EP0809804A1 - Dosage par transfert d'energie chimioluminescente - Google Patents
Dosage par transfert d'energie chimioluminescenteInfo
- Publication number
- EP0809804A1 EP0809804A1 EP95911618A EP95911618A EP0809804A1 EP 0809804 A1 EP0809804 A1 EP 0809804A1 EP 95911618 A EP95911618 A EP 95911618A EP 95911618 A EP95911618 A EP 95911618A EP 0809804 A1 EP0809804 A1 EP 0809804A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- enzyme
- dioxetane
- hydrophobic
- substrate
- attophos
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
- C12Q1/68—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving nucleic acids
- C12Q1/6813—Hybridisation assays
- C12Q1/6816—Hybridisation assays characterised by the detection means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/58—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving labelled substances
- G01N33/582—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving labelled substances with fluorescent label
Definitions
- This invention relates to the energy transfer chemiluminescent assays for the determination of the presence or amount of a biological substance in surface-bound assays using 1,2-dioxetanes in connection with hydrophobic fluorometric substrates such as AttoPhosTM as chemiluminescent substrates for enzyme-labeled fluorometric substrate targets or probes.
- hydrophobic fluorometric substrates such as AttoPhosTM as chemiluminescent substrates for enzyme-labeled fluorometric substrate targets or probes.
- the chemiluminescence of the dioxetane AttoPhosTM acceptor substrate pair can be enhanced by the addition of a polymeric enhancer. Further enhancement can be achieved by adding, in sequence, AttoPhos" and then the 1,2-dioxetane.
- Chemiluminescent assays for the detection of the presence or concentration of a biological substance have received increasing attention in recent years as a fast, sensitive and easily read method of conducting bioassays.
- a chemiluminescent compound is used as a reporter molecule, the reporter molecule chemiluminescing in response to the presence or the absence of the suspected biopolymer.
- 1,2- dioxetanes A wide variety of chemiluminescent compounds have been identified for use as reporter molecules.
- One class of compounds receiving particular attention is the 1,2- dioxetanes.
- 1,2-dioxetanes can be stabilized by the addition of a stabilizing group to at least one of the carbon atoms of the dioxetane ring.
- An exemplary stabilizing group is spiro- bound adamantane.
- Such dioxetanes can be further substituted at the other carbon position with an aryl moiety, preferably phenyl or naphthyl, the aryl moiety being substituted by an oxygen which is, in turn, bound to an enzyme-labile group.
- Such dioxetane ⁇ represent an advance over earlier-recognized dioxetane ⁇ , such a ⁇ 3-(4- methoxyspiro [l,2-dioxetane-3,2'-tricyclo]-3.3.1.1 3 ' 7 Jdecan]- 4-yl) phenylphosphate, and in particular, the disodium salt thereof, generally identified a ⁇ AMPPD.
- the chlorine- substituted counterpart which convert ⁇ the stabilizing adamantyl group from a passive group which allows the decomposition reaction to go forward, to an active group which gives rise to enhanced chemiluminescence signal due to faster decomposition of the dioxetane anion, greater signal-to-noise values and better sensitivity, is referred to as CSPD.
- Other dioxetanes such as the phenyloxy-0-D-galactopyranoside (AMPGD) are also well-known, and can be used a ⁇ reporter molecules. These dioxetanes, and their preparation, do not constitute an aspect of the invention herein, per se.
- Assays employing these dioxetanes can include conventional assays, such as Southern, Northern and Western blot assays, DNA sequencing, ELISA, as well as other liquid phase and mixed phase assays performed on membranes and beads. In general, procedures are performed according to standard, well-known protocols except for the detection step.
- DNA assays the target biological substance is bound by a DNA probe with an enzyme covalently or indirectly linked thereto, the probe being admixed with the sample immobilized on a membrane, to permit hybridization. Thereafter, excess enzyme complex is removed, and dioxetane added to the hybridized sample.
- the dioxetane will be activated by the bound enzyme, leading to decomposition of the dioxetane, and chemiluminescence.
- the enzyme is frequently conjugated to a nucleic acid probe or immune complexed with an antibody responsive to the target biological substance, unbound components being removed, and the dioxetane added, chemiluminescence being produced by the decomposition of the dioxetane activated by the amount of enzyme present.
- the dioxetane need only be added to the sample.
- Patent 4,978,614 addresses the addition of variou ⁇ water-soluble "enhancement" agents to the sample, although the patent speaks to the problem of suppressing non-specific binding reactions in solid state assays.
- preferred water-soluble polymeric quaternary ammonium salts such as poly(vinylbenzyltrimethylammonium chloride) (TMQ) poly(vinyl- benzyltributylammonium chloride) (TBQ) and poly(vinylbenzyl- dimethylbenzylammonium chloride) (BDMQ) are identified as water-soluble polymeric quaternary ammonium salts which enhance chemiluminescence and provide greater sensitivity by increa ⁇ ing the signal-to-noise ratio. Similar phosphonium and sulfonium polymeric salts are also disclosed.
