Next-Generation Rapid and Ultrasensitive Lateral Flow Immunoassay for Detection of SARS-CoV-2 Variants

Abstract

The coronavirus disease 2019 (COVID-19) pandemic highlighted the need for rapid and accurate viral detection at the point-of-care testing (POCT). Compared with nucleic acid detection, lateral flow immunoassay (LFIA) is a rapid and flexible method for POCT detection. However, the sensitivity of LFIA limits its use for early identification of patients with COVID-19. Here, an innovative surface-enhanced Raman scattering (SERS)-LFIA platform based on two-dimensional black phosphorus decorated with Ag nanoparticles as important antigen-capturing and Raman-signal-amplification unit was developed for detection of SARS-CoV-2 variants within 5–20 min. The novel SERS-LFIA platform realized a limit of detection of 0.5 pg/mL and 100 copies/mL for N protein and SARS-CoV-2, demonstrating 1000 times more sensitivity than the commercial LFIA strips. It could reliably detect seven different SARS-CoV-2 variants with cycle threshold (Ct) < 38, with sensitivity and specificity of 97 and 100%, respectively, exhibiting the same sensitivity with q-PCR. Furthermore, the detection results for 48 SARS-CoV-2-positive nasopharyngeal swabs (Ct = 19.8–38.95) and 96 negative nasopharyngeal swabs proved the reliability of the strips in clinical application. The method also had good specificity in double-blind experiments involving several other coronaviruses, respiratory viruses, and respiratory medications. The results showed that the innovative SERS-LFIA platform is expected to be the next-generation antigen detection technology. The inexpensive amplification-free assay combines the advantages of rapid low-cost POCT and highly sensitive nucleic acid detection, and it is suitable for rapid detection of SARS-CoV-2 variants and other pathogens. Thus, it could replace existing antigens and nucleic acids to some extent.

Rapid Detection of Malaria Based on Hairpin-Mediated Amplification and Lateral Flow Detection

“…(2) The reaction conditions for the HMA process are relatively less demanding and do not require professional personnel to achieve the whole testing procedure [38,39]. This study proves that the HMA-LFD technology is applicable for detecting Plasmodium.…”

Development of Detection Antibody Targeting the Linear Epitope in SARS-CoV-2 Nucleocapsid Protein with Ultra-High Sensitivity

“…The LOD of this system was 3.59 pg/mL N protein, 100 times more sensitive than a commercially available colloidal gold LFIA [36]. With the help of the surface-enhanced Raman scattering (SERS) technique, Liu et al greatly lowered the LOD of LFIA to 0.5 pg/mL for N protein by replacing traditional colloidal gold nanoparticles with Ag/black phosphorus nanosheets [37]. Our system, only through the rational selection of antigens and antibodies, achieved ultra-high sensitivity to the N protein, superior to the sensitivities of many analogous detection systems reported in the literature [6,31,[38][39][40][41] and many commercially available detection products [42], manifesting the superiority of antibodies obtained by rational screening antigens with bioinformatical and structural biological means.…”

A High-Avidity, Thermostable, and Low-Cost Synthetic Capture for Ultrasensitive Detection and Quantification of Viral Antigens and Aerosols

“…LCB1-BSA is a proof-of-concept synthetic, multivalent capture that can prolong the shelf life of any mAb-based diagnostic and decrease their manufacturing costs. However, our reported sensitivity improvements may only be applicable to assays with inherent ultrasensitivity like p-LFA and surface-enhanced Raman scattering-based LFAs . Further experiments are needed to explore LCB1-BSA’s ability to improve the colorimetric sensitivity of commercial LFAs.…”