FLUORESCENT SILANE LAYERS FOR DETECTING EXPLOSIVES

Abstract

Detection reagent for an analyte comprising an NO.sub.x group, wherein the detection reagent comprises an arylamine, and a structural formula of the arylamine is selected from the structural formulae 1, 2 and 3:

##STR00001##

or of the formulae 4 or 5:

##STR00002##

where R.sub.1 and R.sub.7 are selected from CO.sub.2or PhCO.sub.2X with X=4-iodophenyl; 4-bromophenyl or 4-chlorophenyl; 4-vinylphenyl or 4-allylphenyl; or

R.sub.1 and R.sub.7 are selected from CO.sub.2Y or PhCO.sub.2Y with Y=2-methyl-3-pentyn-2-yl or 3-tert-butyl-4,4-dimethyl-1-pentyn-3-yl, or R.sub.7 is selected from CO.sub.2Z, PhCO.sub.2Z, C(O)NZ.sub.2 or PhC(O)NZ.sub.2 with (Z=alkyl, perfluoroalkyl, vinyl, allyl, homoallyl, aryl); where R.sub.2, R.sub.3, R.sub.4, and/or R.sub.5 are independently selected from H, F, an alkyl and an aryl; and where R.sub.6 is selected from an alkyl and an aryl.

Claims

1. Detection reagent for an analyte comprising an NO.sub.x group, wherein the detection reagent comprises an arylamine, and a structural formula of the arylamine is selected from the structural formulae 1, 2 and 3: ##STR00017## or of the formulae 4 and 5: ##STR00018## where R.sub.1 and R.sub.7 are selected from CO.sub.2X and PhCO.sub.2X with X=4-iodophenyl; 4-bromophenyl, 4-chlorophenyl, 4-vinylphenyl or 4-allylphenyl; or R.sub.1 and R.sub.7 are selected from CO.sub.2Y and PhCO.sub.2Y with Y=2-methyl-3-pentyn-2-yl or 3-tert-butyl-4,4-dimethyl-1-pentyn-3-yl; or R.sub.7 is selected from CO.sub.2Z, PhCO.sub.2Z,C(O)NZ.sub.2 and PhC(O)NZ.sub.2 with Z=alkyl, perfluoroalkyl, vinyl, allyl, homoallyl, aryl; where R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are independently selected from: H, F, alkyl, aryl; and R.sub.6 is selected from alkyl or aryl.

2. original) Detection reagent according to claim 1, wherein R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are H.

3. Detection reagent according to claim 1, wherein R.sub.6 is a phenyl group and the arylamine thus comprises a triphenylamine motif.

4. Detection reagent according to claim 3, wherein the triphenylamine motif is joined covalently to a phenyl group in at least one para position, and the remaining para positions are unsubstituted or methylated.

5. Detection reagent according to claim 4, wherein the triphenylamine motif and the phenyl group are joined via a triple bond, via a double bond or via a single bond.

6. Detection reagent according to claim 3, wherein the structural formula of the arylamine is selected from a triphenylamine compound of the structural formulae 6.1 to 6.5 or 4.1: ##STR00019## ##STR00020## where the triphenylamine motif as a donor releases an electron to the NO.sub.x group of the analyte or as a receptor accepts an electron from the NOx group of the analyte, extinguishment of fluorescence of the detection reagent is measurable when the electron is released to the NOx group of the analyte, and/or regeneration or recovery of fluorescence is measurable when the electron is accepted, such that the analyte is optically determinable qualitatively and/or quantitatively.

7. Detection reagent according to claim 6, wherein the analyte comprising the NO.sub.x group is selected from: TNT, DNT, tetryl, PETN, NG, EGDN, DNDMB, ammonium nitrate, RDX and HMX.

8. Detection reagent according to claim 1, wherein the analyte comprising the NOx group is present in a sample comprising an organic solution, an aqueous solution, a mixed organic/aqueous solution, an air sample and/or a wiped sample.

9. Detection reagent according to claim 1, wherein R.sub.1 and R.sub.7 in the detection reagent are selected from CO.sub.2X and PhCO.sub.2X with X=4-iodophenyl; 4-bromophenyl; 4-chlorophenyl; 4-vinylphenyl or 4-allylphenyl and the detection reagent, after a reaction with a reactive organosilane by means of Heck or metathesis reaction, is covalently bonded to a substrate and/or forms a monomolecular layer over at least parts of the substrate.