- This enhancement is achieved, at least in part, through the formation of hydrophobic regions in which the dioxetane oxyanion i ⁇ sequestered. Decomposition in these hydrophobic regions enhances chemiluminescence, because water-based light quenching reactions are suppressed.
- TBQ provides -unexpectedly superior enhancement, through this hydrophobic region-forming mechanism.
- the chemiluminescent enhancement achieved by the addition of water-soluble polymeric substances such as ammonium, phosphonium and sulfonium polymeric salts can be further improved by the inclusion, in the aqueous sample, of an additive, which improves the ability of the quaternary polymeric salt to sequester the dioxetane oxyanion and the resulting excited state emitter reporting molecule in a hydrophobic region.
- an additive which improves the ability of the quaternary polymeric salt to sequester the dioxetane oxyanion and the resulting excited state emitter reporting molecule in a hydrophobic region.
- the synergistic combination of the polymeric quaternary salt and additives gives enhancement effects making low-level, reliable detection possible even in aqueous samples through the use of 1,2-dioxetanes.
- the polymeric quaternary salts, coupled with the additives, are sufficiently powerful enhancers to show dramatic 4 and 5-fold increases at levels below 0.005 percent down to 0.001 percent. Increased signal, and improved signal/noise ratios are achieved by the addition of further amounts' of the polymeric quaternary salt, the additive, or both, in amounts up to as large as 50 percent or more.
- levels for both polymeric quaternary salt and additive can be preferably within the range of 0.01 - 25 percent, more preferably from 0.025 - 15 percent by weight. The details of this improvement are disclosed in U.S. Application Serial No. 08/031,471 which is incorporated herein by reference.
- U.S. Patent 5,208,148 describes a class of fluorescent substrates for detection of cells producing the glycosidase enzyme.
- the substrate is a fluorescein diglycoside which is a non-fluorescent substrate until hydrolyzed by glycosidase enzyme inside a cell to yield a fluorescent detection product excitable between about 460 nm and 550 nm.
- the fluorescent enzymatic hydrolysis products are specifically formed and adequately retained inside living cells, and are non-toxic to the cells.
- the substrates can penetrate the cell membrane under physiological conditions. Therefore, the invention permits analysis, sorting and cloning of the cells and monitoring of cell development in vitro and in vivo.
- these fluorescent products are detected in the single cells and within specific organelles of single cells only after the spectral properties of the substrates are excited by an argon laser at its principle wavelengths.
- U.S. patents 4,959,182 and 5,004,565 describe methods and compositions for energy transfer enhancement of chemiluminescence from 1,2-dioxetanes. These patents utilize a fluorescent micelle comprising a surfactant and a fluorescent co-surfactant which exists in the bulk phase of the buffer solution used.
- the fluorescent cosurfactant is present in a form capable of energy transfer-based fluorescence at all times. In contact with a solid phase containing an enzyme-labeled ligand binding pair, the fluorescent moiety tends to remain associated with the micelle in the bulk phase.
- any fluorescent co-surfactant is deposited on the solid phase, this occurs indiscriminately, in areas containing the immobilized ligand binding pair, and in areas which do not contain said pair. Thus a problem results in that the fluorescent emitters never are, or do not remain associated with the immobilized enzyme conjugate. Thus the close proximity needed for energy transfer from the dioxetane to the fluorescent emitter is not efficient. Further because the fluorescent emitters can be deposited anywhere on the solid phase matrix, this method does not allow for specificity when used in bound a ⁇ say. The majority of the examples in the 1182 and 1565 patents are solution phase enzyme assays or chemical triggering experiments not utilizing enzymes.
- this fluorescent co-surfactant is not a non- fluorescent enzyme substrate such as AttoPhos.
- a fluorescent energy acceptor is produced directly, and locally on a surface, by the same enzyme which catalytically decomposes the dioxetane energy donor, is not suggested by these art references.
- the present invention provides a method for determining the presence or the amount of a biological substance in a biological sample, wherein the method comprises the steps of: a) forming an enzyme conjugated binder (antibody or DNA probe) with the biological ligand from the sample; b) adding a hydrophobic fluorometric substrate such as AttoPhos" and a 1,2-dioxetane to the bound enzyme conjugated binder; c) wherein the enzyme of the enzyme conjugated biopolymer cleaves an enzyme cleavable group such as a phosphate moiety from the AttoPhos" and from the dioxetane causing the dioxetane to decompose through an excited state emitter form such that energy transfer occurs from the excited state chemiluminescent emitter to the dephosphorylated AttoPhos", causing this moiety to emit; and d) determining the presence or amount of the biological substance as a function of the amount of fluorescence.
- kits for conducting a bioassay for the presence or concentration of a biological substance which is detected either bound to a surface or in a solution assay comprising: a) an enzyme complex which will stably bind to a surface-bound biological substance; b) a 1,2-dioxetane which when contacted by the enzyme complex will be caused to decompose into a decomposition product which is capable of transferring its energy; and c) AttoPhos".
