Luminescent ZIF-8 material as well as preparation method and application thereof
By modifying the surface of ZIF-8 with 8-hydroxyquinoline to prepare FZIF-8 material, the shortcomings of traditional latent fingerprint detection methods are overcome, and a simple and efficient latent fingerprint development method is achieved, revealing primary, secondary and tertiary structural information.
Patent Information
- Application Number
- CN202511174809.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-21
- Publication Date
- 2025-11-28
AI Technical Summary
In the existing technology, traditional latent fingerprint detection methods such as powder methods have low sensitivity, low contrast and large background interference. Furthermore, existing nanomaterials are complex to prepare or cannot identify tertiary structural information. There is a lack of simple, efficient and accurate new materials for latent fingerprint development.
By employing the PSM strategy to modify the ZIF-8 surface with 8-hydroxyquinoline, FZIF-8 material that can stably emit light in both solid and solution states was prepared, and its strong green fluorescence was used to reveal latent fingerprints.
FZIF-8 material can reveal primary, secondary, and tertiary structural information of latent fingerprints, exhibiting high sensitivity and selectivity. It is suitable for revealing different types of latent fingerprints and overlapping fingerprints, and the preparation process is simple and environmentally friendly.
Smart Images
Figure CN121021846A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of material science and forensic science, and relates to a novel luminescent ZIF-8 material, a preparation method thereof and the use thereof in forensic science, in particular to the use of the luminescent ZIF-8 material in the preparation of a latent fingerprint developing agent. BACKGROUND
[0002] Fingerprint is the ridge formed by the concave-convex skin on the human fingertip, which is formed during embryonic development and has the characteristics of uniqueness, certainty and lifelong invariability, and is an important basis for identifying personal information. Statistics, modern genetics and sociological surveys have proved that fingerprints can provide a scientific basis for individual identity identification, and are known as the "first evidence" in forensic science. The macro and micro information of fingerprints can greatly help the police to identify the suspect information at the crime scene, but these fingerprints are difficult to distinguish with the naked eye, which are called latent fingerprints (LFPs). The structural characteristics of fingerprints can be divided into three levels. The first-level structural characteristics provide the overall ridge flow and pattern structure information of fingerprints, such as the delta, loop and spiral of fingerprints, which are the basis for fingerprint classification and are not sufficient for identity recognition, but can be used for preliminary screening to simplify the retrieval process. The second-level structural information describes the specific ridge path in detail, including the terminal, bifurcation, island, hook, etc., which is the most discriminative characteristic. The third-level structural information such as sweat pores, creases and scars is generally not used alone for detection, but mainly provides supplementary information for part of the defective or blurred second-level latent fingerprint structure. At present, many methods have been developed to improve the visualization degree of LFPs, such as powder method, ninhydrin method, metal deposition method and fumigation method, etc. Among them, the powder method is the oldest and most commonly used latent fingerprint detection method, which is convenient to carry and easy to operate, and can visualize LFPs in a short time, but the traditional powder method has the disadvantages of low sensitivity, low contrast, and large background interference. In order to overcome these problems, fluorescent nanomaterials with size and functional advantages and optical characteristics are increasingly popular. Researchers have prepared a series of new nanomaterials for latent fingerprint development, such as quantum dots, carbon dots, metal and oxide nanoclusters, rare earth luminescent nanomaterials, nanocomposites, etc., but the preparation process of these materials is relatively complex; in addition, some materials cannot identify the third-level structural information of LFPs. Therefore, it is very necessary to develop a new type of material which is simple to prepare, efficient, accurate, has strong universality and can identify the microstructure of LFPs.
