Up-conversion luminescent nano composite material as well as preparation method and application thereof

Abstract

The invention discloses an up-conversion luminescent nano composite material and a preparation method and application thereof, and belongs to the technical field of up-conversion nano materials, and the up-conversion luminescent nano composite material comprises a NaYF4: 20% Yb, 2% Er and gold nanoparticle double-layer structure. Through the strategy of preparing the double-layer up-conversion luminescent nanocomposite, the obtained nanocomposite has the characteristics of high conversion efficiency, high fluorescence intensity, uniform distribution and the like, and is suitable for environmental analysis and detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of upconversion nanomaterials, and in particular relates to an upconversion nanocomposite material and a preparation method and application thereof. Background Art

[0002] Environmental analysis and detection technologies have received widespread attention in recent years. However, traditional analytical and detection methods suffer from insufficient sensitivity and selectivity. With the development of nanomaterial technologies, nanocomposites with unique optical properties, such as upconversion luminescence and surface-enhanced Raman scattering, can be prepared using nanomaterial technologies to effectively improve the sensitivity and selectivity of environmental analysis and detection.

[0003] Upconversion luminescent nanomaterials can convert long-wavelength near-infrared light into short-wavelength visible or ultraviolet light. They offer advantages such as high sensitivity, strong tissue penetration, lack of autofluorescence, and no damage to biological tissues. They hold great promise for applications in biological detection and imaging. However, existing upconversion luminescent nanomaterials suffer from low conversion efficiency and weak fluorescence intensity, limiting their application in environmental analysis and detection.

[0004] Surface-enhanced Raman scattering (SERS) utilizes the plasmon resonance effect of noble metal nanoparticles to significantly amplify the Raman signal of molecules, enabling ultrasensitive detection at the single-molecule level. However, current noble metal nanoparticles suffer from uneven distribution and susceptibility to environmental influences, leading to signal degradation, which hinders the widespread application of this technology in environmental analysis and detection. Therefore, improving the conversion efficiency and fluorescence intensity of upconversion luminescent nanomaterials, as well as improving the uniformity and environmental adaptability of noble metal nanoparticles, are key to achieving highly sensitive and selective environmental analysis and detection.

[0005] Prior art, Chinese patent CN 116751591 A discloses an upconversion composite nanomaterial, its preparation method, and its use in cyanide detection. This upconversion composite nanomaterial exhibits high detection accuracy and enables quantitative detection of nanogram-level cyanide concentrations. Its preparation is simple and inexpensive. However, this patent still faces challenges in optimizing the preparation methods of the upconversion nanomaterial and quantum dot particles to increase the yield and purity of the materials.

[0006] In summary, the existing technology has the following defects:

[0007] (1) Existing upconversion luminescent nanomaterials have the defects of low conversion efficiency and weak fluorescence intensity, which limits their application in environmental analysis and detection.

[0008] (2) The currently used noble metal nanoparticles have problems such as uneven distribution and susceptibility to environmental influences, resulting in signal reduction, which restricts the promotion and application of surface-enhanced Raman scattering technology in the field of environmental analysis and detection.

[0009] (3) Existing technologies lack the ability to develop new double-layer functionalized ligands to expand the application scope of nanomaterials in environmental testing and biomedical fields.

[0010] (4) Existing technologies need to further optimize the preparation methods of upconversion nanomaterials and quantum dot particles to improve the yield and purity of the materials.

[0011] (5) Existing technologies have problems with insufficient sensitivity and selectivity and cannot meet the needs of environmental analysis and detection. Summary of the Invention

[0012] The purpose of the present invention is to provide a novel up-conversion luminescent nanocomposite material and its preparation method and application. The nanocomposite material has high conversion efficiency, high fluorescence intensity and uniform distribution, and is suitable for environmental analysis and detection.

[0013] The present invention achieves the above technical objectives through the following technical means.

[0014] The first object of the present invention is to provide an up-conversion luminescent nanocomposite material, which comprises a double-layer structure of NaYF4: 20% Yb, 2% Er and gold nanoparticles.

