G-rich sequence-functionalized polystyrene microsphere-based instantaneous derivatization for the chemiluminescent amplified detection of DNA.

Herein, we develop a novel chemiluminescence (CL) approach with high sensitivity and excellent selectivity, by taking advantage of magnetic beads as preconcentration carriers and polystyrene microspheres as an amplification platform. Briefly, a 'sandwich-type' detection strategy is employed in our design, which involves capture probe DNA immobilized on the surface of carboxyl-terminated magnetic beads and multiple biotinylated reporter DNA self-assembled on the surface of streptavidin-modified polystyrene microspheres. The reporter DNA includes a guanine nucleobase-rich (G-rich) sequence domain for the generation of light and an additional tethered nucleic acid domain complementary with the target DNA. The CL signal is obtained via a novel instantaneous derivatization reaction between a specific CL reagent and the guanine nucleo-bases rich in the target and reporter DNA. As a result, we demonstrate that this DNA assay is reproducible, stable, easy to use, and can sensitively detect femtomolar target DNA related to anthrax lethal factors with excellent differentiation ability for single-base mismatched sequences. Overall, this new CL protocol couples the high sensitivity of CL analysis with effective magnetic separation for discriminating against unwanted constituents such as mismatched sequences, and hence, offers great promise for DNA hybridization analysis.