10. Detection reagent according to claim 1, wherein R.sub.1 and R.sub.7 in the detection reagent are selected from CO.sub.2Y and PhCO.sub.2Y with Y=2-methyl-3-pentyn-2-yl or 3-tert-butyl-4,4-dimethyl-1-pentyn-3-yl and the detection reagent has been adsorbed on at least parts of the substrate, where there is no polymer between substrate and adsorbed detection reagent.

11. Detection reagent according to claim 9, wherein the substrate comprises a silicatic material or is a silicate glass.

12. Detection reagent according to claim 9, wherein the reactive organosilane is selected from: a trimethoxysilane and/or a triethoxysilane and/or a dimethoxysilane and/or a diethoxysilane.

13. Detection reagent according to claim 12, wherein the trimethoxysilane is selected from: allyltrimethoxysilane; butenyltrimethoxysilane; vinyltrimethoxysilane or (styrylethyl)trimethoxysilane; (stilbenylethyl)trimethoxysilane; 3-(trimethoxysilyl)propyl methacrylate; trimethoxy(4-vinylphenyl)silane; (trimethoxysilyl)benzene; trimethoxy(2-phenylethyl)silane; octyltrimethoxysilane; propyltrimethoxysilane; (trimethoxysilyl)stilbene, or the triethoxysilane is selected from triethoxyvinylsilane; (3-chloropropyl)-triethoxysilane or the dimethoxysilane is selected from dimethoxydiphenylsilane, or the diethoxysilane is selected from diallyldiethoxysilane; methylvinyldiethoxysilane or allylmethyldiethoxysilane.

14. Method of detecting an analyte having an NOx group, comprising: providing an analyte-sensitive layer on a silicatic substrate, comprising: a detection reagent according to claim 1, bonded covalently to the silicatic substrate via at least one SiC bond; or a detection reagent according to claim 1, bound adsorptively to the silicatic substrate, where the silicatic substrate does not comprise any polymer film, and the analyte-sensitive layer is provided by contacting a silicatic substrate with a detection reagent according to claim 1, wherein the contacting for the detection reagent with R.sub.1 and R.sub.7 selected from CO.sub.2X or PhCO.sub.2X is effected under the conditions of a Heck reaction or metathesis reaction and the contacting for the detection reagent wherein R.sub.1 and R.sub.7 are selected from CO.sub.2Y or PhCO.sub.2Y comprises adsorbing the detection reagent from a solution of the detection reagent on the silicatic substrate; interaction of the analyte comprising the NOx group with the analyte-sensitive layer; measuring a fluorescence property of at least one section of the analyte-sensitive layer.

15. Method according to claim 14, further comprising: heating and/or evaporating a defined amount of sample that potentially contains the analyte comprising the NO.sub.x group; guiding a gas or gas mixture comprising the evaporated or heated defined amount of sample to the analyte-sensitive layer, such that the analyte comprising the NO.sub.x group can interact with the detection reagent; ascertaining a composition and/or a concentration of the analyte comprising the NO.sub.x group using measurement data from a comparative measurement.

16. Method according to claim 14, further comprising: regenerating the analyte-sensitive layer by contact with an NOx-free fluid, by baking it and/or by passing a flow of steam over it.

17. Method according to claim 14, wherein the fluorescence property is selected from: a fluorescence quantum yield, a fluorescence lifetime, a decrease in fluorescence intensity or a quenching of fluorescence or an increase in fluorescence after a preceding quenching of fluorescence.

18. Method according to claim 14, wherein the measuring of the fluorescence property comprises direct detection of an electrical signal from at least one detector or forming of a quotient from electrical signals that are detected at different excitation wavelengths by at least one detector.

19. Method according to claim 14, wherein the fluorescence property is measured with a portable, preferably handheld, measurement device, and the measurement device comprises a scanning device set up to measure the fluorescence property at at least one fixed wavelength.

20. Method according to claim 14, wherein the detection reagent is covalently bonded to the silicatic substrate at least via a CSiC bond and a surface concentration of the detection reagent of the analyte-sensitive layer is selected from 50-350 mol/cm.sup.2; or the detection reagent described in one of claims 1 to 13 has been adsorbed on the silicatic substrate, where the surface concentration thereof on the substrate is between 100-750 mol/cm.sup.2.

