A water-based reagent for rapid fingerprint spraying

Abstract

The present invention provides an aqueous reagent for rapid fingerprint display, belonging to the field of fingerprint detection technology. The rapid fingerprint display reagent is composed of an organic carboxylic acid with a planar symmetrical structure, a buffer reagent with a pH higher than the isoelectric point of protein, and a mixed solution of europium ions and aluminum ions. The steps for using it are as follows: spray the mixed solution on the surface of a latent fingerprint object, and bright red fingerprint lines can be observed under ultraviolet light. The present invention does not require the pre-preparation of rare earth ion coordination polymers or solid powder particles, has good water solubility, is not restricted by the object to be displayed when used, displays fingerprints quickly, has high reagent fluorescence efficiency, and requires a small amount of material. After the fingerprint is displayed using this reagent, the displayed object does not affect the evidence for the determination of the DNA result. The reagent of the present invention can be used as a guide reagent for DNA sampling.

Description

Technical Field

[0001] The present invention relates to the technical field of fingerprint detection, in particular to an aqueous reagent for rapidly spraying fingerprints. Background Art

[0002] Fingerprints are unique to each person, remain unchanged throughout life, and leave traces on objects. Fingerprint identification is one of the most reliable methods for personal identification. Scientifically and correctly discovering, extracting, and identifying fingerprints plays an important practical role in conducting investigative work and punishing crimes.

[0003] The main methods currently used for on-site fingerprint development are: optical development, physical development, and chemical development. These methods have the following two main problems: (1) The development reagents used pose a great threat to the health of on-site investigators. Powder (single powder, synthetic powder, magnetic powder, fluorescent powder, etc.), volatile reagents, and solvents are easily inhaled; fluorescent powders are highly toxic and carcinogenic, which makes technicians afraid to use them. (2) A large number of accessories and operations are required, such as hot ironing, steam, brushing, and fumigation, which makes technicians reluctant to use them. For example, patent application number 202310921979.5, on the use of trichloro-di-(1,10)-phenanthroline europium complex in latent fingerprint development, requires a complex process to prepare fluorescent powder for brushing, and cannot be applied on vertical, horizontal, wet, or uneven surfaces. Application No. 202311048186.3, Application of 1,10-phenanthroline-tris[4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione] europium in latent fingerprint visualization and Application No. 202110766049.8, A method for preparing an orange-red phosphor and its application in latent fingerprint extraction, adopts the traditional brushing method, which treats the object to be visualized similarly to immersion. The reagent has low fluorescence efficiency and large dosage. It is only effective for non-permeable objects (such as glass, etc.), and the cost and technical requirements for use are very high.

[0004] The display effect on common permeable objects is of great significance, but the existing technology has little obvious display effect on permeable objects.

[0005] Therefore, on-site investigators have an urgent need for new technologies, methods and products for fingerprint visualization that are efficient, convenient, green and safe. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide an aqueous reagent for rapid visualization of latent fingerprints.

[0007] Another object of the present invention is to provide a method for preparing the aqueous reagent for rapid fingerprint spraying and its application.

[0008] The object of the present invention is achieved in the following ways:

[0009] A water-based reagent for rapid fingerprint spraying, comprising a symmetrically structured organic carboxylic acid, a pH buffer solution, a europium ion solution, and an aluminum ion solution. The molar ratio of the organic carboxylic acid to the europium ion is (0.5-5):1, preferably 1:1; and the molar ratio of the organic carboxylic acid to the aluminum ion is (1-10):1, preferably 2:1.

[0010] The organic carboxylic acid has a symmetrical structure, preferably one of phthalic acid, trimesic acid or pyromellitic acid. A symmetrical structure (tumbling symmetry, axisymmetry, rotational symmetry) can further facilitate the formation of larger molecules extending in all directions of the plane with europium, thereby enhancing the fluorescence effect.

[0011] The organic carboxylic acid solution is an organic carboxylic acid aqueous solution with a concentration of 1.0×10 -3 mol·L -1 ~20×10 - 3 mol·L -1 , the preferred concentration is 2.0×10 -3 mol·L -1 The concentration of the europium ion solution is 1.0×10 -3 mol·L -1 ~10×10 -3 mol·L -1 , the preferred concentration is 2.0×10 -3 mol·L -1 The concentration of the aluminum ion solution is 1.0×10 - 3 mol·L -1 ~10×10 -3 mol·L -1 , the preferred concentration is 1.0×10 -3 mol·L -1 Preferably, the europium ion solution is an aqueous europium sulfate solution, and the aluminum ion solution is an aqueous aluminum sulfate solution.

