Specific fluorescent probe for fingerprint development

Abstract

The invention relates to the technical field of fluorescent probes, in particular to a specific fluorescent probe for fingerprint development. The specific fluorescent probe for fingerprint development is prepared from a triphenylamine derivative and piperazine through microwave hydrothermal synthesis; the weight ratio of the triphenylamine derivative to the piperazine is 1.5: (2-3). The specific fluorescent probe for fingerprint development has an aggregation-induced emission effect, can specifically develop potential fingerprints, has excellent salt resistance, effectively improves the stability and application flexibility of fingerprint development, reduces background interference, and enhances the precision and accuracy of fingerprint recognition.

Description

Technical Field

[0001] The invention relates to the technical field of fluorescent probes, and in particular to a specific fluorescent probe for fingerprint visualization. Background Art

[0002] Fluorescent probes refer to chemicals or materials that can detect specific target substances through light emission signals. The basic principle is that when the probe interacts with the target molecule, the fluorescence properties of the probe change, thereby achieving detection. This change is usually manifested as an increase or decrease in fluorescence intensity, a shift in fluorescence wavelength, etc. The design of fluorescent probes focuses on selectivity, sensitivity, and environmental stability. Especially in complex sample matrices, the specific recognition ability of fluorescent probes is crucial.

[0003] Fluorescent probe method is one of the most commonly used methods for fingerprint visualization. As a fluorescent probe, carbon quantum dots have received extensive attention in fingerprint visualization applications. Due to the characteristics of low cost, simple synthesis, good biocompatibility and rich functional groups, carbon quantum dots are used for latent fingerprint visualization on various objects through spray and powder methods to obtain blue fingerprint images. The surface functional groups of carbon quantum dots can be covalently coupled or electrostatically adsorbed with fingerprint residues to achieve the development of carbon quantum dots on fingerprints to obtain the desired biological characteristics. However, most of the existing carbon quantum dots are fluorescent in solution, but due to resonance energy transfer or direct π-π interaction, they show aggregation-induced fluorescence quenching in the solid state, which limits the application of carbon quantum dot-type fluorescent probes in the field of latent fingerprint detection and imaging. Summary of the invention

[0004] In view of this, the purpose of the present invention is to propose a specific fluorescent probe for fingerprint visualization, so as to overcome the fluorescence quenching of traditional carbon quantum dot fluorescent probes under aggregation, and provide a fluorescent probe that can specifically identify latent fingerprints.

[0005] Based on the above purpose, the present invention provides a specific fluorescent probe for fingerprint visualization, wherein the specific fluorescent probe for fingerprint visualization is synthesized from triphenylamine derivatives and piperazine by microwave hydrothermal method;

[0006] Furthermore, the structural formula of the triphenylamine derivative is as follows:

[0007]

[0008] Furthermore, the weight ratio of the triphenylamine derivative to piperazine is 1.5:2-3.

[0009] Preferably, the preparation method of the triphenylamine derivative is as follows:

[0010] (1) adding tri(4-iodophenyl)amine, methyl acrylate, palladium acetate, 1,3-bis(diphenylphosphine)propane and triethylamine to N,N-dimethylformamide, heating to 115-125° C. under a nitrogen atmosphere, stirring for 20-30 hours, and purifying after the reaction to obtain a triphenylamine derivative intermediate;

[0011] (2) Add the triphenylamine derivative intermediate and potassium hydroxide to a mixed solvent of tetrahydrofuran and deionized water, raise the temperature to 90-95° C., stir and react for 10-14 hours, and purify after the reaction to obtain a triphenylamine derivative.

[0012] Preferably, in the step (1), the usage ratio of tri(4-iodophenyl)amine, methyl acrylate, palladium acetate, 1,3-bis(diphenylphosphine), triethylamine and N,N-dimethylformamide is 2.4 g:1.54 g:2.45 mg:103.1 mg:1.8 g:10 g.

[0013] Preferably, in the step (2), the usage ratio of the triphenylamine derivative intermediate, potassium hydroxide, tetrahydrofuran and deionized water is 2.46 g:1.12 g:30 g:5 g.

