Nanocomposite material for enhancing fluorescence intensity of micromolecular organic dye based on CeO2 and preparation

Abstract

The invention relates to a CeO2-based nano composite material for enhancing the fluorescence intensity of a small-molecule organic dye and preparation, and belongs to the technical field of nano composite materials. The preparation method comprises the step of connecting cerium dioxide subjected to organic phosphate surface treatment with activated non-phosphate fluorescent dye. According to the fluorescent material, the dye can be successfully connected to CeO2, the fluorescence intensity of the non-phosphate small-molecule fluorescent dye is enhanced, the synthesis mode is simple, the cost is low, the limitation that CeO2 can only enhance the fluorescence intensity of the phosphate dye is broken through, the fluorophore application range is wide, and meanwhile due to the multifunctionality of low cost, oxygen storage, catalysis and the like of the CeO2 material, the fluorescence intensity of the non-phosphate small-molecule fluorescent dye can be enhanced. The design of the CeO2 (at) Dye model provides value reference for synthesis of the integrated multifunctional nanocomposite material, and provides potential application prospects in the aspects of fluorescence sensing, optical recording, photoelectric conversion and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of nanocomposite materials, and more specifically, relates to a nanocomposite material based on CeO2 and capable of enhancing the fluorescence intensity of small molecule organic dyes and its preparation. Background Art

[0002] Surface enhanced fluorescence (SEF) technology significantly improves the intensity and stability of fluorescence signals by optimizing the electromagnetic environment around fluorescent molecules. This technology is widely used in biological markers, fluorescence imaging and cancer diagnosis and treatment in the biological field, improving detection sensitivity and imaging resolution; in the field of optoelectronic devices, it is used as a fluorescent probe and sensor to enhance detection performance; at the same time, it also shows potential in the fields of photography and nonlinear optical devices, promoting the progress of modern science and technology. In the research progress based on plasmon enhanced spectroscopy technology, the surface plasmon effect of noble metal materials is well known and widely used in surface enhanced Raman scattering (SERS) and SEF. Semiconductor materials also show similar physical effects, which lays the foundation for the success of semiconductor materials in the field of SERS and has achieved remarkable results, but is relatively lagging behind in direct enhanced fluorescence (SEF). However, why semiconductors have not developed as rapidly as Raman enhancement in fluorescence enhancement has become a scientific blind spot worth exploring.

[0003] Cerium dioxide CeO2 is an important rare earth material with a unique crystal structure and rich oxygen vacancies. Its ions can cycle between 3+ and 4+ valence states. This feature gives it unique advantages in optoelectronic devices, chip manufacturing, catalysis, energy conversion, environmental protection, chemical sensing and biomedicine. Although cerium dioxide itself has a weak luminescence effect, its luminescence effect is not significant. There are still difficulties in material synthesis, degree of fluorescence enhancement and wavelength control by doping rare earth ions in CeO2 to enhance fluorescence. Therefore, cerium dioxide itself is generally not used as a luminescent material. However, as a semiconductor material, CeO2 can also show effects similar to surface plasmons. It is more appropriate to use it as a substrate to enhance optical signals, which has been confirmed in semiconductor enhanced Raman. However, there are few reports on CeO2 as a substrate in the enhancement of small molecule fluorescence.

[0004] Due to the new applications of small molecule organic dyes in chemical sensing, nanophotonics, catalysis, drug delivery and therapeutic diagnostics, people are increasingly interested in the synthesis of inorganic nanoparticles and organic dyes, as well as performance research and application expansion. The unique characteristics of fluorescent dyes and nanoparticles can be combined to produce new effects. At present, most of the research on cerium dioxide and dyes is adsorption removal, photocatalytic degradation, and a few studies on fluorescence regulation, such as the report on the formation of J-polymers in cerium dioxide by dyes in the Journal of Physical Chemistry C (J.Phys.Chem.C, 2018, 122, 36, 20996–21003). In order to fill this research gap, it is of great research value and practical significance to use semiconductor materials, especially low-cost and highly abundant metal oxide CeO2, to finely control its synthesis process and the type of fluorophores to explore new ways to enhance fluorescence and broaden the function and application range of CeO2 materials. Summary of the invention

