Highly sensitive quantitative and rapid immunochromatographic diagnosis of the clinical samples using scanning electron microscopy - preparing for future outbreaks.

Kawasaki, H.; Suzuki, H.; Maekawa, M.; Hariyama, T.

As pathogens such as the influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can easily cause pandemics, the development of rapid diagnostic tests is crucial for implementing efficient quarantine measures, providing effective treatments to patients, and preventing or containing a pandemic infection. Here, we developed the immunochromatography-NanoSuit method, an improved immunochromatography method combined with a conventional scanning electron microscope (SEM), which enables the observation of immunocomplexes labeled with a colloidal metal. The detection ability of our method is comparable to that of real-time reverse transcription-polymerase chain reaction with a detection time of approximately 15 min. Our new immunochromatography-NanoSuit method suppresses cellulose deformity and makes it possible to easily focus and acquire high-resolution images of gold/platinum labeled immunocomplexes of influenza A, without the need for conductive treatment as with a conventional SEM. This easy and highly sensitive quantitative analysis by immunochromatography can be utilized to diagnose various infections including SARS-CoV-2.