Gold nanoparticles probe for recognition of specific DNA sequence based on non-cross-link system

Abstract

Simpler, cheaper method for DNA sequence recognition is of a greater scientific and economic interest. In this paper, we develop a novel colorimetric detection method for recognition of specific DNA. The detection method bases on the strong distance-dependent optical properties of gold nanoparticles (Au-nps) and the DNA sequences' electrostatic interactions with the Au-nps. As a result of the single-stranded DNA (ssDNA) displaying far higher affinities than double-stranded DNA (dsDNA) to negatively charged Au-nps, when the concentration of salt is added, Au-nps in ssDNA keep stable because of the absorption of large amount of ssDNA, the mixture's color is red. But Au-nps in dsDNA aggregate immediately, and the mixture's color turns out to be blue. Therefore, we can judge whether the hybridization occurs by the mixture's color or absorption spectrums. Au-nps aggregation in this detection mode is not induced by hybridization of target DNA which cross-links the nanoparticles but by salt, then the color transition is rapid and clearly visible. This method is simple, cheap, and we can detect about 2Opmol specific DNA sequences.