Label-Free Detection of Single Protein Molecules Using Deep UV Fluorescence Lifetime Microscopy

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Label-Free Detection of Single Protein Molecules Using Deep UV Fluorescence Lifetime Microscopy
Received for review December 8, 2005. Accepted February 21, 2006.
Web Release Date: March 15, 2006
Qiang Li and Stefan Seeger*
Anal. Chem.,
ACS Publications
Copyright? 2006 American Chemical Society
Physikalisch-Chemisches Institut der Universit?t Z?rich, Winterthurerstrasse 190, CH-8057 Z?rich, Switzerland
Abstract:
We present the detection of single -galactosidase molecules from Escherichia coli (Ec Gal) using deep UV laser-based fluorescence lifetime microscopy. The native fluorescence from intrinsic tryptophan emission has been observed after one-photon excitation at 266 nm. Applying the time-resolved single-photon counting method, we investigated the fluorescence lifetime distribution and the bursts of autofluorescence photons from tryptophan residues in Ec Gal protein as well as fluorescence correlation spectroscopy of Ec Gal. The results demonstrate that deep UV laser-based fluorescence lifetime microscopy is useful for identification of biological macromolecules at the single-molecule level using intrinsic fluorescence.
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