Fluorescent guanine nanosheet crystal, preparation method and application thereof

Abstract

The present application relates to a kind of fluorescent guanine nanocrystals and its preparation method and application, belong to fluorescent crystal and new functional material technical field, specifically, the synthesis method of fluorescent molecule doped guanine nanocrystals.The specific exposed surface color guanine crystal nanosheet of synthesis in the present application is mainly the same anhydrous guanine beta phase nanosheet with biological sample, and preferentially exposes the (100) crystal surface with best refractive index.The fluorescent guanine crystal nanosheet synthesized in the present application is hexagonal sheet, length is between 2-10 nanometers, and shows bright structural color under optical microscope.The specific exposed surface fluorescent guanine crystal nanosheet synthesized in the present application has good water or other solvent dispersibility, and the dispersion liquid has obvious pearl color, color is bright and beautiful, and can emit red or green fluorescence under the irradiation of specific wavelength light.

Description

Technical Field

[0001] This invention relates to a fluorescent guanine nanosheet crystal, its preparation method, and its application, belonging to the technical field of fluorescent crystals and new functional materials, specifically a method for synthesizing guanine nanosheet crystals doped with fluorescent molecules. Background Technology

[0002] When a substance at room temperature is irradiated by incident light of a certain wavelength, it absorbs light energy and enters an excited state, and immediately de-excites and emits outgoing light with a longer wavelength than the incident light. Substances with this property are called fluorescent substances. Fluorescence is widely used in anti-counterfeiting, fluorescent lamps, fluorescent marking, fingerprint extraction, and gem and mineral identification. Currently, artificially synthesized fluorescent nanocrystals have achieved high quantum yield, high fluorescence intensity, and long fluorescence lifetime, and are widely used in the field of photoluminescence. With the development of science and technology, people's demand for highly reflective, stable, and biocompatible fluorescent materials is increasing. For example, the synthesis and application of fluorescent materials such as biomarkers and fluorescent localization. However, the fluorescence stability and biocompatibility of artificially synthesized fluorescent crystals are poor, making them unable to perfectly integrate with organisms. Given that guanine crystals are the most widely used organic crystals in biology, their preferentially expressed (100) crystal plane has a very high refractive index (n = 1.85), which can achieve effective control of light. Orderedly assembled guanine crystals can serve as optical devices such as broadband reflectors, narrow-band reflectors, and three-dimensional photonic crystals. Combining low-density, non-toxic, and highly reflective guanine crystals with fluorescence could create highly reflective, biocompatible, multifunctional fluorescent materials. However, to date, there have been no reports of artificially synthesized highly reflective fluorescent guanine crystal nanosheets.

[0003] Therefore, embedding fluorescent molecules into the lattice of guanine crystals during the crystal synthesis process, and artificially synthesizing fluorescent guanine crystal nanosheets with specific exposed surfaces, can solve the problems of poor biocompatibility of conventional fluorescent crystals, as well as the limited resources and single performance of guanine crystals, and has important application value. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a fluorescent guanine nanosheet crystal, its preparation method, and its application.

[0005] The technical solution of this invention is:

[0006] A fluorescent guanine nanosheet crystal, wherein the fluorescent guanine nanosheet crystal is a β-phase anhydrous guanine crystal nanosheet with exposed (100) crystal planes, and fluorescent molecules are embedded in the crystal lattice of the fluorescent guanine nanosheet crystal.

[0007] A method for preparing fluorescent guanine nanosheet crystals involves a hydrolysis reaction in an organic solvent, using both polymeric and small molecule additives to simultaneously control the synthesis of guanine crystal nanosheets with preferential expression of the (100) crystal facet; and the use of fluorescent dye additives to embed fluorescent molecules into the lattice of the guanine crystal to control the synthesis of fluorescent guanine crystal nanosheets with preferential expression of the (100) crystal facet. The specific steps of this method include:

[0008] The first step is to prepare a sodium or potassium salt solution of guanine. The specific method is to prepare a solution by mixing guanine powder with sodium hydroxide or potassium hydroxide.

[0009] The second step is to prepare the dispersion. The specific method is to prepare the formamide, small molecule additive, high molecular weight additive and fluorescent dye additive into a dispersion according to the set ratio.

[0010] The third step involves adding the dispersion prepared in the second step to the solution prepared in the first step, mixing, and allowing it to stand for 0.5–24 hours to obtain a dispersion of colored guanine nanosheets that emit fluorescence. The dispersion is then subjected to multiple centrifugation and washing processes to obtain fluorescent guanine nanosheet crystals.

[0011] In the first step, sodium hydroxide or potassium hydroxide mainly provides an alkaline environment that can dissolve guanine. Preferably, the molar ratio of guanine to sodium hydroxide or potassium hydroxide is 1:(3-5), for example, 0.1M (M represents mol / L) guanine is dissolved in 0.4M sodium hydroxide or potassium hydroxide; the concentration of guanine in the resulting solution is 0.05-0.2M, and the concentration of sodium hydroxide or potassium hydroxide is 0.3-0.5M.

