CN105482804B - A kind of latent fingerprint detection probe and preparation method thereof - Google Patents

Abstract

The invention belongs to a latent fingerprint detection probe and a preparation method thereof, and provides a preparation method of a monodisperse ring-shaped structure Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanocomposite material and its application in Applications in latent fingerprint visualization. Synthesize Fe ₂ O ₃ nanoparticles using anhydrous FeCl ₃ as a raw material by high-temperature hydrolysis, and then coat Fe ₂ O ₃ nanoparticles with PAA-NH ₄ in an isopropanol-water mixed system, and then add them to the system Add GdCl ₃ ·6H ₂ O, YCl ₃ ·6H ₂ O and ErCl ₃ ·6H ₂ O aqueous solution, stir, centrifuge, dry, and then calcined at high temperature, you can get monodisperse bell-shaped structure Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanocomposite. The composite material prepared by the invention has good dispersibility, has both magnetic properties and fluorescent properties, and can display latent fingerprints on A4 paper, glass flakes, laboratory table tops, apples and leather surfaces.

Description

A kind of latent fingerprint detection probe and preparation method thereof

technical field

The invention belongs to the technical field of nanocomposite materials and their applications, and in particular relates to a preparation method of a monodisperse bell-shaped structure Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanocomposite material and its latent fingerprint application in display.

Background technique

Fingerprint, that is, the pattern of the skin of the human hand, in the usual sense, refers to the mastoid line pattern on the skin of the first section of the palm of the finger. Second, fingerprints have been used in investigations and judgments for a long time. Because it has a special physiological structure and characteristic system, it has become a rather superior physical evidence. Fingerprints remain unchanged for life means that from the time when the fingerprints are formed at 6 months of the fetus to the time when the papillae of the dermis rots after death, the pattern type, specific shape, and shape, quantity, and position of the papillae of the fingers The sum of features constituted by the and interrelationships is always constant. By analyzing and comparing latent fingerprints and known individual fingerprints, a conclusion can be made to determine or exclude a certain criminal suspect. Early fingerprint identification mainly refers to visual identification of visible fingerprints left at crime scenes; modern forensic scientists use a variety of scientific techniques to search for fingerprints. At present, the methods used in on-site fingerprint display mainly include: optical display method, physical display method and chemical display method. The common weakness of these methods is low sensitivity, some of which interfere with the sensitivity and results of DNA testing after application. Compared with other methods, the fluorescence visualization method has special advantages. It can reveal some latent fingerprints on the background surface that are not clearly distinguished. The background fluorescence generated by the photoluminescence technology currently used at the same time has great interference to the conventional photoluminescence bioprint recognition. Big, difficult to meet the expected requirements. Therefore, the research and development of non-toxic, easy-to-operate and high-sensitivity on-site bio-imprint display technology has become the focus of forensic research and the direction of efforts of criminal technicians from all over the world.

Rare-earth up-conversion luminescent nanomaterials are a kind of fluorescent materials that are excited by near-infrared light and emit at short wavelengths. Up-conversion luminescent nanomaterials can overcome the shortcomings of strong background fluorescence in imaging of down-conversion fluorescent materials and have attracted widespread attention. They can convert near-infrared light into short-wave radiation through a multi-photon mechanism and emit ultraviolet or visible light. Compared with other fluorescent materials, this type of material has many advantages: good chemical stability, the luminescence process is almost not affected by temperature, humidity, pH, etc.; optical stability; the excitation wavelength of up-conversion luminescent materials is generally near-infrared light, and in biological systems, most of the interfering substances will not be excited, which reduces the detection background and greatly improves the sensitivity; the up-conversion luminescent materials Near-infrared or infrared excitation light has a long wavelength and low energy, so it can penetrate some biological tissues well without causing damage to them; the emission wavelength is adjustable, and different colors of emission can be obtained by doping different rare earth ions during the synthesis process fluorescence. From the above advantages, it can be seen that upconversion nanomaterials are a kind of very superior biomarker materials. Therefore, in order to adapt to more application conditions and scope of use, we invented a Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanoparticle with both magnetic properties and upconversion fluorescence, which can be used as a visualization reagent To display latent fingerprints, the material synthesis method is simple and the display process is fast.

Contents of the invention

The purpose of the present invention is to provide a preparation method of a monodisperse bell-shaped structure Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanocomposite material and its application in the development of latent fingerprints. The prepared monodisperse bell-shaped Fe ₃ O ₄ @Gd ₂ O ₃ :Y ^{3 +} /Er ³⁺ nanocomposite has good dispersion, strong magnetism, and high fluorescence intensity, and can be displayed on A4 paper, glass slides, laboratory benches, Potential fingerprints on apple and leather surfaces. The powder adheres to the sweat of latent fingerprints to show lines, and the excess powder will be sucked away by the magnetic brush, and clear fingerprint lines can be observed. Under the irradiation of a 980 nm laser light source, the luminous fingerprint lines can be observed.