[0015] Furthermore, the NaYF4:20% Yb, 2% Er is NaYF4:20% Yb, 2% Er modified by distearoylphosphatidylethanolamine-polyethylene glycol-amino group.

[0016] Furthermore, the gold nanoparticles are gold nanoparticles modified with distearoylphosphatidylethanolamine-polyethylene glycol-amino groups.

[0017] The second object of the present invention is to provide a method for preparing an upconversion luminescent nanocomposite material, comprising the following steps:

[0018] Step S1: Preparation of upconversion luminescent nanoparticles modified with distearoylphosphatidylethanolamine-polyethylene glycol-amino groups:

[0019] Step S2: Preparation of noble metal nanoparticles modified with distearoylphosphatidylethanolamine-polyethylene glycol-amino groups:

[0020] Step S3: mixing the upconversion luminescent nanoparticles prepared in step 1 and the noble metal nanoparticles prepared in step 2 in a certain proportion, performing ultrasonic dispersion for 30 minutes to make them uniformly distributed, and freeze-drying to obtain a nanocomposite material.

[0021] Furthermore, the step S1 includes:

[0022] Step S101: Y(CF3COO)3, Yb(CF3COO)3, Er(CF3COO)3 and Na(CF3COO) are mixed and reacted to prepare NaYF4:20%Yb,2%Er upconversion luminescent nanoparticles by a hydrothermal method;

[0023] Step S102: NaYF4:20% Yb, 2% Er and distearoyl phosphatidylethanolamine-polyethylene glycol-amino are mixed in a certain proportion to modify the surface of NaYF4:20% Yb, 2% Er with distearoyl phosphatidylethanolamine-polyethylene glycol-amino;

[0024] Step S103: centrifugally separating the surface-modified upconversion luminescent nanoparticles and washing with water to obtain a purified surface-modified upconversion luminescent nanoparticle dispersion.

[0025] Furthermore, the step S2 includes:

[0026] Step S201: HAuCl4 solution and trisodium citrate solution are mixed in a certain proportion, and noble metal nanoparticles are prepared by chemical reduction method to obtain gold nanoparticle solution;

[0027] Step S202: mixing the gold nanoparticle solution prepared above and distearoylphosphatidylethanolamine-polyethylene glycol-amino in a certain proportion, so that the distearoylphosphatidylethanolamine-polyethylene glycol-amino is modified on the surface of the gold nanoparticles;

[0028] Step S203: centrifuging the surface-modified gold nanoparticles and washing with water to obtain a purified surface-modified gold nanoparticle dispersion.

[0029] Furthermore, in step S3, the mass ratio of upconversion luminescent nanoparticles to noble metal nanoparticles is 6:4-5.

[0030] Furthermore, in step S101, the molar ratio of Y(CF3COO)3:Yb(CF3COO)3:Er(CF3COO)3:Na(CF3COO) is 39:10:1:50; in step S102, the mass ratio of upconversion luminescent nanoparticles:distearoylphosphatidylethanolamine-polyethylene glycol-amino is 10:12-8

[0031] Furthermore, in step S202, the mass ratio of the gold nanoparticle solution to distearoylphosphatidylethanolamine-polyethylene glycol-amino is 10:10-6.

[0032] The third object of the present invention is to provide an application of an upconversion luminescent nanocomposite material in environmental analysis and detection.

[0033] Beneficial effects: (1) The conversion efficiency and fluorescence intensity of upconversion luminescent nanomaterials are improved, overcoming the defects of low conversion efficiency and weak fluorescence intensity of existing upconversion luminescent nanomaterials, thereby improving the sensitivity of environmental analysis and detection;

[0034] (2) Improved the distribution uniformity and environmental adaptability of noble metal nanoparticles, solved the problem of uneven distribution of existing noble metal nanoparticles and susceptibility to environmental influences, resulting in signal reduction, and improved the application effect of surface-enhanced Raman scattering technology in environmental analysis and detection;

[0035] (3) Developed a new double-layer functionalized ligand, expanding the application scope of nanomaterials in environmental analysis and detection;

[0036] (4) Optimized the preparation methods of upconversion nanomaterials and quantum dot particles, improved the yield and purity of the materials, and reduced the preparation costs;

[0037] (5) The comprehensive use of nanomaterial technologies such as upconversion luminescence and surface-enhanced Raman scattering has improved the sensitivity and selectivity of environmental analysis and detection, meeting the needs of environmental analysis and detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is an electron microscope image of the nanocomposite material in Example 1.

