Preparation of water-soluble thiazolothiazolyl fluorescent probe and application of water-soluble thiazolothiazolyl fluorescent probe in latent fingerprint development

Abstract

The invention relates to a water-soluble thiazolothiazole (TzTz)-based aggregation-induced emission (AIE) probe for visualizing latent fingerprints (LFPs) and an application method of the water-soluble thiazolothiazole (TzTz)-based aggregation-induced emission (AIE) probe. According to the probe TPA-TzTz-OH, a triphenylamine donor, a TzTzpi-bridge and a pyridinium receptor are integrated through reasonable molecular design, and a terminal hydroxyl group is introduced into a pyridine ring. Under excitation of visible light of 425 nm, the probe can rapidly (less than 40 seconds) achieve imaging of high contrast and three-level details (sweat pores and finger ridge microstructures) of latent fingerprints on various base materials (such as metal, glass, plastic, ceramic and wood), and organic solvents and post-treatment are not needed. According to the imaging principle, after fingerprint lipid components (such as oleic acid and cholesterol) are specifically combined, intramolecular movement is limited, the AIE effect is remarkably enhanced, and signal'off-on 'response is achieved. The method provided by the invention is green and environment-friendly, has excellent biocompatibility, is compatible with different matrixes, also efficiently shows old fingerprints, and is suitable for collection and storage of fingerprint evidences in judicial expertise and criminal investigation sites.

Description

Technical Field

[0001] The present invention relates to the fields of forensic medicine, criminal technology, and chemical detection, and specifically to a visualization method and preparation for achieving three-level detail resolution of latent fingerprints using novel water-soluble aggregation-induced emission reagents (AIEgens) with thiazolo[5,4-d]thiazole (TzTz) structures. Background Art

[0002] Latent fingerprints (LFPs) are crucial evidence in forensic identification. However, existing fingerprint imaging methods suffer from low contrast, substrate incompatibility, high toxicity, and limited excitation methods. These limitations make it difficult to effectively visualize L3 features such as sweat pores and finger ridge details, hindering the ultimate confirmation of personal identity. While currently used techniques, such as chemical visualization, powder dispensing, mass spectrometry, and fluorescent materials, have achieved some progress, they all suffer from limitations such as high reagent toxicity, cumbersome procedures, damage to fingerprints, significant background interference, and unsafe UV excitation. Furthermore, some fluorescent visualization probes still require organic solvents and complex processing, and their ability to image LFPs rich in microstructure at high resolution is limited, making them incapable of meeting the demands of forensic evidence collection for rapid, secure, and high-resolution imaging. Summary of the Invention

[0003] The purpose of the present invention is to provide an AIE luminescent agent (TPA-TzTz-OH) based on a novel water-soluble thiazolothiazole structure, which can realize high-contrast, high-resolution, and especially rapid visualization of level 3 details (microstructures of sweat pores and finger ridge edges) of latent fingerprints on a variety of substrates, thereby overcoming the shortcomings of existing LFP imaging methods in terms of contrast, resolution, operational safety, and substrate compatibility.

[0004] The molecular structure of the water-soluble thiazolothiazole structure AIE fluorescent material TPA-TzTz-OH described in the present invention is shown in Formula I.

[0005] The reagent described in this invention is a water-soluble aggregation-induced emission molecule, TPA-TzTz-OH, whose structure comprises an electron donor, triphenylamine, a thiazolothiazole π bridge, a pyridinium acceptor, and a terminal hydroxyl group. Through the design of a donor-π bridge-acceptor (D-π-A) system, it achieves efficient intermolecular charge transfer and aggregation-induced emission properties.

[0006] The invention provides a preparation method of the developer, as well as absorption and fluorescence spectra, and application of the developer in latent fingerprint development.

[0007] The present invention provides a method for presenting latent fingerprints using the developer, wherein the TPA-TzTz-OH aqueous solution (recommended concentration is about 100 μM) is applied to the surface of a substrate containing the latent fingerprint by immersion or spraying. Subsequently, under excitation of 425 nm visible light, the fingerprint area produces an "off-on" type fluorescence response. After 40 seconds, all details such as the ridges, sweat pores, and bifurcations can be quickly revealed without the need for organic solvents or additional treatment.

[0008] The present invention provides a mechanism for the developer's latent fingerprint imaging. The molecule, through its cationic moiety, undergoes electrostatic interactions and hydrogen bonding with lipid components (such as oleic acid and cholesterol). This binding restricts intramolecular motion, blocking non-radiative attenuation pathways and achieving aggregation-induced intense red light emission. Using control probes with different structures and molecular simulations, the synergistic effect of the cationic charge and terminal hydroxyl groups on high-resolution LFP imaging was confirmed.

