Chemical apparatus and process disinfecting – deodorizing – preser – Analyzer – structured indicator – or manipulative laboratory... – Means for analyzing liquid or solid sample
Reexamination Certificate
1999-03-19
2001-03-06
Soderquist, Arlen (Department: 1749)
Chemical apparatus and process disinfecting, deodorizing, preser
Analyzer, structured indicator, or manipulative laboratory...
Means for analyzing liquid or solid sample
C422S068100, C422S082050, C422S082060, C422S082080, C435S004000, C435S018000, C436S073000, C436S080000, C436S081000, C530S350000, C530S412000
Reexamination Certificate
active
06197258
ABSTRACT:
FIELD OF THE INVENTION
The field of this invention generally relates to the detection, determination, and quantitation of certain ions and small molecules in solution. The field more specifically relates to improvements in the area of photoluminescent sensors for use in combination with a detection scheme involving changes in the photoluminescence of a photoluminescent moiety, said moiety either free in solution or associated with an analyte binding macromolecule. The change of photoluminescence may be manifested by changes in photoluminescence lifetime, changes in ratios of photoluminescence intensity or changes in photoluminescence polarization (anisotropy). The photoluminescence change measured correlates to the concentration of the ion or molecule in solution.
BACKGROUND OF THE INVENTION
For scientific, regulatory, or other applications, many persons, institutions, and agencies often require analyses of samples to determine whether such small molecule and ionic analytes are present. Examples of such analyses include the determination of metal ions in sea water to understand the processes of chemical oceanography; determination of toxic materials such as Hg(II), Ni(II), CN
−
, or HS
−
in groundwater or wastewater; detection of the corrosion of metal alloys by the presence of Co(II), Zn(II), or Cu(II) in condensates; or the presence of metals in lubricating oil as an indicator of machinery wear and incipient failure.
Many methods are known in the art for such analyses. For metal ions, such methods include graphite furnace atomic absorption spectrophotometry, inductively coupled plasma atomic emission spectroscopy and mass spectroscopy, various electrochemical means, and photoluminescence spectroscopy using metallo-photoluminescent indicators. For common anionic analytes there are fewer techniques available; they include ion chromatography, mass spectrometry, and electrochemical means.
Most of these techniques involve analysis of single or multiple discrete samples in a specialized instrument which may not be close to the sample. This is a particular drawback for analytical tasks that require a continuous or quasi-continuous determination of the analyte with real time readout of the result; require samples to be collected from remote, inaccessible, or hazardous environments; or require such extensive sampling that it is prohibitively costly. For many of these methods a sensor capable of remotely, continuously, and selectively monitoring the analyte of interest in situ is required, and subsequent reporting of the results of the analysis back to the operator in real time.
Improvements have been made in the development of photoluminescence-based sensors for a variety of applications (Thompson, R. B. (1991) in
Topics in Fluorescence Spectroscopy,
Vol. 2:
Principles,
Lakowicz, J. R. (Ed.) Plenum Press, NY; Wolfbeis, O. S. (Ed.) (1992)
Fiber Optic Chemical Sensors and Biosensors
Vols. I and II, CRC Press, Boca Raton, Fla.; Lakowicz, J. R., and Thompson, R. B. (Eds.) (1993)
Proc. of the SPIE Conference on Advances in Fluorescence Sensing Technology
Vol. 1885, Society of Photooptical Instrumentation Engineers, Bellingham, Wash.) A central issue in the development of such sensors has been the means of transduction, whereby the presence or relative amount of the chemical analyte is transduced as a change in the photoluminescence which may be quantitated. Thus, workers in the field have mainly transduced analyte levels as changes in photoluminescence intensity (Thompson (1991); Saari, L. A., and Seitz, W. R. (1982)
Anal. Chem.
54, 821; Thompson, R. B. and Ligler, F. S. (1991) in
Biosensors with Fiber Optics.,
Wise, D., and Wingard, L. (Eds.) pp. 111-138, Humana Press, Clifton, N.J.), or ratios of photoluminescence intensity at two different wavelengths (wavelength ratiometric) (Tsien, R. Y. (1989)
Ann. Rev. Neurosci.
12, 227; Opitz, N., and Lubbers, D. W. (1984)
Adv. Exp. Med. Biol.
180, 757; Thompson, R. B. and Jones, E. R. (1993)
Anal. Chem.