[0003] Zeolitic imidazolate frameworks-8 (ZIF-8) is a classic nanoscale metal-organic framework (MOF) material, which is composed of ZnN4 tetrahedron as a structural unit formed by coordination of zinc ions and nitrogen elements in 2-methylimidazole (2-MIM). ZIF-8 has a simple preparation process, high porosity and specific surface area, and shows good water dispersibility, thermal stability and biocompatibility. Based on the 2-MIM unit and Zn 2+ The charge / energy transfer between the centers, ZIF-8 itself can emit a light blue fluorescence, but the fluorescence intensity is low, which limits its application in the field of optical sensing to some extent. In order to overcome this obstacle, researchers combine carbon dots, graphene quantum dots, rhodamine B, metal nanoclusters and other luminescent substances with ZIF-8 through in-situ embedding or adsorption, so as to obtain a fluorescent probe with excellent performance, and improve the detection sensitivity and selectivity of the target. However, this process usually takes several hours or several days, and it is necessary to consider whether the size of the embedded or adsorbed molecule matches the pore size of ZIF-8.
[0004] Post-synthetic modification (PSM) is a method for preparing luminescent metal-organic frameworks (LMOFs) by post-processing of MOFs. It not only enhances the fluorescence performance, but also has the following advantages: (1) it can obtain LMOFs containing specific functional groups without limiting the synthesis conditions; (2) it can introduce new functional sites while maintaining the single crystal nature of MOFs. PSM strategy is one of the effective methods to endow MOFs with functionality, and is also applicable to ZIF-8. Existing research shows that the new MOFs obtained by PSM modification of ZIF-8 have more excellent performance than ZIF-8 in gas storage, separation, adsorption and catalysis, but so far there has been almost no related report on its application in the field of optical sensing. Therefore, if a luminescent ZIF-8 (FZIF-8) with stable and high-intensity fluorescence emission in solid and solvent states can be prepared based on the PSM method and applied in the field of latent fingerprint development, it will be of great significance. SUMMARY
[0005] The purpose of the present application is to prepare a new luminescent ZIF-8 material (denoted as FZIF-8) which can emit light stably in solid and solution states by using PSM strategy, and apply it to latent fingerprint development.
[0006] To achieve the above object, the present application adopts the following technical solutions:
[0007] A novel luminescent ZIF-8 material, which is prepared by modifying 8-HQ onto the surface of ZIF-8 through solid phase grinding method, using ZIF-8 and 8-hydroxyquinoline (8-HQ) as raw materials and NaCl as dispersion medium.
[0008] The luminescent ZIF-8 material is yellow solid.
[0009] The ZIF-8 used in the present application can be purchased or prepared according to the preparation method disclosed in the prior art.
[0010] The mass ratio of 8-hydroxyquinoline to ZIF-8 is 1:5 to 1:25, preferably 1:15; and the mass ratio of 8-hydroxyquinoline to NaCl is 1:5 to 1:25, preferably 1:14.
[0011] A preparation method of the luminescent ZIF-8 material, comprising: uniformly mixing and finely grinding 8-hydroxyquinoline and NaCl solids to obtain a mixture of 8-hydroxyquinoline and NaCl; finely grinding ZIF-8 to obtain ZIF-8 powder; adding the mixture of 8-hydroxyquinoline and NaCl into the ZIF-8 powder in batches; completely modifying 8-HQ onto the surface of ZIF-8 through solid phase grinding method; washing the product with ethanol water, centrifuging, and vacuum drying to obtain the luminescent ZIF-8 material.
[0012] The mixture of 8-hydroxyquinoline and NaCl is added in batches to avoid affecting the mixing effect after adding the mixture of 8-hydroxyquinoline and NaCl all at once, and there is no special requirement for the amount of the mixture of 8-hydroxyquinoline and NaCl added each time. Preferably, the solid phase grinding method comprises: adding the mixture of 8-hydroxyquinoline and NaCl into the ZIF-8 powder in 3 to 5 times; after each addition, uniformly mixing the mixture of 8-hydroxyquinoline and NaCl and the ZIF-8 powder and grinding to facilitate the complete modification of 8-HQ onto the surface of ZIF-8; after the last addition, uniformly mixing and grinding; and the end point of grinding is that the powder becomes uniform yellow under natural light and no longer continues to turn yellow.
[0013] The volume fraction of ethanol in the ethanol water is 5% to 80%, preferably 20%.