[0009] The present invention provides the applicability and advantages of the developer for imaging latent fingerprints. The developer is applicable to a variety of substrates, including glass, stainless steel, plastic, ceramics, aluminum foil, and wood, achieving Level 3 detail imaging. It is capable of imaging both fresh and old (over 10 days old) fingerprints, and the fluorescence signal is stable over a long period of time, facilitating evidence storage and re-examination. The developer exhibits excellent cell biocompatibility (survival rate >85%) at the working concentration, balancing operational safety and environmental requirements. The development process is simple, completed within 40 seconds, and does not require organic solvents or complex post-processing.

[0010] The beneficial effects of the present invention are: the water-soluble AIE luminescent probe TPA-TzTz-OH of the present invention is simple to prepare and can be mass-produced, and has outstanding advantages such as fast imaging, high contrast, excellent resolution, green and environmentally friendly operation, wide substrate compatibility, and low cytotoxicity. It provides a new sustainable, safe and practical means for fingerprint detection, especially in the fields of forensic medicine and criminal investigation and evidence collection, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The synthetic route of the latent fingerprint developer TPA-TzTz-OH for real-time imaging of the present invention

[0012] Figure 2 Hydrogen spectrum of the latent fingerprint developer TPA-TzTz-OH for real-time imaging according to the present invention

[0013] Figure 3 Carbon spectrum of the latent fingerprint developer TPA-TzTz-OH for real-time imaging according to the present invention

[0014] Figure 4 The high-resolution mass spectrometer of the latent fingerprint developer TPA-TzTz-OH for real-time imaging of the present invention

[0015] Figure 5The present invention discloses a latent fingerprint developer TPA-TzTz-OH for real-time imaging. The developer adopts an immersion method to image the latent fingerprint.

[0016] Figure 6 The present invention is used for the real-time imaging of latent fingerprint developer TPA-TzTz-OH using a spraying method to image the latent fingerprint.

[0017] Figure 7 The latent fingerprint developer TPA-TzTz-OH for real-time imaging of the present invention uses a fluorescence microscope to image and analyze the three-level fingerprint details of the latent fingerprint. DETAILED DESCRIPTION

[0018] The present invention will be described in detail below with reference to specific embodiments. It should be noted that the following description is intended to explain the present invention rather than to limit it. Example 1

[0019] Synthesis of TPA-TzTz-OH, a latent fingerprint developer for real-time imaging, according to the present invention

[0020] The synthetic route of the latent fingerprint developer TPA-TzTz-OH for real-time imaging of the present invention is as follows: Figure 1 As shown, the synthesis method is:

[0021] Synthesis of Compound 1: Dithioacetamide (120.2 mg, 1 mmol), 4-(N,N-diphenylamino)benzaldehyde (409.5 mg, 1.5 mmol), and 4-pyridinecarboxaldehyde (160.5 mg, 1.5 mmol) were placed in a 50 mL flask, and anhydrous N,N-dimethylformamide (DMF, 10 mL) was added. The mixture was stirred at 140°C for 8 hours. After the reaction was completed, the reaction mixture was cooled to room temperature, filtered, and the solvent was removed under reduced pressure. The crude product was purified by column chromatography (DCM:MeOH = 50:1, v / v) to obtain 177.3 mg of the yellow solid compound in a yield of 16.7%. 1 H NMR (400MHz, CDCl3) δ8.73(d,J=5.1Hz,2H),7.87–7.78(m,4H),7.32(t,J=7.5Hz,4H),7.22–7.05(m,8H). 13 C NMR (100MHz, CDCl3) δ171.1,164.5,152.1,150.8,150.7,150.6,146.7,140.8,129.6,127.6,126.4,125.6,124.3,121.5,119.8.HR-MS(TOF-ESI + ):m / z calculated for[M+H] + C27 H 19 N4S2,463.1051; Found,463.1054.

[0022] Synthesis of TPA-TzTz-OH: Compound 1 (92.5 mg, 0.2 mmol) and 2-bromoethanol (141.9 mg, 1 mmol) were added to a 50 mL flask containing anhydrous DMF (5 mL). The mixture was stirred at 80°C for 12 hours. After the solvent was removed from the reaction mixture under reduced pressure, a small amount of silica gel was added, and the solvent was removed under reduced pressure. The resulting mixture was directly applied to a silica gel column and purified using DCM:methanol = 50:1 (volume ratio) as the eluent to obtain TPA-TzTz-OH as an indigo solid in a yield of 99.6%. 1 HNMR(400MHz,DMSO-d6)δ9.07(d,J=6.4Hz,2H),8.65(d,J=6.3Hz,2H),7.94(d,J=8.5Hz,2H),7.41(t,J=7.7Hz,4 H),7.25–7.13(m,6H),6.97(d,J=8.5Hz,2H),5.33(t,J=5.3Hz,1H),4.68(t,J=4.6Hz,2H),3.89(t,J=5.5Hz,2H). 13 C NMR (100MHz, DMSO-d6) δ173.3,160.2,155.3,151.9,151.3,146.9,146.4,146.3,130.5,128.7,126.4,125.5,125.1,123.3,120.3,63.2,60.5. HR-MS(TOF-ESI + ):m / z calculated for[M+H] + C 29 H 23 N4OS2,507.1308; Found,507.1315. Example 2