[0039] Figure 2 This is an electron microscope image of the gold nanoparticles in Example 2. DETAILED DESCRIPTION

[0040] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The accompanying drawings illustrate preferred embodiments of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure. The present invention will be further described below with reference to the accompanying drawings and specific examples.

[0041] The reagents used in the following examples are all commercially available.

[0042] Example 1:

[0043] This embodiment provides an upconversion nanocomposite material and a preparation method thereof, comprising the following steps:

[0044] Step 1: Preparation of upconversion luminescent nanoparticles:

[0045] Step 101: Prepare upconversion luminescent nanoparticles with high conversion efficiency and high fluorescence intensity using a hydrothermal method. The specific operations are as follows:

[0046] 0.78mmol Y(CF3COO)3, 0.2mmol Yb(CF3COO)3, 0.02mmol Er(CF3COO)3, and 1.0mmol Na(CF3COO) were added to a 100mL three-necked flask, and then 6mL oleic acid and 15mL octadecene were added. Nitrogen was connected to remove oxygen, a stirring bar was added and the temperature was raised to 120℃ with a heating mantle and stirred for 20 minutes to remove the low-boiling solvent. After the solution was clarified, the low-boiling solvent was further removed by vacuum pumping with an oil pump for 30 minutes. The reaction system was quickly heated to 300℃ and reacted for 60 minutes. After cooling to room temperature, 10mL cyclohexane and ethanol (volume ratio 1:1) were added, ultrasonically washed for 5 minutes, the precipitate was collected by centrifugation, and the washing and centrifugation were repeated three times to obtain NaYF4:20% Yb, 2% Er upconversion luminescent nanoparticles.

[0047] Step 102: Surface modification of the upconversion luminescent nanoparticles is performed by introducing a novel double-layer functionalized ligand, distearoylphosphatidylethanolamine-polyethylene glycol-amino (DSPE-PEG2000-NH2), to improve their biocompatibility and environmental adaptability. The specific steps are as follows:

[0048] The NaYF4:20% Yb, 2% Er upconversion luminescent nanoparticles and DSPE-PEG2000-NH2 prepared above were added to water in a mass ratio of 1:1, with the dosage ratio of DSPE-PEG2000-NH2 to water being 5 mg:1 mL. Ultrasonication was performed for 2 minutes to fully disperse the particles, and the mixture was stirred at room temperature for 12 hours.

[0049] Step 103 , centrifugally separating the surface-modified upconversion luminescent nanoparticles, and washing them twice with water to obtain a purified surface-modified upconversion luminescent nanoparticle dispersion with a concentration of 6 mg / mL.

[0050] Step 2: Preparation of precious metal nanoparticles:

[0051] Step 201: Prepare uniformly distributed noble metal nanoparticles using a chemical reduction method. The specific operations are as follows:

[0052] HAuCl4 solution and trisodium citrate solution were mixed in a mass ratio of 1:4, heated to 80°C, and freshly prepared NaBH4 solution was slowly added dropwise until the deep red color disappeared. The heating reaction was continued for 30 minutes to obtain a uniformly dispersed gold nanoparticle solution.

[0053] Step 202: Surface modification of the noble metal nanoparticles to improve their chemical stability and environmental adaptability. The specific operations are as follows:

[0054] The gold nanoparticle solution prepared above and DSPE-PEG2000-NH2 were mixed in a mass ratio of 1:1 and stirred at room temperature for 12 hours to modify the surface of the gold nanoparticles with DSPE-PEG2000-NH2.