[0012] In the second step, the polymer additive is preferably a vinylpyrrolidone-based polymer, a copolymer of vinyl acetate and N-vinylpyrrolidone (P(VP-co-VA)) or polyvinylpyrrolidone (PVP), and the small molecule additive is uric acid; the fluorescent dye additive is preferably Nile Red or fluorescein isothiocyanate (FITC), and the dispersion is preferably prepared at RT to 60°C.

[0013] The ratio of formamide, small molecule additives, high molecular weight additives, and fluorescent dye additives is: 10:(0.1~50):(1~100):(0.5~5)*10 -3 ;

[0014] The volume ratio of formamide, sodium guanine salt, or potassium guanine salt solution is 10:0.25–1.5;

[0015] For example, formamide 10ml, water: 0-5ml, small molecule additives: 0.1mg-50mg, vinylpyrrolidone polymer: 1mg-100mg, dye: 0.5mg-5mg, temperature: RT-60℃, guanine sodium or potassium salt solution: 0.25ml-1.5ml.

[0016] An application of fluorescent guanine nanosheet crystals: The obtained fluorescent guanine nanosheet crystals are used as pearlescent pigments in fields such as fluorescent probes, skin care products, cosmetics, paper, coatings, rubber, paints, and coatings.

[0017] Compared with existing technologies, the present invention has the following main advantages:

[0018] (1) The fluorescent guanine crystal nanosheets with specific exposed surfaces synthesized in this invention have high fluorescence intensity and excellent fluorescence stability.

[0019] (2) In this invention, the artificially synthesized fluorescent guanine crystal nanosheets have good biocompatibility and can be further used for biological fluorescence functions.

[0020] (3) In this invention, the artificially synthesized fluorescent guanine crystal nanosheets have good stability and solubility, and can be continuously dispersed in water for several months without significant changes.

[0021] (4) In this invention, the artificially synthesized fluorescent guanine crystal nanosheets use fluorescent dye as an additive to dope the dye molecules into the lattice of the guanine crystal. The fluorescent dye enters the interior of the crystal, so the fluorescent molecules will not be washed away and the natural and non-toxic characteristics of the synthesized guanine crystal are maintained, while also maintaining the fluorescent properties of the fluorescent material.

[0022] (5) In this invention, uric acid is used as a small molecule additive to synthesize colored guanine crystal nanosheets with specific exposed surfaces. The crystal form is mainly the same as that of anhydrous guanine β-phase nanosheets as biological samples, and the (100) crystal plane with the best refractive index is preferentially exposed.

[0023] (6) The fluorescent guanine crystal nanosheets synthesized in this invention are hexagonal sheets with a length between 2 and 10 nanometers, and show bright structural colors under an optical microscope.

[0024] (7) The fluorescent guanine crystal nanosheets with specific exposed surfaces synthesized in this invention have good dispersibility in water or other solvents. The dispersion has obvious pearlescent color, which is bright and beautiful. Moreover, it can emit red or green fluorescence under the irradiation of light of a specific wavelength. Attached Figure Description

[0025] Figure 1SEM image of FITC-doped β-phase anhydrous guanine fluorescent nanosheets;

[0026] Figure 2 XRD pattern of FITC-doped β-phase anhydrous guanine fluorescent nanosheets;

[0027] Figure 3 Fluorescence micrograph of FITC-doped β-phase anhydrous guanine fluorescent nanosheets;

[0028] Figure 4 SEM image of Nile Red-doped β-phase anhydrous guanine fluorescent nanosheets;

[0029] Figure 5 Fluorescence micrograph of Nile Red-doped β-phase anhydrous guanine fluorescent nanosheets. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] Example 1

[0032] A method for preparing fluorescent guanine nanosheet crystals, the specific steps of which include:

[0033] The first step is to prepare a sodium hydroxide solution of guanine. The specific method is as follows: mix guanine powder and sodium hydroxide solution to obtain a solution with a guanine concentration of 0.1M and a sodium hydroxide concentration of 0.4M.

[0034] The second step is to prepare a dispersion. The specific method is as follows: prepare a dispersion by mixing 10 ml of formamide, 100 mg of P (VP-co-VA), 5 mg of uric acid and 5 mg of FITC.

[0035] The third step involves adding the dispersion prepared in the second step to the solution prepared in the first step, mixing them, and reacting at 40°C for 10 hours to obtain a pale yellow dispersion of guanine nanosheets that emits fluorescence. The dispersion is then subjected to multiple centrifugation and washing processes to obtain fluorescent guanine nanosheet crystals. The obtained fluorescent guanine nanosheet crystals emit green fluorescence when irradiated with light in the wavelength range of 460 nm to 550 nm.

