In the course of our goal to carry out research leading to tangible benefits for future generations, Imego is in the process of developing a micro sensor system based on molecular imprints in polymeric materials for the purpose of detecting toxic substances. The aim is to develop a sensor capable of detecting the toxins that appear in drinking water, agricultural products and food.
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Molecularly Imprinted Polymers in sensorics | |
Molecularly Imprinted Polymers (MIPs) are used to specifically bind and enrich medium and small sized molecules. MIPs can be used to detect a wide variety of compounds and most molecules below less than approximately 5 kDa are suitable for imprinting.
A specific MIP is designed and prepared for each molecule of interest. It can then be used as a selective sensing material integrated in a sensoric system. MIPs can be designed to be used in a sensor system for the detection of the toxins that can appear in drinking water, agricultural products and food to name some examples.
The detection part of the sensor system is fairly generic, so similar detection techniques can be used to sense a variety of different compounds. Imego´s strategy involves the evaluation and optimization of several detection techniques using model imprint systems. After identifying the optimal detection technique, we produce molecular imprints of target analytes of commercial interest or environmental importance then use them in our sensor system.
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Principle of Molecularly
Imprinted Polymer production | |
Molecularly Imprinted Polymers act by specific binding of the molecule they are made to bind. The specificity is established by the production procedure. The molecule of interest, the blue target molecule in the figure above, is mixed with functional monomers. The monomers bind to the target molecule via for example hydrogen bonds, electrostatic interaction or hydrophobic interactions. A crosslinking molecule is added and by illuminating or heating the reaction mixture a polymerisation process is started, linking the crosslinkers to the monomers and to each other and locking the structure around the target molecule. The target molecules are then washed away, leaving hollow spaces in a sponge like polymeric network. The hollow spaces are able to encase and rebind the target molecule if encountered with for example a water sample containing the molecule. The rebinding has a specificity connected to both the geometrical structure of the hollow site and the chemically functional groups within the site.
When the target molecule is absorbed by the molecularly imprinted polymer network and binds to the tailor made hollow spaces in the polymer, the characteristics of the polymer are altered. At Imego we evaluate two different detection techniques for monitoring of the target binding.
It is known that the dielectric properties of the imprinted polymer with and without the bound analyte are different. One of the detection techniques used at Imego is based on the measurement of the frequency dependent complex impedance of a MIP layer. We use microelectrodes developed at Imego that are covered with a thin film MIP. See figure "Imego developed microelectrode" below. The electric signal can be related to the target uptake in the polymer and the concentration of the target in the sample solution. It is also known that some MIPs tend to expand or shrink upon target absorption and their surface energy changes. These changes are monitored using micro-cantilevers. The changes of volume and surface energy upon target binding cause the cantilever to bend, see figure "Cantilever" below. Changes in the beam curvature can be detected either optically or using strain gauges and can be related to the target uptake and the concentration of the target in the sample solution. In addition to the mentioned detection techniques we use well established sensor techniques such as Quartz Crystal Microbalance with Dissipation monitoring and radioactivity measurements to evaluate the function of the thin MIP layers. 
Imego is working together with a research group at Lund University with several years of experience and expertise in Molecularly Imprinted Polymer production. The group at Lund University develops the MIP chemistry and produces thin film MIPs on sensor substrates provided and/or developed by Imego.
Imego’s expertise lies in the development of an appropriate sensoric system, with MIPs used as the absorbing material.
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