[0055] Step 203: centrifuge the surface-modified noble metal nanoparticles and wash them three times with water to obtain a purified surface-modified gold nanoparticle dispersion with a concentration of 996 ppm.

[0056] Step 3: Mix the upconversion luminescent nanoparticles prepared in step 1 and the noble metal nanoparticles prepared in step 2 in a mass ratio of 6:5, disperse them uniformly by ultrasonic dispersion for 30 minutes, and freeze-dry to obtain a nanocomposite material.

[0057] The above nanocomposites were characterized and the results are as follows Figure 1 shown.

[0058] Figure 1 In the figure, a and c are electron micrographs of the nanocomposite at 100 μm, while b and d are electron micrographs of the nanocomposite at 10 μm. Transmission electron microscopy observations show that the upconversion luminescent nanoparticles and gold nanoparticles in the composite retain their respective morphological characteristics, with no apparent agglomeration, indicating a certain interaction between the two nanoparticles.

[0059] At the same time, optical performance tests show that the nanocomposite can emit green (540nm) and red (660nm) fluorescence under 980nm near-infrared light excitation, while exhibiting significant surface plasmon resonance absorption at 520nm. It is worth noting that because the emission spectrum of the upconversion luminescent nanoparticles partially overlaps with the absorption spectrum of the gold nanoparticles, fluorescence resonance energy transfer occurs between the two, resulting in a relative weakening of the green fluorescence (540nm) intensity, while the red fluorescence (660nm) is less affected. This selective fluorescence quenching phenomenon can be used to design ratiometric sensors to improve detection sensitivity and accuracy.

[0060] Example 2:

[0061] This embodiment provides a second upconversion luminescent nanocomposite material and a preparation method thereof, comprising the following steps:

[0062] Step 1: Preparation of upconversion luminescent nanoparticles:

[0063] Step 101: Prepare upconversion luminescent nanoparticles with high conversion efficiency and high fluorescence intensity using a hydrothermal method. The specific operations are as follows:

[0064] 0.78mmol Y(CF3COO)3, 0.2mmol Yb(CF3COO)3, 0.02mmol Er(CF3COO)3, and 1.0mmol Na(CF3COO) were added to a 100mL three-necked flask, and then 6mL oleic acid and 15mL octadecene were added. Nitrogen was connected to remove oxygen, a stirring bar was added and the temperature was raised to 120℃ with a heating mantle and stirred for 20 minutes to remove the low-boiling solvent. After the solution was clarified, the low-boiling solvent was further removed by vacuum pumping with an oil pump for 30 minutes. The reaction system was quickly heated to 300℃ for 1 hour, cooled to room temperature, and 10mL cyclohexane and ethanol (volume ratio 1:1) were added. Ultrasonic washing was carried out for 10 minutes, the precipitate was collected by centrifugation, and the washing and centrifugation were repeated three times to obtain NaYF4:20% Yb, 2% Er upconversion luminescent nanoparticles.

[0065] Step 102: Surface modification of the upconversion luminescent nanoparticles is performed by introducing a novel double-layer functionalized ligand, distearoylphosphatidylethanolamine-polyethylene glycol-amino (DSPE-PEG2000-NH2), to improve their biocompatibility and environmental adaptability. The specific steps are as follows:

[0066] The NaYF4:20% Yb, 2% Er upconversion luminescent nanoparticles and DSPE-PEG2000-NH2 prepared above were added to water at a mass ratio of 1:0.8, with the dosage ratio of DSPE-PEG2000-NH2 to water being 4 mg:1 mL. Ultrasonication was performed for 5 minutes to fully disperse the mixture, and the mixture was stirred at room temperature for 16 hours.

[0067] Step 103: centrifuge the surface-modified upconversion luminescent nanoparticles, and wash them three times with water to obtain a purified surface-modified upconversion luminescent nanoparticle dispersion with a concentration of 5 mg / mL.