21. Method according to claim 14, wherein the analyte is an explosive.

22. Production method for an analyte-sensitive layer on a silicatic substrate, comprising: providing the silicatic substrate; contacting the detection reagent according to claim 1 with the silicatic substrate.

23. Production method according to claim 22, wherein the providing of the silicatic substrate comprises: activating the silicatic substrate, comprising treating the silicatic substrate with a mixture comprising hydrogen peroxide and sulfuric acid; and silanizing the activated silicatic substrate with an organosilane.

24. Production method according to claim 22, wherein the contacting of the detection reagent with the silicatic substrate for the detection reagent with R.sub.1 and R.sub.7=CO.sub.2X or PhCO.sub.2X is preceded by silanizing of the detection reagent with an organosilane bearing a double bond, wherein the organosilane is present in an equimolar amount or in a molar excess, such that a silanization product or a silanization reaction mixture is contacted with the silicatic material.

25. Production method according to claim 23, wherein the organosilane is selected from: a trimethoxysilane and/or a triethoxysilane and/or a dimethoxysilane and/or a diethoxysilane.

26. Production method according to claim 25, wherein the trimethoxysilane is selected from: allyltrimethoxysilane; butenyltrimethoxysilane; vinyltrimethoxysilane; (trimethoxysilyl)stilbene or (styrylethyl)trimethoxysilane; (stilbenylethyl) trimethoxysilane; 3-(trimethoxysilyl)propyl methacrylate; trimethoxy(4-vinylphenyl)silane; (trimethoxysilyl)benzene; trimethoxy(2-phenylethyl)silane; octyltrimethoxysilane; propyltrimethoxysilane, or the triethoxysilane is selected from triethoxyvinylsilane, or (3-chloropropyl)triethoxysilane, or the dimethoxysilane is selected from dimethoxydiphenylsilane, or the diethoxysilane is selected from diallyldiethoxysilane, methylvinyldiethoxysilane or allylmethyldiethoxysilane.

27. Production method according to claim 22, wherein the silicatic substrate provided has a flat surface, for example is a pane, and the detection reagent is contacted with the silicatic substrate at least in parts on one side and/or in parts on both sides.

28. Production method according to claim 22, wherein the silicatic substrate has a curved surface at least in parts and encloses a cavity having at least one entry opening for an analyte feed and at least one exit opening for the analyte removal.

29. Production method according to claim 22, wherein the contacting is effected by dipping or using a spin-coater, a spray-coater, a piezoelectric metering system, a printer, a nanoplotter, an inkjet printer, or a die.

30. Production method according to claim 22, wherein the silicatic substrate is selected from a silicate glass, a borosilicate glass, a quartz glass, a silicon wafer, a polycrystalline silicon, a silicate nanoparticle and/or a silicon-containing ceramic.

31. Analyte-sensitive layer for an analyte comprising an NOx group, comprising: a silicatic substrate, a detection reagent arranged directly, without involvement of a polymer layer, on the silicatic substrate, wherein the detection reagent is selected from a substance of one of the formulae 1 to 5: ##STR00021## ##STR00022## where R.sub.1 and R.sub.7 are selected from CO.sub.2X or PhCO.sub.2 with X=4-iodophenyl; 4-bromophenyl, 4-chlorophenyl, 4-vinylphenyl or 4-allylphenyl; or R.sub.1 and R.sub.7 are selected from CO.sub.2Y or PhCO.sub.2Y with Y=2-methyl-3-pentyn-2-yl or 3-tert-butyl-4,4-dimethyl-1-pentyn-3-yl; or R.sub.7 is selected from CO.sub.2Z, PhCO.sub.2Z, C(O)NZ.sub.2 or PhC(O)NZ.sub.2 with Y=alkyl, perfluoroalkyl, vinyl, allyl, homoallyl, aryl; where R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are independently selected from: H, F, alkyl, aryl; and R.sub.6 is selected from alkyl or aryl, wherein the detection reagent is covalently bonded to the silicatic substrate at least via a CSiC bond and a surface concentration of the detection reagent on the analyte-specific layer is selected from 50-350 mol/cm.sup.2; or the detection reagent has been adsorbed on the silicatic substrate, where its surface concentration is between 100-750 mol/cm.sup.2, and wherein a fluorescence intensity of the detection reagent in the presence of the analyte changes with respect to a fluorescence intensity of the detection reagent in the absence of the analyte as a function of a concentration of the analyte.

