Colourimetric detection of swine-specific DNA for halal authentication using gold nanoparticles

Detecting pork contamination is critical for halal food preparation. A fragment of species-specific DNA from swine mitochondrial genome was selected as a target, and two oligonucleotides complementary to the target were used as probes for pork identification. The probe-conjugated gold nanoparticles bound to the target DNA, leading to the aggregation of gold nanoparticles and thus causing the colour of the gold nanoparticles to change from red to blue. More than 0.1 μmol/L of DNA led to an obvious colour change, which was observed by naked eyes after dotting test solutions onto a thin layer chromatography (TLC) plate. Furthermore, 0.001-1 μmol/L of the target was semi-quantified by using a digital camera and image processing software. This colourimetric detection might be a promising technique for differentiation of pork from other animal meat products without using any sophisticated machines, and thus will be used for halal authentication.