[0068] Step 2: Preparation of precious metal nanoparticles:

[0069] Step 201: Prepare uniformly distributed noble metal nanoparticles using a chemical reduction method. The specific operations are as follows:

[0070] HAuCl4 solution and trisodium citrate solution were mixed in a mass ratio of 1:3, heated to 90°C, and freshly prepared NaBH4 solution was slowly added dropwise until the deep red color disappeared. The heating reaction was continued for 45 minutes to obtain a uniformly dispersed gold nanoparticle solution.

[0071] Step 202: Surface modification of the noble metal nanoparticles to improve their chemical stability and environmental adaptability. The specific operations are as follows:

[0072] The gold nanoparticle solution prepared above and DSPE-PEG2000-NH2 were mixed at a mass ratio of 1:0.6 and stirred at room temperature for 18 hours to modify the surface of the gold nanoparticles with DSPE-PEG2000-NH2.

[0073] Step 203 : centrifugally separate the surface-modified noble metal nanoparticles, and wash them with water four times to obtain a purified surface-modified gold nanoparticle dispersion with a concentration of 996 ppm.

[0074] Step 3: Mix the upconversion luminescent nanoparticles prepared in step 1 and the noble metal nanoparticles prepared in step 2 in a mass ratio of 6:4, disperse them uniformly by ultrasonication for 45 minutes, and freeze-dry to obtain a nanocomposite material.

[0075] The gold nanomaterial obtained in step 203 is shown in the following figure under a 10nm electron microscope: Figure 2 As shown, the gold nanoparticles modified with DSPE-PEG2000-NH2 have a stable structure, are evenly dispersed, and have no agglomeration phenomenon.

[0076] Example 3:

[0077] This embodiment provides a third upconversion nanocomposite material and a preparation method thereof, comprising the following steps:

[0078] Step 1: Preparation of upconversion luminescent nanoparticles:

[0079] Step 101: Prepare upconversion luminescent nanoparticles with high conversion efficiency and high fluorescence intensity using a hydrothermal method. The specific operations are as follows:

[0080] 0.78mmol Y(CF3COO)3, 0.2mmol Yb(CF3COO)3, 0.02mmol Er(CF3COO)3, and 1.0mmol Na(CF3COO) were added to a 100mL three-necked flask, and then 6mL oleic acid and 15mL octadecene were added. Nitrogen was connected to remove oxygen, a stirring bar was added and the temperature was raised to 120℃ with a heating mantle and stirred for 30 minutes to remove the low-boiling solvent. After the solution was clarified, the low-boiling solvent was further removed by vacuum pumping with an oil pump for 45 minutes. The reaction system was quickly heated to 320℃ and reacted for 90 minutes. The reaction was cooled to room temperature, 10mL cyclohexane and ethanol (volume ratio 1:1) were added, and ultrasonic washing was performed for 15 minutes. The precipitate was collected by centrifugation and the washing and centrifugation were repeated four times to obtain NaYF4:20% Yb, 2% Er upconversion luminescent nanoparticles.

[0081] Step 102: Surface modification of the upconversion luminescent nanoparticles is performed by introducing a novel double-layer functionalized ligand, distearoylphosphatidylethanolamine-polyethylene glycol-amino (DSPE-PEG2000-NH2), to improve their biocompatibility and environmental adaptability. The specific steps are as follows:

[0082] The NaYF4:20% Yb, 2% Er upconversion luminescent nanoparticles and DSPE-PEG2000-NH2 prepared above were added to water at a mass ratio of 1:1.2, with the dosage ratio of DSPE-PEG2000-NH2 to water being 6 mg:1 mL. Ultrasonication was performed for 8 minutes to fully disperse the particles, and the mixture was stirred at room temperature for 24 hours.

[0083] Step 103 : centrifugally separate the surface-modified upconversion luminescent nanoparticles, and wash them with water five times to obtain a purified surface-modified upconversion luminescent nanoparticle dispersion with a concentration of 7 mg / mL.