32. Analyte-sensitive layer according to claim 31, wherein the analyte comprising the NOx group is selected from TNT, DNT, tetryl, PETN, NG, EGDN, NH.sub.4NO.sub.3, RDX and HMX.

33. Use of a detection reagent according to claim 1 for monitoring a threshold of an explosive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0137] The appended figures illustrate embodiments and, together with the description, serve to elucidate the principles of the invention. The elements of the drawings are relative to one another and not necessarily to scale. Identical reference numerals denote correspondingly similar parts.

[0138] FIG. 1 shows a synthesis scheme for synthesis of the fluorescence probes;

[0139] FIG. 2 shows reaction of a detection reagent of formula 6.1 by means of a Heck reaction;

[0140] FIG. 3 shows a fluorescent signal progression of detection reagent of structure 6.5;

[0141] FIGS. 4, 4A and 4B show fluorescence signal progression of dye on glass;

[0142] FIGS. 5, 5A and 5B show fluorescence signal progression of dye on a coated glass substrate;

[0143] FIGS. 6, and 6A-6D show fluorescence signal progression of dye under different conditions;

[0144] FIG. 7 shows fluorescence spectra of dye on differently coated glass substrates; and

[0145] FIG. 8 shows different examples of adsorptive binding of different fluorescent probes to the glass substrates.

DETAILED DESCRIPTION

[0146] FIG. 1 shows a synthesis scheme for synthesis of the fluorescence probes 6 and 7.

[0147] FIG. 2 shows, by way of example, the reaction of the detection reagent of formula 6.1 with trimethoxy(4-vinylphenyl)silane by means of a Heck reaction. The organosilanes can also be used here in excess. The silane dye formed or the reaction mixture can be reacted directly with the surface of the substrate.

[0148] FIG. 3 shows the fluorescence signal progression of the detection reagent of structure 6.5 adsorbed directly on glass (with no polymer cushion or organosilane layer) after sustained operation for 30 min. The measurement was conducted in a portable measuring instrument at a thermal head temperature of 155 C., with minimal light intensity of the excitation source and in an air stream.

[0149] FIG. 4; FIG. 4A shows the fluorescence signal progression of the dye 6.5 on glass; after sustained operation for 30 min, two TNT wiped samples each with 1.9 ng of TNT were detected. FIG. 4B shows a fluorescence signal progression of the dye 6.5 on glass; after sustained operation for 30 min, 4 L of water were evaporated in the thermal head (155 C.) and gave a corresponding signal. All measurements were conducted at a thermal head temperature of 155 C., with minimal light intensity of the excitation source and in an air stream; red=detection limit for 10% fluorescence quenching; blue=detection limit for 15% fluorescence quenching.

[0150] FIG. 5; FIG. 5A shows the fluorescence signal progression of the dye 6.5 on a glass substrate coated with (styrylethyl)trimethoxysilane after sustained operation for 30 min.

[0151] FIG. 5B shows the fluorescence signal progression of the dye 6.5 on a glass substrate coated with dimethoxydiphenylsilane after sustained operation for 30 min. The measurements were conducted in a portable measuring instrument at a thermal head temperature of 155 C., with minimal light intensity of the excitation source and in an air stream.

[0152] FIG. 6; FIG. 6A shows the fluorescence signal profile of the dye 6.5 on a glass substrate coated with (styrylethyl)trimethoxysilane; after sustained operation for 30 min, three TNT wiped samples each with 1.9 ng of TNT were detected. FIG. 6B shows the fluorescence signal progression of the dye 6.5 on a glass substrate coated with (styrylethyl)trimethoxy-silane; after sustained operation for 30 min, 2 4 L of water were evaporated in the thermal head (155 C.) and gave the corresponding signals. FIG. 6C shows the fluorescence signal progression of the dye 6.5 on a glass substrate coated with dimethoxydiphenylsilane; after sustained operation for 30 min, three TNT wiped samples each with 1.9 ng of TNT were detected. FIG. 6D shows the fluorescence signal progression of the dye 6.5 on a glass substrate coated with dimethoxydiphenylsilane; after sustained operation for 30 min, 2 4 L of water were evaporated in the thermal head (155 C.) and gave the corresponding signals. The measurements were effected at a thermal head temperature of 155 C., with minimal light intensity of the excitation source and in an air stream; red=detection limit for 10% fluorescence quenching; blue=detection limit for 15% fluorescence quenching.

