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Biosensor permits ultra-fast and low-cost detection of SARS-CoV-2

Publicado em 11 agosto 2021

The challenges posed by the COVID-19 pandemic have stimulated innovation on a number of fronts. One is the event of low-cost strategies of medical prognosis. Genosensors are a living proof. Based on nucleic acids that detect easy complementary DNA or RNA sequences, genosensors are biosensors that make potential mass testing for rapid and delicate testing of genetic materials.

A tool of this sort, already proven to be environment friendly in detecting SARS-CoV-2, has simply been produced in Brazil by a multidisciplinary workforce of researchers affiliated with numerous establishments and led by physicist Osvaldo Novais de Oliveira Junior, a professor on the University of São Paulo’s São Carlos Institute of Physics (IFSC-USP).

The results of the evaluation will be prepared in half-hour, for a laboratory-scale price of lower than 1 US greenback per genosensor. The elements of the impedance analyzer, a sturdy a part of the machine, price lower than 200 US {dollars}. The machine already exists on the laboratory scale, and the know-how will be transferred to any firm with the wherewithal to mass-produce it.

“Our genosensor can immobilize a simple DNA strip used as a capture probe. Under appropriate conditions, the immobilized strip binds to a complementary DNA strip contained in the liquid sample to be analyzed. This process, called hybridization, demonstrates the presence of SARS-CoV-2 in the sample, which may be saliva or another body fluid,” chemist Juliana Coatrini Soares instructed.

Soares is first creator of an article describing the analysis and printed in Materials Chemistry Frontiers.

How it really works

The machine consists of a self-assembled monolayer of 11-mercaptoundecanoic acid (11-MUA) chemically bonded to glass electrodes containing micrometric gold leads or surfaces containing gold nanoparticles. This setting is ready to immobilize the easy DNA or RNA strip used as a seize probe. Hybridization with the complementary strip, if it exists within the pattern, is proven via variations in bodily parameters detected by electrical or electrochemical impedance spectroscopy and localized floor plasmon resonance.

“After hybridization, there is an increase in electrical resistance on the surface of the sensor, which can be monitored by a low-cost impedance analyzer costing about 100 US dollars, and developed in our lab by engineer Lorenzo Buscaglia, a member of the group. Another effect of hybridization between the capture sequence and the complementary SARS-CoV-2 sequence is a shift in the absorbance peak in the transmitted spectrum, which can be monitored by means of localized surface plasmon resonance using a spectrophotometer,” stated chemist Paulo Augusto Raymundo-Pereira, a researcher at IFSC-USP who took half within the analysis.

The highest sensitivity achieved within the research corresponded to 0.3 copies per microliter, adequate to detect the DNA sequence in saliva or different physique fluids. The complementary SARS-CoV-2 sequences have been additionally recognized via machine studying methods utilized to scanning electron microscope photographs obtained from genosensors uncovered to numerous totally different concentrations of complementary DNA sequences.

“By applying machine learning algorithms to image processing, we were able to obtain a high degree of precision in distinguishing between the different concentrations of complementary SARS-CoV-2 DNA sequences,” Raymundo-Pereira stated.

In the detection experiments, the sensitivity of the genosensors was verified in management samples, together with a unfavourable sequence for SARS-CoV-2 and different DNA biomarkers unrelated to the virus. Analysis of the information obtained by a multidimensional projection method referred to as interactive doc mapping (IDMAP) confirmed a transparent separation between complementary DNA sequences at numerous concentrations and samples containing a non-complementary sequence or different DNA biomarkers unrelated to SARS-CoV-2.

“The advantage of using several detection methodologies is the versatile mode of operation so that the diagnostic method can be implemented in accordance with the reality of each country, or of the different regions of continent-sized countries like Brazil. Our genosensor is also promising as a detector of genetic material from novel variants of SARS-CoV-2. To do this, if the variant’s genetic sequence is known, you simply swap out the simple DNA strip used as the capture probe,” Oliveira Junior defined.

The multidisciplinary workforce that developed the machine included researchers on the University of São Paulo’s São Carlos Institute of Physics (IFSC-USP), São Carlos Institute of Chemistry (IQSC-USP), Institute of Mathematical Sciences and Computing (ICMC-USP), the Instrumentation unit of the Brazilian Agricultural Research Corporation (EMBRAPA), and the Pelé Pequeno Príncipe Research Institute in Curitiba, Paraná state.

More data:

Juliana Coatrini Soares et al, Detection of a SARS-CoV-2 sequence with genosensors utilizing information evaluation primarily based on data visualization and machine studying methods, Materials Chemistry Frontiers (2021). DOI: 10.1039/D1QM00665G