Unicamp researchers in partnership with the University of Pennsylvania, in the United States, developed the prototype of a low-cost rapid test to diagnose the new coronavirus. The portable biosensor uses electrodes printed on paper or polymeric plates that are modified with elements for recognizing the virus, SARS-CoV-2, and can be operated directly on the cell phone.
The method developed presented results as accurate as the RT-PCR reference standard, which searches for genetic material of the virus in the patient's cells, and is capable of providing results as simply as a blood glucose test.
The technology is based on a technique known as electrochemical impedance spectroscopy and seeks to assist in the early diagnosis of the disease, as it makes it possible to detect the presence and quantity of the virus in samples – and not antibodies, like the most common rapid tests.
The device works based on the difference in electrical signal produced by the interaction of SARS-CoV-2 on the surface of the sensor. During tests at the university, the result is ready in just 4 minutes and the materials cost 4,5 dollars, just over R$20. But the final price of the test may vary when manufactured on a large scale by a company. The Inova Unicamp Innovation Agency, together with the UPenn Technology Transfer Office, are engaged in finding the business partner to transfer the technology.
Regarding the application of the test, William Reis de Araújo, professor at the Unicamp Chemistry Institute and co-inventor of the low-cost rapid diagnosis, explains that the electrochemical sensor does not depend on highly trained personnel or several steps and hours of analysis like RT -PCR. “With our method, the person only needs to have basic knowledge of how to collect the sample and insert it into the analysis device”, said the professor.
The devices were produced at Unicamp's Portable Chemical Sensors Laboratory and sent to the United States, where they were tested at the partner laboratory (La Fuente Lab) specializing in microbiology, at the Perelman School of Medicine at the University of Pennsylvania. There, the studies were led by professor Cesar de la Fuente-Nunez and post-doctoral student Marcelo Der Torossian Torres, who is Brazilian.
In bench tests, the electrochemical sensor achieved 97,4% accuracy, which is the accuracy of the diagnostic results, with material collected by swab (“swab”) from the patients' nose and throat and 83.9% with saliva samples, when compared with the RT-PCR method.
The good detectability presented by the device allows diagnosis in the early stages of the disease, which correspond to 2 to 3 days after infection. New adjustments still seek to improve the accuracy of saliva tests. Less invasive methods have received greater attention from the scientific community and industry, as they allow for simpler collection with less discomfort.
The patent was provisionally filed with the United States Patent and Trademark Office (USPTO) with monitoring by the Inova Unicamp Innovation Agency. The so-called US Provisional guarantees the right to property while scientists finalize the last details of the invention.
The next step will be to carry out clinical tests on a large number of samples, which will be carried out at the Hospital of the University of Pennsylvania, starting in January. In Brazil, there is still no forecast for use of the device, until a business partner is found interested in licensing the technology and financing the next stages of the product's development and launch.
How works
The new diagnostic method basically uses three inputs: paper or printed circuit boards; conductive inks made from carbon and silver; and ACE-2 converting enzymes. At the base of the sensor, similar to glucose measuring strips, the scientists printed an electronic microcircuit with three electrodes that was covered with enzymes. They facilitate the entry of SARS-CoV-2 into the human body.
In contact with contaminated biofluids, these receptor enzymes bind to proteins that are on the surface of the coronavirus, known as protein spikes, generating a chemical interaction that blocks part of the circuit area. This creates resistance in the electrode to charge transfer, hindering the flow of electrical current and indicating the presence of the virus. In addition to being faster, easier and cheaper, the test can be taken anywhere.
“The same device can be operated both on a laboratory scale and directly at the point of need, as the analysis can be carried out using benchtop equipment or with a miniaturized version that can be attached directly to the cell phone. In the future, the idea is that tests can even be carried out at home”, explains de Araújo.
original article published on the website of the Inova Unicamp Innovation Agency.
