Abstract
We proposed "single-molecule immunoassay", quantification of single protein molecules, by developing a nanofluidics-based enzyme-linked immunosorbent assay (ELISA) device. Extremely small volume(pL-aL) and high surface-to-volume ratio of nanochannels enables ∼100% capture of analyte molecules. Enzymatic amplification reaction and differential interference contrast thermal lens microscope (DIC-TLM) enables detection of individual molecules. Quantification of countable protein molecules was verified for the first time. Our method will contribute to single cell analysis field, in particular for ultrasensitive protein counting.