- Figure 1 is an illustration of the method of the present invention showing the energy transfer from CS-D to dephosphorylated Atto, thereby releasing energy in the form of fluorescence.
- Figure 2 (A) - (D) is a CCD image of Western blot analysis of rabbit IgG on Nitrocellulose Membrane. A detailed description of Figure 2 can be found in Example 1.
- Figure 3 is a graph of a Western blot analysis of rabbit IgG on Nitrocellulose Membrane showing chemiluminescent intensity (average and maximum) .
- Figure 4 (A) - (D) is a CCD image of Western blot analysis of rabbit IgG on PVDF membrane. Figure 4 is specifically explained in Example 1.
- Figure 5 is a graph of a Western blot analysis of rabbit IgG on PVDF membrane showing chemiluminescent intensity (average and maximum) .
- Figure 6 (A) - (B) are graphs of PSA (Prostate Specific Antigen) , ng/mL versus RLU, 5 sec of chemiluminescent detection of PSA comparison of CSPD to CSPD + AttoPhos".
- PSA Prostate Specific Antigen
- Figure 7 is a chemiluminescent emission spectrum (intensity v. wavelength) obtained with 0.25 mM CSPD, 50% AttoPhos", and alkaline phosphatase, as described in Example 3.
- Figure 8 is a chemiluminescence spectrum (intensity v. wavelength) obtained with 1.0 mM CSPD, 50% AttoPhos", and alkaline phosphatase, as described in Example 3.
- Figure 9 is a chemiluminescence spectrum (intensity v. wavelength) obtained with 0.1 mM CSPD, 50% AttoPhos", 20% BDMQ, and alkaline phosphatase, as described in Example 3.
- Figure 10 is a chemiluminescence spectrum (intensity v. wavelength) obtained with 0.25 mM CSPD, 50% AttoPhos", 20% BDMQ, and alkaline phosphatase, as described in Example 3.
- Figure 11 is a chemiluminescence spectrum (intensity v. wavelength) obtained with 0.5 mM CSPD, 50% AttoPhos", 20% BDMQ, and alkaline phosphatase, as described in Example 3.
- Figure 12 is a chemiluminescence spectrum (intensity v. wavelength) obtained with 1.0 mM CSPD, 50% AttoPhos", 20% BDMQ, and alkaline phosphatase, as described in Example 3.
- Figure 13 is a chemiluminescence spectrum (intensity v. wavelength) obtained with 1.0 mM CSPD, 50% AttoPhos", 10% BDMQ, and alkaline phosphatase, as described in Example 3.
- Figure 14 is a chemiluminescence spectrum (intensity v. wavelength) obtained with 1.0 mM CSPD, 10% AttoPhos", 20% BDMQ, and alkaline phosphatase, as described in Example 3.
- Figure 15 is a chemiluminescent emission spectrum (intensity v. wavelength) obtained using 1.0 mM CSPD, 50% AttoPhos", 2.0 mg/ml polyvinylbenzyltriphenyl phosphonium chloride-copolyvinylbenzylenzyldimethyl ammonium chloride (40 mole% TPP/60 mole% BDMQ) , and alkaline phosphatase as described in Example 3.
- Figure 16 is a chemiluminescent emission spectrum (intensity vs. wavelength) obtained using 1. 0 mM CSPD, 50% AttoPhos", 2.0 mg/ml polyvinylbenzyltriphenyl phosphonium chloride-copolyvinylbenzyltributyl ammonium chloride (45 mole% TPP/55 mole% TBQ) , and alkaline phosphatase as described in Example 3.
- Figure 17 is a chemiluminescent emission spectrum (intensity vs. wavelength) obtained using a 30 minute preincubation of alkaline phosphatase in 50% AttoPhos", 20% BDMQ, followed by the addition of CSPD (0.25 M final concentration) at time zero as described in Example 3.
- Figure 18 is a graph showing the ratio of emission at 545 nm/465 nm obtained from the data in Figures 7-14 and Figure 17.
- Figure 19 is a graph showing the sum of emission at 465 nm and 545 nm, obtained from the data in Figures 7-14 and Figure 17.
- Figure 20 is a graph showing the ratio of emission at 545 nm/465 nm obtained from the data in Figures 15 and 16.
- Figure 21 is a graph showing the sum of emission at 465 nm and 545 nm, obtained from the data in Figures 15 and 16.
- Figure 22 is a CCD camera image detecting the presence of biotinylated DNA. Best Mode for Carrying Out the Invention
- This invention makes use of a hydrophobic fluorometric substrate.
- a hydrophobic fluorometric substrate By this is intended a compound which upon activation by an enzyme can be induced to emit in respon ⁇ e to energy transfer from an excited state dioxetane decomposition product donor.
- the substrate when activated, must be sufficiently hydrophobic as to be sequestered in the same hydrophobic regions to which the donor migrates, for energy and transfer to occur.
- the present invention is described in terms of a method for determining the presence or amount of a substance or determined in a solution-phase assay biological substance using 1,2-dioxetanes using the hydrophobic fluorometric substrate AttoPhos".
