Developing oligonucleotide microarray-based resonance light scattering assay for DNA detection on the PAMAM dendrimer modified surface

Here, a three-dimensional (3D) oligonucleotide microarray-based resonance light scattering (RLS) assay has been developed for DNA detection. Oligonucleotide conjugated gold nanoparticles are used as RLS probes for labeling the detection system, followed by silver deposition for signal enhancement. The 3D oligonucleotide microarray is fabricated on the home-made fourth-generation (G4) NH2-terminated poly(amidoamine) dendrimers (PAMAM) modified substrate. After activated by glutaraldehyde (GA), the PAMAM modified substrate enables to react with NH2-modified oligonucleotide with highly efficiency and generates highly signal-to-background ratio. This assay makes it possible to discriminate an oligonucleotide sequence from the target with single nucleotide mismatch with high selectivity. And detection sensitivity of the 3D microarray is nearly 3-fold higher than that of two-dimensional (2D) microarray which is fabricated on the commercial planar slide. The discrimination between G : T and C : T mismatch as well as the mismatch sites, a particularly difficult task for microarray-based assays, has also evaluated.