DNA Biosensor Prepared by Electrodeposited Pt-nanoparticles for the Detection of Specific Deoxyribonucleic Acid Sequence in Genetically Modified Soybean

DNA biosensors were prepared by electrodepositing platinum nanoparticles (Pt-nano) on the surface of a glassy carbon electrode (GCE). A 19-mer ssDNA of promoter 35S, which was specific to most inserted sequences in genetically modified food, was immobilized on the Pt nanoparticle-deposited GC electrode. The morphology of the surface of Pt nanoparticle-deposited GC electrodes (Pt-nano/GCE) was investigated under a scanning electron microscope. The electrochemical response of the sensor to the complementary DNA was studied with [Co(phen)3]3+ ion (phen = 1,10-phenanthroline), as an electrochemical indicator. The response of the Pt nanoparticle-deposited GC electrode was significantly higher when compared with that of an electrode prepared based on a bare GC electrode of the same geometric surface area. A linear calibration graph for the complementary DNA over a concentration range of 2.14 × 10−9−2.14 × 10−7 M was obtained and the limit of detection was 1.0 × 10−9 M, whereas, almost no response was observed for the three-base-mismatched DNA. The detection response of the sample DNA digested by restricted enzyme (Hind?) was higher than that of the undigested sample DNA. When the DNA sensors were used for the determination of concentration of the DNA sequence extracted from the genetically modified soybean sample, the results were satisfactory. The relative standard deviation was 5.89% for the extracted sample DNA (n = 5). The DNA sensor could be used eight times repeatedly without deterioration.