One-step synthesized multisize AuAg alloy nanoparticles with high SERS sensitivity in directly detecting SARS-CoV-2 spike protein.

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in widespread disease transmission, challenging the stability of global healthcare systems. Surface-enhanced Raman scattering (SERS) as an easy operation, fast, and low-cost technology illustrates a good potential in detecting SARS-CoV-2. In the study, one-step fabrication of gold-silver alloy nanoparticles (AuAgNPs) with adjustable metal proportions and diameters is employed as SERS substrates. The angiotensin-converting enzyme 2 (ACE2) functionalized AuAgNPs are applied as sensor surfaces to detect SARS-CoV-2 S protein. By optimizing the SERS substrates, ACE2/Au35Ag65NPs illustrate higher performance in detecting the SARS-CoV-2 S protein with a limit of detection (LOD) of 10 fg/mL in both phosphate-buffered saline (PBS) and pharyngeal swabs solution (PSS). It also provides excellent reproducibility with a relative standard deviation (RSD) of 7.7 % and 7.9 %, respectively. This easily preparable and highly reproducible SERS substrate has good potential in the practical application of detecting SARS-CoV-2.

Directly and ultrasensitivity detecting SARS-CoV-2 spike protein in pharyngeal swab solution by using SERS-based biosensor.

The global pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a great disaster to the economy and human society. Nowadays, SARS-CoV-2 is fading away from people's memory but it still exists around us. PCR plays an important role in detecting SARS-CoV-2 but it requires a long detecting time, equipped laboratory, and professional operators. In comparison with polymerase chain reaction (PCR), surface-enhanced Raman scattering (SERS) is a promising method for detecting SARS-CoV-2 due to its fast, easily operated, and high-sensitivity properties. In this study, the monolayer Ag nanoparticles (MAgNPs) covered with single-layer graphene (SLG) are applied as a SERS substrate. The angiotensin converting enzyme 2 (ACE2) is selected as a bio-probes that can specifically bind to the SARS-CoV-2 S protein. The SERS-based biosensor is formed by ACE2 functionalized SLG/MAgNPs and the LODs of detecting SARS-CoV-2 S protein in phosphate-buffered saline (PBS) and in pharyngeal swabs solution (PSS) are 0.1 fg mL-1 and 10 fg mL-1, respectively. This biosensor provides a way of directly detecting SARS-CoV-2 S protein with high sensitivity and specificity. It illustrates a practical potential in the rapid detection of the SARS-CoV-2 virus.

Nano-biosensor for SARS-CoV-2/COVID-19 detection: methods, mechanism and interface design.

The epidemic of coronavirus disease 2019 (COVID-19) was a huge disaster to human society. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which led to COVID-19, has resulted in a large number of deaths. Even though the reverse transcription-polymerase chain reaction (RT-PCR) is the most efficient method for the detection of SARS-CoV-2, the disadvantages (such as long detection time, professional operators, expensive instruments, and laboratory equipment) limit its application. In this review, the different kinds of nano-biosensors based on surface-enhanced Raman scattering (SERS), surface plasmon resonance (SPR), field-effect transistor (FET), fluorescence methods, and electrochemical methods are summarized, starting with a concise description of their sensing mechanism. The different bioprobes (such as ACE2, S protein-antibody, IgG antibody, IgM antibody, and SARS-CoV-2 DNA probes) with different bio-principles are introduced. The key structural components of the biosensors are briefly introduced to give readers an understanding of the principles behind the testing methods. In particular, SARS-CoV-2-related RNA mutation detection and its challenges are also briefly described. We hope that this review will encourage readers with different research backgrounds to design SARS-CoV-2 nano-biosensors with high selectivity and sensitivity.