- the kit of the present invention also for determining the presence or amount of a substance, is described using a suitable enzyme conjugate, a 1,2-dioxetane and AttoPhos".
- Other fluorometric substrates may be used.
- the present inventors have found for the first time that 1,2-dioxetane in connection with AttoPhos" improves both the specificity and sensitivity of surf ace-bound assays. Further, these assays using 1,2-dioxetane in connection with AttoPhos” alleviate the need for light sources necessary for excitation. Specifically, the present invention uses the high quantum yield of fluorescence, affinity for surfaces possessed by AttoPhos", coupled with the enzyme activated chemiluminescence of 1,2-dioxetane as the excitation source for the dephosphorylated AttoPhos".
- dephosphorylated AttoPhos is produced at the surface and stays in close proximity with the enzyme environment throughout the assay, and the excitation of the acceptor—dephosphorylated AttoPhos” can be performed without any external instrumentation and without possible excitation of chromophores which are other than the dephosphorylated AttoPhos".
- the method can be used for determining the presence or the amount of a biological substance in a biological sample.
- the method comprises the steps of: a) forming a enzyme conjugated binder (antibody or nucleic acid probe) complex with a biological substance from the biological sample; b) adding AttoPhos" and a 1,2-dioxetane to the bound enzyme conjugate biological substance complex; c) wherein the enzyme of the enzyme conjugate cleaves a pho ⁇ phate moiety from the AttoPhos" and from the dioxetane, thereby causing the dioxetane to decompose through an excited state form such that an energy transfer occurs from the excited state donor of dioxetane to the dephosphorylated AttoPhos" acceptor, causing it to luminesce; and d) determining the presence or amount of the biological substance as a function of the amount of luminescence.
- the kit of the present invention is also for determining the presence or concentration of a biopolymer and comprises: a) an enzyme complex which will bind to a biological substance upon admixture therewith; b) a 1,2-dioxetane which when contacted by the enzyme of the enzyme complex will be caused to decompose into a decomposition product which is in an excited state; and c) AttoPhos".
- the assays and kits of this invention employ water- soluble chemiluminescent 1,2-dioxetanes.
- these dioxetanes are well established in the art, and their identity and preparation do not constitute a novel aspect of this invention, per se.
- any chemiluminescent dioxetane which exhibits sufficient solubility and stability in aqueous buffers to conduct the assay, and which may be caused to decompose and chemiluminesce by interaction with an enzyme, and cleavage, by the enzyme, of an enzyme labile group inducing the decomposition, can be used in connection with this invention.
- 1,2-dioxetane ⁇ useful in this invention will have the general formula:
- R 1 is Ci-C j Q alkyl or C ⁇ l2 aryl or aralkyl
- Y is phenyl or naphthyl, unsubstituted or substituted with an electron donating or electron withdrawing group
- R 2 is meta-substituted or non-conjugated on Y with respect to the dioxetane, and is OX, wherein;
- X is an enzyme cleavable group which, when cleaved, leaves the dioxetane phenoxy or naphthoxy anion.
- Suitable dioxetanes are those disclosed in U.S. Patent Application 08/057,903, the entire disclosure of which is incorporated herein by reference.
- Preferred dioxetanes include dioxetanes in which X is a phosphate moiety.
- Particularly preferred dioxetanes include AMPPD, and in particular, its disodium salt, as well as CSPD, and in particular, its disodium salt.
- Methods of preparing these dioxetanes are disclosed in the afore-referenced, commonly- assigned patents, as well as, e.g., U.S. Patent 4,857,652, assigned to Wayne State University. The preparation, purification and isolation of the dioxetanes does not constitute a novel aspect of the invention disclosed and claimed herein per se.
- AttoPhos is a highly sensitive fluorometric substrate for the detection of alkaline phosphatase.
- the chemical structure of AttoPhos is not known at the present time. However, the chemical properties of AttoPhos” are known.
- AttoPhos was developed by JBL Scientific and can be obtained from the JBL-Scientific catalog (1993) at catalog number 1670A.
- AttoPhos is a pale, yellow crystalline solid having a molecular weight of approximately 580 gram ⁇ /mol.
- the turnover number for AttoPhos is 85,400 molecules of AttoPhos" per minute per molecule of alkaline phosphatase in 2.40 M DEA (diethanolamine) pH 9.0, 0.23 mM MgCl 2 and 0.005% NaN, by weight.
- the solubility of AttoPhos is > 10 mM in aqueous 2.4 M DEA buffer at a pH of 9.0.
- the optimum alkaline phosphatase turnover occurs at a substrate concentration of 0.5-1.5 mM AttoPhos".
- AttoPhos has a Km value of 0.030 mM and a molar absorptivity of 31.412.
- AttoPhos When contacted with alkaline phosphatase, AttoPhos" is known to become a fluorescent emitter.
- the molecular weight of the fluorescent emitter is approximately 290 g/mole.