[0036] Figure 1 This is a SEM image of the FITC-doped β-phase anhydrous guanine fluorescent nanosheets in this embodiment, showing their elongated hexagonal shape;

[0037] Figure 2 The XRD of the FITC-doped β-phase anhydrous guanine fluorescent nanosheets in this embodiment shows a strong preferred orientation.

[0038] Figure 3A fluorescence micrograph of FITC-doped β-phase anhydrous guanine fluorescent nanosheets, showing bright green fluorescence.

[0039] An application of fluorescent guanine nanosheet crystals: The obtained fluorescent guanine nanosheet crystals are used as pearlescent pigments in fields such as fluorescent probes, skin care products, cosmetics, paper, coatings, rubber, paints, and coatings.

[0040] Example 2

[0041] A method for preparing fluorescent guanine nanosheet crystals, the specific steps of which include:

[0042] The first step is to prepare a sodium hydroxide solution of guanine. The specific method is as follows: mix guanine powder and sodium hydroxide solution to obtain a solution with a guanine concentration of 0.1M and a sodium hydroxide concentration of 0.4M.

[0043] The second step is to prepare a dispersion. The specific method is as follows: prepare a dispersion by mixing 10 ml of formamide, 10 mg of P (VP-co-VA), 50 mg of uric acid and 0.5 mg of FITC.

[0044] The third step involves adding the dispersion prepared in the second step to the solution prepared in the first step, mixing them, and reacting them at 40°C for 24 hours to obtain a dispersion of purple guanine nanosheets that emits fluorescence. The dispersion is then subjected to multiple centrifugation and washing processes to obtain fluorescent guanine nanosheet crystals. The obtained fluorescent guanine nanosheet crystals emit red or orange fluorescence when irradiated with light in the wavelength range of 480 nm to 540 nm.

[0045] Figure 4 This is a SEM image of the Nile Red-doped β-phase anhydrous guanine fluorescent nanosheets in this embodiment, showing the elongated hexagonal sheet shape and preferred orientation.

[0046] Figure 5 This is a fluorescence microscope image of the Nile Red-doped β-phase anhydrous guanine fluorescent nanosheets in this embodiment, showing bright red fluorescence.

[0047] An application of fluorescent guanine nanosheet crystals: The obtained fluorescent guanine nanosheet crystals are used as pearlescent pigments in fields such as fluorescent probes, skin care products, cosmetics, paper, coatings, rubber, paints, and coatings.

[0048] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Those skilled in the art can modify or make equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention. The scope of protection of the present invention should be determined by the claims.

Claims

1. A fluorescent guanine nanosheet crystal, characterized in that: The fluorescent guanine nanosheet crystal is a β-phase anhydrous guanine crystal nanosheet with exposed (100) crystal planes, and fluorescent molecules are embedded in the crystal lattice of the fluorescent guanine nanosheet crystal. The preparation method of the fluorescent guanine nanosheet crystals includes the following steps: The first step is to prepare a sodium or potassium salt solution of guanine; The second step is to prepare the dispersion. The specific method is to prepare the formamide, small molecule additive, high molecular weight additive and fluorescent dye additive into a dispersion according to the set ratio. The third step is to add the dispersion prepared in the second step to the solution prepared in the first step, mix them, and let them stand for 10 to 24 hours to obtain a dispersion of colored guanine nanosheets that can emit fluorescence. The dispersion is then subjected to a centrifugation-washing process to obtain fluorescent guanine nanosheet crystals. In the first step, the method for preparing a sodium or potassium salt solution of guanine is as follows: prepare a solution by mixing guanine powder with sodium hydroxide or potassium hydroxide; The molar ratio of guanine to sodium hydroxide or potassium hydroxide is 1:(3~5), and the concentration of guanine in the resulting solution is 0.05-0.2M, and the concentration of sodium hydroxide or potassium hydroxide is 0.3-0.5M. In the second step, the polymer additive is a vinylpyrrolidone-based polymer, a copolymer of vinyl acetate and N-vinylpyrrolidone, or polyvinylpyrrolidone; the small molecule additive is uric acid; the fluorescent dye additive is Nile red or fluorescein isothiocyanate, and a dispersion is prepared at RT~60℃. The mass ratio of formamide, small molecule additive, polymeric additive, and fluorescent dye additive is 10:(0.1~50):(1~100):(0.5~5)*10 -3 ; The volume ratio of formamide, sodium guanine salt, or potassium guanine salt solution is 10:0.25~1.

5.

2. An application of the fluorescent guanine nanosheet crystal according to claim 1, characterized in that: The obtained fluorescent guanine nanosheet crystals were used as pearlescent pigments in fluorescent probes, skin care products, cosmetics, paper, coatings, rubber, paints, and varnishes.

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