[0084] Step 2: Preparation of precious metal nanoparticles:

[0085] Step 201: Prepare uniformly distributed noble metal nanoparticles using a chemical reduction method. The specific operations are as follows:

[0086] HAuCl4 solution and trisodium citrate solution were mixed in a mass ratio of 1:2, heated to 85°C, and freshly prepared NaBH4 solution was slowly added dropwise. The heating reaction was continued for 60 minutes to obtain a uniformly dispersed gold nanoparticle solution.

[0087] Step 202: Surface modification of the noble metal nanoparticles to improve their chemical stability and environmental adaptability. The specific operations are as follows:

[0088] The gold nanoparticle solution prepared above and DSPE-PEG2000-NH2 were mixed at a mass ratio of 1:0.8 and stirred at room temperature for 20 hours to allow DSPE-PEG2000-NH2 to be modified on the surface of the gold nanoparticles.

[0089] Step 203: centrifuge the surface-modified noble metal nanoparticles and wash them three times with water to obtain a purified surface-modified gold nanoparticle dispersion with a concentration of 996 ppm.

[0090] Step 3: Mix the upconversion luminescent nanoparticles prepared in step 1 and the noble metal nanoparticles prepared in step 2 in a mass ratio of 6:5, disperse them uniformly by ultrasonic dispersion for 60 minutes, and freeze-dry to obtain a nanocomposite material.

[0091] Comparative Example 1:

[0092] NaYF4:20% Yb, 2% Er upconversion luminescent nanoparticles were prepared according to the method of Example 1, but the novel double-layer functionalized ligand distearoylphosphatidylethanolamine-polyethylene glycol-amino (DSPE-PEG2000-NH2) was not introduced, and the upconversion luminescent nanoparticles without surface modification were mixed with surface-modified noble metal nanoparticles to prepare a nanocomposite material.

[0093] Comparative Example 2:

[0094] NaYF4:20% Yb, 2% Er upconversion luminescent nanoparticles were prepared by referring to the method of Example 1. The surface-modified upconversion luminescent nanoparticles were mixed with non-surface-modified noble metal nanoparticles to prepare a nanocomposite material.

[0095] Comparative Example 3:

[0096] NaYF4:20% Yb, 2% Er upconversion luminescent nanoparticles were prepared by referring to the method of Example 1. A nanocomposite material was prepared by mixing upconversion luminescent nanoparticles without surface modification with noble metal nanoparticles without surface modification.

[0097] Environmental analysis and detection applications were performed on the upconversion luminescent nanocomposites obtained in Examples 1-3 and Comparative Examples 1-3. The results are shown in the following table:

[0098]

[0099] Stability testing showed that the nanocomposite maintained good dispersibility and optical properties across various pH values ​​(4-10) and ionic strengths (0-500 mM NaCl), making it suitable for use in complex environments. Furthermore, after one year of dry storage at room temperature, the material retained its original optical properties upon redispersion, demonstrating excellent long-term stability.

[0100] Environmental analysis and detection application tests have demonstrated that this nanocomposite can be used to detect a variety of environmental pollutants. For example, by modifying the nanocomposite surface with specific recognition molecules, highly sensitive detection of heavy metal ions (such as Hg2+, Pb2+, and Cd2+) can be achieved, with detection limits reaching the ppb level. Specifically, the nanocomposite dispersion is mixed with samples containing varying concentrations of the target analyte, and the target concentration is quantitatively analyzed by measuring changes in the fluorescence intensity ratio (I660 / I540).

[0101] Furthermore, this nanocomposite can be used to detect organic pollutants in water quality monitoring, such as polycyclic aromatic hydrocarbons and pesticide residues. By modifying the surface with appropriate molecular recognition elements, selective identification and detection of specific organic pollutants can be achieved. Compared to traditional detection methods, the fluorescence resonance energy transfer-based detection method of this nanocomposite offers advantages such as ease of operation, rapid response, and high sensitivity, making it suitable for rapid on-site detection and continuous monitoring applications.

[0102] The series of detailed descriptions listed above are merely specific descriptions of feasible implementation methods of the present invention, but the present invention is not limited to the above implementation methods. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention are within the scope of protection of the present invention.