[0014] Preferably, the microwave power of the microwave hydrothermal synthesis is 700-800 W, and the time is 5-10 min.

[0015] Preferably, after the microwave hydrothermal synthesis, the product is filtered with a filter having a pore size of 0.22-0.24 μm, and then dialyzed with deionized water in a 500 Da dialysis bag for purification.

[0016] Furthermore, the specific fluorescent probe for fingerprint visualization and deionized water are prepared into a developer at a concentration of 3 mg / ml.

[0017] Furthermore, the developer is used for fingerprint visualization.

[0018] Beneficial effects of the present invention:

[0019] The present invention synthesizes carbon quantum dots with rich functional groups on the surface through microwave hydrothermal reaction of triphenylamine derivatives and piperazine, which can specifically identify latent fingerprints. The rich functional groups on the surface of carbon quantum dots give them aggregation-induced luminescence effect and water solubility. The water-soluble fluorescent probe can be used directly in aqueous solution, which is easy to operate and handle. Compared with organic solvent systems, water-based systems are safer and easier to handle during the detection process.

[0020] The invention introduces carboxylic acid groups on the surface of triphenylamine, thereby affecting the electron density distribution of carbon quantum dots, optimizing the energy difference between the excited state and the ground state, and effectively improving the quantum yield and fluorescence lifetime of the fluorescent probe.

[0021] The present invention introduces piperazine in the synthesis process of carbon quantum dots. Piperazine helps to form a stable conjugated system and restrict molecular motion, thereby improving the quantum yield and fluorescence lifetime, and synergistically improving the salt resistance of the fluorescent probe with a carboxyl-containing triphenylamine derivative.

[0022] The fluorescent probe provided by the present invention improves the sensitivity, clarity and reliability in fingerprint visualization through its excellent water-solubility characteristics and aggregation-induced luminescence effect, making it an ideal and efficient fingerprint detection tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art description;

[0024] Figure 1 A schematic diagram of the synthesis process of the specific fluorescent probe for fingerprint visualization of the present invention;

[0025] Figure 2 The fluorescence spectra of the specific fluorescent probe for fingerprint visualization provided in Example 1 of the present invention at different excitation wavelengths;

[0026] Figure 3 These are latent fingerprint visualization images of the fluorescent probes provided in Example 1(a), Comparative Example 1(b) and Comparative Example 2(c) of the present invention. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0028] Embodiment 1:

[0029] (1) 2.4 g of tri(4-iodophenyl)amine, 1.54 g of methyl acrylate, 2.45 mg of palladium acetate, 103.1 mg of 1,3-bis(diphenylphosphine)propane and 1.8 g of triethylamine were added to 10 g of N,N-dimethylformamide, heated to 120° C. under a nitrogen atmosphere, and stirred for reaction for 24 h. After the reaction, the mixture was mixed with deionized water, extracted with dichloromethane, evaporated under reduced pressure, and separated by column chromatography (stationary phase: 200 mesh silica gel, fluidity: a mixture of petroleum ether and ethyl acetate in a volume ratio of 50:1) to obtain a triphenylamine derivative intermediate;

[0030] (2) Add 2.46 g of the triphenylamine derivative intermediate and 1.12 g of potassium hydroxide to a mixed solvent of 30 g of tetrahydrofuran and 5 g of deionized water, raise the temperature to 95° C., and stir to react for 12 h. After the reaction is completed, perform vacuum rotary evaporation, adjust the pH to 1.4 with hydrochloric acid, filter, and dry to obtain a triphenylamine derivative;

[0031] (3) 1.5 g of triphenylamine derivative and 2.5 g of piperazine were added to 50 g of deionized water, dissolved by ultrasonication, and then treated under 800 W microwave for 10 min. After cooling to room temperature, the mixture was filtered through a filter with a pore size of 0.24 μm, and then dialyzed and purified with deionized water in a 500 Da dialysis bag, and vacuum dried to obtain a specific fluorescent probe for fingerprint visualization.