[0005] The present invention solves the technical problem of the lack of enhancement of the fluorescence intensity of non-phosphate fluorescent dyes in the prior art, and provides a nanocomposite material based on CeO2 for enhancing the fluorescence intensity of small molecule organic dyes, which is obtained by connecting surface-treated cerium dioxide (organophosphate-modified cerium dioxide) with activated non-phosphate fluorescent dyes. The fluorescent material of the present invention can enhance the fluorescence intensity of non-phosphate fluorescent dyes, and the synthesis method is simple and low-cost, which expands the new application of fluorescence enhancement of semiconductor materials. The fluorescence enhancement material provides a reference for the design of multifunctional integrated nanocomposites, and provides potential application prospects for bioluminescence imaging, sensor devices, fluorescence anti-counterfeiting, dye-sensitized solar cells, and integrated diagnosis and treatment.

[0006] According to a first aspect of the present invention, a method for preparing a nanocomposite material based on CeO2 for enhancing the fluorescence intensity of small molecule organic dyes is provided, comprising the following steps:

[0007] (1) adding a complexing precipitant to a cerium source solution to react and obtain cerium dioxide;

[0008] (2) adding an organic phosphate to the cerium dioxide obtained in step (1) under a protective atmosphere to obtain a fluorescence enhancing substrate material;

[0009] (3) placing the non-phosphate small molecule fluorescent dye in a buffer solution, adding 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide for activation, thereby obtaining an activated non-phosphate small molecule fluorescent dye;

[0010] (4) reacting the fluorescence enhancement base material obtained in step (2) with the activated non-phosphate small molecule fluorescent dye obtained in step (3) under protective atmosphere conditions to obtain the nanocomposite material.

[0011] Preferably, in step (2), the mass ratio of cerium dioxide to organic phosphate is 5:(1-25), and the organic phosphate is one or more of 2-phosphonobutane-1,2,4-tricarboxylic acid, 5-aminolevulinic acid phosphate, hexapotassium hexamethonium diaminetetramethylenephosphonic acid, and the like.

[0012] Preferably, in step (4), the molar ratio of the fluorescence enhancing substrate material to the activated non-phosphate small molecule fluorescent dye is 9:(1-81).

[0013] Preferably, the non-phosphate small molecule fluorescent dye is carboxycoumarin, aminocoumarin, rhodamine B, cyanine, carboxyfluorescein or tetracarboxyphenylporphyrin.

[0014] Preferably, in step (1), the reaction temperature is 70-100° C. and the reaction time is 2-6 h.

[0015] Preferably, in step (1), the cerium source is one of cerium nitrate, cerium sulfate, and ammonium cerium nitrate; and the complex precipitant is one of arginine, citric acid, and disodium ethylenediaminetetraacetic acid.

[0016] Preferably, the concentration of the cerium source is 1-15 g / L, and the molar ratio of the cerium source to the complex precipitant is 5:(1-25).

[0017] Preferably, in step (3), the mass ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to N-hydroxysuccinimide is 3:(1-9), the activation time is 0.5-2.5h, and the activation temperature is 20-40°C.

[0018] Preferably, in step (3), the concentration of the non-phosphate small molecule fluorescent dye is 0.01-1 mM.

[0019] According to another aspect of the present invention, there is provided a CeO2-based nanocomposite material for enhancing the fluorescence intensity of small molecule organic dyes prepared by any of the methods described above.

[0020] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0021] (1) Since natural phosphate fluorescent dyes are relatively rare, the cost of artificially synthesized phosphate fluorescent dyes is high, which limits the scope of fluorescent dye enhancement. Therefore, the present invention uses organic phosphates to expand the scope of application of fluorescent dyes to common non-phosphate small molecule fluorescent dyes by treating the surface of CeO2, thereby solving the limitation of only being able to enhance the fluorescence intensity of very few phosphate dyes. The obtained material has a wider application range and lower cost. At the same time, the synthesis method of the present invention is simple.

