Preparation of solid fluorescent carbon dots and application thereof in aspect of latent fingerprint detection

A solid-state fluorescence and latent fingerprint technology, which is applied in applications, luminescent materials, diagnostic recording/measurement, etc., can solve the problems of poor resolution of fluorescent fingerprints, enlarged nanoparticle size, cumbersome preparation process, etc., and achieve excellent solid-state fluorescence The properties and preparation method are simple and fast, and the raw materials are safe and easy to obtain

Active Publication Date: 2017-07-07
JIANGNAN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method of compounding carbon dots with a solid matrix, on the one hand, increases the experimental steps and makes the preparation process cumbersome; on the other hand, making the size of the nanoparticles larger is not conducive to obtaining high-resolution fingerprint images
At present, although some researchers have synthesized solid-state fluorescent carbon dots by microwave method, the method is cumbersome, and the synthesis conditions need to be precisely controlled, otherwise solid-state fluorescent carbon dots cannot be obtained. The fluorescence quantum yield is very low (1%) and the fluorescence lifetime is short. (1.42ns); and due to the limitation of the type and quantity of its active groups, it is not easy to combine with the surface texture of fingerprints. If it is used for latent fingerprints, the resolution of fluorescent fingerprints obtained is not good, and the third-level information of fingerprints cannot be obtained.

Method used

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  • Preparation of solid fluorescent carbon dots and application thereof in aspect of latent fingerprint detection
  • Preparation of solid fluorescent carbon dots and application thereof in aspect of latent fingerprint detection
  • Preparation of solid fluorescent carbon dots and application thereof in aspect of latent fingerprint detection

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] Example 1: Preparation of solid-state fluorescent carbon dots

[0046] Put 3.5g CA (Sinopharm Group), 5.1g GSH (Bailingwei), and 20mL ultrapure water in a 100mL polytetrafluoroethylene beaker, mix and stir at room temperature and ultrasonicate for 10min to make the solution uniform and stable. Put it into a microwave oven with adjustable power, dehydrate it with 750W microwave for 2 minutes, then continue heating and drying with 300W microwave for 2 minutes to obtain a light yellow sol, and obtain a solid after cooling to room temperature. The product is filtered, 13000r·min -1 Centrifuge for 15 minutes, and dialysis with 8kD dialysis bag for 2 days. Keep the solution in the dialysis bag and freeze-dry it. The obtained solid was pulverized and placed in a constant temperature and humidity chamber (25° C., 15% humidity) to prevent deliquescence.

[0047] The obtained carbon dots have solid-state blue fluorescence characteristics, and the particle size is uniform and st...

Embodiment 2

[0049] Embodiment 2: Application of liquid spray method to visualize latent fingerprints on aluminum foil

[0050] (1) Preparation of latent fingerprints: After washing and drying hands, lightly touch the bridge of the nose or forehead with fingertips, and then press the surface of the aluminum foil with moderate force to obtain latent fingerprints.

[0051] (2) Prepare 1mM SFCDs with ultrapure water, and adjust the pH of the solution to about 9 with 1M NaOH solution.

[0052] (3) Place the 1mM SFCDs solution in an ultrasonic nebulizer to atomize the solution. The atomized small droplet size is about 1-3μm. The aluminum foil object loaded with latent fingerprints is placed about 20cm away from the spray source and sprayed for 60s.

[0053] (4) Place the sprayed aluminum foil object under a UV lamp for irradiation, the excitation light source is 365nm, and obtain a fluorescent fingerprint image containing tertiary information with an ordinary digital camera (see image 3 shown...

Embodiment 3

[0057] Example 3: Application of powder method to visualize latent fingerprints on aluminum foil

[0058] (1) Preparation of latent fingerprints: After washing and drying hands, lightly touch the bridge of the nose or forehead with fingertips, and then press the surface of the aluminum foil with moderate force to obtain latent fingerprints.

[0059] (2) Dip the preserved solid powder with a fingerprint brush, brush lightly in the same direction, and finally shake off the excess powder with a fingerprint brush.

[0060] (3) Place the sprayed aluminum foil object under ultraviolet light for irradiation, the excitation light source is 365nm, and obtain a fluorescent fingerprint image containing tertiary information with an ordinary digital camera (see image 3 shown).

[0061] Change the object of above-mentioned step (1), obtain the fluorescent fingerprint image on the object being printing paper, plastics, glass, aluminum foil, pottery and stainless steel respectively, as Fi...

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Abstract

The invention discloses preparation of solid fluorescent carbon dots and application thereof in an aspect of latent fingerprint detection, belongs to the technical fields of material synthesis and fingerprint detection. The solid fluorescent carbon dots are synthesized by adopting glutathione as a nitrogen/sulfur source and adopting citric acid as a carbon source by virtue of a microwave method. Raw materials are safe and easy to obtain, a preparation method is simple and rapid, and particles are safe and nontoxic. The surfaces of the solid fluorescent carbon dots (SFCDs) provided by the invention contain an amino, a sulfydryl and a carboxyl functional group, a particle size is 2 to 7 nm, and the solid fluorescence property is excellent. The SFCDs are used as a fingerprint developing agent and can develop the aged fingerprint, and the developing time can reach 30 days in an experimental range; and the solid fluorescent carbon dots can be applied to a liquid spray method and powder method, the two methods are complementary to each other, and the universality of the developing agent is improved.

Description

technical field [0001] The invention relates to the preparation of a solid-state fluorescent carbon point and its application in latent fingerprint detection, and belongs to the technical field of material synthesis and fingerprint detection. Background technique [0002] Due to its uniqueness and lifetime invariance, fingerprint is one of the most reliable evidences for personal identification and is widely used in the field of criminal search. Therefore, chemical or physical processing of latent fingerprints to make them visualized is a key step in crime scene evidence collection. Traditional fingerprint detection is often limited to a certain special object. In addition, due to the lack of effective fingerprint quality of aged fingerprints, the detection effect will also be affected. Therefore, it is very important to use a general-purpose fingerprint developer to detect various surface and aging fingerprints. The safety of fingerprint developer that damages the health ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K11/65A61B5/1172
Inventor 王婵宋启军周静丹
Owner JIANGNAN UNIV
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