[0153] FIG. 7 shows fluorescence spectra of the dye 6.5 on differently coated glass substrates. The numbers in the legend represent: [0154] 1=activated glass; [0155] 2=3-(trimethoxysilyl)propyl methacrylate; [0156] 3=trimethoxy(4-vinylphenyl)silane; [0157] 4=dimethoxydiphenylsilane; [0158] 5=trimethoxy(2-phenylethyl)silane; [0159] 6=(styrylethyl)trimethoxysilane; [0160] 7=octyltrimethoxysilane; [0161] 8=propyltrimethoxysilane; [0162] 9=(3-chloropropyl)trimethoxysilane; [0163] 10=baseline;
Measurement Parameters=exc. 370 nm; slit 1.5 nm; em. 380-600 nm; slit 5 nm

[0164] FIG. 8 shows, by way of example, the adsorptive binding of the fluorescence probes 1-5 to the glass substrates (with or without organosilane layer).

Detailed Description of the Test Method

[0165] A first variant of the detection method proposed is based on the providing of a detection reagent in adsorbed form on a solid phase. The substrate has been coated with a fluorescent molecular probe that serves, under the measurement conditions, as a specific detection reagent for NO.sub.x explosives and markers of practical relevance (for example for TNT and DMDNB). The fluorescence probe comprises a triphenylamine core and an electron-withdrawing phenyl unit joined covalently to the core in the para position via a triple bond. A fluorescence probe in this connection is understood to mean a molecule that indicates the presence of an explosive via specific fluorescence properties, i.e. in the present context a triphenylamine derivative of the above-specified structures.

[0166] In this connection, a receptor unit is understood to mean a motif that interacts specifically with the NO.sub.x explosive to be detected, comprising a phenylamino derivative that can interact with the electron-deficient NO.sub.x explosive through through its high electron density. The receptor unit comprising the phenylamino group is selected such that, after optical excitation, it favors an electron transfer to the acceptor and can stabilize the radical cation formed. The two unsubstituted phenyl radicals of the phenylamino group, in steric terms, permit a rapid interaction with the explosive and at the same time increase the fluorescence quantum yield of the molecular probe.

[0167] The receptor unit of the molecular probe is also adapted such that it firstly releases an electron to the explosive as a donor and secondly accepts it again depending on the volatility of the explosive or its residence time on the sensor surface. Thus, the binding of the explosive to the receptor unit that has taken place is detected with high sensitivity with reference to a change in characteristics with respect to fluorescence optics, especially fluorescence spectroscopy, of the fluorescence probe, with typically no significant change in the position of the absorption maximum of the fluorescence probe present in bound form in said section for radiative excitation. This facilitates the readout of the measurements with a typically inexpensive and robust portable reading device (handheld device) that works at a fixed excitation wavelength (for example an LED).

[0168] Preferably, an amount of the NO.sub.x compound bound by the probe per unit time (at a given temperature) corresponds to a defined concentration of the explosive in air or as a water sample or wiped sample with an initially as yet unknown concentration of the explosive in a defined mass of sample with an initially as yet unknown content of the explosive. Naturally, the temperature has a certain effect on the establishment of equilibrium at the molecular level. By means of a suitable calibration, it is possible to match any disruptive effects, such as the temperature-dependent regeneration of the sensor layers, to the measurement conditions. Thus, the fluorescence probes are usable without difficulty for the proposed detection of explosives within a temperature range of 0-130 C.

[0169] Accordingly, a detection method for quantitative and qualitative detection of these explosives in the air, as wiped samples from surfaces and in water samples is proposed. It is a particular feature of the detection method that it is performable in a problem-free manner even by users with no specific training and it is possible to dispense with costly laboratory-based measurement technology.

[0170] For the application of the probes to the surface of the substrate, it is possible to utilize various methods. For example, the corresponding amounts of the dissolved substances can be applied to the substrate in a suitable solvent mixture with a spin-coater, spray-coater, piezoelectric dosage system, a nanoplotter or an adapted inkjet printer. Commercial single-droplet dosage systems likewise give reproducible results. Analogously, the dyes can also be applied by a suitable die techniques or contact printing methods.

