Long-afterglow silicon dioxide nanoparticles as well as preparation method and application thereof

Abstract

The invention provides a long-afterglow silicon dioxide nanosphere as well as a preparation method and application thereof, and belongs to the technical field of inorganic nano materials. In order to solve the problems that an existing room temperature phosphorescence (RTP) material depends on metal or organic fluorophores, the light stability is poor, the biotoxicity is high and the like, the long afterglow silicon dioxide nanospheres free of the metal and the organic fluorophores are prepared through a silicon source copolycondensation and calcination defect engineering strategy. According to the material, a silicon source precursor and a silane coupling agent are used as raw materials, polysaccharide-assisted copolycondensation is performed to form a triple bond Si-O-network, and then high-temperature calcination is performed to generate optical activity defects related to carbon impurities in a silicon dioxide matrix, so that long-life room-temperature phosphorescence (the afterglow life reaches 1.852 s) is realized. The material has the characteristics of excellent light stability, low biotoxicity and no autofluorescence interference, is suitable for anti-counterfeiting device imaging, and breaks through the defects of low luminous efficiency and poor stability of the traditional RTP material.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of inorganic nanomaterials, and particularly relates to a long-afterglow silica nanosphere with room-temperature phosphorescence (RTP) characteristics and a preparation method thereof, and application of the material in the fields of anti-counterfeiting devices, biomedical imaging, cancer diagnosis, etc. BACKGROUND

[0002] Room-temperature phosphorescence (RTP) materials have important application value in the fields of optical imaging and biomedical detection due to their characteristic of sustained luminescence after the excitation light source is turned off. Traditional RTP materials are mainly divided into two categories: one is a system based on metal complexes (such as ruthenium, iridium, etc.), which has a long phosphorescence lifetime but has a risk of heavy metal toxicity and a complex synthesis process; the other is a non-metallic organic compound (such as an organic molecule containing an aromatic ring or a heteroatom), which has the advantage of low toxicity but has a short phosphorescence lifetime, poor light stability, and is prone to performance decay due to photobleaching or molecular aggregation. In addition, the above-mentioned materials are prone to interact with biological molecules in a complex biological environment, triggering uncontrollable metabolic or immune reactions, which limits their application in long-term in vivo imaging. Although in recent years there have been attempts to coat organic phosphors with inorganic carriers (such as silica and carbon dots) to improve stability, the residual organic fluorophores may still produce background fluorescence interference, and the interface defects between the carrier and the phosphor will reduce the energy transfer efficiency, making it difficult to meet the needs of high signal-to-noise ratio and self-fluorescence-free biological imaging.

[0003] To solve the above problems, it is an urgent need to develop a RTP material that is completely free of metal and organic fluorophores, has long afterglow lifetime and excellent biocompatibility. Silica nanoparticles (SNP) are considered as ideal carriers due to their chemical inertness, tunable pore structure and good biological safety. However, existing silica-based RTP materials mostly rely on physical adsorption or covalent bonding to introduce external phosphors (such as carbon dots, organic molecules), which cannot fundamentally solve the problems of residual organic components or insufficient stability. For example, the research of Jinan University embeds carbon dots into silica microspheres by hydrothermal method, and uses the rigidity of SiO2 to protect the triplet excitons of carbon dots, but its luminescence still depends on the doping of carbon dots, and the preparation of carbon dots needs complex hydrothermal and purification steps (CN202410955143.1). Similarly, Liu Jian prepares CDs@SiO2 material by in-situ loading amine / phenolic precursor and calcination, although the phosphorescent lifetime is as long as 4954.73 ms, but still needs carbon dots as the luminescent center, which may cause performance degradation due to oxidation or solvent erosion of carbon dots (CN202410356688.0). In addition, the pure organic RTP material developed by Professor Yang Bing avoids metal toxicity, but needs complex organic synthesis steps, and the high temperature resistance and light stability of organic components are limited. The team of Professor Benzhong Tang of the Chinese University of Hong Kong uses biological fermentation method to dope indole carbazole derivatives into bacterial cellulose, although long afterglow is achieved, but it still belongs to physical blending strategy, and there is a risk of phase separation, which may cause phosphorescence quenching due to molecular migration in long-term use. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art, and provides a long afterglow silica nanoparticle and its preparation method and application. Specifically, to solve the problem that the preparation and purification steps of the material prepared by the prior art are complicated, the cost is high, the time is consumed, and the application is restricted, the present application provides a phosphorescent silica / carbon nanocomposite with core-shell structure and its preparation method and application.