[0022] (2) The present invention fills the gap in semiconductor enhanced fluorescence and successfully constructs a "CeO2@Dye" fluorescence enhancement model. At present, there has been great progress in plasmon enhanced fluorescence and semiconductor enhanced Raman, but there are almost no detailed reports on the use of semiconductor enhanced fluorescence. Semiconductors (especially metal oxides) are highly abundant in the earth's crust and have low costs, and have more advantages and potential in industrial applications. CeO2 is a semiconductor material that contains abundant oxygen vacancies and has a plasmon-like effect. By regulating the synthesis of CeO2, CeO2 can regulate the signal of surface enhanced Raman. Similarly, this property can be used to enhance fluorescence, broadening the application of cerium dioxide materials in new fields. By flexibly changing the type of fluorescent dye connected, the fluorescence intensity and emission wavelength of the composite material can be achieved, and the designability is stronger. Specifically, CeO2 can significantly enhance the fluorescent dye under specific conditions through its unique physical and chemical properties. The surface plasmon-like effect of CeO2 further amplifies this fluorescence signal and achieves effective enhancement of fluorescence. This discovery not only reveals a new mechanism of CeO2 in fluorescence enhancement, but also provides new ideas and approaches for the application of cerium dioxide materials in biosensing, optoelectronics, energy conversion and other fields.

[0023] (3) The present invention cleverly utilizes organic phosphates to successfully connect CeO2 and non-phosphate small molecule fluorescent dyes in the form of covalent bonds. Cerium dioxide can strongly interact with the phosphate groups on the organic phosphates, and at the same time connect the activated non-phosphate fluorescent dyes through chemical reactions. Compared with the method of directly using cerium dioxide and fluorescent dyes to electrostatically adsorb and change the fluorescence intensity of the dye polymer state, chemical bonding can better stabilize the fluorescent dye small molecules, thereby achieving fluorescence enhancement. At the same time, the synthesis method is relatively simple, the temperature used is relatively mild and safe, and it has certain potential for industrial application; the resulting nanocomposite material has multiple integrated functions, combined with the characteristics of fluorescent dyes and cerium dioxide itself, and exerts the effect of "1+1>2". In addition to providing application value guidance in fluorescence sensing, bioimaging, and integrated diagnosis and treatment, as a composite material, it has certain application potential in photoelectric conversion materials, interface modification and compatibility improvement, photocatalysis, and energy storage.

[0024] (4) The present invention can change the degree of fluorescence enhancement by adjusting the synthesis conditions of CeO2, the content of organic phosphate and the amount of activated dye added, thereby changing the effect of fluorescence enhancement.

[0025] In summary, the fluorescent material of the present invention can achieve fluorescence enhancement and improve detection sensitivity; the synthesis method is simple and low-cost, and has a very significant fluorescence enhancement effect. In addition, since amino or carboxyl fluorescent dyes are relatively common and low-cost, they are widely used, and the enhanced fluorescent material can be applied to a wide range of fluorescent dyes, providing potential application prospects for optoelectronic devices, bioluminescent imaging, integrated diagnosis and treatment, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the fluorescence spectrum of cyanine dye Cy and cerium dioxide and cyanine dye composite nanomaterial CeO2@Cy, wherein the synthesis sequence of CeO2@Cy is to prepare CeO2' first and then connect activated Cy.

[0027] Figure 2 The present invention is the fluorescence spectrum of carboxycoumarin dye coumarin-COOH and cerium dioxide and carboxycoumarin dye composite nanomaterial CeO2@coumarin-COOH, wherein the synthesis sequence of CeO2@coumarin-COOH is to prepare CeO2' first and then connect activated coumarin-COOH.

[0028] Figure 3 The fluorescence spectrum of cyanine dye Cy and cerium dioxide and cyanine dye composite nanomaterial CeO2@Cy-2, where the synthesis order of CeO2@Cy is to first prepare Cy-PO3 4- , and then connect the activated Cy-PO3 with CeO2 4- .

[0029] Figure 4 The fluorescence spectrum of carboxy coumarin dye coumarin-COOH and cerium dioxide and carboxy coumarin dye composite nanomaterial CeO2@coumarin-COOH-2 is shown in Figure 2. The synthesis order of CeO2@coumarin-COOH is to prepare PO3 4- -coumarin-COOH, and then connect the activated PO3 with CeO2 4- -coumarin-COOH. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] The preparation method of the CeO2-based small molecule fluorescence enhancement material of the present invention is generally obtained by connecting surface-treated cerium dioxide (CeO2') with an activated fluorescent dye with a carboxyl group or an amino group (CeO2@Dye), which may include the following steps:

[0032] (1) adding a complexing precipitant to a cerium source solution and reacting at a certain temperature, and then separating and washing the product to obtain cerium dioxide CeO2;

[0033] (2) adding an organic phosphate to the CeO2 obtained in step (1) under a protective gas atmosphere, stirring at a certain temperature for a period of time, separating and washing the product to obtain the corresponding fluorescence enhancement substrate material CeO2';

[0034] (3) placing a small molecule fluorescent dye Dye with a carboxyl group or an amino group in a buffer, adding 1-ethyl-(3-dimethylaminopropyl) carbodiimide EDC and N-hydroxysuccinimide NHS, and activating at a certain temperature for a period of time to obtain Dye';

[0035] (4) The CeO2' obtained in step (2) is mixed and stirred with the activated fluorescent dye Dy obtained in step (3) in a protective gas atmosphere at a certain temperature for a period of time, and the products are separated and washed to obtain the corresponding enhanced fluorescent material CeO2@Dye.

