Electrochemical DNA Sensor for Determination of p53 Tumor Suppressor Gene Incorporating Gold Nanoparticles Modification

A novel electrochemical DNA (E-DNA) sensor was designed with incorporating gold nanoparticles on a gold electrode for the determination of p53 tumor suppressor gene. A modified gold nanoparticles (GNPs) was prepared by modifying the GNPs prepared by the in situ potentiostatic deposition method on the gold electrode surface. The surface topography of the gold electrode and GNPs/Au were characterized by field emission scanning electron microscope. The E-DNA sensor was prepared through the self-assembly of a 5'-end thiolated probe DNA onto the surface of GNPs/Au followed by the hybridization of complementary sequence DNA. Cyclic voltammetry and electrochemical impedance spectroscopy were used to investigate each immobilization and hybridization step. By using methylene blue (MB) as an indicator for electrochemical hybridization detection, p53 tumor suppressor gene was quantitatively detected by differential pulse voltammetry (DPV) with the reduction peak current of MB. The increase in electrochemical signal upon hybridization was due to that MB had a higher affinity for dsDNA rather than ssDNA. Under the optimal conditions, the reduction peak current of MB was linearly related to the concentration of p53 tumor suppressor gene from 1.0 to 1000 nM with a detection limit of 0.8 nM (S/N = 3). The relative standard deviation obtained was 3.8%. The E-DNA sensor could differentiate the complete complementary DNA sequence, single-base mismatch DNA sequence and three-base mismatched DNA sequence, indicating a good selectivity.