[0005] For the first time, the present application directly constructs intrinsic defect luminescent centers in the silica matrix through the strategy of "polysaccharide assisted co-condensation-calcination defect engineering". Specifically, the carbon impurities produced by the pyrolysis of polysaccharide / silane coupling agent in the calcination process combine with the dangling bonds (such as ≡Si-O- defects) in the SiO2 network to form localized electron trap states, which can realize long afterglow emission (1.852 s) without any external phosphor. This method not only completely eliminates organic or metal components, but also inhibits non-radiative transition through inorganic rigid network, solving the stability problem caused by component residues or interface defects in traditional materials, and providing a safer and long-acting solution for biomedical applications.

[0006] The technical solution of the present application is as follows: The first aspect of the present application provides a preparation method of long-afterglow silica nanoparticles, comprising the following steps: Mixing anhydrous ethanol, ammonia water and deionized water to obtain a mixed solution; Adding a silicon source and a silane coupling agent into the mixed solution, stirring, standing and aging, and washing with water and alcohol alternately to obtain a white precursor after drying; Calcining the white precursor to obtain long-afterglow silica nanoparticles.

[0007] Optionally, the preparation raw material further comprises a polysaccharide, and when the preparation raw material comprises the polysaccharide, the preparation method comprises the following steps: S1, mixing anhydrous ethanol, ammonia water and deionized water to obtain a mixed solution; dissolving a polysaccharide in the mixed solution and stirring to obtain a polysaccharide solution; S2, adding a silicon source and a silane coupling agent into the polysaccharide solution, stirring, standing and aging, and washing with water and alcohol alternately to obtain a white precursor after drying; S3, calcining the white precursor to obtain long-afterglow silica nanoparticles.

[0008] Optionally, in S1, the polysaccharide is at least one of pectin, starch, mannan and galactose.

[0009] Optionally, in S1, the adding ratio of the polysaccharide, anhydrous ethanol, ammonia water and deionized water is 0-200 mg: 20-100 mL: 0.1-20 mL: 0.1-50 mL.

[0010] Optionally, in S1, the stirring temperature is 25-80 ℃, and the stirring time is 10-120 min.

[0011] Optionally, in S2, the adding ratio of anhydrous ethanol, a silicon source and a silane coupling agent is 20-100 mL: 1 mol: 0.1-1.4 mol, and the silicon source is an inorganic or organic silicon source.

[0012] Optionally, in S2, the silicon source is sodium silicate or tetraethyl orthosilicate, and the silane coupling agent is one or more of vinyltriethoxysilane, KH-550, APTES and GPTMS.

[0013] Optionally, in S3, the calcination temperature is 400-1000 ℃, and the calcination time is 2-6 h.

[0014] Optionally, the preparation method specifically comprises the following steps: Dissolve a certain mass of pectin (0~200 mg) in a mixed solution of anhydrous ethanol, ammonia water and deionized water with a volume ratio of (20~100) mL:(0.1~20) mL:(0.1~50) mL, stir at (25~80 ℃) for (10~120) min, then add a certain molar ratio of a silicon source and a silane coupling agent, stir vigorously, and then stir gently for (6~48) h. After standing and aging, the white precursor is obtained after washing with water and alcohol alternately and drying. The dried white powder is placed in a high-temperature furnace and calcined at (400~1000) ℃ for (2~6) h, and the target product is obtained after natural cooling.

[0015] The second aspect of the present application provides a long afterglow silicon dioxide nanoparticle prepared by the above preparation method.