[0012] The pH of the pH buffer solution of the present invention should be higher than the isoelectric point of the protein. The preferred buffer solution is a Tris buffer solution or a borax-hydrochloric acid buffer solution, and the pH of the buffer solution is more preferably 8-9.

[0013] The method for preparing the aqueous reagent for rapid fingerprint spraying is to mix an organic carboxylic acid, a pH buffer solution, a europium ion solution and an aluminum ion solution.

[0014] The aqueous reagent for rapid fingerprint detection described in the present invention can be used in fingerprint detection. Specifically, the aqueous mixture is sprayed onto the surface of a latent fingerprint object, and a bright red fingerprint pattern is observed under ultraviolet light. The wavelength of the ultraviolet light is 254 nm. The latent fingerprint object can be metal, glass, plastic, ceramic, leather, wood, organic glass, or painted surfaces.

[0015] Protein is an important component of fingerprint lines. This method uses a buffer solution to raise the pH of the medium above the isoelectric point of the protein, thereby imparting a negative charge to the protein molecules, facilitating their binding with europium ions. The europium ions then combine with symmetrical organic carboxylic acids to form macromolecules with spatially extended structures and fluorescent properties. Aluminum ions fill the vacancies left by the europium ions, reducing reagent costs without compromising fluorescence intensity.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) All reagents used are water-soluble and are colorless, odorless, water-based, green and safe.

[0018] (2) There is no need to pre-prepare rare earth ion coordination polymers or solid powder particles, and fingerprints appear quickly.

[0019] (3) The liquid solution of the present application can well adapt to different object surfaces such as metal, glass, plastic, ceramic, leather, log, organic glass, paint surface, etc., and can be applied on vertical surface, upward surface, wet surface, and uneven surface without being restricted by the surface. In particular, it has a good display effect on permeable objects (paper, leather, log, etc.), which can minimize the impact of fingerprint display on the object to be displayed.

[0020] (4) This application adopts a spray display method, which has high reagent fluorescence efficiency and small dosage.

[0021] (5) After preparation, it can be stored stably at room temperature for a long time and can be used directly.

[0022] (6) Trivalent aluminum ions have no fluorescent effect. The present invention uses cheap trivalent aluminum ions without affecting the formation of luminescent macromolecules with spatial ductility, which not only reduces costs but also maintains a high luminous efficiency.

[0023] (7) After the fingerprint is revealed using the present reagent, the revealed object does not affect the evidence for determining the DNA result. The present reagent can be used as a guide reagent for DNA sampling. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the effect of fingerprint visualization on the A4 paper surface in Example 1;

[0025] Figure 2This is the effect of fingerprints appearing on the surface of latex gloves in Example 2;

[0026] Figure 3 This is the effect of fingerprints appearing on the surface of the Chlorophytum leaf in Example 3.

[0027] Figure 4 This is the effect of fingerprint display on the desktop of Example 1.

[0028] Figure 5 This is the effect of fingerprints appearing on the wall of Example 2. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments and the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0030] Example 1

[0031] 1 mL of phthalic acid aqueous solution (2.0×10 -3 mol·L -1 ), 1 mL Tris aqueous solution (1.5×10 - 3 mol·L -1 ), 1 mL europium sulfate solution (2.0×10 -3 mol·L -1 ) and 1 mL of aluminum sulfate aqueous solution (1.0×10 -3 mol·L -1 ) Mix well and set aside. Use a spray bottle to spray the mixed solution onto the surface of the latent fingerprint object. Under the irradiation of 254nm ultraviolet light, the fingerprint lines emit red fluorescence (see Figure 1 ).

[0032] Example 2

[0033] 1 mL of trimesic acid aqueous solution (2.0×10 -3 mol·L -1 ), 1 mL Tris aqueous solution (1.5×10 - 3 mol·L -1 ), 1 mL of europium sulfate aqueous solution (2.0×10 -3 mol·L -1 ) and 1 mL of aluminum sulfate aqueous solution (1.0×10 -3 mol·L -1 ) Mix well and set aside. Use a spray bottle to spray the mixed solution onto the surface of the latent fingerprint object. Under the irradiation of 254nm ultraviolet light, the fingerprint lines emit red fluorescence (see Figure 2 ).

