Nanotechnology, allergens, contaminants & authenticity
The Nanotechnology Laboratory in the NoWFOOD building contains equipment for DNA testing and ELISA testing. DNA testing is performed using PCR where two very small pieces of DNA are designed to flank a gene of interest. Using a specific enzyme and other biological reagents, a programme of cycling temperatures is performed in a specially made PCR machine and the target gene is reproduced many times over. So much of the target DNA molecule is amplified that this can then be visualised either on a gel using ultra violet light or by fluorescence.
PCR can be used for many things in food testing including species identification/authentication (with reference to the horsemeat scandal and also authentication of premium products, e.g. monkfish), identification of allergen DNA and identification of genetically modified DNA from relevant species (maize, soya etc.) The Nanotechnology Laboratory will have the capability for standard PCR (end-point/qualitative testing, otherwise known as presence/absence testing) and also real-time PCR which is quantitative (where an unknown sample is run against calibrated standards). Development of a method for food testing with PCR can be quite simple provided you know or can find out the sequence of the target gene. There are various on line databases where gene sequences are freely available, and other databases which will design specific ‘primers’ around the gene of interest.
Therefore, with DNA testing, it is possible to produce a new testing method within a very quick timeframe, sometimes a week or two, rather than months. ELISA testing is antibody-based testing – targeting the protein specific to a plant or animal. This is the ‘gold-standard’ method for things like allergen identification since it is the protein that is being targeted rather than the DNA, which is the molecule that people react to if they have an allergy of some sort (eg. peanut allergy). ELISA assays are also used for species identification and identification and quantitation of mycotoxins (fungal toxins). It can take some time to develop an ELISA method unless you can find a suitable antibody that is commercially available.
If there are no readily available commercial antibodies, it can take several months to raise a new one and then several more weeks or months to check the suitability of the antibody for the test in mind. ELISA assays are lab-based, requiring various pieces of equipment (plate reader, plate washer) but on-site antibody-based tests are now also available which can be used for detection of species and also allergens. These are really useful in manufacturing environments when people want to make ‘allergen-free’ claims so that they can validate and verify their cleaning practices, or to check authenticity of meat products. The Nanotechnology Lab will also have the capability to do chemiluminescent protein analysis using a state-of-the-art camera system, also utilised as part of the DNA testing equipment. This will be useful for method development and the identification of specific proteins for new rapid testing methods.
1. Bio-Rad CFX Connect Real-Time PCR Detection System
Enables two-target multiplex PCR and quantitation of PCR reactions. Will be used for detection of species (animal and/or fish), allergen DNA and genetically modified organisms.
2. Bio-Rad S1000 PCR instrument
Split 48/48 well head enables two different PCR programmes to be performed on the one instrument. Will be used for qualitative PCR – species identification (animal and/or fish), detection of genetically modified organisms and allergen DNA.
3. Bio-Rad Chemi-Doc XRS+ System
A completely automated detection system for chemiluminescence, fluorescence, and colorimetric imaging. Used for DNA and protein visualisation.
4. Bio-Tek Cytation 3 Multi-Mode Reader
A combination of automated digital microscopy and conventional microplate detection. Will be used for analysis of ELISA assays. Potential for cellular imaging with fluorescence module.