[0016] Optionally, the particle size of the long afterglow silicon dioxide nanoparticle is 150~300 nm. Optionally, the fluorescence optimal excitation wavelength of the long afterglow silicon dioxide nanoparticle is 344 nm, the optimal emission wavelength is 447 nm, the phosphorescence optimal excitation wavelength of the long afterglow silicon dioxide nanoparticle is 300 nm, the optimal emission wavelength is 487 nm, and the phosphorescence lifetime of the long afterglow silicon dioxide nanoparticle is 1.852 s.

[0017] The third aspect of the present application provides an application of a long afterglow silicon dioxide nanoparticle in biomedical imaging and cancer diagnosis.

[0018] The long afterglow silicon dioxide nanoparticle prepared by the present application has excellent light stability, low biological toxicity and no self-fluorescence interference characteristics, and is suitable for high-contrast biomedical imaging, cancer diagnosis and targeted therapy fields, and can break through the limitations of traditional RTP materials in long-term in vivo applications.

[0019] The technical principle of the present application is: 1. The core of the present application is to construct stable luminescent centers in a silicon dioxide matrix through a polysaccharide / silane coupling agent template-calcination defect engineering strategy: 2. Defect formation mechanism: carbon impurities generated by pyrolysis of polysaccharide / silane coupling agent templates during the calcination process combine with dangling bonds (such as ≡Si–O– defects) in the silicon-oxygen network to form localized electronic trap states. These defect states realize long-lifetime phosphorescence emission through the capture-release of charge carriers; 3. Inorganic matrix stability: the rigid network of silicon dioxide inhibits non-radiative transitions, prolongs the afterglow lifetime, and its chemical inertness ensures the long-term stability of the material in a biological environment.

[0020] The present application has at least one of the following beneficial effects: Compared with the prior art, the phosphorescent long afterglow silica nanospheres prepared by the application have the following remarkable advantages: 1. No metal / no organic fluorophore: completely abandoning the heavy metals or organic components in traditional RTP materials, fundamentally solving the biological toxicity problem; 2. Long afterglow characteristics: afterglow lifetime of more than 100 ms, far exceeding the non-metallic organic RTP materials (usually <10 ms); 3. High light stability: inorganic silica matrix resists photobleaching, phosphorescence intensity retention rate >90% under continuous light (traditional organic materials <50%); BRIEF DESCRIPTION OF DRAWINGS In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings in the embodiment or prior art description, but the drawings in the following description are only some embodiments described in the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0021] Figure 1 SEM images of long afterglow silica nanospheres prepared in Example 1, Example 2, Example 3 and Example 4.

[0022] Figure 2 XRD pattern of long afterglow silica nanospheres prepared in Example 1 to Example 8.

[0023] Figure 3 Fluorescence excitation and emission spectrum (a) and phosphorescence excitation and emission spectrum (b) of long afterglow silica nanospheres prepared in Example 1.

[0024] Figure 4 Phosphorescence lifetime diagram of long afterglow silica nanospheres prepared in Example 1.

[0025] Figure 5 Fluorescence excitation and emission spectrum (a) and phosphorescence excitation and emission spectrum (b) of long afterglow silica nanospheres prepared in Example 3.

[0026] Figure 6 Phosphorescence lifetime diagram of long afterglow silica nanospheres prepared in Example 3.

[0027] Figure 7 is the actual picture of long afterglow silica nanospheres applied in anti-fake device under sunlight and ultraviolet lamp irradiation in Example 9.

[0028] Figure 8 is the actual picture of long afterglow silica nanospheres applied in anti-fake device under sunlight and ultraviolet lamp irradiation in Example 9. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0030] All other examples obtained by a person of ordinary skill in the art without making creative efforts belong to the scope of protection of the present application.

[0031] The experimental methods described in each example are conventional methods unless otherwise specified; the reagents and materials, unless otherwise specified, can be purchased on the market.