- Thi ⁇ fluorescent emitter has an excitation maximum in the visible range at 430-450 nm with fluorescence monitored at 550-570 nm, in a DEA buffer. Best conditions are at 440 nm for excitation with 550 nm emission.
- the fluorescent emitter also has an emission maximum at 560 nm, and a large Stokes Shift of 140 nm.
- the Water Raman emission occurs at 470 nm with an excitation at 413 nm.
- the fluorescent emitter has a maximum at 418 nm with an coefficient of 26,484 in 0.392 M Na 2 C0 3 and a pH of li.o and is fully ionized at a pH > 10.0.
- the dioxetane is added to an enzyme complex which is bound to a biological binder (antibody or nucleic probe) .
- the enzyme complex is also bound to the target biological substance.
- the dioxetane is therefore the substrate for the enzyme, the enzyme-catalyzed cleavage of the labile groups of the substrate from the body of the dioxetane resulting in the formation of the unstable oxyanion, and subsequent decomposition of the dioxetane.
- the enzyme is usually complexed with a binder moiety, such as a DNA probe in a hybridization step or suitable antibody in an incubation step, so as to help bind to the biological substance.
- the hybridization step can be carried out using standard, wellknown procedures and using a suitable probe.
- an incubation step can be carried out in the usual manner using a suitable antibody.
- the enzyme conjugate can be any enzyme conjugate capable of stably binding to the biological substance.
- the enzyme conjugate are any ligand-binder pair, probe with a covalently attached enzyme, or antibody labeled directly with alkaline phosphata ⁇ e.
- the nucleic acid probe ⁇ and antibodies may be labelled indirectly with enzymes via a biotin-[strept ⁇ avidin or antigen-antibody ( ⁇ uch as degoxigenin-antidigoxigenin, fluorescein-antifluorescein) and other type coupling.
- Derivatized alkaline phosphata ⁇ e such a ⁇ Streptavidin-alkaline phosphatase alkaline phosphata ⁇ e labeled antibodies and DNA probe ⁇ , are the preferred enzyme conjugates useful in the present invention.
- AttoPhos and the 1,2-dioxetane are added to the bound enzyme conjugate complexed with biological substance either simultaneously, or AttoPhos" is added first, allowed to dephosphorylate, and subsequently, a 1,2-dioxetane is added.
- Patent 5,208,148 describee fluorescein diglycoside ⁇ which are specifically modified by the inclusion of a range of hydrophobic moietie ⁇ attached to the planar, fluorophore itself.
- hydrophobic substrates would be useful for performing the bioassays of the invention where the enzyme label utilized is a glycosidase such as beta-galactosidase and the dioxetane was of the general structure shown above where for example, Z*C1, R 1 -no_ethy1, Y «phenylene, and X-beta-D-galactopyranoside.
- hydrophobic hydroxyfluore ⁇ cein ⁇ shown in this patent a ⁇ precursors to the diglycosidee may instead by pho ⁇ phorylated u ⁇ ing known art to give hydrophobic fluore ⁇ cein mono- and diphosphate derivatives which are u ⁇ eful in the present invention.
- the enzyme cleaves a phosphate moiety from both the 1,2- dioxetane and AttoPhos". ⁇ the 1,2-dioxetane becomes dephosphorylated by the enzyme, the formed oxyanion become ⁇ the excited state donor, and its energy is transferred to the closely positioned acceptor—the dephosphorylated AttoPhos" emitter, causing it to emit.
- Figure 1 illustrates the energy transfer from the l,2dioxetane (CS"D) to the dephosphorylated AttoPhos", which in turn, releasing energy in the form of luminescence.
- the energy transfer efficiency is enhanced as the dephosphorylated product of AttoPhos"—acceptor, is hydrophobic and is immobilized in the surface/biological substance sites and therefore is in very close proximity to the chemiluminescent dephosphorylated 1,2-dioxetane's excited state fragment which is the energy donor.
- the 1,2-dioxetane is added to the bound enzyme conjugate complexed with biological substance in an amount of from 0.01 to 2.5 mM, preferably 0.25 to 1 mM. Most preferably, the 1,2- dioxetane is added in an amount of 0.25 mM.
- AttoPhos in the 2.40 M diethanolamine (DEA) in water buffer is added to the enzyme or enzyme conjugated binder completed with biological substance in an amount of from l- 100%, preferably 25 to 75% by volume. Most preferably, 10 to 50% by volume AttoPhos" is added.
- DEA diethanolamine
- AttoPhos is added first, allowed to dephosphorylate, and subsequently, a 1,2- dioxetane is added.
- the time period between addition of AttoPhos" and addition of a 1,2-dioxetane is preferably 10 to 60 minutes, more preferably 20 to 40 minutes, and most preferably 25 to 30 minutes.
- the signal can be further enhanced by the addition of a water-soluble macromolecule along with AttoPhos" or other hydropic fluorometric enzyme substrate.
- Preferred water- soluble polymers useful in practicing the invention are based, in general, on polymeric onium salts, particularly quaternary salts based on phosphonium, sulfonium and, preferably, ammonium moieties.