[0032] Embodiment 2:

[0033] (1) 2.4 g of tri(4-iodophenyl)amine, 1.54 g of methyl acrylate, 2.45 mg of palladium acetate, 103.1 mg of 1,3-bis(diphenylphosphine)propane and 1.8 g of triethylamine were added to 10 g of N,N-dimethylformamide, heated to 115° C. under a nitrogen atmosphere, and stirred for reaction for 30 h. After the reaction, the mixture was mixed with deionized water, extracted with dichloromethane, evaporated under reduced pressure, and separated by column chromatography (stationary phase: 200 mesh silica gel, fluidity: a mixture of petroleum ether and ethyl acetate in a volume ratio of 50:1) to obtain a triphenylamine derivative intermediate;

[0034] (2) Add 2.46 g of the triphenylamine derivative intermediate and 1.12 g of potassium hydroxide to a mixed solvent of 30 g of tetrahydrofuran and 5 g of deionized water, raise the temperature to 90° C., and stir to react for 14 h. After the reaction is completed, perform vacuum rotary evaporation, adjust the pH to 1.2 with hydrochloric acid, filter, and dry to obtain a triphenylamine derivative;

[0035] (3) 1.5 g of triphenylamine derivative and 2 g of piperazine were added to 50 g of deionized water, dissolved by ultrasonication, and then treated under 800 W microwave for 5 min. After cooling to room temperature, the mixture was filtered through a filter with a pore size of 0.22 μm, and then dialyzed and purified with deionized water in a 500 Da dialysis bag, and vacuum dried to obtain a specific fluorescent probe for fingerprint visualization.

[0036] Example 3

[0037] (1) 2.4 g of tri(4-iodophenyl)amine, 1.54 g of methyl acrylate, 2.45 mg of palladium acetate, 103.1 mg of 1,3-bis(diphenylphosphine)propane and 1.8 g of triethylamine were added to 10 g of N,N-dimethylformamide, heated to 125° C. under a nitrogen atmosphere, and stirred for reaction for 20 h. After the reaction, the mixture was mixed with deionized water, extracted with dichloromethane, evaporated under reduced pressure, and separated by column chromatography (stationary phase: 200 mesh silica gel, fluidity: a mixture of petroleum ether and ethyl acetate in a volume ratio of 50:1) to obtain a triphenylamine derivative intermediate;

[0038] (2) Add 2.46 g of the triphenylamine derivative intermediate and 1.12 g of potassium hydroxide to a mixed solvent of 30 g of tetrahydrofuran and 5 g of deionized water, raise the temperature to 95° C., and stir to react for 10 h. After the reaction is completed, perform vacuum rotary evaporation, adjust the pH to 1.6 with hydrochloric acid, filter, and dry to obtain a triphenylamine derivative;

[0039] (3) 1.5 g of triphenylamine derivative and 3 g of piperazine were added to 50 g of deionized water, dissolved by ultrasonication, and then treated under 800 W microwave for 10 min. After cooling to room temperature, the mixture was filtered through a filter with a pore size of 0.24 μm, and then dialyzed and purified with deionized water in a 500 Da dialysis bag, and vacuum dried to obtain a specific fluorescent probe for fingerprint visualization.

[0040] Comparative Example 1:

[0041] The difference between Comparative Example 1 and Example 1 is that the triphenylamine derivative in step (3) is replaced by triphenylamine;

[0042] The specific preparation steps are as follows:

[0043] 1.5 g of triphenylamine and 2.5 g of piperazine were added to 50 g of deionized water, ultrasonically dispersed, and then treated under 800 W microwave for 10 min. After cooling to room temperature, the mixture was filtered through a filter with a pore size of 0.24 μm, and then dialyzed and purified with deionized water in a 500 Da dialysis bag, and vacuum dried to obtain a fluorescent probe.