[0032] Example 1: A preparation method of long afterglow silica nanoparticles, comprising the following steps: Mixing 60 mL:2 mL:2 mL of anhydrous ethanol, ammonia water and deionized water in a volume ratio, stirring at 40 ℃ for 30 min to obtain a mixed solution, then adding 1 mol:0.2 mol of tetraethyl orthosilicate and silane coupling agent A-151 in a molar ratio, stirring vigorously, and then stirring gently for 12 h. After standing and aging, the white precursor is obtained after washing with water and alcohol alternately and drying. The dried white powder is placed in a high-temperature furnace and calcined at 600 ℃ for 5 h, and the target product is obtained after natural cooling.

[0033] Figure 1 (a) is the SEM image of the long afterglow silica nanoparticles prepared in Example 1, from Figure 1 As can be seen from (a), the long afterglow silica nanoparticles prepared in Example 1 are uniformly distributed, and the particle size is about 150 nm.

[0034] Figure 2 The XRD pattern of the long afterglow silica nanoparticles prepared in Example 1 to Example 8, from Figure 2 As can be seen from (a), the long afterglow silica nanoparticles prepared in Example 1 are uniformly distributed, and the particle size is about 150 nm.

[0035] Figure 3 The fluorescence excitation and emission spectrum (a) and phosphorescence excitation and emission spectrum (b) of the long afterglow silica nanoparticles prepared in Example 1. From Figure 3 The optimal excitation wavelength of the sample is 365 nm, and the optimal emission wavelength is 442 nm; the optimal excitation wavelength of the phosphorescence is 312 nm, and the optimal emission wavelength is 484 nm.

[0036] Figure 4This is the phosphorescence lifetime diagram of the long afterglow silica nanoparticles prepared in Example 1. Figure 4 It can be seen that the phosphorescence lifetime of the prepared long afterglow silica nanoparticles is 1.332 s.

[0037] Example 2: A method for preparing long-lasting silica nanoparticles comprises the following steps: 50 mg of pectin was dissolved in a mixture of anhydrous ethanol, ammonia, and deionized water (60 mL:2 mL:2 mL, by volume) and stirred at 40°C for 30 min. Then, ethyl orthosilicate and silane coupling agent A-151 (1 mol:0.1 mol) were added, followed by vigorous stirring and then gentle stirring for 12 h. The mixture was allowed to age, washed alternately with water and alcohol, and dried to obtain a white precursor. The dried white powder was calcined in a high-temperature furnace at 600°C for 5 h, then cooled naturally to obtain the desired product.

[0038] Figure 1 (b) is the SEM image of the long afterglow silica nanoparticles prepared in Example 2. Figure 1 (b) shows that the phosphorescent long-lasting silica nanoparticles prepared in Example 2 are evenly distributed and have a particle size of about 200 nm.

[0039] Figure 2 The XRD patterns of the long afterglow silica nanoparticles prepared in Examples 1 to 8 are as follows: Figure 2 It can be seen that the long afterglow silica nanoparticles prepared in Example 2 have no crystal structure, further verifying that it is an amorphous material.

[0040] Example 3: A method for preparing long-lasting silica nanoparticles comprises the following steps: 50 mg of pectin was dissolved in a mixture of anhydrous ethanol, ammonia, and deionized water (60 mL:2 mL:2 mL, by volume) and stirred at 40°C for 30 min. Then, ethyl orthosilicate and silane coupling agent A-151 (1 mol:0.2 mol) were added, followed by vigorous stirring and then gentle stirring for 12 h. The mixture was allowed to age, washed alternately with water and alcohol, and dried to obtain a white precursor. The dried white powder was calcined in a high-temperature furnace at 600°C for 5 h, then cooled naturally to obtain the desired product.

[0041] Figure 1 (c) is the SEM image of the long afterglow silica nanoparticles prepared in Example 3. Figure 1 (c) shows that the long afterglow silica nanoparticles prepared in Example 3 are evenly distributed and have a particle size of about 250 nm.