[0023] The present invention relates to a method for developing latent fingerprint developer TPA-TzTz-OH for real-time imaging.

[0024] Before development, prepare TPA-TzTz-OH into a 100 μM aqueous solution in advance. Prepare a dropper, beaker or small spray device for subsequent dripping, immersion or spraying of TPA-TzTz-OH developer. Prepare imaging equipment such as mobile phones, SLR cameras, fluorescence microscopes, etc. for imaging and detail analysis after latent fingerprint development.

[0025] Immersion method for latent fingerprint visualization: A 100 μM TPA-TzTz-OH aqueous solution is added dropwise to the substrate surface (including steel, glass, plastic, ceramic, tin foil, and wood) on which the latent fingerprint is printed. The latent fingerprint sample is completely immersed in the TPA-TzTz-OH aqueous solution for approximately 1 minute. The solution is then blotted dry and a fluorescence image of the latent fingerprint after visualization is obtained using a SLR camera equipped with a universal cutoff filter (JB510) under 425 nm LED light. The results are shown below. Figure 5 shown.

[0026] Spraying method to reveal latent fingerprints: Use a sprayer to spray an appropriate amount of TPA-TzTz-OH aqueous solution (100μM) on the latent fingerprint on the substrate and wait for about 30 seconds. Then use a SLR camera with a universal cutoff filter (JB510) to obtain a fluorescent image of the revealed latent fingerprint under 425nm LED light. The results are as follows Figure 6 shown.

[0027] Latent fingerprint three-level details: Latent fingerprints were developed on glass substrates using a TPA-TzTz-OH aqueous solution (100 μM). Local areas of latent fingerprints were observed and imaged using an IX73 fluorescence microscope (Olympus, Japan) under 460-495 nm excitation light. The images obtained were analyzed using ImageJ software at the three-level detail level, including parameters such as fingerprint ridge width and sweat pore spacing. The results are shown in Figure 2. Figure 7 shown.

[0028] Although some embodiments of the present invention have been described herein, those skilled in the art will appreciate that modifications may be made to the embodiments herein without departing from the spirit of the present invention. The above embodiments are merely exemplary and should not be used as limitations on the scope of the present invention.

Claims

1. A water-soluble thiazolyl-thiazolyl AIE probe for latent fingerprint visualization, characterized in that: The probe comprises a triphenylamine donor, a thiazolothiazole π-bridge linker, and a pyridinium receptor with a terminal hydroxyl group, and has the following chemical formula: A nitroreductase-activated chemiluminescent prodrug for real-time monitoring of camptothecin release in the diagnosis and treatment of peritoneal metastases, having a chemical structure shown in Formula I:

2. As claimed in claim 1, its counterion (or counterion) X – Can be: fluoride ion, chloride ion, bromide ion, iodide ion, hexafluorophosphate ion PF6 – .

3. The AIE probe according to claim 1, wherein The probe exhibits an "off-on" fluorescence response under 425 nm visible light excitation.

4. The AIE probe according to claim 1, wherein The probe uses water as solvent and is used at a concentration of 100 μM.

5. A method for applying the AIE probe according to claims 1 to 4 in latent fingerprint visualization, characterized in that: The method comprises the following steps: immersing or spraying a substrate containing a latent fingerprint in the AIE probe aqueous solution for 20 to 60 seconds; exciting with 425 nm visible light to visualize high-contrast imaging of the third-level details (microstructures such as sweat pores and finger ridges) of the fingerprint area; and after visualization, no solvent washing or additional post-processing is required.

6. The application method according to claim 5, characterized in that: The substrate is not limited to glass, stainless steel, plastic, ceramic, aluminum foil, wood, paper, wall and the like.

7. The application method according to any one of claims 1 to 6, characterized in that: The development method is applicable to fresh latent fingerprints and latent fingerprints stored for more than 10 days, and the developed fingerprints have long-term fluorescence stability.

8. The probe and visualization method according to any one of claims 1 to 7, further characterized in that: The probe has good biocompatibility with human cells (cell survival rate at working concentration is >85%), and the visualization process is green, safe, non-toxic and harmless.

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