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| Fluorescent
image of single molecules of cholesterol
oxidase and probe tip used to
image single molecules. |
With conventional optics, scientists
can image an area no smaller than
one-half of the wavelength of light
being used. But scientists at Pacific
Northwest National Laboratory found
a way to deliver light energy to areas
much smaller than its wavelength.
During the 1990s, Sunney Xie, Peter
Lu, and coworkers developed a near-field
optical imaging technique that provides
spectral information about the interaction
of single molecules with surfaces,
making it possible to study, for example,
the dynamic behaviors of proteins
in real time on the microsecond time
scale. Similar research tools, such
as optical tweezers and atomic force
microscopy, provide spatial and structural
information with sub-nanometer resolution,
but not the spectral information that
is vital for understanding the chemical
properties of molecules and other
sub-nanometer structures. Near-field
optical probes enable the study of
individual molecules in their own
environments, providing new insights
into the nature of reactions in natural
systems.
Scientific Impact:
This technique has proven very helpful
for studying reactions of biological
molecules and other condensed phase
processes in natural systems. Many
such processes cannot be understood
without some means, such as optical
probes, of resolving the effects of
time- and geometry-dependent perturbations.
Social Impact: This
instrumentation is being used to elucidate
the biological effects of chemical
and radiation exposure and thus may
help improve human health. It also
may contribute to new ways of using
natural enzymes in the remediation
of contaminated soils and groundwater,
and to the development of nanoscale
electro-optical devices.
Reference: Xie,
X. Sunney. "Single-Molecule Spectroscopy
and Dynamics at Room Temperature,"
Accounts of Chemical Research,
29, 598 (1996).
Xie, X. Sunney; Lu, H. Peter, "Single-Molecule
Enzymology," Journal of Biological
Chemistry 274, 15967 (1999).
URL:
http://www.emsl.pnl.gov:2080/homes/csd/sms/subhomes/r3.html
Technical Contact:
Dr. Roland Hirsch, Medical Sciences
Division, Office of Biological and
Environmental Research, 301-903-9009
Press Contact: Jeff
Sherwood, DOE Office of Public Affairs,
202-586-5806
SC-Funding Office:
Office of Biological and Environmental
Research |
