Chemiluminescent detection of DNA hybridization based on signal DNA probe modified with gold and cobalt nanoparticles

A novel and sensitive chemiluminescence (CL) assay for sequence-specific DNA detection based on signal amplification with gold and cobalt nanoparticles (NPs) was reported. The sandwich-type DNA biosensor was fabricated with the amino-functionalized capture DNA immobilized on the magnetic bead and hybridized with one end of target DNA, the other end of which was recognized with a signal DNA probe labeled on the surface of Au NPs. To amplify the detection signals, a single gold NP was modified with 27 cobalt NPs by a reaction between amino-functionalized DNA on the surface of gold NP and carboxyl-functionalized on the surface of cobalt NPs. The hybridization events were monitored by the CL intensity of luminol-H ₂O ₂-Co ²⁺ after the cobalt ions were dissolved from the hybrids. This method could detect as low as 6.0 × 10 ^-17 M target DNA and the line range was from 1.0 × 10 ^-16 to 1.0 × 10 ^-15 M.