Abstract
Current point-of-care (POC) screening of Coronavirus disease 2019 (COVID-19) requires further improvements to achieve highly sensitive, rapid, and inexpensive detection. Here we describe an immunoresistive sensor on a polyethylene terephthalate (PET) film for simple, inexpensive, and highly sensitive COVID-19 screening. The sensor is composed of single-walled carbon nanotubes (SWCNTs) functionalized with monoclonal antibodies that bind to the spike protein of SARS-CoV-2. Silver electrodes are silkscreen-printed on SWCNTs to reduce contact resistance. We determine the SARS-CoV-2 status via the resistance ratio of control- and SARS-CoV-2 sensor electrodes. A combined measurement of two adjacent sensors enhances the sensitivity and specificity of the detection protocol. The lower limit of detection (LLD) of the SWCNT assay is 350 genome equivalents/mL. The developed SWCNT sensor shows 100% sensitivity and 90% specificity in clinical sample testing. Further, our device adds benefits of a small form factor, simple operation, low power requirement, and low assay cost. This highly sensitive film sensor will facilitate rapid COVID-19 screening and expedite the development of POC screening platforms.
Highlights
The emerging SARS-CoV-2 virus, including its reemerging coronavirus variants, continues to pose a serious threat to global public health and economy
The sensor was composed of two resistive sensing sections; the left section detected the SARS-CoV-2 virus, and the right section served as a control electrode
Given that swab samples were replete with human cell fragments, bacteria, and other interferents, these results demonstrated the specificity of the developed single-walled carbon nanotubes (SWCNTs) se1n3-of 18 sors
Summary
The emerging SARS-CoV-2 virus, including its reemerging coronavirus variants, continues to pose a serious threat to global public health and economy. Other Ag-based commercial POC antigen tests have a limit of detection (LOD) greater than 106 copies/mL [14] These reported levels are not sensitive enough to detect the target virus in nasal swab samples at an early stage of infection where the viral load can be lower than 100 copies/mL, according to a clinical study [15]. Mycobacterium tuberculosis (MTB) was detected at 100 CFU/mL in sputum samples using SWCNT sensors combined with magnetic particles [33] This assay did not demonstrate sufficient sensitivity for detecting early-stage SARS-CoV-2 patients. The previous sensor was susceptible to temperature change and aging In this SWCNT sensor, such effects could be calibrated by comparing the resistance change of sensing and control electrodes. Quality control needs to be improved to increase the fabrication yield
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