LiU iGEM’s vision is to develop a biosensor system for the private consumer. This system would detect the Ara h1 allergen and give an easily interpreted result, thus making it simple to analyze food and drink for potential peanut content. Being able to detect peanut protein in consumable goods would allow the allergic individual to avoid ingesting it and thereby completely evade an allergic reaction.

We believe that our device will be of great use for all peanut allergic individuals in everyday life but also for those who, for example, travel abroad and are unsure whether or not their food contains peanuts. Miscommunication or bad labeling is an extremely unnecessary reason to end up in a potentially life threatening situation. Therefore, by providing the individual with a chance to scan their food for peanuts, we will give them the security that they deserve.

By designing a Biobrick which includes the sequence for the Ara h1 epitope linked to a red fluorescent protein (RFP), we will be able to express the protein and thereby mix it with a purchased solution of Ara h1 specific IgG antibodies. The epitope - RFP protein complex will then bind to the antibodies, which in turn are labeled with a green fluorescent probe, Fluorescein isothiocyanate (FITC). Hence, a phenomenon called FRET will occur when light is transferred from the green fluorescent probe to the red fluorescent protein by the use of a light source, thus creating an overlap in wavelength followed by detection in the form of a red light.

Furthermore, this red light is in turn converted to a green signal meaning the food is safe to consume. However, if the full length Ara h1 protein exists in the solution it will bind to the antibodies with a higher affinity leading to a loss of the epitope – RFP complex and a deletion or severe reduction of FRET. Furthermore, when Ara h1 has bound to the antibodies, only the wavelength of FITC will be detected which will be characterized by a red light, meaning that the food is not safe from peanut protein content. If you want to read more about this go to Results

To detect the FRET effect we will need an apparatus which can excite FITC and at the same time detect FRET between FITC and RFP (Fig. 1).

Our aim is to build a very small fixed wavelength spectrophotometer with good performance to a relatively low cost.

The excitation energy will come from a LED source and only wavelengths between 480-500 nm will pass a short band pass optical filter with a peak maximum at 488 nm. This overlaps very precisely with the excitation peak for FITC. This light hits the sample cuvette and makes FRET occur between the complexes. The now red-shifted photons emitted from RFP will pass another filter, which only allows red light through, and hits a calibrated Si-photodiode detector. This will give an output that can be read by a microcontroller, in our case an Arduino (Fig. 2).

If ara h 1 protein is available, the antibodies will bind the protein instead of the RFP-complex and thus give a reduction or extinction of FRET. This will be measured with the Si-detector as very little or no photons will pass the second optical filter. The signal will be reduced and a red LED lamp on the top of the detector will shine, indicating that peanut protein is present in the sample. If the sample does not contain any peanut protein a green LED will indicate this instead.

Fig 1. First prototype of our biosensor. Second generation under construction.

Figure 1. First prototype of our biosensor. Second generation under construction.