 2.9x10-13mol/L (3 sigma). The electrochemical DNA biosensor was further used for the detection of PCR products of transgenic soybean with satisfactory results.