DNA biosensors were prepared using platinum (Pt) nanoparticles that are electrochemically deposited on the surface of a glassy carbon (GC) electrode. The morphology of the surface of Pt nanoparticle-deposited GC electrodes was investigated with a scanning electron microscope (SEM). A cyclic voltammetry (CV) was also used for evaluating electrochemical performance of the Pt nanoparticle-deposited GC electrodes to establish the optimum conditions in electrochemical deposition of Pt nanoparticles. It was found that a highly sensitive electrode can be prepared by the deposition of Pt nanoparticles by applying step functions. A 19-mer ssDNA was immobilized on the Pt nanoparticle-deposited GC electrode and its electrochemical response to the complementary and three base-mismatched DNAs was studied using [Co(phen)3]3+ ion (phen = 1,10-phenanthroline) as an electrochemical indicator. The response of the Pt nanoparticle-deposited GC electrode is significantly higher as compared with that prepared based on a Pt disk electrode of same geometric surface area, suggesting a usefulness of the Pt nanoparticle-deposited electrodes. A linear calibration graph for the complementary DNA over the concentration of 2.1 × 10-9 - 2.1 × 10-7 mol/L was obtained and the limit of detection was 1.0 × 10-9 mol/L, while virtually no response was observed for the three-base-mismatched DNA. The DNA sensor can be used repeatedly over 8 times without deterioration.
ASJC Scopus subject areas