Nano-Gold Modified Genosensor for Direct Detection of DNA Hybridization

In this paper, nano‐gold modified carbon paste electrode (NGMCPE) was employed to develop an electrochemical DNA hybridization biosensor. The proposed sensor was made up by immobilization of 15‐mer single stranded oligonucleotide probe for detection of target DNA. Hybridization detection relies on the alternation in guanine oxidation signal following hybridization of the probe with complementary genomic DNA. The guanine oxidation was monitored using differential pulse voltammetry (DPV). Different factors such as activation potential, activation time and probe immobilization conditions were optimized. The selectivity of the sensor was investigated by non‐complementary oligonucleotides. Diagnostic performance of the biosensor was described and the detection limit was found 1.9 × 10−13 M at the NGMCPE surface. All of the investigations were performed in both CPE and NGMCPE and finally their results were compared. The DPV signals of probe modified NGMCPE before hybridization (a), after hybridization with NC1 (b), NC2 (c) and after hybridization with complementary oligonucleotide (d). This figure represents that complementary target DNA can only form an effective duplex formation with probe and consequently causes a significant increase in guanine oxidation current. This sensor can discriminate effectively between complementary and non‐complementary DNA.