The preparation method of the monodisperse bell-shaped structure Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanocomposite material of the present invention comprises the following steps:

(1) Add a certain amount of ferric chloride solution (2×10 ^-2 M) into a round-bottomed flask with a condenser, and stir the reaction in a 100 ^o C oil bath for 70 to 80 h, and the reaction is complete After centrifugation, the obtained solid was washed several times with deionized water, and the obtained solid was vacuum-dried at 50 ~ 75 ^o C for 8 ~ 10 h to obtain dry Fe ₂ O ₃ nanoparticles.

(2) Mix 4~6 mg of Fe ₂ O ₃ nanoparticles obtained in step (1), 50~100 µL polyacrylic acid aqueous solution (0.2g/mL), 75~150 µL ammonia water (2 mol/L) and 10~100 µL Add 15mL deionized water into a 100mL round bottom flask, and ultrasonically disperse for 10-20 min.

(3) Slowly add 100 ~ 150 mL of isopropanol dropwise into the solution obtained in step (2) under magnetic stirring, then add 10 ~ 15 mg GdCl ₃ ·6H ₂ O, 2 ~ 3 mg YCl ₃ ·6H ₂ O and 0.2 ~ 0.3 mg ErCl ₃ ·6H ₂ O were successively added to the solution, stirred magnetically for 2-4 hours, centrifuged after the reaction was completed, and the obtained solid was dried in vacuum at 50 ~ 75 ^o C for 8 ~ 12 hours.

(4) Put the solid obtained in step (3) in a tube furnace and calcinate it under the protection of argon at 600 ~ 700 ^o C for 2 ~ 3 hours to obtain a bell-shaped structure Fe ₃ O ₄ @Gd ₂ O ₃ :Y ^{3 +} /Er ³⁺ nanocomposites.

The present invention has the following advantages:

1. The present invention adopts the unique PAA-NH ₄ template method, with the help of its guiding and stabilizing effects, to synthesize the bell-shaped nano-particles, which not only shortens the reaction steps but also ensures the high dispersion of the particles.

2. The monodisperse Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanoparticles obtained in the present invention are multifunctional nanoparticles with both magnetic properties and up-conversion fluorescence, which can be applied to more conditions and range, and no toxic side effects.

3. The monodisperse Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanoparticles obtained in the present invention, whose shell is an up-conversion luminescent nanomaterial, can overcome the disadvantage of strong background fluorescence when the down-conversion fluorescent material is used for imaging , greatly improving the display effect.

4. The monodisperse Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanoparticles obtained in the present invention have uniform particle size and good dispersibility, and can display various texture surfaces (A4 paper, glass sheet, laboratory table , apple and leather surface) latent fingerprints.

Description of drawings

Accompanying drawing 1, is the transmission electron microscope picture of the _Fe3O4 @ ^{Gd2O3:Y3+/Er3+} _{nanoparticle prepared} ^by _the present invention;

Accompanying drawing 2, is the image showing latent fingerprint on glass surface with Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ material brush;

Accompanying drawing 3, it is the image that uses Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ material to display the latent fingerprint on the surface of the test bench;

Accompanying drawing 4, is the image of the latent fingerprint on the A4 paper surface of the permeable object by brushing with Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ material;

Figure 5 is an image of latent fingerprints on the surface of an apple brushed with Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ material.

Detailed ways

The present invention is further described below in conjunction with specific examples, and the examples are only used to illustrate the present invention and are not intended to limit the protection scope of the present invention.

specific embodiment

Example 1:

Add 100 mL of ferric chloride aqueous solution (2×10 ^-2 M) into a round-bottomed flask with a condenser tube, stir the reaction in an oil bath at 100 ^o C for 70 h, wash with deionized water, sonicate, And centrifuge (7000 rpm, 10 min), repeat the ultra-three times, the obtained solid was vacuum-dried at 75 ^o C for 8 h, and dried Fe ₂ O ₃ nanoparticles were obtained. Add ₅ mg of prepared _Fe2O3 nanoparticles and 10 mL of deionized water into a 100 mL flask, ultrasonically disperse for 10 min, then add 50 µL of 0.2 g/mLPAA aqueous solution and 75 µL of 2 mol/L ammonia water successively, Then 10 mg GdCl ₃ ·6H ₂ O, 2 mg YCl ₃ ·6H ₂ O and 0.2 mgErCl ₃ ·6H ₂ O were added to the solution successively, stirred by magnetic force for 2 h, centrifuged after the reaction was completed, and the obtained solid was 75 ^o C Dry in vacuum for 8 h. The obtained solid was placed in a tube furnace and calcined at 600 ^o C for 2 h under the protection of argon to obtain a bell-shaped Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanocomposite.

