Sensitive DNA detection by polymerase chain reaction with gold nanoparticles.

We developed a novel strategy for rapid colorimetric detection of specific DNA sequence based on gold nanoparticles assemblies induced by polymerase chain reaction (PCR) product. In the presence of target DNA, the two DNA-functionalized AuNP probes selectively hybridized with the prohibited nucleic acid segments of two primers owing to the zipping off of the hairpin structures during PCR process, resulted in the aggregation of AuNPs with a concomitant color change from red to blue-purple. It is a convenient and universal method for sensitive DNA detection with no need for any further post-treatment of the PCR products. Most importantly, our method showed a low limit of detection (LOD) of 4.3 fM with a wide range of target DNA from 16 fM to 1.6 nM. Owing to the versatility and low cost, the proposed strategy could be extremely useful for a wide range of applications, providing a promising tool for rapid disease diagnostics and gene sequencing.