[0014] The centrifugation speed is 4000 r / min, and the centrifugation time is 5 min.
[0015] The washing and centrifugation is performed 3 to 4 times.
[0016] The temperature of the vacuum drying is 80℃, the pressure of the vacuum drying is <0.1 kPa, and the time of the vacuum drying is 6-120 h, preferably 48 h. The vacuum drying is used in the present application mainly to avoid oxidation of FZIF-8 and prevent structure collapse.
[0017] The FZIF-8 solid itself has photoluminescence properties. As can be seen from the excitation spectrum, light in the wavelength range of 280-500 nm can all excite FZIF-8 to emit fluorescence. The maximum excitation wavelength of the FZIF-8 solid is 293 nm, and the maximum emission wavelength is 512 nm. With 375 nm as the excitation wavelength, the fluorescence intensity of the FZIF-8 solid at 512 nm is 51 times higher than that of ZIF-8, indicating that the successful modification of 8-HQ makes ZIF-8 obtain excellent fluorescence performance. The fluorescence spectrum of the FZIF-8 aqueous dispersion is almost the same as that of the solid state. With 375 nm as the excitation wavelength, the fluorescence emission intensity of the FZIF-8 aqueous dispersion at 512 nm is 230 times that of ZIF-8 at the same concentration. ZIF-8 itself can show weak blue fluorescence, while the FZIF-8 aqueous solution after introducing 8-HQ emits strong green fluorescence.
[0018] Another object of the present application is to provide the use of the luminescent ZIF-8 material in the preparation of a latent fingerprint developing agent or in the development of a latent fingerprint.
[0019] The use of the luminescent ZIF-8 material in the development of a latent fingerprint comprises uniformly spreading the luminescent ZIF-8 material on the fingerprint surface of an object; irradiating the object containing the fingerprint with a light source with a wavelength of 280-500 nm, using a digital camera to take a picture to record the overall fluorescence pattern of the latent fingerprint, and using an inverted fluorescence microscope to record the local enlarged detail features.
[0020] The development of the latent fingerprint is completed by a powder brush developing method, which comprises dipping a special fingerprint brush with FZIF-8 powder, uniformly shaking off the FZIF-8 powder on the fingerprint first, then carefully developing along the fingerprint lines, and blowing off the excess powder.
[0021] Preferably, an ultraviolet lamp with a wavelength of 293-375 nm is used to irradiate the object containing the fingerprint.
[0022] Specifically, an ultraviolet lamp with a wavelength of 312 nm or 365 nm is used to irradiate the object containing the fingerprint.
[0023] The present application has the following beneficial effects:
[0024] The application provides a simple, green and environmentally-friendly solvent-free mechanical grinding method, based on a coordination PSM strategy, 8-HQ is introduced to coordinate with open zinc ion metal sites on the surface of ZIF-8, and a novel solid luminescent material FZIF-8 is successfully prepared. FZIF-8 can emit strong green fluorescence in both solid and aqueous solution states.
[0025] FZIF-8 can be used for latent fingerprint development. After LFPs are developed by FZIF-8, the fluorescence image can be collected and saved by using an ordinary digital camera under the irradiation of a 365 nm ultraviolet lamp, in addition, the primary and secondary structure information can be clearly observed by naked eyes without the aid of other observation tools, and even the distribution of sweat pores in the tertiary structure can be observed by further enlarging the local image under a microscope. In addition, the FZIF-8 powder is only attached to the fingerprint ridges, and does not contaminate other areas, which indicates that FZIF-8 has good sensitivity and selectivity in LFPs detection, and has low background interference. FZIF-8 has universality in LFPs visualization, and is suitable for the development of different types of LFPs, different trace-bearing objects and overlapping fingerprints. FZIF-8 has broad application prospects and high identification value in latent fingerprint identification. BRIEF DESCRIPTION OF DRAWINGS
[0026] Figure 1 A flowchart for preparing FZIF-8 by solid-phase grinding.
