Ultrasensitive fluorescence detection of single protein molecules manipulated electrically on Au nanowire.

Proteins assembled on an Au nanowire are manipulated by an electrical potential applied on the nanowire, which leads to the modulation of molecular fluorescence. The molecular modality can be unequivocally correlated with the modulated fluorescence, which enables the specific fluorescence from a single target protein to be unambiguously distinguished from background noise and nonspecific fluorescence. As demonstrated through a thrombin assay, this simple method can significantly improve the sensitivity and specificity of the protein detection down to the single molecule level.