Gold nanoparticle-mediated immobilization strategy for DNA microarray: a simple and effective method to obtain homogeneous spots with higher capacities over conventional method

Abstract

In order to obtain reliable results from DNA microarray system, one of the key issues is the strategy for efficient immobilization of capture probe DNAs. The conventional immobilization methods, however, have not been regarded as good enough in several points such as capture probe capacity, spot homogeneity, and data consistency with repeated experiments. Therefore, we developed a novel strategy for DNA immobilization on slide glass utilizing gold nanoparticle as an immobilization mediator. Prior to spotting, the capture probe DNA molecules were mixed with relavent gold nanoparticles followed by the conventional immobilization processes on aldehyde- or amine-activated slide glass. Through the investigation of the DNA chips prepared by the strategy, we found out that it offers following key major advantages. First, the gold nanoparticles provide the capture probe DNAs with three dimensional surfaces leading to the increased surface area for DNA immobilization, which results in higher probe capacity and consequently higher signal intensity after final hybridization step. Second, since the gold nanoparticle-DNA complex was more uniformly dispersed on the slide glass, more highly uniformed spots could be obtained. Finally, with this strategy, we were able to check the spot quality immediately after the spotting by just performing silver enhancement on the spotted gold nanoparticles, which can be detected by the naked eye. Since this strategy is very simple and effective for DNA immobilization, it has enormous potentials in the area of DNA microarray.