[0027] Figure 2 Transmission electron microscopy (TEM) images of FZIF-8 (A) and ZIF-8 (B).
[0028] Figure 3 X-ray energy spectrum analysis (EDS) images of FZIF-8 (A) and ZIF-8 (B).
[0029] Figure 4 PXRD images of ZIF-8, FZIF-8, 8-hydroxyquinoline zinc (Znq2) and 8-HQ.
[0030] Figure 5 FT-IR images of ZIF-8, FZIF-8, Znq2 and 8-HQ.
[0031] Figure 6 Optical property investigation results of FZIF-8 solid; wherein, A: fluorescence excitation (dashed line) and emission spectrum (solid line) of FZIF-8 solid; B: fluorescence emission spectra of ZIF-8 (black) and FZIF-8 (red), and the inserted images are fluorescence photos of ZIF-8 (left) and FZIF-8 (right) under the irradiation of a 365 nm ultraviolet lamp.
[0032] Figure 7The optical properties of the FZIF-8 aqueous dispersion are investigated. A: fluorescence excitation (dashed line) and emission spectra (solid line) of the FZIF-8 aqueous dispersion; B: fluorescence emission spectra of FZIF-8 (red) and ZIF-8 (black) aqueous dispersions (both at a concentration of 1 mg / mL), and the insets are fluorescence photographs of ZIF-8 (left) and FZIF-8 (right) aqueous solutions under 365 nm ultraviolet light.
[0033] Figure 8 The normalized fluorescence spectra of FZIF-8 dispersed in different solvents, and the right inset is a photograph of the corresponding solution under natural light and 365 nm ultraviolet light.
[0034] Figure 9 The fluorescence properties of FZIF-8 in water / DMSO mixed solvents with different proportions are investigated. A: fluorescence spectra of FZIF-8 dispersed in water / DMSO mixed solvents with different proportions, and the inset is a photograph of the corresponding solution under natural light and 365 nm ultraviolet light; B: a curve of the fluorescence intensity (black line) and the maximum excitation wavelength (red line) of FZIF-8 as a function of the volume fraction of water; C: normalized fluorescence spectra of FZIF-8 when the volume fraction of water is 15% to 20%.
[0035] Figure 10 The structural details of the latent fingerprint revealed by FZIF-8 are shown. A is the overall fingerprint image under white light, B is the fingerprint fluorescence image under 365 nm ultraviolet light, and C is the corresponding fingerprint fine structure of the marked position in B under inverted fluorescence microscopy
[0036] Figure 11 The effect of FZIF-8 on the latent fingerprints on different substrates.
[0037] Figure 12 The effect of FZIF-8 on the overlapping fingerprints. DETAILED DESCRIPTION
[0038] The technical solutions of the present application will be described in detail below through specific embodiments.
[0039] Unless otherwise specified, the raw materials and equipment used in the present application are conventional raw materials and equipment used in the art.
