Team:Linkoping Sweden/Project/Biology

Our approach is to use an antibody or functionally similar structure in combination with fluorescence probes to detect the Ara h antigen. This system will have three potential parts: an antibody complex consisting of an antibody connected to a fluorescent probe, a default-epitop complex consisting of an epitop linked to a fluorescent probe, and the Ara h protein. These are potential parts in the sense that system will always contain the first two parts (antibody complex and the default antigen complex), but will only contain the third part, Ara h protein, if the inserted sample has been contaminated with peanut protein. The biosensor system is to be implemented in a device consisting of a box containing the sensors necessary to detect fluorescence and any eventual changes in fluorescence. This information is then processed by a microprocessor to give a color indication, red or green, correlating to the changes in fluorescence. So how exactly will the system work? Let’s break it down step-by-step:

There are two possible scenarios for our biosensor system, either the system does not contain peanut protein (Ara h) or it does. The first scenario is default for our biosensor; it contains two interacting parts in the form of an antibody connected to a fluorescent probe (Green Fluorescence Protein or GFP) and an antigen bound to a fluorescent probe (Red Fluorescence Protein or RFP). The antigen binds to the antibody, and when a light source is shone on the biosensor the incoming light is absorbed by GFP and transferred to RFP through Förster Resonance Energy Transfer (FRET). The emitted wavelength is detected and then processed by a microprocessor which makes an LED light-panel shine green. Green light thus indicates that the system only contains the antibody and antigen complexes, and has not been contaminated by peanut protein.

The other possible scenario is that the inserted food sample has been contaminated by peanut and that system thus contains Ara h. The peanut protein will bind with a higher affinity to the GFP-antibody complex, thus forcing the antigen-RFP complex out of the picture. Ara h bound to the antibody-GFP complex reduces FRET as applied light is absorbed and emitted solely by GFP. This results in a wavelength change which is detected and processed, causing in an LED light-panel change from green to red. Red light thus indicates that the system has been contaminated by peanut and that the food is unsafe to consume.