Impedance analyzer connected to DNA biosensor that can be used to detect genetic sequence from SARS-CoV-2. (Credit: Lorenzo A. Buscaglia/IFSC-USP)

Based on nucleic acids that detect simple complementary DNA or RNA sequences, genosensors are biosensors that make possible mass testing for immediate and sensitive testing of genetic material. Researchers have developed a genosensor that is efficient in detecting SARS-CoV-2.

The device consists of a self-assembled monolayer of 11-mercaptoundecanoic acid (11-MUA) chemically bonded to glass electrodes containing micro-metric gold leads or surfaces containing gold nanoparticles. This environment is able to immobilize the simple DNA or RNA strip used as a capture probe. Hybridization with the complementary strip, if it exists in the sample, is shown by means of variations in physical parameters detected by electrical or electrochemical impedance spectroscopy and localized surface plasmon resonance.

In the detection experiments, the sensitivity of the genosensors was verified in control samples, including a negative sequence for SARS-CoV-2 and other DNA biomarkers unrelated to the virus. Analysis of the data showed a clear separation between complementary DNA sequences at various concentrations and samples containing a non-complementary sequence or other DNA biomarkers unrelated to SARS-CoV-2.

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