[0042] Figure 2 The XRD pattern of the long afterglow silica nanoparticles prepared in Example 3 can be seen from Figure 2 It can be seen from (d) that the long afterglow silica nanoparticles prepared in Example 3 are uniformly distributed, and the particle size is about 300 nm.

[0043] Figure 5 The fluorescence excitation and emission spectra (a) and phosphorescence excitation and emission spectra (b) of the long afterglow silica nanoparticles prepared in Example 3. From Figure 3 The optimal excitation wavelength of the sample fluorescence is 344 nm, and the optimal emission wavelength is 447 nm; the optimal excitation wavelength of the phosphorescence is 300 nm, and the optimal emission wavelength is 487 nm.

[0044] Figure 6 The phosphorescence lifetime diagram of the long afterglow silica nanoparticles prepared in Example 3. From Figure 4 It can be seen that the phosphorescence lifetime of the prepared long afterglow silica nanoparticles is 1.852 s.

[0045] Example 4: A preparation method of long afterglow silica nanoparticles, comprising the following steps: Dissolve 50 mg of pectin in a mixed solution of 60 mL:2 mL:2 mL of anhydrous ethanol, ammonia water and deionized water in a volume ratio, stir at 40°C for 30 min, then add 1 mol:0.3 mol of tetraethyl orthosilicate and silane coupling agent A-151 in a molar ratio, after vigorous stirring, then gently stir for 12 h. After standing and aging, the white precursor is obtained after alternating washing with water and alcohol and drying. The dried white powder is placed in a high temperature furnace and calcined at 600°C for 5 h, and the target product is obtained after natural cooling.

[0046] Figure 1 (d) The SEM diagram of the long afterglow silica nanoparticles prepared in Example 4 can be seen from Figure 1 It can be seen from (d) that the long afterglow silica nanoparticles prepared in Example 4 are uniformly distributed, and the particle size is about 300 nm.

[0047] Figure 2 The XRD pattern of the long afterglow silica nanoparticles prepared in Example 1 to Example 8 can be seen from Figure 2 It can be seen from (d) that the long afterglow silica nanoparticles prepared in Example 4 are uniformly distributed, and the particle size is about 300 nm.

[0048] Example 5: A preparation method of long afterglow silica nanoparticles, comprising the following steps: 100 mg pectin was dissolved in a mixed solution of anhydrous ethanol, ammonia water and deionized water with a volume ratio of 60 mL:2 mL:2 mL, stirred at 40 ℃ for 30 min, then 1 mol:0.1 mol of tetraethyl orthosilicate and silane coupling agent A-151 were added, after vigorous stirring, then gentle stirring for 12 h. After standing and aging, the white precursor was obtained after washing with water and alcohol alternately and drying. The dried white powder was placed in a high temperature furnace and calcined at 600 ℃ for 5 h, and the target product was obtained after natural cooling.

[0049] Figure 2 The XRD pattern of the long afterglow silica nanoparticles prepared in Example 1 to Example 8 can be seen from Figure 2 , which shows that the long afterglow silica nanoparticles prepared in Example 5 have no crystal structure, further verifying that it is an amorphous material.

[0050] Example 6: A method for preparing long afterglow silica nanoparticles, comprising the following steps: A mixed solution was obtained by mixing anhydrous ethanol, ammonia water and deionized water with a volume ratio of 60 mL:2 mL:2 mL, stirred at 40 ℃ for 30 min, then 1 mol:0.1 mol of tetraethyl orthosilicate and silane coupling agent A-151 were added, after vigorous stirring, then gentle stirring for 12 h. After standing and aging, the white precursor was obtained after washing with water and alcohol alternately and drying. The dried white powder was placed in a high temperature furnace and calcined at 600 ℃ for 5 h, and the target product was obtained after natural cooling.

[0051] Figure 2 The XRD pattern of the long afterglow silica nanoparticles prepared in Example 1 to Example 8 can be seen from Figure 2 , which shows that the long afterglow silica nanoparticles prepared in Example 6 have no crystal structure, further verifying that it is an amorphous material.

