Molecular test for COVID-19 diagnosis based on a colorimetric genomagnetic assay

Author(s)

de Oliveira, Tassia Regina ; Leite, Taise Helena Oliveira ; Miranda, Wyllian Neves ; Manuli, Erika Regina ; Leal, Fabio ; Sabino, Ester ; Pott-Junior, Henrique ; Melendez, Matias ; Faria, Ronaldo Censi

• Document type: Journal article
• Source: Analytica Chimica Acta; v. 1257, p. 7-pg., 2023-04-06.

Abstract

The world is in a long pandemic period caused by the SARS-CoV-2 virus and massive diagnostic tests to assist efforts to control the spread of the disease and also to avoid new coronavirus variants are still needed. Herein, we propose a simple and accurate saliva-based colorimetric test for the diagnosis of COVID-19. Magnetic beads (MBs) modified with a sequence of single-strand DNA (ssDNA) complementary to the N gene of the SARS-CoV-2 RNA were developed and used for magnetic capture and separation from a complex saliva sample. A second biotinylated ssDNA sequence was applied, and the colorimetric detection was carried out by adding streptavidin-horseradish peroxidase conjugate, H2O2, and tetramethylbenzidine (TMB) as chromogenic substrate. The test does not require viral RNA isolation, transcription, or amplification steps and can be performed at room tem-perature. The molecular assay test can be run using 96-well microplates, allowing the diagnosis of a large number of samples in 90 min. A simple support for magnets was designed and constructed using a 3D printer that allows the magnetic separations directly in the 96-well microplate. The colorimetric test showed an excellent ability to discriminate between healthy individuals and patients infected with SARS-CoV-2, with 92% and 100% of clinical sensitivity and specificity, respectively. This performance was similar to that achieved using the gold standard RT-PCR technique. The proposed genomagnetic assay offers an opportunity to greatly increase population testing, contribute to controlling the spread of the virus, and improve health equity in testing for COVID-19. (AU)

• FAPESP's process: 20/04635-4 - Development of a simple and affordable disposable device for rapid diagnosis of coronavirus (SARS-CoV-2)
• Grantee: Ronaldo Censi Faria
• Support Opportunities: Regular Research Grants
• FAPESP's process: 20/07539-6 - Development of a simple and affordable disposable device for rapid diagnosis of Coronavirus (SARS-CoV-2)
• Grantee: Tássia Regina de Oliveira
• Support Opportunities: Scholarships in Brazil - Post-Doctoral