[0044] Comparative Example 2:

[0045] The difference between Comparative Example 2 and Example 1 is that the piperazine in step (3) is replaced by cyclohexane;

[0046] The specific preparation steps are as follows:

[0047] (1) 2.4 g of tri(4-iodophenyl)amine, 1.54 g of methyl acrylate, 2.45 mg of palladium acetate, 103.1 mg of 1,3-bis(diphenylphosphine)propane and 1.8 g of triethylamine were added to 10 g of N,N-dimethylformamide, heated to 120° C. under a nitrogen atmosphere, and stirred for reaction for 24 h. After the reaction, the mixture was mixed with deionized water, extracted with dichloromethane, evaporated under reduced pressure, and separated by column chromatography (stationary phase: 200 mesh silica gel, fluidity: a mixture of petroleum ether and ethyl acetate in a volume ratio of 50:1) to obtain a triphenylamine derivative intermediate;

[0048] (2) Add 2.46 g of the triphenylamine derivative intermediate and 1.12 g of potassium hydroxide to a mixed solvent of 30 g of tetrahydrofuran and 5 g of deionized water, raise the temperature to 95° C., and stir to react for 12 h. After the reaction is completed, perform vacuum rotary evaporation, adjust the pH to 1.4 with hydrochloric acid, filter, and dry to obtain a triphenylamine derivative;

[0049] (3) 1.5 g of triphenylamine derivative and 2.5 g of cyclohexane were added to 50 g of deionized water, ultrasonically dispersed, and then treated under 800 W microwave for 10 min. After cooling to room temperature, the mixture was filtered through a filter with a pore size of 0.24 μm, and then dialyzed and purified with deionized water in a 500 Da dialysis bag, and vacuum dried to obtain a fluorescent probe.

[0050] Comparative Example 3:

[0051] The difference between Comparative Example 3 and Example 1 is that the piperazine in step (3) is replaced by 1,5-pentanediamine;

[0052] The specific preparation steps are as follows:

[0053] (1) 2.4 g of tri(4-iodophenyl)amine, 1.54 g of methyl acrylate, 2.45 mg of palladium acetate, 103.1 mg of 1,3-bis(diphenylphosphine)propane and 1.8 g of triethylamine were added to 10 g of N,N-dimethylformamide, heated to 120° C. under a nitrogen atmosphere, and stirred for reaction for 24 h. After the reaction, the mixture was mixed with deionized water, extracted with dichloromethane, evaporated under reduced pressure, and separated by column chromatography (stationary phase: 200 mesh silica gel, fluidity: a mixture of petroleum ether and ethyl acetate in a volume ratio of 50:1) to obtain a triphenylamine derivative intermediate;

[0054] (2) Add 2.46 g of the triphenylamine derivative intermediate and 1.12 g of potassium hydroxide to a mixed solvent of 30 g of tetrahydrofuran and 5 g of deionized water, raise the temperature to 95° C., and stir to react for 12 h. After the reaction is completed, perform vacuum rotary evaporation, adjust the pH to 1.4 with hydrochloric acid, filter, and dry to obtain a triphenylamine derivative;

[0055] (3) 1.5 g of triphenylamine derivative and 2.5 g of 1,5-pentanediamine were added to 50 g of deionized water, ultrasonically dispersed, and then treated under 800 W microwave for 10 min. After cooling to room temperature, the mixture was filtered through a filter with a pore size of 0.24 μm, and then dialyzed and purified with deionized water in a 500 Da dialysis bag, and vacuum dried to obtain a fluorescent probe.

[0056] Performance Test:

[0057] Fluorescence spectrum: The fluorescence spectrum of the specific fluorescent probe for fingerprint visualization prepared in Example 1 in a mixed solution of deionized water and tetrahydrofuran (3 mg / ml) with a volume ratio of 100:1 was measured using a Hitachi FL-7000 fluorescence spectrometer at 360 nm, 400 nm, 440 nm and 480 nm as excitation wavelengths, respectively. The results are shown in FIG. Figure 1 shown.