Example 2:

Add 80 mL of ferric chloride aqueous solution (2×10 ^-2 M) into a round-bottomed flask with a condenser tube, stir the reaction for 80 h in an oil bath at 100 ^o C, wash with deionized water, sonicate, And centrifuge (9000 rpm, 5 min), repeat super for three times, the obtained solid was vacuum-dried at 70 ^o C for 9 h, and dried Fe ₂ O ₃ nanoparticles were obtained. Add 4 mg of prepared Fe ₂ O ₃ nanoparticles and 10 mL of deionized water into a 100 mL flask, ultrasonically disperse for 10 min, then add 70 µL of 0.2 g/mL PAA aqueous solution and 70 µL of 2 mol/L ammonia water , then 12 mg GdCl ₃ ·6H ₂ O, 2.2 mg YCl ₃ ·6H ₂ O and 0.22 mgErCl ₃ ·6H ₂ O were added to the solution successively, stirred by magnetic force for 2 h, centrifuged after the reaction was completed, and the obtained solid was 70 ^o C dried under vacuum for 9 h. The obtained solid was placed in a tube furnace and calcined at 700 ^o C for 2 h under the protection of argon to obtain a bell-shaped Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanocomposite.

Example 3:

Add 100 mL of ferric chloride aqueous solution (2×10 ^-2 M) into a round-bottomed flask with a condenser tube, stir it in an oil bath at 100 ^o C for 80 h, wash with deionized water, sonicate, And centrifuge (8000 rpm, 8 min), repeat super for three times, the obtained solid was dried in vacuum at 60 ^o C for 10 h, and dry Fe ₂ O ₃ nanoparticles were obtained. Add 5 mg of prepared Fe ₂ O ₃ nanoparticles and 10 mL of deionized water into a 100 mL flask, ultrasonically disperse for 8 min, then add 100 µL of 0.2 g/mL PAA aqueous solution and 100 µL of 2 mol/L ammonia water , then 15 mg GdCl ₃ ·6H ₂ O, 2.5 mg YCl ₃ ·6H ₂ O and 0.25 mg ErCl ₃ ·6H ₂ O were added to the solution successively, stirred by magnetic force for 2 h, centrifuged after the reaction was completed, and the obtained solid was 60 ^o C for 10 h in vacuum. The obtained solid was placed in a tube furnace and calcined for 3 h at 700 ^o C under the protection of argon to obtain a bell-shaped Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanocomposite.

The prepared monodisperse ring structure Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanocomposite material is used for fingerprint display. When in use, use a magnetic brush to pick up the magnetic powder, and the powder forms a "magnetic powder ear" under the action of the magnetic force. Use the tip of the powder ear to lightly brush the surface of various objects with latent fingerprints, including A4 paper, glass sheet, laboratory table, Fingerprint lines can be observed on the surface of apples and leather. The magnetic fluorescent powder shows fingerprint lines emitting green light under a 980 nm laser light source, and can be photographed with a digital camera.

Claims (2)

1. a preparation method for latent fingerprint detection probe is characterized in that concrete steps are as follows: (1) Add a certain amount of ferric chloride solution 2×10 ^-2 M into a round-bottomed flask with a condenser, and stir the reaction in an oil bath at 100 ^o C for 70 to 80 h. After the reaction is completed, carry out After centrifugation, the obtained solid was washed several times with deionized water, and the obtained solid was vacuum-dried at 50-75 ^o C for 8-10 h to obtain dry _Fe2O3 nanoparticles _; (2) Mix 4 ~ 6 mg of Fe ₂ O ₃ nanoparticles obtained in step (1), 50 ~ 100 µL polyacrylic acid aqueous solution 0.2 g/mL, 75 ~ 150 µL ammonia water 2 mol/L and 10 ~ 15 mL deionized water Add to a 100 mL round bottom flask, ultrasonically disperse for 10-20 min; (3) Slowly add 100 ~ 150 mL of isopropanol dropwise to the solution obtained in step (2) under magnetic stirring, then add 10 ~ 15 mg GdCl ₃ ·6H ₂ O, 2 ~ 3 mg YCl ₃ ·6H ₂ O and 0.2 ~ 0.3 mg ErCl ₃ 6H ₂ O were successively added to the solution, magnetically stirred for 2-4 hours, centrifuged after the reaction was completed, and the obtained solid was vacuum-dried at 50 ~ 75 ^o C for 8 ~ 12 hours; (4) Put the solid obtained in step (3) in a tube furnace and calcinate it under the protection of argon at 600 ~ 700 ^o C for 2 ~ 3 h to obtain Fe ₃ O ₄ @Gd ₂ O ₃ :Y ³⁺ /Er ³⁺ nanocomposites. 2. the application of the latent fingerprint detection probe prepared according to the method claimed in claim 1 in the latent fingerprints on the surface of paper, glass, laboratory table, apple and leather surface.