Ready-To-Use\nMicrowave Sensor Modified by Antibody-AuNPs\nNanoconjugate for Highly Sensitive and Selective Detection of the\nSARS-CoV‑2 Virus

The COVID-19 outbreak has led to notable developments\nin point-of-care\n(POC) diagnostic devices, as they can be valuable resources in identifying\nand managing the spread of the pandemic. Currently, the majority of\ntechniques demand advanced laboratory equipment and professionals\nto execute precise, efficient, accurate, and sensitive testing. In\nthis work, we report a new method to significantly enhance the sensitivity\nof microwave sensing of the SARS-CoV-2 virus by functionalizing the\nsensor surface using anti-SARS-CoV-2 spike antibody-gold nanoparticle\n(AuNPs) conjugates. AuNPs were surface-functionalized with the antispike\nantibody by EDC/NHS chemistry via PEG as a linker to form the conjugate\n(Ab-PEG-AuNPs). The Ab-PEG-AuNPs nanoconjugate was then coated onto\nthe sensor through APTES and used for selectively capturing the spike\nprotein on the SARS-CoV-2 virus. The sensing performance of the modified\nsensor was demonstrated via both experimental measurements and numerical\nsimulations. Our sensor exhibited high sensitivity, achieving a limit\nof detection of 1,000 copies/mL of the SARS-CoV-2 virus within a 60\nmin time frame while requiring a minimal sample volume of 100 μL.\nThe sensor exhibits outstanding specificity in distinguishing SARS-CoV-2\nfrom other viruses, including influenza A and B, SARS-CoV-1, and MERS-CoV.\nOverall, this sensor provides a sensitive and label-free alternative\nfor COVID-19 POC diagnosis.