Yi Lu Department of Chemistry University of Illinois at Urbana-Champaign Urbana, IL 61801
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Yi Lu
Department of Chemistry
University of Illinois at Urbana-Champaign
Urbana, IL 61801
A major challenge facing ERSP/SBR
Measurement/monitoring of radionuclides and metal ions
across a large spatial and temporal scale
cellular level ecological level
Before ER: How many and how much (identification and quantification)?
Where and when (on-site, real-time with high spatial and temporal resolution)?
What species (e.g., different oxidation states with different bioavailability)?
During ER: How effective are the remediation methods?
After ER: Long-term monitoring (legacy management)
Fundamental science: Mechanistic studies (fundametnal process coupling)
Computer modeling (the more accurate data, the better simulation) More
selective chelators (structural features responsible for binding
different radionuclides and different oxidation states of the same radionuclide)
Current instrumental analysis
Atomic absorption spectrometry
Inductively coupled plasma mass spectrometry
Anodic stripping voltammetry
X-ray fluorescence spectrometry or microscope
Phosphorimetry
Advantages Disadvantages
Industrial standard Require expensive equipment, sample-
Highly sensitive (down to
pretreatment, and skilled operators
~ppb or less) Detect total amount of metal ions
Detect a number of metal (not bioavailable metal ions)
ions simultaneously cannot differentiate different oxidation states
of the same metal ions (U(VI)/U(IV);
Cr(VI)/Cr(III); Fe(III)/Fe(II))
difficult for in-situ, on-site, remote or
real-time detection
Designing highly sensitive and selective sensors is a solution
Number of publications in metal ion sensing
~50,000 publications as of 2009
There are many publications and thus research activities in metal
sensing….but very limited practical or commercially available sensors.
Why are there so few metal ion sensors that
are being used practically?
The process is too much of a trial-and- error process and lack
? a general method to obtain molecules for any specific
metal ions and any specific oxidation state of metal ions
? a general method to improve selectivity;
? a general method to transform molecular recognition
into physical detectable signals without compromising
the binding affinity and selectivity;
? a general method to fine-tune the dynamic range.
What can we do about it?
We need to design general strategies to meet the four key
challenges in metal ion sensing.
Four key steps in designing sensors
? a general method to obtain molecules for any
specific target (e.g., U(VI), Cr(VI), Cr(III), organic
contaminants, proteins, bacteria, viruses)
U(VI)
Cr(III)
Cr(VI)
Method
proteins
bacteria
Organic contaminants
Until recently, antibodies (Abs) is the only method that is general enough for a
broad range of targets, but Abs not very good at sensing small molecular
targets or targets that are either non-immunogenic or too toxic to raise Abs.
Functional DNA: catalytic DNA and aptamers
DNA/RNA = Protein enzymes
DNA/RNA = Antibodies
Catalytic DNA
Kruger, K. et al. Cell 31, 147 (1982).
Guerrier-Takada, C. et al. Cell 35, 849 (1983).
Breaker, R.; Joyce, G. Chem. Biol. 1, 223 (1994).
Combinatorial biology: a general method to
obtain DNA/RNA for a specific target
In vitro Selection
Systematic Evolution of Ligands by Exponential Enrichment (SELEX)
Ellington, A. D.; Szostak, J. W. Nature 346, 818(1990).
Tuerk, C.; Gold, L. Science 249, 505 (1990).
Beaudry, A. A.; Joyce, G. F. Science 257, 635 (1992).
Molecules Recognized/bound by Selected DNA/RNA
Analyte/target type Examples
Metal ions Mg(II), Ca(II), Mn(II), Pb(II), Hg(II), U(VI)
Organics Cibacron blue, reactive green 19
Amino acids L-Valine, D-Tryptophan
Nucleosides/nucleotides Guanosine, ATP
Nucleotide analogs 8-oxo-dG, 7-Me-guanosine
Biological cofactors NAD, FMN, porphyrins, Vitamin B12
Aminoglycosides Tobramycin, Neomycin
Antibiotics Streptomycin, Viomycin
Peptides Rev peptide
Enzymes Human Thrombin, HIV Rev Transcriptase
Growth cofactors Karatinocyte GF, Basic fibroblast GF
Antibodies human IgE
Gene regulatory factors elongation factor Tu
Cell adhesion molecules human CD4, selectin
Intact viral particles Rous sarcoma virus, Anthrax spores
Juewen Liu and Yi Lu, J. Fluoresc. 14, 343-354 (2004).