[0034] Example 3

[0035] 1 mL of pyromellitic acid aqueous solution (2.0×10 -3 mol·L -1 ), 1 mL of borax-hydrochloric acid buffer solution (1.0×10 -2 mol·L -1 )(pH8~9), 1mL europium sulfate aqueous solution (2.0×10 -3 mol·L -1 ) and 1 mL of aluminum sulfate aqueous solution (1.0×10 -3 mol·L -1 ) and mix well for later use. Use a spray bottle to spray the mixed solution onto the surface of the latent fingerprint object. Under 254nm ultraviolet light, the fingerprint lines emit red fluorescence (see Figure 3 ).

[0036] Comparative Example 1

[0037] 1 mL of phthalic acid aqueous solution (2.0×10 -3 mol·L-1), 1mL Tris aqueous solution (1.5×10 - 3 mol·L-1), 1mL europium sulfate solution (1.0×10 -3 mol·L -1 ) and 1 mL of aluminum sulfate aqueous solution (2.0 × 10 -3 mol·L -1 ) Mix well and set aside. Use a spray bottle to spray the mixed solution onto the surface of the latent fingerprint object. Under 254nm ultraviolet light, the fingerprint lines are not clearly fluorescent (see Figure 4 ).

[0038] Comparative Example 2

[0039] 1 mL of benzoic acid aqueous solution (2.0×10 -3 mol·L -1 ), 1 mL Tris aqueous solution (1.5×10 -3 mol·L -1 ), 1 mL of europium sulfate aqueous solution (2.0×10 -3 mol·L -1 ) and 1 mL of aluminum sulfate aqueous solution (1.0×10 -3 mol·L -1 ) Mix well and set aside. Use a spray bottle to spray the mixed solution onto the surface of the latent fingerprint object. Under 254nm ultraviolet light, the fingerprint lines are not clearly fluorescent (see Figure 5 ).

[0040] Test Example 1: Investigating the Effect of Using the Aqueous Reagent in Example 1 to Reveal the Fingerprint on DNA Testing

[0041] The visualization of latent sweat fingerprints and the subsequent DNA detection of the exfoliated cells attached thereto have been important topics in forensic science research in recent years. The latent sweat fingerprints visualized by the verification reagent of the present invention will not affect the subsequent DNA testing.

[0042] 1. Fingerprint sample preparation method

[0043] This experiment involved creating samples in a laboratory at a temperature of 32°C and a relative humidity of 75%. To eliminate other influences, the samples were prepared using a one-shot, double-slide testing method. This involves using two butt-jointed slides, with the fingerprint pressed against the seam between them. Half of the fingerprint is placed on each slide.

[0044] 2. Experimental Design

[0045] The two glass slides carrying fingerprints were separated, half of the fingerprint on one glass slide was sprayed with the reagent of the present invention and then subjected to DNA testing; the other glass slide not sprayed with the reagent of the present invention was directly subjected to DNA testing, and the two test results were compared.

[0046] 3. Sample production

[0047] In order to eliminate the possibility of chance, the experiment selected two volunteers, A and B, to provide samples. Each person provided samples 30 times. Both adopted the one-time forming and double-slide inspection method. The fingerprints were pressed on the joint of the two slides, and half of the fingerprints formed at one time were on each of the two slides.

[0048] The slides were separated according to whether they were sprayed with reagents or not. The original fingerprint samples provided by volunteer A were recorded as A1-A30, and the samples after spraying with reagents were recorded as a1-a30 respectively. The original fingerprint samples provided by volunteer B were recorded as B1-B30, and the samples after spraying with reagents were recorded as b1-b30 respectively. There were a total of 120 samples.

