Microcapsule as well as preparation method and application thereof

Abstract

The invention discloses a microcapsule and a preparation method and application thereof.The microcapsule is composed of a capsule wall and a cavity, the capsule wall is formed by self-assembly of hydrophobic nanoparticles, and the cavity is filled with analyte; the hydrophobic nano particles are prepared by hydrophobic modification of metal nano particles or metal nano particles modified by a benzidine oxide compound by using fluorinated organic mercaptan. The microcapsule disclosed by the invention has relatively high hot spot density on all space planes, has very strong tolerance to laser focus dislocation, and is expected to be used for constructing a high-reproducibility SERS sensing platform. The microcapsule constructed by the invention aims at high-Raman active molecules, and can realize integration of recognition and enrichment and SERS label-free detection so as to improve the detection sensitivity; for a compound with low content and a small Raman scattering cross section, the microcapsule can also realize ultra-sensitive detection of a target object by means of integration of recognition enrichment and SERS sensing detection.

Description

Technical Field

[0001] The invention belongs to the technical field of Raman spectrum detection, and specifically relates to a microcapsule and a preparation method and application thereof. Background Art

[0002] Surface-enhanced Raman scattering (SERS) spectroscopy has attracted widespread attention due to its unique molecular fingerprint information. SERS activity mainly depends on the characteristics of the substrate material, the nanostructure morphology, or the "hot spots" provided by the tips of the metal nanostructures. The "hot spots" are affected by the localized surface plasmon resonance (LSPR), which can provide great electromagnetic enhancement. SERS is widely used in catalytic process monitoring, bioanalysis, and pollutant detection. However, it often encounters problems such as poor reproducibility and limited sensitivity during the analysis and detection process. In addition, most of the current SERS composite substrates are difficult and expensive to prepare, which increases the time cost of detection. Therefore, how to solve the problems of detection sensitivity and reproducibility in the SERS detection process, simplify the operation, and enable it to play a greater role in analysis and detection is still a huge challenge. Summary of the invention

[0003] In order to overcome the problems existing in the above-mentioned prior art, one of the purposes of the present invention is to provide a microcapsule. The second purpose of the present invention is to provide a method for preparing the above-mentioned microcapsule. The third purpose of the present invention is to provide an application of the above-mentioned microcapsule. The fourth purpose of the present invention is to provide a method for detecting an analyte by Raman spectroscopy.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] The first aspect of the present invention provides a microcapsule, which consists of a capsule wall and a cavity. The capsule wall is self-assembled from hydrophobic nanoparticles, and the cavity is filled with an analyte. The hydrophobic nanoparticles are prepared by hydrophobic modification of metal nanoparticles with fluorinated organic thiol.

[0006] Preferably, the fluorinated organic thiol is 1H,1H,2H,2H-perfluoro-1-decanethiol.

[0007] Preferably, the hydrophobic nanoparticles are prepared by a preparation method comprising the following steps: immersing metal nanoparticles in a fluorinated organic thiol solution to perform hydrophobic modification to obtain the hydrophobic nanoparticles.

[0008] More preferably, the metal nanoparticles are immersed in an isopropanol / n-hexane mixed solution containing a 1H,1H,2H,2H-perfluoro-1-decanethiol (PFDT) solution for hydrophobic treatment, and then washed with a large amount of ethanol.

[0009] Further preferably, the concentration of the isopropanol / n-hexane mixed solution containing the 1H,1H,2H,2H-perfluoro-1-decanethiol (PFDT) solution is 0.01-1 mmol / L.

[0010] More preferably, the usage ratio of the metal nanoparticles to 1H,1H,2H,2H-perfluoro-1-decanethiol is (5-30) g:1 mmol.

[0011] More preferably, the soaking time is 5 to 12 hours.

[0012] Preferably, the metal nanoparticles are gold nanoparticles or silver nanoparticles.