[0040] Example 1
[0041] A simple, fast and green PSM strategy for preparing FZIF-8 includes the following steps:
[0042] Step (1), ZIF-8 was synthesized according to the reference "Structural Evolution of Zeolitic Imidazolate Framework-8. Surendar R, Venna, Jacek B. Jasinski, and Moises A. Carreon, Journal of the American Chemical Society, 2010 132 (51): 18030-18033, DOI: 10.1021 / ja109268m", the method is as follows: 0.3 g of zinc nitrate hexahydrate was dissolved in 11.3 g of methanol to obtain a zinc nitrate solution; 0.66 g of 2-methylimidazole (2-MIM) was dissolved in 11.3 g of methanol to obtain a 2-methylimidazole solution, and the 2-methylimidazole solution was added to the zinc nitrate solution, stirred at room temperature (about 25°C) for 2 h to obtain a white reaction liquid, the reaction liquid was centrifuged at 4000 r / min for 5 min, the precipitate was washed with methanol for 3 times to remove excess raw materials, and vacuum dried at 80°C for 24 h to obtain a white solid, i.e. ZIF-8;
[0043] Step (2), FZIF-8 was synthesized by solid phase grinding using PSM strategy, as shown in Figure 1 8.0 mg of 8-hydroxyquinoline powder and 112 mg of NaCl solid were weighed and mixed and finely ground in an agate mortar to obtain a mixture of 8-HQ and NaCl, which was ready for use; 120 mg of ZIF-8 was finely ground in an agate mortar to obtain ZIF-8 powder; the mixture of 8-HQ and NaCl was added to the ZIF-8 powder in three portions, and after each addition, the mixture was mixed and ground to facilitate the complete modification of 8-HQ to the surface of ZIF-8. During the grinding process, the powder changed from white to uniform yellow under natural light, which could be observed by the naked eye. After the third addition of the mixture of 8-HQ and NaCl, the powder was ground until it turned uniform yellow and no longer changed color; the yellow product was washed with 20% ethanol (ethanol and water in a volume ratio of 1:4), centrifuged at 4000 r / min for 5 min, and the washing and centrifugation were repeated three times. The yellow solid, i.e. the novel luminescent ZIF-8 material (denoted as FZIF-8), was obtained by vacuum drying at a temperature of 80°C and a pressure of <0.1 kPa for 48 h.
[0044] Characterization of FZIF-8
[0045] In order to understand the morphology of FZIF-8, the inventors performed transmission electron microscopy (TEM) analysis on ZIF-8 and FZIF-8. As shown in Figure 2ZIF-8 is rhombic dodecahedron with size of about 70 nm, and the size of FZIF-8 is about 60 nm, and FZIF-8 is slightly etched into spherical shape by 8-HQ (see FIG. 1A). Figure 2 The surface element distribution of ZIF-8 and FZIF-8 was further semi-quantitatively analyzed by energy dispersive X-ray spectroscopy (EDS), and the results are shown in FIG. 1B. Figure 3 As shown in FIG. 1B, C, O, N, and Zn elements are uniformly distributed in FZIF-8, while only a small amount of O element is observed on the surface of ZIF-8. The presence of O element in FZIF-8 indicates that 8-HQ has been successfully modified to the surface of ZIF-8.
[0046] The crystal structure of FZIF-8 was analyzed by powder X-ray diffraction (PXRD), and the results are shown in FIG. 1C. Figure 4 As shown in FIG. 1C, FZIF-8 has good crystallinity and has the typical diffraction peaks of ZIF-8. A new diffraction peak is observed at an angle of 10.998°, which corresponds to 8-hydroxyquinoline zinc (Znq2), indicating that 8-HQ is only coordinated with the open Zn 2+ sites on the surface of ZIF-8, without destroying the internal crystal structure of ZIF-8. In addition, no diffraction peak similar to 8-HQ is observed, indicating that there is no free 8-HQ on the surface of FZIF-8, and 8-HQ is all coordinated with Zn 2+ sites on ZIF-8.
[0047] To analyze the surface chemical structure of FZIF-8, the inventors determined the infrared spectra (FT-IR) of ZIF-8, FZIF-8, and Znq2, and the results are shown in FIG. 1D. Figure 5 As shown in FIG. 1D, the infrared spectrum of FZIF-8 observes several new characteristic peaks on the basis of the characteristic peaks of ZIF-8, which correspond to Znq2. Among them, the vibration at 1502 cm -1 and 1333 cm -1 corresponds to the pyridyl group of 8-HQ, the C-O stretching vibration at 1100 cm -1 , and the Zn-O and Zn-N stretching vibration at 426 cm -1 .