[0049] 4. Inspection methods

[0050] This experiment was conducted in accordance with the industry standards GA / T 383-2014 and GA / T 1163-2014. The exfoliated cells at the fingerprint site on the slide were wiped with a cotton swab in a two-step wet and dry wiping method and carefully transferred to a 1.5mL centrifuge tube. DNA was extracted and purified using the silica bead method, and the operation steps were optimized. The above DNA extraction product was used AmpFlSTR The 16 loci were amplified on a 9700 Plus thermal cycler. The system volume was 15 μL, of which 6 μL was DNA template, and the reaction was carried out for 30 cycles. 1 μL of amplified product was mixed with 0.5 μL internal standard LIZ500 and 9.5 μL deionized formamide, and the mixture was placed on a 3500XL genetic analyzer for fully automatic capillary electrophoresis. The data were collected using the Collection software. Allele typing was performed using ID-X software.

[0051] 5. Test results:

[0052] Table 1 Comparison table of fingerprint samples of volunteer A and DNA data before and after spraying the reagent

[0053]

[0054]

[0055] Table 2 Comparison of DNA data of volunteer B's fingerprint sample before and after spraying the reagent

[0056]

[0057]

[0058] 6. Experimental Analysis

[0059] All 30 pairs of samples from volunteer A were detected. The peak value of the fingerprint sample before spraying the reagent was 10,000, the lowest peak value was 1,000, and the average peak value was 3,730. The peak value of the fingerprint sample after spraying the reagent was 15,000, the lowest peak value was 1,000, and the average peak value was 3,516. Both sets of data before and after spraying the reagent were fully detected, and the average peak values ​​were similar, indicating that spraying the reagent on fingerprints does not affect DNA testing.

[0060] Of the 30 pairs of samples from volunteer B, 27 pairs were detected, for a detection rate of 90%. Before spraying the reagent, the fingerprint sample had a peak value of 20,000, a minimum value of 800, and an average value of 2,773. After spraying the reagent, the fingerprint sample had a peak value of 20,000, a minimum value of 1,000, and an average value of 2,783. Both sets of data had all detected DNA, and the average peak values ​​were similar. Statistical analysis revealed no significant difference (P>0.05). This indicates that spraying the reagent of the present invention on fingerprints does not affect DNA testing.

[0061] The data numbers of volunteer B that were not detected are B7, b7, B15, b15, B16, and b16, which happen to be the three fingerprints that were not detected before and after spraying the reagent. This shows that the fingerprint samples in which DNA was not detected after spraying the reagent could not be detected before spraying.

[0062] 7. Experimental conclusion:

[0063] From the DNA test data of the above 60 pairs of 120 samples, it can be seen that DNA data can be detected before spraying the reagent and DNA data can still be detected after spraying the reagent; the samples for which DNA was not detected after spraying the reagent were also not detected before spraying.

[0064] Therefore, the sweat latent fingerprint revealed by the reagent of the present invention will not affect the subsequent DNA test.

Claims

1. A water-based reagent for rapid fingerprint spraying, characterized in that The reagent consists of an organic carboxylic acid aqueous solution with a symmetrical structure, a pH buffer solution, a europium ion aqueous solution, and an aluminum ion aqueous solution; wherein the molar ratio of the organic carboxylic acid to the europium ion is 1:1; the molar ratio of the organic carboxylic acid to the aluminum ion is 2:1; the pH buffer solution is one of a Tris buffer solution and a borax-hydrochloric acid buffer solution, and the buffer solution has a pH of 8-9; the organic carboxylic acid is one of phthalic acid, trimesic acid, or pyromellitic acid; in the fingerprint rapid development reagent, the concentration of the organic carboxylic acid aqueous solution is 1.0×10 -3 mol·L -1 ~20×10 -3 mol·L -1 The concentration of the europium ion aqueous solution is 1.0×10 -3 mol·L -1 ~10×10 -3 mol·L -1 The concentration of the aluminum ion aqueous solution is 1.0×10 -3 mol·L -1 ~10×10 -3 mol·L -1 .

2. The aqueous reagent according to claim 1, characterized in that The europium ion aqueous solution is a europium sulfate aqueous solution, and the aluminum ion aqueous solution is an aluminum sulfate aqueous solution.

3. A method for preparing an aqueous reagent for rapid fingerprint spraying according to claim 1, characterized in that The organic carboxylic acid aqueous solution, the pH buffer solution, the europium ion aqueous solution and the aluminum ion aqueous solution are mixed to obtain the product.

4. Use of the aqueous reagent for rapid fingerprint spraying according to claim 1 in fingerprint detection.

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