Examples of in vitro selected Catalytic DNA
UO22+
Mg2+ (Lu)
(Joyce)
Pb2+ Zn2+
(Lu, Joyce) (Lu)
Cu2+ Co2+
(Breaker) (Lu)
Specific sequence/code
= specificity
Lu, Y. Chem. Euro. J. 8, 4588-4596 (2002).Examples of in vitro selected catalytic DNA
UO22+
Mg2+
Pb2+
Substrate
M(II)
Enzyme
Cu2+
General secondary structure, making it easy for sensor design
Lu, Y. Chem. Euro. J. 8, 4588-4596 (2002).Four key steps in designing sensors √ a general method to obtain molecules for a specific analyte; ? a general method to improve selectivity; What most want to do What most end up doing
2. A general method to improve sensor selectivity
Applying a “negative” selection
strategy in in vitro selection or
SELEX, one can improve sensor’s
analyte selectivity. This method can
be generally applied to any
selection method.
P. J. Bruesehoff, J. Li, A. J. Augustine III, and Y.
Lu, Combinatorial Chemistry and High
Throughput Screening, 5, 327-335 (2002).Four key steps in designing sensors √ a general method to obtain molecules for a specific analyte; √ a general method to improve selectivity; ? a general method to transform molecular recognition into physical detectable signals without compromising the binding affinity and selectivity;
3. A general method to convert catalytic DNA into
fluorescent sensors using catalytic molecular beacon
TAMRA
Dabcyl
I
III +Enz
II
I
+Pb2+
III
II
Li, J.: Lu, Y. J. Am. Chem. Soc., 122, 10466-10467. (2000).A highly sensitive and selective sensor for Uranium
Over 14 fold fluorescence increase,
with a Detection limit: 45 pM = 11 part-per-trillion
Over 1 Million Fold Selectivity
Juewen Liu, Andrea K. Brown, Xiangli Meng, Donald M. Cropek, Jonathan D. Istok, David B. Watson, and Yi Lu,
Proc. Natl. Acd. Sci. USA 104, 2056–2061 (2007).Uranyl Detection in Soil Samples at Oak Ridge IFRC
300×diluted 50×diluted
Catalytic DNA sensor response Phosphorescence in 10% H3PO4
We followed a sample extraction procedure established by P. Zhou and B. Gu,
Environ. Sci. Technol. 39, 4435-4440 (2005).
Juewen Liu, Andrea K. Brown, Xiangli Meng, Donald M. Cropek, Jonathan D. Istok, David B. Watson, and Yi Lu,
Proc. Natl. Acd. Sci. USA 104, 2056–2061 (2007).Further comparison
Method Detection Detection
Limit (pM) Limit (ppt)
X-ray Fluorescence 11,760,000 2,800,000
Atomic Absorption 336,000 80,000
Spectrometry
EPA MCL 126,000 30,000
ICP-Atomic Emission 8,400 2,000
Spectrometry
Antibody fluorescence 1,000 238
ICP-Mass 420 100
Spectrometry
Stripping Voltammetry 100 24
Catalytic DNA Sensor 45 11
Performance is comparable to
Phosphorimetry 42 10
ICP and phosphorescence
Kinetic 4.2 1
Phosphorimetry
Juewen Liu, Andrea K. Brown, Xiangli Meng, Donald M. Cropek, Jonathan D. Istok, David B. Watson, and Yi Lu,
Proc. Natl. Acd. Sci. USA 104, 2056–2061 (2007).The method is general:
more catalytic beacon based fluorescent sensors
Pb2+: Detection limit: 1nM
Fluorescent sensors EPA MCL: 75 nM
Based on catalytic beacon
UO22+: Detection limit: 45 pM
EPA MCL: 126 nM
Cu2+: Detection limit: 35 nM
EPA MCL: 20 µM
Hg2+: Detection limit: 2.4 nM
EPA MCL: 10 nM
Li, J.: Lu, Y. J. Am. Chem. Soc., 122, 10466-10467. (2000).
J. Liu, et al. Proc. Natl. Acad. Sci 104, 2056 (2007).
J. Liu and Y. Lu J. Am. Chem. Soc. 129, 9838 (2007).
J. Liu and Y. Lu, Angew. Chem., Int. Ed., 46,7587 (2007).Design of a Simple Colorimetric Biosensor
Pb
BLUE
Mix
Aggregate
Pb
RED
Pb Pb
= 17E BLUE Pb
5'- rA
= GGAAGAGATG -3' = SubAu
RED
Au 5'-CACGAGTTGACA-3' = DNAAu
=
Liu, J.; Lu, Y. J. Am. Chem. Soc. 125, 6642-6643 (2003).Colorimetric Uranium Sensors
Detection limit: 50 nM
Detection limit: 1 nM
Lee, J.H; Wang, Z; Liu, J; Lu, Y. J. Am. Chem. Soc. 130, 14217-14226 (2008).Four key steps in designing sensors
√ a general method to obtain molecules for a
specific analyte;
√ a general method to improve selectivity;
√ a general method to transform molecular
recognition into physical detectable signals without
compromising the binding affinity and selectivity;
? a general method to fine-tune the dynamic range.