- the polymer ⁇ have the general formula I shown below:
- each of R 1 , R 2 and R 3 can be a straight or branched chain unsubstituted alkyl group having from 1 to 20 carbon atoms, inclusive, e.g., methyl, ethyl, n-butyl, t- butyl, hexyl, or the like; a straight or branched chain alkyl group having from 1 to 20 carbon atoms, inclusive, substituted with one or more hydroxy, alkoxy, e.g., methoxy, ethoxy, benzyloxy or polyoxethylethoxy, aryloxy, e.g., phenoxy, amino or substituted amino, e.g., methylamino, amido, e.g., acetamido or ureido, e.g., phenyl ureido; or fluoroalkane or fluoroaryl, e.g., heptafluorobutyl,
- the symbol X" represents a counterion which can include, alone or in combination, moieties such as halide, i.e., fluoride, chloride, bromide or iodide, sulfate, alkylsulfonate, e.g., methylsulfonate, arylsulfonate, e.g., p-toluenesulfonate, substituted arylsulfonate, e.g., anilinonaphthylenesulfonate (various isomers) , diphenylanthracenesulfonate, Perchlorate, alkanoate, e.g., acetate, arylcarboxylate, e.g., fluorescein or fluorescem derivatives, benzoheterocyclic arylcarboxylate, e.g., 7-diethylamino-4-cyanocoumarin-3-carboxylate, organic dian
- n represents a number such that the molecular weight of such poly(vinylbenzyl Quaternary salts) will range from about 800 to about 200,000 (weight average), and preferably from about 20,000 to about 70,000, as determined by intrinsic visco ⁇ ity or LALLS technique ⁇ .
- the symbol M may also represent phosphorous or sulfur whereupon the corresponding sulfonium or phosphonium polymers have been described in the prior art: U.S. Patents 3,236,820 and 3,065,272.
- Copolymers containing 2 or more different pendant onium groups may also be utilized in the invention described herein:
- the symbols X, M' , R 1 ', R 2 ', R 3 ' are as described above for X, M, R 1 -R 3 .
- the symbols Y and Z represent the mole fraction of the individual monomers comprising the copolymer. The symbols Y and Z may thus individually vary from .01 to .99, with the sum always equalling one.
- M is N or P
- R -R 3 are individually, independently, alkyl, cycloalkyl, polycycloalkyl (e.g. adamantane) aralkyl or aryl, having 1 to 20 carbon atoms, unsubstituted or further substituted with hydroxy1, amino, amido, ureido groups, or combine to form via a spiro linkage to the M atom a heterocyclic (aromatic, aliphatic or mixed, optionally including other N, S or 0 hetero atoms) onium moiety.
- a heterocyclic aromatic, aliphatic or mixed, optionally including other N, S or 0 hetero atoms
- X is preferably selected to improve solubility and to change ionic strength as desired, and is preferably halogen, a sulfate, a sulfonate.
- each of R 1 -R 3 may be the same as or different from the corresponding R 1 -R 3 '.
- Examples of preferred polymers include the following:
- vinylbenzyl quaternary ammonium salt polymers can be prepared by free radical polymerization of the appropriate precursor monomers or by exhaustive alkylation of the corresponding tertiary amines or phosphine ⁇ with polyvinylbenzyl chicride, or copolymers containing a pendant benzyl chloride function. Thi ⁇ same approach can be taken using other polymeric alkylating agents such as chloromethylated polyphenylene oxide or polyepichlorohydrin.
- polymeric alkylating agents can be used a ⁇ initiator ⁇ of oxazoline ring-opening polymerization, which, after hydrolysis, yields polyethyleneimine graft copolymers. Such copolymers can then be quaternized, preferably with aralkyl groups, to give the final polymer.
- each R 4 is the same or a different aliphatic substituent and X : is an anion, as disclosed and claimed in Bronstein-Bonte et al U.S. Patent 4,124,388, can also be used in practicing this invention.
- the individual vinylbenzyl quaternary ammonium salt monomers used to prepare the poly(vinylbenzyl quaternary ammonium salts) of formula I above can also be copolymerized with other ethylenically unsaturated monomers having no quaternary ammonium functionality, to give polymers such as those disclosed and claimed in Land et al U.S. Patent 4,322,489; Bronstein-Bonte et al U.S.
- these quaternized polymers will have molecular weights within the ranges given above for the poly(vinylbenzyl quaternary ammonium salts) of Formula I.
- cationic microgels or crosslinked latices are more suitable for the direct formation of cast membranes, but can also be used for the overcoating of preformed membranes.
- Such materials are well known a ⁇ photographic mordants and may be synthesized using a monomer mixture which contains a crosslinking moiety substituted with two ethylenically unsaturated groups.
- Quaternary ammonium or phosphonium salt containing latices can be prepared using methodologies described in Campbell et al U.S. Patent 3,958,995.
- Formula IV generally represents a useful subset of such water- soluble latex copolymers wherein the symbols X ⁇ , R 1 , R 2 and R 3 are as described above. The symbols X, Y and Z are mole fractions which must add together to give unity.
