Addition of gold nanoparticles to real-time PCR: effect on PCR profile and SYBR Green I fluorescence.

Real-time quantitative polymerase chain reaction (qPCR) is the industry standard technique for the quantitative analysis of nucleic acids due to its unmatched sensitivity and specificity. Optimisation and improvements of this fundamental technique over the past decade have largely consisted of attempts to allow faster and more accurate ramping between critical temperatures by improving assay reagents and the thermal geometry of the PCR chamber. Small gold nanoparticles (Au-NPs) have been reported to improve PCR yield under fast cycling conditions. In this study, we investigated the effect of Au-NPs on optimised real-time qPCR assays by amplifying DNA sequences from genetically modified canola in the presence and absence of 0.9 nM Au-NPs of diameter 12 +/- 2 nm. Contrary to expectations, we found that Au-NPs altered the PCR amplification profile when using a SYBR Green I detection system due to fluorescence quenching; furthermore, high-resolution melt (HRM) analysis demonstrated that Au-NPs destabilised the double-stranded PCR product. The results indicate that effects on the assay detection system must be carefully evaluated before Au-NPs are included in any qPCR assay.