Structured protein probes modified with selenium nanoparticle for 1-minute measurement of SARS-CoV-2 antigen

Conventional point-of-care lateral flow immunoassays are characterized by an antibody-tagged probe irregular coupling that can limit sensitivity and require a long assay's time. We synthesized polyethylene glycol-modified selenium nanoparticles (PEG-SeNPs) by template method and developed a strategy to set antibody probes targeted and orderly by using PEG-SeNPs. Synthesized PEG-SeNPs with high stability could immobilize antibodies in the "stand-up" orientation, resulting in a faster detection time of less than 1 min by direct observer visualization without instruments or equipment. Results showed that SARS-CoV-2 antibody could be systematically structured on the chip, resulting in a detection limit of 10 pg/mL, significantly higher than conventional chips. The new device has been validated on 192 clinical samples and we found 100% negative coincidence, 93.94% positive coincidence, and 95.83% overall coincidence with reverse transcriptional PCR test. The orderly arrayed probe's stability allowed to detect throat swabs, saliva, serum, fingertip blood samples, and mutant strains without cross-reactivity with common respiratory viruses or pathogenic strains, demonstrating promising potential for a universal colorimetric platform for ultrafast field-deployable diagnostics.