- a polymeric enhancer such as a ⁇ BDMQ is added to the enzyme or enzyme conjugate biological substance sources in an amount of 0.01 to 26% (0.1 to 250 mg/ml), more preferably 0.025 to 15% (25 to 150 mg/ml). Most preferably, BDMQ is added in an amount of 0.1 to 0.2% (i to 2 mg/ml).
- the emitted signal resulting from the dephosphorylated AttoPhos is by way of an energy transfer excitation from the excited state dioxetane dense fragment.
- the emitted signal can be captured on a green sensitive film or in a luminometer, CCD camera.
- the amount of emission detected will be responsive both to the presence of the biopolymer, and to the amount of r*_e surface-bound biopolymer.
- the amount of biological substance is a function of the intensity of the emission.
- kits of the present invention can be used to determine the presence or concentration of any biological substance, including RNA, DNA, proteins and hapten ⁇ . Further, the methods and kite of the present invention can be used for detections performed on membranes such as Western, Southern, Northern blotting and DNA sequencing, and can also be used for solution-phase assays. In the solution-based assay or when enhancing polymers are employed, they may require the dephosphorylated products of both AttoPhos" and 1,2-dioxetane substrates, and thereby increasing the proximity between the donor and acceptor moieties.
- Dilutions of rabbit IgG were electrophoresed on a 10% polyacrylamide gel using standard, known methods.
- the IgG samples were 200, 66.7, 22.2, 7.4 and 2.4 ng per lane for nitrocellulose and 100, 33.3, 11.1, 3.7 and 1.2 ng per lane for PVDF.
- the protein was then transferred to the membrane as follows: the gel was equilibrated in transfer buffer (5 mM MOPS, 2 mM sodium acetate, 20% methanol, pH 7.5) and then electrotransferred to nitrocellulose (Schleicher and Schuell BAS85) or PVDF (Tropix) at 90 volts for 1 hour at 4 ⁇ C.
- the membranes were rinsed with phosphate buffered saline (PBS), blocked with 0.2% casein, 0.1% Tween-20 in PBS(blocking buffer), incubated for 30 minutes with a 1- 10,000 dilution of alkaline phosphatase conjugated goat anti- rabbit .ntibody (GAR-AP) in blocking buffer, the PVDF membranes were washed twice for 5 minutes in blocking buffer, the nitrocellulose membranes were washed twice in 0.1% Tween- 20 in PBS, all membranes were washed twice for 5 minutes in 0.1 M diethanolamine, 1 mM MgCl 2 , pH 10 (substrate buffer), incubated for 5 minutes in a 1-20 dilution of Nitro-Block (Tropix) in substrate buffer, washed twice for 5 minutes in substrate buffer, incubated for 5 minutes in 0.25 mM CSPD in substrate buffer and AttoPhos" under various conditions, sealed in a plastic report cover, incubated for approximately 1 hour and imaged
- Chemiluminescent images were obtained by integration of the chemiluminescent signal for 5 minutes with a Star 1 CCD camera interfaced to an Apple Macintosh Ilci computer using IPLab Spectrum software.
- the CCD images were transferred into the NIH Image software package, and average and maximum pixel intensities were measured for each band.
- the CCD images are compositee of the Western blot images.
- Blot A was incubated in 0.25 mM CSPD in substrate buffer.
- Blot B was incubated in 0.25 mM CSPD and 50% AttoPhos" (50% AttoPhos” buffer) simultaneously.
- Blot C was incubated first in 50% AttoPhos" (50% substrate buffer) for 30 minutes, the AttoPhos" was removed, the membrane was washed twice for 5 minutes in substrate buffer, and 0.25 mM CSPD in substrate buffer was added.
- Blot D was incubated for 30 minutes with undiluted AttoPhos" standard, then the membrane was washed twice for 5 minutes in substrate buffer followed by 0.25 mM CSPD in substrate buffer. Images were obtained approximately 1 hour after the initial addition of CSPD. The average and maximum signal intensities were plotted for the top dilution for each of the conditions described above as shown in Figures 3 and 5.
- the standards from a Hybritech Tandem-E PSA kit were quantitated using the protocol and reagents supplied by the manufacturer, except for the detection step.
- the assay was performed as follows. An amount of 100 ⁇ L of each standard was aliquoted into 12 X 75 mm glass tubes (6 triplicates of the zero and triplicate ⁇ of the other standards) . An amount of 100 ⁇ L of the alkaline phosphata ⁇ e conjugated mouse anti-PSA was added to each tube followed by one bead with attached capture anti-PSA antibody. The tube ⁇ were then incubated for 2 hours at room temperature on a shaking platform at 170 RPM.
- the beads were washed three times with 2 L of Hybritech wash solution and once with 0.1 M diethanolamine, 1 mM MgCl 2 , pH 10 (substrate buffer). Substrate was then added to each tube.