65, 730-4; and U.S. Pat. No. 5,545,517).
The ratio approach has proven particularly popular because it is robust in avoiding many of the artifacts which limit the accuracy and precision of simple intensity measurements. The major limitation of the ratio approach has been the limited number of ratiometric photoluminescent indicators (Haugland, R. P. (1992)
Handbook of Fluorescent Probes and Research Chemicals,
Molecular Probes, Eugene, Oreg.).
Intensity based methods, however, are sensitive to artifacts, as any change in photoluminescence intensity, regardless of its origin may be misinterpreted as a change in concentration. Changes in light scattering, or variations in excitation light intensity and/or photobleaching may easily be misinterpreted as a change in the concentration of the metal ion. Although the accuracy and precision of these methods may be improved through the use of internal photoluminescent standards, or with the monitoring of excitation intensity or with the use of kinetic methods of analysis, careful and even repeated calibration of reagents and instrumentation are required to minimize spurious variations in signal intensity.
Recently, many groups have shown that transducing the level of analyte as a change in photoluminescence lifetime is a robust and flexible approach to optical sensing (Demas, J. N., (1994) in
Topics in Fluorescence Spectroscopy,
Vol. 4:
Probe Design and Chemical Sensing,
Lakowicz, J. R. (Ed.) Plenum Press, NY; Lippitsch, M. E., Pusterhofer, J., Leiner, M. J. P. and Wolfbeis, O. S. (1988)
Anal. Chim. Acta
205, 1-6; Keating, S. M., and Wensel, T. G. (1991)
Biophys. J.
59, 186-202; Lakowicz, J. R., Szmacinski, H., and Karakelle, M. (1993)
Anal. Chim. Acta
272, 179-186; Szmacinski, H., and Lakowicz, J. R. (1993)
Anal. Chem.
65, 1668-74; Lakowicz, J. R. (1992) Laser Focus World 28(5) 60-80; Thompson, R. B. and Patchan, M. W. (1993) in
Proc. of the SPIE Conference on Chemical, Biochemical, and Environmental Fiber Optic Sensors V.
Lieberman, R. A. (Ed.) pp. 296-306. Society of Photooptical Instrumentation Engineers, Bellingham, Wash.; Ozinskas, A. J., Malak, H., Joshi, J., Szmacinski, H., Britz, J., Thompson, R. B., Koen, P. A., and Lakowicz, J. R. (1993)
Anal. Biochem.
213, 264-270). Lifetime-based sensing can exhibit a dynamic range of greater than five orders of magnitude in analyte concentration (Szmacinski, H., and Lakowicz, J. R. (1993)
Anal. Chem.
65, 1668-74; Thompson, R. B. and Patchan, M. W. (1993) in
Proc. of the SPIE Conference on Chemical, Biochemical, and Environmental Fiber Optic Sensors V.
Lieberman, R. A. (Ed.) pp. 296-306. Society of Photooptical Instrumentation Engineers, Bellingham, Wash.). Lifetime-based sensing has been adapted to and has particular advantages for fiber optic sensors.
Photoluminescence resonance energy transfer is a dipole-dipole interaction described by Förster (Förster, Th. (1948)
Ann. Physik
2, 55-75) that is very useful for lifetime-based sensing. Förster's theory is very well-established, with thousands of examples in the literature of its predictive power. The rate of energy transfer K
T
is a function of the distance between donor and acceptor r, the refractive index of the medium n, the degree of energy overlap J between the emission spectrum of the donor and the absorbance spectrum of the acceptor, the emissive rate of the donor in the absence of acceptor I
d
, and the relative orientation between the donor and acceptor dipoles k
2
:
K
T
=(
r
−6
Jk
2
n
−4
l
d
)×8.71×10
23
sec
−1
The rate of energy transfer can be simply expressed in terms of a Förster distance R
0
, which is the distance at which the rates of emission and energy transfer are equal, and the lifetime of the donor &tgr; (tau):
K
T
=
1
τ
D
(
R
0
r
)
6
Although, lifetime and ratiometric methods are qualitatively similar with respect to their freedom from spurious variations in photoluminescence intensity, the physical measurement of photoluminescence lifetime is costlier and technically more difficu
Feliccia Vincent L.
Fierke Carol A.
Maliwal Badri P.
Thompson Richard B.
Marks David L.
Smith Chalin A.
Soderquist Arlen
University of Maryland Baltimore
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