Designing and fabrication of electrochemical nano-biosensor for the fast detection of SARS-CoV-2-RNA.

SARS-CoV-2 caused a global panic among populations. Rapid diagnostic procedures for the virus are crucial for disease control. Thus, the designed signature probe from a highly conserved region of the virus was chemically immobilized onto the nanostructured-AuNPs/WO3-screen printed electrodes. Different concentrations of the matched oligonucleotides were spiked to test the specificity of the hybridization affinity whereas the electrochemical impedance spectroscopy was used for tracking the electrochemical performance. After a full assay optimization, limits of detection and quantification were calculated based on linear regression and were valued at 298 and 994 fM, respectively. Further, the high performance of the fabricated RNA-sensor chips was confirmed after testing the interference status in the presence of the mismatched oligos in one nucleotide and completely one. Worthy to mention that the single-stranded matched oligos can be hybridized to the immobilized probe in 5 min at room temperature. The designed disposable sensor chips are capable of detecting the virus genome directly. Therefore, the chips are a rapid tool for SARS-CoV-2 detection.

SARS-CoV-2-Impedimetric Biosensor: Virus-Imprinted Chips for Early and Rapid Diagnosis.

Due to the current global SARS-CoV-2 pandemic, rapid and accurate diagnostic tools are needed to prevent the spread of COVID-19 across the globe. An electrochemical sensing platform was constructed using CNTs/WO3-screen printed electrodes for imprinting the complete virus particles (SARS-CoV-2 particles) within the polymeric matrix to create viral complementary binding sites. The sensor provided high selectivity toward the target virus over other tested human corona and influenza respiratory interference viruses. The sensitivity performance of the sensor chips was evaluated using different viral concentrations, while the limits of detection and quantification were 57 and 175 pg/mL, respectively. Reaching this satisfied low detection limit (almost 27-fold more sensitive than the RT-PCR), the sensor was applied in clinical specimens obtained from SARS-CoV-2 suspected cases. Thus, dealing directly with clinical samples on the chip could be provided as a portable device for instantaneous and simple point of care in hospitals, airports, and hotspots.

Point-of-Care Diagnostics of COVID-19: From Current Work to Future Perspectives.

Coronaviruses have received global concern since 2003, when an outbreak caused by SARS-CoV emerged in China. Later on, in 2012, the Middle-East respiratory syndrome spread in Saudi Arabia, caused by MERS-CoV. Currently, the global crisis is caused by the pandemic SARS-CoV-2, which belongs to the same lineage of SARS-CoV. In response to the urgent need of diagnostic tools, several lab-based and biosensing techniques have been proposed so far. Five main areas have been individuated and discussed in terms of their strengths and weaknesses. The cell-culture detection and the microneutralization tests are still considered highly reliable methods. The genetic screening, featuring the well-established Real-time polymerase chain reaction (RT-PCR), represents the gold standard for virus detection in nasopharyngeal swabs. On the other side, immunoassays were developed, either by screening/antigen recognition of IgM/IgG or by detecting the whole virus, in blood and sera. Next, proteomic mass-spectrometry (MS)-based methodologies have also been proposed for the analysis of swab samples. Finally, virus-biosensing devices were efficiently designed. Both electrochemical immunosensors and eye-based technologies have been described, showing detection times lower than 10 min after swab introduction. Alternative to swab-based techniques, lateral flow point-of-care immunoassays are already commercially available for the analysis of blood samples. Such biosensing devices hold the advantage of being portable for on-site testing in hospitals, airports, and hotspots, virtually without any sample treatment or complicated lab precautions.