2004
RESEARCH PROJECTS
Assessment
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| PROJECT: |
New
Catalytic DNA Biosensors for Radionuclides and Metal ions |
| PRINCIPAL
INVESTIGATOR: |
Yi
Lu |
| Assessment |
We aim to develop new DNA biosensors for simultaneous detection and
quantification of bioavailable radionuclides, such as uranium, technetium,
and plutonium, and metal contaminants, such as lead, chromium, and
mercury. The sensors will be highly sensitive and selective, not only
for different metal ions, but also for different oxidation states or
speciation states of the same metal ion. They will be applied to on-site,
real-time assessment of concentration, speciation, and stability of
the individual contaminants before and during bioremediation, and for
long-term monitoring of DOE contaminated sites.
To achieve
this goal, we will employ a combinatorial method called “in
vitro selection” to search from a large DNA library (~
1015 different molecules) for catalytic DNA molecules that are highly
specific for radionuclides or other metal ions through intricate
3-dimensional interactions as in metalloproteins. Comprehensive biochemical
and biophysical studies will be performed on the selected DNA molecules.
The findings from these studies will help to elucidate fundamental
principles for designing effective sensors for radionuclides and
metal ions. Based on the study, the DNA will be converted to fluorescent
or colorimetric sensors by attaching to it fluorescent donor/acceptor
pairs or gold nanoparticles. Practical application of the biosensors
in the NABIR Field Research Center (FRC) at Oak Ridge will be demonstrated,
using colorimetric sensors mainly for qualitative and semi-quantitative
detections and using fluorescent sensors for quantitative detections.
If time and fund permits, the individual DNA sensors will be assembled
into a DNA microarray for the simultaneous detection and quantification
of all radionuclides and metal contaminants.
While effective techniques for evaluating microbial ecology and community
dynamic have been well established, simple, cost-effective, in-situ and
real-time identification and quantification of radionuclide and metal
contaminants in their different oxidation and speciation states
before, during and after bioremediation is much less advanced. The combinatorial
search for DNA of high metal-ion binding affinity and specificity, coupled
with a rational design of a fluorescent or colorimetric detection scheme
can result in one of the first classes of metal sensors to contain a
single type of molecule (i.e., DNA) to detect and quantify metal ions
in their different oxidation and speciation states simultaneously. The
resulting DNA sensors will be especially useful at sensing water-soluble
or bioavailable metal ions, which are highly transportable in the contaminated
sites and are the most dangerous to human beings and the environment.
Principles for specific binding of radionuclides or metal ions by the
DNA sensor elucidated from the biochemical and biophysical studies of
the selected DNA sensors can be generally applied to the design of other
type of sensors for detection and chelators for remediation. The DNA
used in the study is biocompatible and biodegradable, and is not recombinant
and thus cause no harm to the environment. In addition, DNA is stable,
cost-effective, and easily adaptable to optical fiber and microarray
technology for device manufacture. Thus the DNA sensors proposed here
hold great promise for on-site (or remote) and real-time monitoring of
concentration, speciation and stability of these environmental contaminants.
Practical applications of these simple and portable sensors at the DOE
sites will not only help assess the effectiveness of science-based solutions
for cleanup by researchers and engineers who perform the cleanup, but
also contribute significantly to the long-term monitoring of DOE contaminated
sites by DOE staff members, state and local regulation agents, and concerned
citizens around the sites.
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