Abstract

Nucleic Acid Amplification Tests Based on Nanocomposite Material

Philip Drake, Senior Researcher, ITRI

Magnetic nanoparticles (MNPs) and SERS active nanoparticles (SERS-NPs) were coated with short chain DNA tags. These were then used to identify a bacterial DNA sequence via a nucleic acid amplification test (NAAT). The tags function as primers in a standard PCR reaction with the reverse primers and forward primers on the SERS-NPs and MNPs respectively. On binding to the target DNA the primers on the surface of the NPs can be extended through a PCR reaction. Once extended the MNPs and the SERS-NPs are able to hybridize together and crosslink through the extended DNA chain resulting in the formation of a composite nanostructure. Using a desktop analyser this structure can be magnetically trapped and the SERS signal recorded. The process of extension and annealing can be repeated as in standard PCR reactions building up larger nanostructures. The intensity of the SERS signal was found to be related to the concentration of the target DNA with a detection limit estimated to be less than 1 zeptomole. For comparison a PCR assay based on the standard SYBR Green method was performed. This used the same primers and target DNA and had a detection limit of 10 attomoles, 10000 times less sensitive.