Affinity Peptide-Engineered Magnetic Microswimmers for Ultrafast On-the-Fly Screening of Influenza A Virus in Microliter-Scale Samples

Monitoring respiratory viruses is crucial for mitigating their spread and the associated healthcare costs, especially during the cold season. This study presents an on-the-fly OFF–ON fluorescence approach for the H3N2 subtype of Influenza A virus determination using magnetically propelled WS2/Ni micromotors. The micromotors are modified with a rhodamine B-labeled peptide highly specific toward the hemagglutinin A HA1 protein antigen. The improved fluid mixing imparted by the micromotor motion allows for efficient operation during an assay time of 1 min using just 1 μL of sample. The developed fluorescent assay represents a reliable and robust screening platform for influenza clinical samples, achieving exceptional selectivity and limits of detection in the ng/L range. The method’s performance was validated using nasopharyngeal specimens, demonstrating high reliability and analytical specificity for the Influenza A H3N2 subtype. Notably, the protocol provided high fluorescence signatures for H3N2-infected samples even when cycle threshold (Ct) values were comparable those of to H1N1-infected samples and negative samples. These results highlight the reliability of the proposed micromotor-based strategy for rapid viral subtyping and demonstrate its potential as a fast sample-to-result diagnostic platform requiring minimal sample volume.