Claims

1. An upconversion luminescent nanocomposite material, characterized in that: The composite material includes a double-layer structure of NaYF4:20% Yb, 2% Er and gold nanoparticles.

2. The upconversion luminescent nanocomposite material according to claim 1, characterized in that: The NaYF4:20%Yb,2%Er is NaYF4:20%Yb,2%Er modified with distearoylphosphatidylethanolamine-polyethylene glycol-amino group.

3. The upconversion luminescent nanocomposite material according to claim 1 or 2, characterized in that: The gold nanoparticles are gold nanoparticles modified by distearoylphosphatidylethanolamine-polyethylene glycol-amino groups.

4. The method for preparing the upconversion luminescent nanocomposite material according to any one of claims 1 to 3, characterized in that : The steps are as follows: Step S1: Preparation of upconversion luminescent nanoparticles modified with distearoylphosphatidylethanolamine-polyethylene glycol-amino groups: Step S2: Preparation of noble metal nanoparticles modified with distearoylphosphatidylethanolamine-polyethylene glycol-amino groups: Step S3: mixing the upconversion luminescent nanoparticles prepared in step 1 and the noble metal nanoparticles prepared in step 2 in a certain proportion, performing ultrasonic dispersion for 30 minutes to make them uniformly distributed, and freeze-drying to obtain a nanocomposite material.

5. The method for preparing the upconversion nanocomposite material according to claim 4, characterized in that: The step S1 comprises: Step S101: Y(CF3COO)3, Yb(CF3COO)3, Er(CF3COO)3 and Na(CF3COO) are mixed and reacted to prepare NaYF4:20%Yb,2%Er upconversion luminescent nanoparticles by a hydrothermal method; Step S102: NaYF4:20%Yb,2%Er and distearoylphosphatidylethanolamine-polyethylene glycol-amino are mixed in a certain proportion to modify the surface of NaYF4:20%Yb,2%Er with distearoylphosphatidylethanolamine-polyethylene glycol-amino; Step S103: centrifugally separating the surface-modified upconversion luminescent nanoparticles and washing with water to obtain a purified surface-modified upconversion luminescent nanoparticle dispersion.

6. The method for preparing the upconversion luminescent nanocomposite material according to claim 4, characterized in that: The step S2 comprises: Step S201: HAuCl4 solution and trisodium citrate solution are mixed in a certain proportion, and noble metal nanoparticles are prepared by chemical reduction method to obtain gold nanoparticle solution; Step S202: mixing the gold nanoparticle solution prepared above and distearoylphosphatidylethanolamine-polyethylene glycol-amino in a certain proportion, so that the distearoylphosphatidylethanolamine-polyethylene glycol-amino is modified on the surface of the gold nanoparticles; Step S203: centrifuging the surface-modified gold nanoparticles and washing with water to obtain a purified surface-modified gold nanoparticle dispersion.

7. The method for preparing the upconversion luminescent nanocomposite material according to claim 4, characterized in that: In step S3, the mass ratio of upconversion luminescent nanoparticles to noble metal nanoparticles is 6:4-5.

8. The method for preparing the upconversion luminescent nanocomposite material according to claim 5, characterized in that: In the step S101, the molar ratio of Y(CF3COO)3:Yb(CF3COO)3:Er(CF3COO)3:Na(CF3COO) is 39:10:1:50; in the step S102, the mass ratio of upconversion luminescent nanoparticles:distearoylphosphatidylethanolamine-polyethylene glycol-amino is 10:12-8.

9. The method for preparing the upconversion luminescent nanocomposite material according to claim 6, characterized in that: In step S202, the mass ratio of the gold nanoparticle solution to the distearoylphosphatidylethanolamine-polyethylene glycol-amino group is 10:10-6.

10. Use of the upconversion luminescent nanocomposite material according to any one of claims 1 to 3 or the upconversion luminescent nanocomposite material prepared using the preparation method of the upconversion luminescent nanocomposite material according to any one of claims 4 to 9 in environmental analysis and detection.

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