[0048] Optical properties of FZIF-8
[0049] The optical properties of FZIF-8 were determined by the inventors, and the results are shown in FIG. 1E. Figure 6FZIF-8 solid itself has photoluminescence property as shown in Figure 1A. From the excitation spectrum, it can be seen that light in the range of 280-500 nm can excite FZIF-8 to emit fluorescence. The maximum excitation wavelength of FZIF-8 solid is 293 nm, and the maximum emission wavelength is 512 nm. The fluorescence emission spectra of ZIF-8 and FZIF-8 solid powders were measured at an excitation wavelength of 375 nm, respectively, as shown in Figure 1B. Figure 6 As shown in Figure 1B, the fluorescence intensity of FZIF-8 solid at 512 nm is 51 times higher than that of ZIF-8, indicating that the successful modification of 8-HQ makes ZIF-8 obtain excellent fluorescence performance. The FZIF-8 powder was dispersed in water to prepare a dispersion liquid with a concentration of 1 mg / mL, and the fluorescence excitation and emission spectra were collected, as shown in Figure 2. Figure 7 As shown in Figure 2A, it can be seen that the fluorescence spectrum of FZIF-8 aqueous dispersion is almost the same as that of the solid state. Then, the fluorescence emission spectra of FZIF-8 and ZIF-8 aqueous dispersions with the same concentration were compared at an excitation wavelength of 375 nm, and it was found that the fluorescence emission intensity of FZIF-8 aqueous dispersion at 512 nm is 230 times that of ZIF-8 (Figure 2B). Figure 7 Based on the charge / energy transfer between 2-MIM and Zn 2+ , ZIF-8 itself can show weak blue fluorescence, and FZIF-8 aqueous dispersion after introducing 8-HQ emits strong green fluorescence.
[0050] Solventochromic effect of FZIF-8
[0051] FZIF-8 powders were dispersed in water, benzene, methanol (MeOH), ethanol (EtOH), acetonitrile (ACN), acetone (AC), trichloromethane, dichloromethane, ethyl acetate, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF), twelve common solvents, respectively, and dispersed for 10 min with ultrasonic assistance to prepare FZIF-8 dispersions with a concentration of 1 mg / mL. The fluorescence emission spectra were collected at an excitation wavelength of 375 nm (excitation / emission slit: 5 nm / 5 nm; photo voltage: 500 V). The fluorescence emission spectra were normalized, and the results are shown in Figure 3. Figure 8The maximum emission wavelength of FZIF-8 dispersed in most organic solvents (e.g. chloroform, dichloromethane, ethyl acetate, THF, MeOH, EtOH, ACN, AC, DMSO, DMF) is in the range of 560-583 nm, emitting orange to yellow fluorescence; in benzene, the fluorescence of FZIF-8 becomes yellow-green, with the maximum emission wavelength blue-shifted to around 525 nm; while the solvent is water, the maximum emission wavelength of FZIF-8 is further blue-shifted to around 510 nm, emitting green fluorescence. From the photographs on the right side of FIG. 6, it can also be visually compared that FZIF-8 emits stronger fluorescence in water. The authors believe that the solvatochromic effect of FZIF-8 can be attributed to its special coordination environment on the surface, and the dipole interaction between different solvent molecules and FZIF-8 can affect the energy transfer between ZIF-8 and 8-HQ, resulting in differences in peak intensity and peak position. Figure 8 The photographs on the right side of FIG. 6 can also visually compare the strength of the fluorescence emitted by FZIF-8 in different solvents, i.e. FZIF-8 can emit stronger fluorescence in water. The authors believe that the solvatochromic effect of FZIF-8 can be attributed to its special coordination environment on the surface, and the dipole interaction between different solvent molecules and FZIF-8 can affect the energy transfer between ZIF-8 and 8-HQ, resulting in differences in peak intensity and peak position.
[0052] Fluorescence properties of FZIF-8 in water / DMSO mixed solvents with different proportions
[0053] To further prove the solvatochromic effect of FZIF-8, two miscible solvents, DMSO and water, were selected. The reason for choosing these two solvents is that the maximum emission wavelength of FZIF-8 in DMSO is the longest but the fluorescence intensity is weak, while the maximum emission wavelength of FZIF-8 in water is the shortest and the fluorescence intensity is the strongest.