[0171] In practical embodiments, cover slips typically used in microscopy are used as inert substrate. For example, it is possible to use commercial round cover slips having a diameter of 3-20 mm. The surface of the substrate is preferably planar. However, the substrate may have a curved surface at least in sections and may include a cavity having at least one inlet opening for an analyte feed and at least one exit opening for the analyte removal. Advantageously, an analyte-sensitive layer is formed on the inner surface, or a cavity section. It is likewise possible to arrange sections of different analyte-sensitive layers adjacent to one another, such that the substrate is divided into multiple zones. In a further embodiment, an otherwise homogeneous analyte-sensitive layer on the substrate (planar or interior cavity surface) can be divided into multiple zones by applying different detection reagents adjacent to one another on the substrate. For instance, sensitive layers having different properties are formed on a one-piece substrate. The arrangement thereof can advantageously be chosen such that the medium to be analyzed (analytes, or air, which only possibly contains the analyte . . . ), by virtue of geometric arrangement, flows over or through these zones in a particular sequence and/or at a particular flow rate and/or at a particular pressure. Advantageously, it is thus possible to vary the residence time of the analyte within wide limits in order to assure reliable detection.

[0172] In order to examine the selectivity of the layers for TNT, DNT, tetryl, PETN, NG, EGDN, RDX, HMX, NH.sub.4NO.sub.3 and DMDNB, a mobile measuring device (referred to here as handheld device) was used to conduct measurements of the solutions of the explosives and of some structurally related musk compounds. In the study of cross-sensitivity for musk ambrette, which is not among the explosives or markers, but shows interactions comparable with TNT with the analyte-sensitive layers, much lower sensitivity and distinguishable signal structures were observed.

[0173] It is known that molecular probes on their own cannot distinguish between the explosives sought and substances that likewise have fluorescence-quenching properties. However, the probability of finding such substances in the environment is typically very low. Exceptions are the numerous musk compounds which can occur in groundwater as constituents of various perfumes, cosmetic products and plant protection products. It is of course possible to conduct measurements on a sample with at least two analyte-sensitive layers in order to be able to come to a more exact conclusion as to the composition of the sample.

[0174] To verify the explosives in the air or as a wiped sample, the analyte-sensitive layer is contacted with a heated air stream in the measuring instrument, keeping the (heated) air inlet on the sample or on a wiped sample. For this purpose, for example, a suitable measurement head comprising the air inlet can be heated to a temperature >150 C. On attainment of the detection limit within a particular period under known environmental influences (air humidity and temperature), the presence of an NO.sub.x compound is indicated as quenching of fluorescence of the analyte-sensitive layer.

[0175] The triarylamine-based fluorescence indicators (detection reagents) described, with their high quantum yield, broadband excitability, high photostability, air stability and long-term stability and marked insensitivity to environmental influences (such as changes in air humidity, the presence of organic and/or aqueous solvent vapors and oxygen), are suitable for detection of explosives based on No.sub.x units, for detection of thermal breakdown products of explosives such as nitrogen oxides, starting materials for production of explosives such as nitric acid and for detection of markers such as DMDNB and DNT on the corresponding carrier materials including non-fluorescent, apolar polymer films.

[0176] The triphenylamine motif of the detection reagents 6.1 to 6.5 is used for the detection of nitro compounds. After calibration, the quenching of the fluorescence signal of the analyte-sensitive layer under the influence of the explosive bound to the receptor unit serves for quantitative determination thereof in air, in aqueous and organic solution and on wiped samples. It is likewise possible to use the regeneration of the fluorescence signal of the analyte-sensitive layer that occurs under the action of water vapor, for example, to identify a previously adsorbed fluorescence-quenching analyte on its own or as a supplementary method if an unknown NOx-containing analyte is to be determined.

[0177] In a second variant of the detection method proposed here, the above-described detection reagent modified with an organosilane is covalently bonded directly to the glass substrate. In this second variant too, the glass substrate does not have a polymer film. In addition, the glass substrate may have been hydrophobized with an organosilane, for example with (styrylethyl)trimethoxysilane. The silane forms a monomolecular carrier layer on the glass substrate.

[0178] The fluorescence probe comprises the triphenylamine core already described and the electron-withdrawing phenyl unit covalently bonded to the core in the para position via a triple bond, having the properties already described above for the first variant.

[0179] The embodiments described can be combined with one another as desired. Even though specific embodiments have been presented and described herein, it is within the scope of the present invention to suitably modify the embodiments detailed without departing from the scope of protection of the present invention. The claims that follow constitute a first, non-binding attempt to define the invention in general terms.

REFERENCES

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