Threshold #2: water Threshold #1: soil
yes yes
Signal
no no
Lead concentration
IDEAL CURVE4. A general method to tunable Dynamic Range
A. Active DNA
B. Inactive DNA
B:A = 0:1 B:A = 20:1
Brown, A. K.; Li, J.; Pavot, C. M.-B.; Lu, Y. Biochemistry 42, 7152-7161 (2003).
Liu, J.; Lu, Y. J. Am. Chem. Soc. 125, 6642-6643 (2003).A new and highly sensitive and selective Hg sensor
Detection limit: 3 nM
Wang, Z; Lee, J.H; Lu, Y. Chem. Commun. 6005-6007 (2008)“Dipstick” Litmus paper test for Pb2+ and other metals
It is now possible for even
simpler detection of
radionuclides and metal ions
Debapriya Mazumdar, Juewen Liu, Geng Lu, Juanzuo Zhou and Yi Lu, Chem. Commun. 46, 1416-1418 (2010).Sensing and “budgeted” release of chelators
for on-demand metal ion remediation
M. Veysel Yigit, A. Mishra, R. Tong, J. Cheng, G. C. L. Wong, and Y. Lu, Chem. Biol. 16, 937 – 942 (2009).Sensor product development
www.ANDalyze.comFirst test of ground water samples at ORFRC
Area 3
Thanks to
David B. Watson
Marcella (Sally) Mueller
Kenneth A. Lowe
Area 4 N. Diane Kosier
Tonia L. Mehlhorn
Jennifer E. Earles
Jesse M. StephensFirst test at ORFRC
Sensor
Hannah IhmsFundamental understanding of selectivity:
Using single molecule FRET
Hee-Kyung Kim, Ivan Rasnik, Juewen Liu, Taekjip Ha, and Yi Lu, Nature Chem. Biol. 3, 763-768 (2007).Fundamental understanding of selectivity:
Using biochemical assay and x-ray absorption
spectroscopy
Andrea K. Brown, Juewen Liu, Ying He, and Yi Lu, ChemBioChem 10, 486-492 (2009).
Bruce Ravel, Scott C. Slimmer, Xiangli Meng, Gerard C. L. Wong, and Yi Lu, Rad. Phys. Chem. 78, S75–79 (2009).Future directions
Applications: New sensors: methylHg; Cr(VI), Pu(IV), Fe(II)/Fe(III)
DNAzyme microarrays for multiplexing detection
Pb2+ UO22+
-, -
-, +
+, -
+, +
Fundamental Science: Elucidate structural features for selectivity
UO22+ sensor Pb2+ sensor
(11 ppt) (0.2 ppb)Summary
To obtain sensitive and selective biosensors, we have demonstrated the
following general strategies:
• to obtain sensing molecules;
• to improve selectivity;
• to convert molecular recognition event into physically
detectable signals (e.g., fluorescence and colorimetric);
• to tune the dynamic range.
The new catalytic DNA fluorescent and colorimetric sensors
environmentally benign
cost effective
stable under rather harsh conditions
can be denatured and renatured many times
allow combinatorial search for desired metal-binding properties
adaptable to optic fiber and microarray chip technology
unlimited by the choice of fluorophore/optical tags
easy to attach fluorophore/optical tags to any desired position
activity-based detection immune to source fluctuation and electronic drift
highly sensitive (down to ppt) and selective (more than 1 million fold)
allows on-site, real-time detection and quantification with high spatial (< cm)
and time (< min.) resolution.
detect not only different metal ions, but also different oxidation states of the
same metal ions, allowing sensing of bioavailable toxic metal ions.Acknowledgments
DNA/RNA Lab at UIUC IFRC, ONRL
Graduate Students:
David B. Watson
Ying He Andrea K. Brown
Marcella (Sally) Mueller
Hannah Ihms Peter J. Bruesehoff
Tian Lan Hee-Kyung Kim Kenneth A. Lowe
Darius Brown Jing Li N. Diane Kosier
Nandini Nagraj Jung Heon Lee Tonia L. Mehlhorn
Eric Null Juewen Liu Jennifer E. Earles
Zidong Wang Kevin E. Nelson Jesse M. Stephens
Brian Wong Daryl P. Wernette
Weichen Xu Mehmet V. Yigit Oregon State University
Hang Xing Debapriya Mazumdar
Jonathan D. Istok
Yu Xiang Seyed-Fakhreddin Torabi
Mandy Michalsen
Postdoctoral fellows:
Hui Wei Zehui Cao Funding
Juanzuo Zhou Geng Lu
Department of Energy
Office of Science, ERSP program
Xiangli Meng
(DE-FG02-08ER64568)
Daisuke Miyoshi
Wenchao ZhengA sensor that resists to temperature-dependent variations
Nandini Nagraj, Juewen Liu, Stephanie Sterling, Jenny Wu and Yi Lu, Chem. Comm. 2009, 4103-5.
Label-free DNA sensors for cost-effective sensing
Yu Xiang, Aijun Tong and Yi Lu, J. Am. Chem. Soc. 131,15352-15357 (2009).You can also read