[0054] The experimental operation is as follows: prepare mixed solvents with different proportions of water and DMSO, where the volume fraction of water is 100%, 90%, 80%, 70%, 60%, 50%, 40%, 35%, 30%, 25%, 20%, 19%, 18%, 17%, 16%, 15%, 10%, 5%, 0%, respectively; uniformly disperse FZIF-8 in each solvent to prepare the test solution with a concentration of 1 mg / mL of FZIF-8; record the color state of FZIF-8 in the mixed solution of water / DMSO with different proportions under natural light and ultraviolet light (365 nm) using a camera. In addition, move the test solution to a four-side transparent fluorescence cuvette, and collect the fluorescence emission spectrum under an excitation wavelength of 375 nm (excitation / emission slit: 5 nm / 5 nm; photo voltage: 500 V).
[0055] The experimental results are shown in FIG. 7. Figure 9As shown, with the increase of the volume fraction of water in the water / DMSO mixed system, the maximum emission center of FZIF-8 appears blue shift, and the corresponding fluorescence intensity at the maximum emission wavelength gradually increases, and reaches the maximum value when the volume fraction of water is 60%, which is 20 times of the fluorescence intensity when pure DMSO is used as the solvent, and the fluorescence color of the solution transits from weak orange yellow to strong green. It is found in the experiment that the maximum emission center completes the transition from 580 nm to 510 nm when the volume fraction of water increases from 15% to 20%, and the fluorescence intensity of FZIF-8 does not increase obviously in the process. Thereafter, with the continuous increase of the volume fraction of water, the fluorescence intensity significantly increases, but the maximum emission center does not change. It can be seen that the water content has a significant adjusting effect on the fluorescence performance of FZIF-8.
[0056] Example 2
[0057] The volunteers washed their hands with soap and spread their palms in the air to dry naturally. A cotton ball was dipped in an appropriate amount of anhydrous ethanol to wipe clean different objects (glass slides, glass bottles, mobile phone screens, mineral water bottles, cigarette boxes), and then naturally air-dried for standby use.
[0058] Preparation of latent fingerprints: sweat latent fingerprints: the volunteers clenched their fists for 15 min, and then pressed fresh fingerprints on clean glass slides; grease fingerprints: the volunteers gently wiped their foreheads or the sides of their noses with their fingers, and then pressed fresh fingerprints on clean glass slides; oil-sweat mixed fingerprints: the volunteers first clenched their fists for 15 min, and then gently wiped their foreheads or the sides of their noses with their fingers, and then pressed fresh fingerprints on the surfaces of the above-mentioned different objects; overlapping fingerprints: fresh oil-sweat mixed fingerprints were pressed on clean glass slides in an overlapping manner.
[0059] FZIF-8 was used for latent fingerprint development: a special fingerprint brush was dipped in an appropriate amount of finely ground FZIF-8 powder, the powder was first evenly shaken onto the fingerprints, and then carefully swept along the fingerprint lines, and the excess powder was blown off with an ear bulb. The object containing the fingerprints was irradiated with an ultraviolet lamp (365 nm), and the overall fluorescence pattern of the LFPs was recorded by a digital camera, and the local amplified detail features were recorded by an inverted fluorescence microscope.
[0060] Figure 10The overall and local fluorescence images of LFPs on the glass slide were depicted. The overall direction of the fingerprint ridge line was shown in the overall fluorescence image, and the primary structure information of LFPs such as ring (1) and triangle (2) could be seen. In fact, some subtle structures of LFPs including the point (3), island (4), terminal (5), intersection (6) and bifurcation (7) in the secondary structure information and the fold (8) in the tertiary structure information could be easily distinguished by naked eye. Then, we magnified the local structure of LFPs using an inverted fluorescence microscope, and it could be seen that FZIF-8 did not completely cover the fingerprint ridge, but retained some circular holes, which were the sweat pores (9) without being attached. These macro and micro details led to the individualization of fingerprints, and at the same time proved the feasibility of FZIF-8 in latent fingerprint identification. In addition, the magnified local image showed that FZIF-8 was attached only to the papillary ridge of the fingerprint, and almost no contamination was caused to other areas, which indicated that FZIF-8 had high development selectivity and low background interference.
