Highly sensitive detection of DNA by electrogenerated chemiluminescence amplification using dendritic Ru(bpy)(3)(2+)-doped silica nanoparticles.

This study describes the development and characterization of a novel dendritic signal amplification strategy. It relies on the use of two different Ru(bpy)(3)(2+)-doped silica nanoparticles (Probe(1,2)RSNP and Probe(2c)RSNP) coated with complementary DNAs, which can be simply and conveniently self-assembled to build sandwich-type dendritic architectures on a gold grid. The performance of this dendritic amplification route was demonstrated in conjunction with the electrogenerated chemiluminescent (ECL) detection of the target DNA. Compared to normal amplification, dendritic amplification allowed a 5-fold enhancement of the ECL signals. The higher sensitivity allowed by the dendritic amplification route was attributed to the hybridization between the DNA (Probe(2)DNA) on Probe(1,2)RSNP (normal amplification) and the complementary DNA (Probe(2c) DNA) on the additional Probe(2c)RSNP. As low as 1 fM of 22-bp-long target DNA was clearly detected. The experimental results demonstrated that the ECL intensity achieved through dendritic amplification showed a good linear relationship with the concentration of the target DNA over a wide linear range (10 fM-10 pM).