Smartphone-assisted upconversion nanoparticle assay for rapid multiplex detection of H5, H7, and H10 avian influenza viruses.

Avian influenza viruses (AIVs) of the H5, H7, and H10 subtypes pose substantial threats to global public health owing to their high pathogenicity, cross-species transmissibility, and potential to spark epidemics. Rapid and accurate detection is essential for outbreak control and zoonotic risk mitigation. Here, we report the development of a multiplex lateral flow immunoassay (LFA) based on core-shell upconversion nanoparticles (UCNPs) conjugated with subtype-specific monoclonal antibodies targeting the haemagglutinin proteins of H5, H7, and H10 AIVs. The assay achieved limits of detection of 0.0313, 0.0156, and 0.0625 ng/mL for recombinant HA proteins and 2-4, 2-4, and 2-3 haemagglutination units for viral titres of H5, H7, and H10, respectively. No cross-reactivity was observed with other AIV subtypes or respiratory pathogens, and intra- and inter-assay variation remained below 6%, demonstrating high specificity and reproducibility. Validation with 135 avian and 125 human clinical samples showed complete concordance with real-time RT-PCR results. Integration with a smartphone-based analytical platform enabled rapid readout, automated quantification, and cloud-based data sharing, providing results within 10 min. This intelligent UCNPs-LFA system combines ultra sensitivity, multiplexing, and field-deployable usability, representing a significant advance over conventional methods. By enabling timely and reliable detection of H5, H7, and H10 AIVs in both animal and human samples, this platform offers a practical tool for early warning, surveillance, and control of emerging zoonotic influenza, thereby contributing to global preparedness against avian influenza outbreaks.