Deep Ultraviolet Plasmonic Enhancement of Single Protein Autofluorescence in Zero-Mode Waveguides.
Nano Lett
; 19(10): 7434-7442, 2019 10 09.
Article
in En
| MEDLINE
| ID: mdl-31526002
ABSTRACT
Single molecule detection provides detailed information about molecular structures and functions but it generally requires the presence of a fluorescent marker which can interfere with the activity of the target molecule or complicate the sample production. Detecting a single protein with its natural UV autofluorescence is an attractive approach to avoid all the issues related to fluorescence labeling. However, the UV autofluorescence signal from a single protein is generally extremely weak. Here, we use aluminum plasmonics to enhance the tryptophan autofluorescence emission of single proteins in the UV range. Zero-mode waveguide nanoapertures enable the observation of the UV fluorescence of single label-free ß-galactosidase proteins with increased brightness, microsecond transit times, and operation at micromolar concentrations. We demonstrate quantitative measurements of the local concentration, diffusion coefficient, and hydrodynamic radius of the label-free protein over a broad range of zero-mode waveguide diameters. Although the plasmonic fluorescence enhancement has generated a tremendous interest in the visible and near-infrared parts of the spectrum, this work pushes further the limits of plasmonic-enhanced single molecule detection into the UV range and constitutes a major step forward in our ability to interrogate single proteins in their native state at physiological concentrations.
Key words
Full text:
1
Database:
MEDLINE
Main subject:
Spectrometry, Fluorescence
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Tryptophan
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Beta-Galactosidase
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Escherichia coli
Language:
En
Year:
2019
Type:
Article