[0036] In some embodiments, in step (1), the solvent used for the cerium source solution is ethanol, methanol, water, DMF, DMSO or a mixed solution in a fixed ratio.

[0037] In some embodiments, in step (1), the cerium source is one of cerium nitrate, cerium sulfate, and ammonium cerium nitrate, and the concentration is 1-15 g / L.

[0038] In some embodiments, in step (1), the complexing precipitant is one of arginine, citric acid, and disodium ethylenediaminetetraacetic acid.

[0039] In some embodiments, in step (1), the molar ratio of the cerium source solution to the complexing precipitant is 5:1-1:5.

[0040] In some embodiments, in step (1), the reaction temperature is 70-100° C. and the reaction time is 2-6 h.

[0041] In some embodiments, in step (2) and step (4), the protective atmosphere is one of nitrogen or argon.

[0042] In some embodiments, in step (2), the mass ratio of CeO2 to organic phosphate is 5:1-1:5.

[0043] In some embodiments, in step (2), the type of the organic phosphate is one or more of 2-phosphonobutane-1,2,4-tricarboxylic acid, 5-aminolevulinic acid phosphate, hexapotassium hexamethonium diaminetetramethylenephosphonic acid, and the like.

[0044] In some embodiments, in step (2), the certain temperature is 20-40° C., and the time is 0.5-3 days.

[0045] In some embodiments, in step (3), the small molecule fluorescent dye with a carboxyl group or an amino group is a small molecule fluorescent dye with an amino group or a carboxyl group, such as carboxycoumarin, aminocoumarin, rhodamine B, cyanine, carboxyfluorescein, or carboxyporphyrin.

[0046] In some embodiments, in step (3), the buffer component is morpholine buffer (MES) or phosphate buffer (PBS) with a concentration of 0.01-0.1 M and a pH of 5-7.

[0047] In some embodiments, in step (3), the mass ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide EDC to N-hydroxysuccinimide NHS is 3:1-1:3, the activation time is 0.5-2.5h, and the activation temperature is 20-40°C.

[0048] In some embodiments, in step (3), the concentration of the non-phosphate small molecule fluorescent dye is 0.01-1 mM.

[0049] In some embodiments, in step (4), the molar ratio of CeO2' to the activated fluorescent dye Dye' is 9:1-1:9.

[0050] In some embodiments, in step (4), the stirring time is 0.5-3 days, and the stirring temperature is 20-40°C.

[0051] The following are specific embodiments

[0052] Example 1

[0053] In a cerium nitrate solution, arginine was added and reacted at 80°C for 3h. The product was then separated and cleaned to obtain CeO2. Under a nitrogen atmosphere, 6mL of the above-prepared CeO2 solution (0.8g / L) was added with 0.012g of 5-aminolevulinic acid phosphate. After stirring at room temperature overnight, the product was separated and cleaned to obtain the corresponding fluorescence enhancement substrate material CeO2'.

[0054] The cyanine dye Cy was placed in a 0.1 M MES buffer, 1-ethyl-(3-dimethylaminopropyl)carbodiimide EDC and N-hydroxysuccinimide NHS were added, and the mixture was activated at 37°C for 2.5 h to obtain Cy'; CeO2' and the activated fluorescent dye Cy' were mixed and stirred at a molar ratio of 1:1 at 25°C for 2 days, and the product was separated and cleaned to obtain the corresponding enhanced fluorescent material CeO2@Cy.

[0055] The obtained CeO2@Cy solution was diluted 10000 times and then fluorescence detection was performed with an excitation wavelength of 370 nm, a scanning speed of 2000 nm / min, a slit width of 5 nm, and the emission spectrum from 390 to 700 nm was recorded. Figure 1 As shown, the fluorescence emission intensity of CeO2@Cy near 460nm and 650nm is enhanced by about 5 times compared with Cy, which has a fluorescence enhancement effect.