- the following three substrate compositions (200 ⁇ L per tube) were tested: 0.25 mM CSPD, 1 mg/mL BDMQ in substrate buffer added at time zero; 0.25 mM CSPD, 1 mg/mL BDMQ, 50% AttoPhos" in substrate buffer added at time zero; 50% AttoPhos", 1 mg/mL BDMQ in substrate buffer for 30 minutes followed by the addition of CSPD (final concentration 0.25 mM) .
- the chemiluminescent signal was measured 25 minutes after the addition of CSPD (or CSPD/AttoPhos" mixture) with a Berthold 952T luminometer.
- Figures 6(A) and (B) demonstrate that both the signal and signal/noise ratios are greater with CSPD and AttoPhos" than with CSPD alone. Therefore, increased signal was the result of use of CSPD in connection with AttoPhos".
- alkaline phosphata ⁇ e wa ⁇ added to each sample (f inal concentration, 1.12 X 10 ⁇ n M) and the cuvette wa ⁇ inserted into the fluorimeter (Spex Fluorolog) .
- Emission spectra were obtained with the monochrometer slits set at 10 mm and signal wa ⁇ integrated for 0.5 seconds per nm. Spectra were recorded at 2, 10, 20, 30, 40, 50 and 60 minutes, in most cases.
- Figures 7-21 This set of experiments shows energy transfer from CSPD to AttoPhos" in a buffer, such solution-based assays are used with immunoassays which are performed in buffers.
- Figures 7-21 demonstrate that there is an energy transfer between the dephosphorylated emitter of CSPD and the dephosphorylated AttoPhos".
- Figures 9-17 further show that this energy transfer is greatly improved by the presence of enhancing polymers.
- Figures 7 and 8 demonstrate that an increase in the donor, dephosphorylated CSPD emitter increases the signal via energy transfer, i.e., the Attoemission. In this case, the blue emission (CSPD chemiluminescence) increases.
- FIG. 14 demonstrates that the green signal originates from Atto', because when the concentration of AttoPhos" is low, the energy transfer signal is also very low.
- Figure 12 shows that the relative energy transfer signal when the substrates are added sequentially, i.e., first adding AttoPhos" which becomes dephosphorylated creating the ground state emitter, followed by CSPD addition which upon dephosphorylanon, fragments and, generates the excited state donor which transfers its energy to the accumulated acceptor from the dephosphorylated AttoPhos" .
- Biotinylated DNA was detected by binding streptavidin alkaline phosphatase, and then subsequently incubating with either CSPD 1,2-dioxetane substrate for alkaline phosphatase or mixtures of CSPD and the fluorescent alkaline phosphatase substrate AttoPho ⁇ ".
- biotinylated 35mer wa ⁇ spotted on to Pall Biodyne A nylon membrane, 210 pg in the top spot followed by successive 1:3 dilution ⁇ .
- DNA wa ⁇ detected by performing the Tropix Southern-LightTm procedure up to the substrate incubation step. Each membrane was then individually incubated with a different substrate solution as follows:
- Figure 22 show ⁇ an increa ⁇ ed light signal from the samples of AttoPhos" in combination with CSPD.
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Abstract
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PCT/US1995/001506 WO1996025667A1 (fr) | 1995-02-13 | 1995-02-13 | Dosage par transfert d'energie chimioluminescente |
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EP (1) | EP0809804A4 (fr) |
JP (1) | JPH11500222A (fr) |
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US6660529B2 (en) | 1998-07-28 | 2003-12-09 | Pe Corporation | Heteroaryl substituted benzothiazole dioxetanes |
CA2338883A1 (fr) | 1998-07-28 | 2000-02-10 | Tropix, Inc. | Dioxetanes de benzothiazole |
US7368296B2 (en) * | 2002-01-17 | 2008-05-06 | Applied Biosystems | Solid phases optimized for chemiluminescent detection |
JP4259229B2 (ja) | 2003-08-28 | 2009-04-30 | 東ソー株式会社 | 1,2−ジオキセタンの化学発光方法および化学発光用組成物 |
EP2028250A4 (fr) * | 2006-06-08 | 2010-07-21 | Fujirebio Kk | Activateur de luminescence |
EP2705031B1 (fr) * | 2011-05-03 | 2018-04-11 | Life Technologies Corporation | 1,2-dioxétanes incandescents et luminescents |
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US5004565A (en) * | 1986-07-17 | 1991-04-02 | The Board Of Governors Of Wayne State University | Method and compositions providing enhanced chemiluminescence from 1,2-dioxetanes |
US5112960A (en) * | 1989-07-17 | 1992-05-12 | Bronstein Irena Y | Chemiluminescent 3-(substituted adamant-2'-ylidene) 1,2-dioxetanes |
-
1995
- 1995-02-13 WO PCT/US1995/001506 patent/WO1996025667A1/fr not_active Application Discontinuation
- 1995-02-13 JP JP8524903A patent/JPH11500222A/ja not_active Ceased
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AU704940B2 (en) | 1999-05-06 |
EP0809804A4 (fr) | 1999-03-31 |
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