[0058] Fluorescence quantum yield test: quinine sulfate standard substance is used as a reference for determination, quinine sulfate solid is dissolved with 0.1M sulfuric acid, the absorption value A of the solution at 360nm is determined with a UV-visible spectrophotometer, and then the fluorescence peak integrated area I of the quinine sulfate solution under the absorption value is determined with 360nm as the excitation wavelength on the fluorescence spectrophotometer. Repeat the above steps to obtain 4 groups of absorption values ​​and corresponding fluorescence integrated areas F, and draw the quantum yield standard curve of quinine sulfate with F as the ordinate and absorbance A as the abscissa. According to the above method, the quantum yield of the fluorescent probe prepared in the embodiment and comparative example is obtained by replacing the quinoline sulfate solution with a mixed solution (3mg / ml) of deionized water and tetrahydrofuran in a volume ratio of 10:1 and its aqueous solution (3mg / ml), and the results are shown in Table 1.

[0059] Fluorescence lifetime: The fluorescence lifetime of the fluorescent probes prepared in the examples and comparative examples in a mixed solution (3 mg / ml) of deionized water and tetrahydrofuran in a volume ratio of 10:1 was tested by Hitachi FL-7000 fluorescence spectrometer, with 360 nm as the excitation wavelength. The results are shown in Table 1.

[0060] Salt resistance: Sodium chloride was added to a mixed solution of deionized water and tetrahydrofuran in a volume ratio of 10:1 to prepare a 1 mol / L sodium chloride solution, and then the fluorescent probe prepared in the embodiment and the comparative example was added at a concentration of 3 mg / ml. The maximum fluorescence intensity was measured at 360 nm as the excitation wavelength. The salt resistance was expressed by the ratio of the maximum fluorescence intensity in the sodium chloride solution to the maximum fluorescence intensity in the mixed solution of deionized water and tetrahydrofuran in a volume ratio of 10:1. The results are shown in Table 1.

[0061] Latent fingerprint visualization: The aqueous solution (3 mg / ml) of the fluorescent probe prepared in Example 1 and Comparative Examples 1 and 2 was used as the developer, and the tin foil with fingerprints was immersed in the developer for 15 seconds. After being taken out, it was rinsed with deionized water, dried naturally, placed in a dark room, excited with 360 nm ultraviolet light, and then photographed with a digital camera. The results are shown in FIG. Figure 3 shown.

[0062] Table 1 Performance test data

[0063]

[0064] Data Analysis:

[0065] From the data of Examples 1-3 in Table 1, it can be seen that the specific fluorescent probe for fingerprint visualization provided by the present invention has a high quantum yield in a mixed solution of deionized water and tetrahydrofuran with a volume ratio of 10:1, which can reach 62.15%, while the quantum yield in deionized water does not exceed 5%, which is much lower than the level in the mixed solution. This is a typical phenomenon of aggregation-induced luminescence, and further illustrates that the specific fluorescent probe for fingerprint visualization has good water solubility and has a high fluorescence lifetime in the mixed solution. The high fluorescence lifetime helps to improve the sensitivity and reliability of fingerprint visualization. Crucially, the specific fluorescent probe for fingerprint visualization provided by the present invention also has high salt resistance, which can effectively improve the stability and application flexibility of fingerprint visualization, reduce background interference, and enhance the precision and accuracy of fingerprint recognition.

[0066] It can be seen from the data of Example 1 and Comparative Example 1 in Table 1 that the carboxylation of the triphenylamine end group helps to improve the quantum yield and fluorescence lifetime of the fluorescent probe. This is mainly because the carboxylic acid group can affect the electron density distribution of the carbon quantum dots, and by changing the energy level, optimize the energy difference between the excited state and the ground state, thereby improving the quantum yield and fluorescence lifetime.

[0067] From the data of Example 1 and Comparative Example 2 in Table 1, it can be seen that, relative to cyclohexane, piperazine helps to improve the quantum yield and fluorescence lifetime of the fluorescent probe, because piperazine helps to form a stable conjugated system and restrict molecular motion, and piperazine and triphenylamine derivatives synergistically improve the salt resistance of the fluorescent probe, which is mainly due to the introduction of polar functional groups such as carboxyl and amino groups by carboxyl-containing triphenylamine derivatives and piperazine on the surface of carbon quantum dots. These functional groups can enhance the dispersibility and stability of carbon quantum dots and enhance the aggregation-induced emission effect. At high salt concentrations, these functional groups can interact with salt ions, thereby reducing the effect of salt on the structure of quantum dots and improving their salt resistance.