[0056] Example 2

[0057] In the cerium nitrate solution, arginine was added and reacted at 80°C for 3h. The product was then separated and cleaned to obtain CeO2. Under a nitrogen atmosphere, 6mL of the above-prepared CeO2 solution (0.8g / L) was added with 0.012g of 5-aminolevulinic acid phosphate. After stirring at room temperature overnight, the product was separated and cleaned to obtain the corresponding fluorescence enhanced substrate material CeO2'.

[0058] The carboxyl coumarin dye coumarin-COOH was placed in 0.1M MES buffer, 1-ethyl-(3-dimethylaminopropyl) carbodiimide EDC and N-hydroxysuccinimide NHS were added, and the mixture was activated at 37°C for 2.5h to obtain coumarin-COOH'; CeO2' and the activated fluorescent dye coumarin-COOH' were mixed and stirred at 25°C for 2 days in a mass ratio of 1:1, and the product was separated and cleaned to obtain the corresponding enhanced fluorescent material CeO2@coumarin-COOH.

[0059] The obtained CeO2@coumarin-COOH solution was diluted 10000 times and then fluorescence detection was performed with an excitation wavelength of 345 nm, a scanning speed of 2000 nm / min, a slit width of 5 nm, and the emission spectrum from 400 to 700 nm was recorded. Figure 2 As shown, the fluorescence emission intensity of CeO2@coumarin-COOH near 410nm is enhanced by about 6 times compared with coumarin-COOH, which has a fluorescence enhancement effect.

[0060] In order to better illustrate the rationality of the synthetic sequence design, the following comparative examples illustrate that the fluorescence enhancement effect of the material obtained by "preparing CeO2' first and then connecting the activated Dye" is far better than that of "preparing Dye-PO3 first". 4- , and then use CeO2 to connect the activated Dye-PO3 4- "The fluorescence enhancement effect of the obtained material.

[0061] Comparative Example 1

[0062] In the cerium nitrate solution, arginine is added and reacted at 80°C for 3 hours, and then the product is separated and washed to obtain CeO2.

[0063] The cyanine dye Cy was placed in 0.1M MES buffer, 1-ethyl-(3-dimethylaminopropyl) carbodiimide EDC and N-hydroxysuccinimide NHS were added, and after activation at 37°C for 2.5h, 5-aminolevulinic acid phosphate of the same mass as the fluorescent dye was added under nitrogen atmosphere, and after stirring at room temperature overnight, the product was separated and washed to obtain the corresponding phosphorylated cyanine dye Cy-PO3 4- .

[0064] CeO2 and activated phosphorylated cyanine dye Cy-PO3 4- The substances were mixed and stirred at a mass ratio of 1:1 at 25°C and in a nitrogen atmosphere for 1 day, and the products were separated and washed to obtain the corresponding nanomaterial CeO2@Cy-2.

[0065] The obtained CeO2@Cy-2 solution was diluted 10000 times and then fluorescence detection was performed with an excitation wavelength of 370 nm, a scanning speed of 2000 nm / min, a slit width of 5 nm, and the emission spectrum from 390 to 700 nm was recorded. Figure 3 As shown in the figure, compared with Cy, the fluorescence emission of CeO2@Cy near 460nm and 650nm is weakened, and it does not have a fluorescence enhancement effect, which shows that the preparation of Dye-PO3 4- , and then use CeO2 to connect the activated Dye-PO3 4- It is difficult to achieve fluorescence enhancement effect.

[0066] Comparative Example 2

[0067] In the cerium nitrate solution, arginine is added and reacted at 80°C for 3 hours, and then the product is separated and washed to obtain CeO2.

[0068] The carboxy coumarin dye coumarin-COOH was placed in 0.1M MES buffer, 1-ethyl-(3-dimethylaminopropyl) carbodiimide EDC and N-hydroxysuccinimide NHS were added, and after activation at 37°C for 2.5h, 5-aminolevulinic acid phosphate of the same mass as the fluorescent dye was added under a nitrogen atmosphere, and after stirring at room temperature overnight, the product was separated and washed to obtain the corresponding phosphorylated carboxy coumarin dye PO3 4- -coumarin-COOH.