[0052] Example 7: A method for preparing long afterglow silica nanoparticles, comprising the following steps: A mixed solution was obtained by mixing anhydrous ethanol, ammonia water and deionized water with a volume ratio of 60 mL:2 mL:2 mL, stirred at 40 ℃ for 30 min, then 1 mol:0.1 mol of tetraethyl orthosilicate and silane coupling agent A-151 were added, after vigorous stirring, then gentle stirring for 12 h. After standing and aging, the white precursor was obtained after washing with water and alcohol alternately and drying. The dried white powder was placed in a high temperature furnace and calcined at 600 ℃ for 5 h, and the target product was obtained after natural cooling.

[0053] Figure 2 The XRD pattern of the long afterglow silica nanoparticles prepared in Example 1 to Example 8 shows that the long afterglow silica nanoparticles prepared in Example 1 to Example 8 have no crystal structure, further verifying that they are amorphous materials. Figure 2 The XRD pattern of the long afterglow silica nanoparticles prepared in Example 1 to Example 8 shows that the long afterglow silica nanoparticles prepared in Example 1 to Example 8 have no crystal structure, further verifying that they are amorphous materials.

[0054] Example 8 A method for preparing long afterglow silica nanoparticles, comprising the following steps: Mixing anhydrous ethanol, ammonia water and deionized water in a volume ratio of 60 mL:2 mL:2 mL, stirring at 40 ℃ for 30 min to obtain a mixed solution, then adding tetraethyl orthosilicate and silane coupling agent A-151 in a molar ratio of 1 mol:0.4 mol, stirring vigorously, and then stirring gently for 12 h. After standing and aging, the white precursor is obtained after washing with water and alcohol alternately and drying. The dried white powder is placed in a high-temperature furnace and calcined at 600 ℃ for 5 h, and the target product is obtained after natural cooling.

[0055] Figure 2 The XRD pattern of the long afterglow silica nanoparticles prepared in Example 1 to Example 8 shows that the long afterglow silica nanoparticles prepared in Example 1 to Example 8 have no crystal structure, further verifying that they are amorphous materials. Figure 2 The XRD pattern of the long afterglow silica nanoparticles prepared in Example 1 to Example 8 shows that the long afterglow silica nanoparticles prepared in Example 1 to Example 8 have no crystal structure, further verifying that they are amorphous materials.

[0056] Example 9 The application of long afterglow silica nanoparticles in anti-counterfeiting devices in Example 2 comprises the following steps: placing the prepared long afterglow silica nanoparticles in the device, which is white powder under sunlight, blue-violet fluorescence under ultraviolet lamp irradiation, and yellow-green phosphorescence after removing the ultraviolet lamp irradiation light source. As shown in Figure 7 , Figure 8 .

[0057] Comparative Example 1 The difference from Example 2 is that no silane coupling agent A-151 is added, and the other steps are the same as Example 2.

[0058] The prepared sample has fluorescence and phosphorescence, but the fluorescence and phosphorescence are very weak.

[0059] Comparative Example 2 The difference from Example 2 is that the calcination temperature is changed to 300 ℃, and the other steps are the same as Example 2.

[0060] The prepared sample only has fluorescence and no phosphorescence.

[0061] Comparative Example 3 The difference from Example 2 is that the calcination temperature is changed to 1200 ℃, and the other steps are the same as Example 2.

[0062] The prepared sample has neither fluorescence nor phosphorescence.

[0063] Comparative Example 4 The difference from Example 2 is that no ammonia water is added, and other steps are the same as Example 2.

[0064] The prepared sample has only fluorescence and weak phosphorescence.

[0065] Comparative Example 5 The difference from Example 2 is that no anhydrous ethanol is added, and other steps are the same as Example 2.

[0066] No precipitate is produced after the reaction, and the long afterglow silicon dioxide nanoparticles cannot be obtained.