[0061] Development of latent fingerprints on different substrates: FZIF-8 was used to develop latent fingerprints on several objects (such as glass bottle, mobile phone screen, plastic mineral water bottle and cigarette box) that were easy to leave fingerprints in daily life, and the results are shown in Fig. 5. Figure 11 As shown in Fig. 5, the latent fingerprints on different substrates could be clearly distinguished by naked eye after being developed by FZIF-8, and the clear fingerprint information could be collected under the irradiation of ultraviolet light (365 nm), even in a complex background, the fingerprint could be clearly developed.
[0062] Development of overlapping fingerprints: In the collection of fingerprints in the crime scene, there must be the phenomenon of fingerprint overlap, so the volunteers were asked to stamp two fingerprints on the glass slide in an overlapping manner, and after being treated with FZIF-8 powder, it could be observed that the directions of the ridges of the two fingerprints in the overlapping part were different and did not interfere with each other (Fig. 6). Figure 12 )
Claims
1. A luminescent ZIF-8 material, characterized in that: It is a luminescent material made from ZIF-8 and 8-hydroxyquinoline as raw materials, with NaCl as the dispersion medium, and 8-HQ modified onto the surface of ZIF-8 by solid-phase grinding.
2. The luminescent ZIF-8 material according to claim 1, characterized in that: The mass ratio of 8-hydroxyquinoline to ZIF-8 is 1:5 to 1:25; the mass ratio of 8-hydroxyquinoline to NaCl is 1:5 to 1:
25.
3. The luminescent ZIF-8 material according to claim 1 or 2, characterized in that: The mass ratio of 8-hydroxyquinoline to ZIF-8 is 1:15; the mass ratio of 8-hydroxyquinoline to NaCl is 1:
14.
4. A method for preparing the luminescent ZIF-8 material according to claim 1, characterized in that: include: 8-Hydroxyquinoline and NaCl solid were mixed evenly and ground finely to obtain a mixture of 8-hydroxyquinoline and NaCl. ZIF-8 was ground finely to obtain ZIF-8 powder. The mixture of 8-hydroxyquinoline and NaCl was added to the ZIF-8 powder in batches. 8-Hydroxyquinoline was modified onto the surface of ZIF-8 by solid-phase grinding. The product was washed with ethanol and water, centrifuged, and vacuum dried to obtain luminescent ZIF-8 material.
5. The method for preparing the luminescent ZIF-8 material according to claim 4, characterized in that: The solid-phase grinding method is as follows: the mixture of 8-hydroxyquinoline and NaCl is added to ZIF-8 powder in 3 to 5 portions; after each addition, the mixture of 8-hydroxyquinoline and NaCl and ZIF-8 powder are mixed evenly and ground. After the last addition, the grinding endpoint is that the powder turns into a uniform yellow color under natural light and no longer turns yellow.
6. The method for preparing the luminescent ZIF-8 material according to claim 4, characterized in that: The volume fraction of ethanol in the ethanol-water mixture is 5% to 80%, preferably 20%.
7. The method for preparing the luminescent ZIF-8 material according to claim 4, characterized in that: The vacuum drying temperature is 80℃, the vacuum drying pressure is <0.1kPa, and the vacuum drying time is 6-120h.
8. Use of the luminescent ZIF-8 material of claim 1 in the preparation of a latent fingerprint developer or in the development of latent fingerprints.
9. The use according to claim 8, characterized in that: The application of the luminescent ZIF-8 material in latent fingerprint development includes: uniformly spreading the luminescent ZIF-8 material on the fingerprint surface of the object; irradiating the object containing the fingerprint with a light source of wavelength 280-500nm; taking pictures of the overall fluorescence pattern of the latent fingerprint with a digital camera; and recording the magnified details of the local area with an inverted fluorescence microscope.
10. The use according to claim 9, characterized in that: The object containing fingerprints was irradiated with an ultraviolet lamp with a wavelength of 293–375 nm.