[0069] CeO2 is reacted with activated phosphorylated carboxycoumarin dye PO3 4- -coumarin-COOH were mixed and stirred at a mass ratio of 1:1 at 25°C under a nitrogen atmosphere for 1 day, and the product was separated and washed to obtain the corresponding nanomaterial CeO2@coumarin-COOH-2.

[0070] The obtained CeO2@coumarin-COOH-2 solution was diluted 10000 times and then fluorescence detection was performed with an excitation wavelength of 345 nm, a scan rate of 2000 nm / min, and a slit width of 5 nm. The emission spectrum from 390 to 700 nm was recorded, as shown in Figure 4 As shown in the figure, the fluorescence emission of CeO2@coumarin-COOH near 410nm is weakened compared with coumarin-COOH, and it does not have a fluorescence enhancement effect, which indicates that the preparation of Dye-PO3 4- , and then use CeO2 to connect the activated Dye-PO3 4- It is difficult to achieve fluorescence enhancement effect.

[0071] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a nanocomposite material based on CeO2 for enhancing the fluorescence intensity of small molecule organic dyes, characterized in that: The following steps are involved: (1) adding a complexing precipitant to a cerium source solution to react and obtain cerium dioxide; (2) adding an organic phosphate to the cerium dioxide obtained in step (1) under a protective atmosphere to obtain a fluorescence enhancing substrate material; (3) placing the non-phosphate small molecule fluorescent dye in a buffer solution, adding 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide for activation, thereby obtaining an activated non-phosphate small molecule fluorescent dye; (4) reacting the fluorescence enhancement base material obtained in step (2) with the activated non-phosphate small molecule fluorescent dye obtained in step (3) under protective atmosphere conditions to obtain a nanocomposite material.

2. The method for preparing a nanocomposite material for enhancing the fluorescence intensity of small molecule organic dyes based on CeO2 as claimed in claim 1, characterized in that: In step (2), the mass ratio of cerium dioxide to organic phosphate is 5:(1-25), and the organic phosphate is one or more of 2-phosphonobutane-1,2,4-tricarboxylic acid, 5-aminolevulinic acid phosphate, hexapotassium hexamethonium diaminetetramethylenephosphonic acid, and the like.

3. The method for preparing a nanocomposite material for enhancing the fluorescence intensity of small molecule organic dyes based on CeO2 as claimed in claim 1, characterized in that: In step (4), the molar ratio of the fluorescence enhancing substrate material to the activated non-phosphate small molecule fluorescent dye is 9:(1-81).

4. The method for preparing a nanocomposite material for enhancing the fluorescence intensity of small molecule organic dyes based on CeO2 as claimed in claim 1, characterized in that: The non-phosphate small molecule fluorescent dye is carboxycoumarin, aminocoumarin, rhodamine B, cyanine, carboxyfluorescein or tetracarboxyphenylporphyrin.

5. The method for preparing a nanocomposite material for enhancing the fluorescence intensity of small molecule organic dyes based on CeO2 as claimed in claim 1, characterized in that: In step (1), the reaction temperature is 70-100°C and the reaction time is 2-6h.

6. The method for preparing a nanocomposite material for enhancing the fluorescence intensity of small molecule organic dyes based on CeO2 as claimed in claim 1, characterized in that: In step (1), the cerium source is one of cerium nitrate, cerium sulfate, and ammonium cerium nitrate; and the complex precipitant is one of arginine, citric acid, and disodium ethylenediaminetetraacetic acid.

7. The method for preparing a nanocomposite material for enhancing the fluorescence intensity of small molecule organic dyes based on CeO2 as claimed in claim 1, characterized in that: The concentration of the cerium source is 1-15 g / L, and the molar ratio of the cerium source to the complex precipitant is 5:(1-25).

8. The method for preparing a nanocomposite material for enhancing the fluorescence intensity of small molecule organic dyes based on CeO2 as claimed in claim 1, characterized in that: In the step (3), the mass ratio of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to N-hydroxysuccinimide is 3:(1-9), the activation time is 0.5-2.5h, and the activation temperature is 20-40°C.

9. The method for preparing a nanocomposite material for enhancing the fluorescence intensity of small molecule organic dyes based on CeO2 as claimed in claim 1, characterized in that: In the step (3), the concentration of the non-phosphate small molecule fluorescent dye is 0.01-1 mM.

10. A nanocomposite material based on CeO2 for enhancing the fluorescence intensity of small molecule organic dyes prepared by the method according to any one of claims 1 to 9.

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