Hydroxylamine-amplified gold nanoparticles for the homogeneous detection of sequence-specific DNA

Herein, we report the development of a simple, sensitive, inexpensive, and homogeneous detection method for the analysis of DNA hybridization based on the optical properties of hydroxylamine-amplified gold nanoparticles (Au NPs) in solution phase. The assay relies on a sandwich-type DNA hybridization in which DNA targets are first hybridized with capture DNA probes immobilized on the surface of magnetic beads and then sandwiched with Au NPs modified with biotinylated reporter DNA. Au NPs, after being anchored on the magnetic beads, are then dispersed in solution by the dehybridization and enlarged by using a mixture of HAuCl4 and NH2OH. The Au NP growth signal which is used for the quantitative analysis of sequence-specific DNA can be easily monitored by the naked eye directly or an UV-vis spectrophotometer. Surface plasmonic signature of the enlarged Au NPs and the kinetics of the Au NP growth in the homogenous phase containing of HAuCl4 and NH2OH have also been studied. As a result, such a homogeneous assay allows the detection of 30-base DNA targets down to the 100 amol level, which offers great promise for facilitating sensitive detection of other biorecognition events.