The rapid test protocol is developed by the Research Laboratory of Biofunctional Materials of Tallinn University of Technology and is based on the molecular imprinting technology. This technology enables "molecular memory sites” be created within a polymer structure. These sites act as synthetic receptors and recognise the target molecule (e.g., virus particles), using a principle similar to that of biological receptors (e.g., antibodies); however, their properties are more stable and cost-effective.

To prepare the test, a synthetic receptor with selectivity towards the viral protein (antigen) is interfaced with a sensor chip. The given phase involves a series of technological processes: binding of the protein to the surface of the sensor chip, synthesis of the polymer around the protein and finally, and removal of the protein from the polymer structure. The resulting sensor chip, covered with a synthetic receptor selective for the viral protein, is ready for use (see the figure). In the next phase of the research, a solution is developed that allows scaling up the preparation of the sensor chips for possible mass-production.

For the analysis of the viral infection, the sensor chip is exposed to the solution of the nasopharynx swab sample for approx. 15-20 minutes for initiating interaction between the viral protein (in the case of the presence of the virus) and the synthetic receptor. Thereafter, the sensor chip is placed in the indicator solution and connected to a portable potentiostat controlled by software in a tablet computer or mobile phone. The potentiostat measures the reduction in the intensity of the electrochemical reaction at the interface of the sensor chip and the solution (see red line in the drawing). The reduction rate is correlated with the concentration of the virus protein in the sample. The reduction of the signal below a certain limit indicates the presence of the virus in the sample.

Thus, in addition to detecting the virus, the test developed by the researchers of Tallinn University of Technology can also establish its concentration, which is an advantage over the classical PCR method.

Vitali Syritski explained: "We have, in cooperation with Synlab, tested and compared real negative and positive patients’ samples. The preliminary results allow us to claim that our method works well and as of today, a prototype has been prepared."

The researchers from Tallinn University of Technology have filed a patent application in the United States. With the support of a targeted grant of the Estonian Research Council (ETAG) and together with the School of Science of Tallinn University of Technology, the research group is studying the possibility of using the test in saliva or blood samples.

The head of the Biofunctional Materials Laboratory of Tallinn University of Technology, Vitali Syritski, would like to thank Icosagen AS and Prof. M. Ustav for kindly providing the viral proteins required for creating the “molecular memory sites”.