However, recent studies have found false negative rates ranging from 12 to 48% mainly because of inappropriate conditions of sample transportation and inappropriate samples. ID NOW is a rapid, point-of-care (POC) test that allows the direct detection of viral RNA from the clinical sample without the need for RNA extraction. Isothermal nucleic acid amplification, which allows rapid amplification of target sequences at a single constant temperature, is employed in several tests including the ID NOW COVID-19 test from Abbott Diagnostics. (15−18) Several laboratories around the world are working on improving RT-PCR methods and developing alternative molecular diagnostic platforms. In addition, studies have found up to 30% false negative rate for RT-PCR in the early course of infection. (12−14) Although RT-PCR is a sensitive technique, it requires expensive laboratory equipment and trained technicians to perform the test and can take up to 48 h to generate results. RT-PCR detects SARS-CoV-2 RNA and targets different genomic regions of viral RNA. (9−11) Currently, real-time reverse-transcription polymerase chain reaction (RT-PCR) is the most widely used laboratory test for the diagnosis of COVID-19. Because clinical manifestation of COVID-19 ranges from mild flulike symptoms to life-threatening pneumonia and acute respiratory illness, it is essential to have a proper diagnosis during an early stage of infection for efficient implementation of control measures to slow the spread of COVID-19. There is currently no medication to treat COVID-19. (8) The major structural proteins of coronavirus are spike (S), envelope (E), membrane (M), and nucleocapsid (N). (6,7) The coronavirus genomic RNA encodes replication and transcription complexes from a single large open reading frame (ORF1ab) and structural proteins of the virus. SARS-CoV-2 is an enveloped, positive-strand RNA virus with a large RNA genome of ∼30kb with genome characteristics similar to those of known coronaviruses. COVID-19 was declared a pandemic by WHO on March 11, 2020, because of its rapid spread in various countries around the world. (4,5) The outbreak that began in China has rapidly expanded worldwide, and on January 30, 2020, the World Health Organization (WHO) declared the novel coronavirus infection a “Public Health Emergency of International Concern”, and the illness was named coronavirus disease 2019 (COVID-19). (2,3) The virus was initially named 2019 novel coronavirus (2019-nCoV) and later renamed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). (1) Later, a novel strain of coronavirus belonging to the broad family of coronaviruses was subsequently isolated from bronchoalveolar lavage fluid. In December 2019, a cluster of severe pneumonia cases was reported in Wuhan, Hubei Province, China. The goal of this review is to inform the researchers of diagnostic and surveillance platforms for SARS-CoV-2 and their performances.
In addition, other platforms that use magnetic nanomaterials as auxiliary tools for enhanced pathogen and virus detection are also covered.
Magnetic point-of-care diagnostic kits are also reviewed aiming at developing plug-and-play diagnostics to manage the SARS-CoV-2 outbreak as well as preventing future epidemics. We review popular magnetic nanosensing techniques including magnetoresistance, magnetic particle spectroscopy, and nuclear magnetic resonance. Herein, this review covers the literature of magnetic nanosensors for virus and pathogen detection before COVID-19. Recent advances in magnetic nanomaterials and nanotechnologies have transformed current diagnostic methods to nanoscale and pushed the detection limit to early-stage disease diagnosis. The past decade has seen rapid growth in applying magnetic tools for biological and biomedical applications. Magnetic nanosensing is an emerging topic representing the frontiers of current biosensing and magnetic areas. As of July 2020, no specific drugs or vaccines are yet available for COVID-19 a fast and accurate diagnosis for SARS-CoV-2 is essential in slowing the spread of COVID-19 and for efficient implementation of control and containment strategies. The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), is a threat to the global healthcare system and economic security.
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