Detection of DNA immobilized on bare gold electrodes and gold nanoparticle-modified electrodes via electrogenerated chemiluminescence using a ruthenium complex as a tag

Electrogenerated chemiluminescence (ECL) for DNA hybridization detection is demonstrated based on DNA that was self-assembled onto a bare gold electrode and onto a gold nanoparticles modified gold electrode. A ruthenium complex served as an ECL tag. Gold nanoparticles were self-assembled on a gold electrode associated with a 1,6-hexanedithiol monolayer. The surface density of single stranded DNA (ssDNA) on the gold nanoparticle modified gold electrode was 4.8 × 1014 molecules per square centimeter which was 12-fold higher than that on the bare gold electrode. Hybridization was induced by exposure of the target ssDNA gold electrode to the solution of ECL probe consisting of complementary ssDNA tagged with ruthenium complex. The detection limit of target ssDNA on a gold nanoparticle modified gold electrode (6.7 × 10−12 mol L−1) is much lower than that on a bare gold electrode (1.2 × 10−10 mol L−1). The method has been applied to the detection of the DNA sequence related to cystic fibrosis. This work demonstrates that employment of gold nanoparticles self-assembled on a gold electrode is a promising strategy for the enhancement of the sensitivity of ECL detection of DNA.