[0068] From the data of Example 1 and Comparative Example 3 in Table 1, it can be seen that, relative to the chain-like 1,5-pentanediamine, piperazine containing an alicyclic bond helps to improve the quantum yield and fluorescence lifetime, which may be due to the ability to restrict the rotation and vibration within the molecule. This restriction reduces the possibility of non-radiative transitions, thereby improving the quantum yield and fluorescence lifetime.

[0069] from Figure 2 It can be seen that when the excitation wavelength is 360nm, its fluorescence is strongest, and the position of its maximum emission peak red-shifts to the long-wave direction with the increase of the excitation wavelength, accompanied by a decrease in fluorescence intensity and an increase in half-peak width, which has typical excitation wavelength-dependent photoluminescence.

[0070] from Figure 3It can be seen that the fingerprint display image of the specific fluorescent probe for fingerprint display provided in Example 1 has the characteristics of clear contours, continuous lines, large background contrast, and more detailed features. This is mainly due to the chemical coupling or specific physical adsorption between the carboxyl group, amino group and other groups on the surface of the fluorescent probe and the amino acids, oils and sweat stains in the fingerprint. The fingerprint display images of Comparative Examples 1 and 2 have the characteristics of unclear contours in some parts and blurred lines in some parts. This may be because the fluorescent probes provided in Comparative Examples 1 and 2 are difficult to effectively adsorb into the fingerprint lines or the fluorescent probes adsorbed into the fingerprint lines fall off during the rinsing and removal of the developer.

[0071] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

Claims

1. A specific fluorescent probe for fingerprint visualization, characterized in that: The specific fluorescent probe for fingerprint visualization is synthesized from triphenylamine derivatives and piperazine by microwave hydrothermal method; The structural formula of the triphenylamine derivative is as follows: The weight ratio of the triphenylamine derivative to piperazine is 1.5:2-3.

2. The specific fluorescent probe for fingerprint visualization according to claim 1, characterized in that: The preparation method of the triphenylamine derivative is as follows: (1) adding tri(4-iodophenyl)amine, methyl acrylate, palladium acetate, 1,3-bis(diphenylphosphine)propane and triethylamine to N,N-dimethylformamide, heating to 115-125° C. under a nitrogen atmosphere, stirring for 20-30 hours, and purifying after the reaction to obtain a triphenylamine derivative intermediate; (2) Add the triphenylamine derivative intermediate and potassium hydroxide to a mixed solvent of tetrahydrofuran and deionized water, raise the temperature to 90-95° C., stir and react for 10-14 hours, and purify after the reaction to obtain a triphenylamine derivative.

3. The specific fluorescent probe for fingerprint visualization according to claim 2, characterized in that: In the step (1), the usage ratio of tri(4-iodophenyl)amine, methyl acrylate, palladium acetate, 1,3-bis(diphenylphosphine), triethylamine and N,N-dimethylformamide is 2.4 g:1.54 g:2.45 mg:103.1 mg:1.8 g:10 g.

4. The specific fluorescent probe for fingerprint visualization according to claim 2, characterized in that: In the step (2), the usage ratio of the triphenylamine derivative intermediate, potassium hydroxide, tetrahydrofuran and deionized water is 2.46 g:1.12 g:30 g:5 g.

5. The specific fluorescent probe for fingerprint visualization according to claim 1, characterized in that: The microwave power of the microwave hydrothermal synthesis is 700-800W, and the time is 5-10min.

6. The specific fluorescent probe for fingerprint visualization according to claim 1, characterized in that: After the microwave hydrothermal synthesis, the product was filtered with a filter having a pore size of 0.22-0.24 μm, and then dialyzed with deionized water in a 500 Da dialysis bag for purification.

7. The specific fluorescent probe for fingerprint visualization according to claim 1, characterized in that: The specific fluorescent probe for fingerprint visualization and deionized water are prepared into a developer at a concentration of 3 mg / ml, and the developer is used for fingerprint visualization.

Images