Chemistry: analytical and immunological testing – Phosphorus containing – Organic
Reexamination Certificate
2001-04-04
2004-02-03
Snay, Jeffrey (Department: 1743)
Chemistry: analytical and immunological testing
Phosphorus containing
Organic
C436S172000
Reexamination Certificate
active
06686206
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the methods for signal amplification in the detection of target molecules with luminescence-based sensors. The amplification involves energy transfer between two or more fluorescent chromophores in a carefully selected polymer matrix. The developed technology can be applied to any luminescence sensors comprising donor-acceptor pairs, and it can be generalized to multichromophore systems with n-chromophores leading to n-fold signal amplification and improved selectivity.
In one preferred embodiment, the signal amplification has been demonstrated experimentally in the fluorescent sensing of dimethyl methylphosphonate (DMMP) using two dyes, 3-aminofluoranthene (AM) and Nile Red (NR), in a hydrogen bond acidic polymer matrix. The selected polymer matrix quenches the fluorescence of both dyes and shifts dye emission and absorption spectra relative to more inert matrices. Upon DMMP sorption, the AM fluorescence shifts to the red. At the same time the NR absorption shifts to the blue, resulting in better band overlap and increased energy transfer between chromophores.
In another preferred embodiment, the sensitive material is incorporated into an optical fiber system enabling efficient excitation of the dye and collecting the fluorescent signal form the sensitive material on the remote end of the system.
The method can be used in all applications where highly sensitive detection of basic gases, such as dimethyl methylphosphonate (DMMP), Sarin, Soman and other chemical warfare agents having basic properties, is required, including environmental monitoring, chemical industry and medicine.
2. Information Disclosure Statement
Today, there is a high demand for chemical sensor for detecting low concentration levels of analytes present in the liquid and gaseous phase. Selectivity to target molecules is also highly desired. Traditional methods of quantitative detection of analytes based on gas chromatography and mass spectrometry require complex laboratory equipment. Among modern approaches for the real time monitoring of gaseous analytes, mainly three kinds of sensing elements have been investigated: microelectrodes, quartz crystal microbalance and surface acoustic wave devices. Generally all these methods are based on detection of only one parameter—signal intensity. Therefore reliable analyte identification requires significant increasing the number of individual sensors in the detector array.
Meanwhile, optical chemosensors, especially fluorescence-based chemosensors can provide many kinds of complex information, including changes in intensity, wavelengths and spectral shape, fluorescence lifetime. Hence such promising approach allowing detection of many parameters simultaneously should make possible fabrication of highly sensitive, robust, multi-analyte-detecting arrays with fewer independent sensors. Moreover, the possibility of remote sensing using optical fluorescence technique offers many serious advantages over other traditional methods of real-time monitoring of toxic gases and pollutants.
Most of the luminescence sensory materials known today consist of chromophores isolated in an inert matrix and cannot use the amplification effect resulting from energy migration/transfer in the excited states. Meanwhile the luminescence sensitivity can be considerably increased by the use of radiationless direct energy transfer (RDET) or emissive energy transfer (EET) between donor and acceptor chromophores isolated in an inert matrix. RDET is a distance-dependent transfer of electronic excitation from donor to acceptor due to dipole-dipole interaction and EET is a result of the acceptor reabsorption of the donor emission.
The present invention suggests new approach to the highly sensitive and selective detection of analyte employing the energy transfer between two or more fluorescent chromophores in a carefully selected polymer matrix. A quantitative model has been derived that can be applied to any luminescence sensors comprising donor-acceptor pairs, and it can be generalized to multichromophore systems with n-chromophores leading to n-fold signal amplification and enhanced sensor selectivity.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to improve performance of chemical sensors of analyte molecules by employing the effect of the signal amplification due to energy transfer between two sensory chromophores isolated in special polymer matrix.
Another object of the invention is to provide a quantitative model that can be applied to any luminescence sensors comprising donor-acceptor pairs, and it can be generalized to multichromophore systems with n-chromophores leading to n-fold signal amplification.
A further object is to provide simple and efficient method of detection of the fluorescence signal by measuring enhancement of the fluorescence of acceptor chromophore at the excitation of donor chromophore in the presence of target molecules.
A further object is to provide a selection of efficient sensitive fluorescent material comprising a film of Nile Red (NR, acceptor chromophore) and 3-aminofluoranten (AM, donor chromophore) dyes having functional basic group and isolated in BSP3 polymer matrix that is a strong hydrogen bond acidic polymer.
Another object is to provide efficient method of processing the fluorescent signal from the sensitive material.
Still another object is to provide a possibility of remote monitoring of large contaminated area by incorporating the sensitive fluorescent material into an optical fiber system.
An additional object of the invention is to provide a method for fabrication of the fiber-optic fluorescence sensors achieving efficient excitation of the sensitive material and efficient collecting the fluorescence signal.
Briefly stated, the present invention provides a method of signal amplification in luminescence based chemical sensors where energy transfer effect between donor and acceptor chromophore can considerably increase the response signal with respect to mono chromophore sensor. This approach can be applied to any bi- or multichromophore sensors for detection of analyte molecules in gases or liquids. In particular, a signal amplification was demonstrated in the fluorescent sensing of dimethyl methylphosphonate (DMMP) using two dyes, AM and NR, in a hydrogen bond acidic polymer matrix. The selected polymer matrix quenches the fluorescence of both dyes and shifts dye emission and absorption spectra relative to more inert matrices. Upon DMMP sorption, the AM fluorescence shifts to the red. At the same time the NR absorption shifts to the blue, resulting in better band overlap and increased energy transfer between chromophores. Importantly that this also provides the better selectivity to DMMP vapors with respect to monochromophore sensor. The method can be used in fluorescence chemical sensors of basic gases for different applications including environmental monitoring, control of industrial processes and medicine.
The above, and other objects, features and advantages of the present invitation will become apparent from the following description read in conjunction with the accompanying drawings.
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Krivoshlykov Sergei G.
Levitsky Igor A.
ALTAIR Center, LLC
Snay Jeffrey
LandOfFree
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