[0067] In summary, according to the content of Examples 1-8, it can be seen that the long afterglow silicon dioxide nanoparticles can be prepared with or without pectin, but the phosphorescence lifetime of the long afterglow silicon dioxide nanoparticles prepared in Example 1 is 1.332 s, and the phosphorescence lifetime of the long afterglow silicon dioxide nanoparticles prepared in Example 3 is 1.852 s, which indicates that the long afterglow performance of the silicon dioxide nanoparticles prepared after adding pectin is better than that without adding pectin.

[0068] According to Example 9, it can be seen that the long afterglow silicon dioxide nanoparticles prepared in the application present yellow-green phosphorescence after the ultraviolet light source is removed, and yellow-green phosphorescence can still be displayed after 4 s, so it can be used in anti-counterfeiting devices.

[0069] It can be seen from Comparative Examples 1-5 that whether to add a silane coupling agent, the calcination temperature, and whether to add a solvent all affect the long afterglow performance of the silicon dioxide nanospheres.

[0070] The above is only a preferred specific embodiment of the application, but the protection scope of the application is not limited thereto, and any person skilled in the art can make equivalent substitutions or changes to the technical solution and the inventive concept of the application within the technical scope disclosed by the application, which should be covered within the protection scope of the application.

Claims

1. A method for preparing long-lasting silica nanoparticles, characterized in that: The following steps are involved: mixing anhydrous ethanol, aqueous ammonia and deionized water to obtain a mixed solution; Adding a silicon source and a silane coupling agent to the mixed solution, stirring, standing for aging, washing alternately with water and alcohol, and drying to obtain a white precursor; The white precursor is calcined to obtain long-lasting silica nanoparticles.

2. The preparation method according to claim 1, characterized in that The preparation raw materials also include polysaccharides. When the preparation raw materials include polysaccharides, the preparation method includes the following steps: S1. Mixing anhydrous ethanol, aqueous ammonia, and deionized water to obtain a mixed solution; dissolving a polysaccharide in the mixed solution and stirring to obtain a polysaccharide solution; S2. Adding a silicon source and a silane coupling agent to the polysaccharide solution, stirring, standing for aging, washing alternately with water and alcohol, and drying to obtain a white precursor; S3. calcining the white precursor to obtain long-lasting silica nanoparticles.

3. The preparation method according to claim 2, characterized in that In S1, the polysaccharide is at least one of pectin, starch, mannan and galactose; The addition ratio of polysaccharide, anhydrous ethanol, ammonia water and deionized water is 0-200 mg: 20-100 mL: 0.1-20 mL: 0.1-50 mL, the stirring temperature is 25-80 °C, and the stirring time is 10-120 min.

4. The preparation method according to claim 2, characterized in that In S2, the addition ratio of anhydrous ethanol, silicon source and silane coupling agent is 20~100 mL: 1 mol: 0.1~1.4 mol, and the silicon source is an inorganic or organic silicon source.

5. The preparation method according to claim 2, characterized in that In S2, the silicon source is sodium silicate or ethyl orthosilicate, and the silane coupling agent is one or more of vinyltriethoxysilane, KH-550, APTES and GPTMS.

6. The preparation method according to claim 2, characterized in that In S3, the calcination temperature is 400~1000℃, and the calcination time is 2~6 h.

7. A long afterglow silica nanoparticle, characterized in that: The preparation method according to any one of claims 1 to 6 is used to prepare the compound.

8. The long afterglow silica nanoparticles according to claim 7, characterized in that: The particle size of the long afterglow silica nanoparticles is 150-300 nm.

9. The long afterglow silica nanoparticles according to claim 7, characterized in that: The optimal fluorescence excitation wavelength of the long afterglow silica nanoparticles is 344 nm, and the optimal emission wavelength is 447 nm. The optimal phosphorescence excitation wavelength of the long afterglow silica nanoparticles is 300 nm, and the optimal emission wavelength is 487 nm. The phosphorescence lifetime of the long afterglow silica nanoparticles is 1.852 s.

10. Use of the long-lasting silica nanoparticles according to any one of claims 7 to 9 in anti-counterfeiting devices.

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