[0013] Preferably, the particle size of the metal nanoparticles is 25 to 325 nm.

[0014] Preferably, the metal nanoparticles are metal nanoparticles modified with an oxidized benzidine compound.

[0015] More preferably, the metal nanoparticles modified with oxidized benzidine compounds are prepared by a preparation method comprising the following steps: immersing metal nanoparticles in a solution of oxidized benzidine compounds to perform hydrophobic modification to obtain metal nanoparticles modified with oxidized benzidine compounds.

[0016] More preferably, the oxidized benzidine compound is modified to 3,3',5,5'-tetramethylbenzidine monoxide.

[0017] More preferably, the metal nanoparticles are immersed in the oxidized benzidine compound solution for 7 to 12 hours.

[0018] Further preferably, the 3,3',5,5'-tetramethylbenzidine monoxide is prepared by a preparation method comprising the following steps: 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2 are reacted under acidic conditions with horseradish peroxidase (HRP) as a catalyst to obtain the oxidation product of TMB 3,3',5,5'-tetramethylbenzidine monoxide (TMB) by solvent thermal reaction. OX ).

[0019] Further preferably, the hydrophobic nanoparticles are prepared by a preparation method comprising the following steps: immersing metal nanoparticles in a 3,3',5,5'-tetramethylbenzidine monoxide solution for modification to obtain metal nanoparticles modified with oxidized benzidine compounds; immersing the metal nanoparticles modified with oxidized benzidine compounds in a 1H,1H,2H,2H-perfluoro-1-decanethiol solution for hydrophobic modification to obtain the hydrophobic nanoparticles.

[0020] Preferably, the analyte is an organic small molecule or a biological macromolecule.

[0021] More preferably, the organic small molecules include additives and harmful substances.

[0022] Further preferably, the additive includes a water-soluble dye.

[0023] Further preferably, the harmful substances include toxins.

[0024] The second aspect of the present invention provides a method for preparing the microcapsules described in the first aspect, comprising the following steps: dispersing the hydrophobic nanoparticles in an oil phase to obtain an oil phase dispersion; dispersing the analyte in an aqueous phase to obtain an aqueous phase dispersion; mixing the oil phase dispersion with the aqueous phase dispersion and emulsifying them to obtain the microcapsules.

[0025] Preferably, the oil phase is a long-chain alkane.

[0026] More preferably, the oil phase is a halogen-substituted or unsubstituted C8-C 18 of straight chain alkanes.

[0027] Further preferably, the oil phase is selected from one of chloroform, carbon tetrachloride, ethyl bromide, dichloromethane, pentamethylheptane, decane, hexane and hexadecane.

[0028] Preferably, the mass volume ratio of the hydrophobic nanoparticles to the oil phase in the oil phase dispersion is (1-100) mg:1 mL;

[0029] Preferably, the volume ratio of the oil phase dispersion to the water phase dispersion is (1.5-200):1.

[0030] Preferably, the mixing method is to drop the aqueous dispersion into the oil dispersion.

[0031] Preferably, the emulsification is performed under ultrasonic conditions.

[0032] More preferably, the ultrasound frequency is 30 to 100 kHz; the ultrasound time is 1 to 15 min. Further preferably, the ultrasound time is 1 to 5 min.

[0033] The third aspect of the present invention provides the use of the microcapsule described in the first aspect in Raman spectroscopy detection.

[0034] Preferably, the microcapsule is used in SERS detection of analyte molecules in the fields of chemical analysis, environmental monitoring, biomedicine or food safety.

[0035] The fourth aspect of the present invention provides a method for detecting an analyte by Raman spectroscopy, wherein the analyte is made into the microcapsule described in the first aspect, or the analyte is made into a microcapsule according to the preparation method of the second aspect, and a SERS spectrum is collected on the microcapsule.

[0036] Preferably, a method for detecting an analyte by Raman spectroscopy comprises the following steps:

[0037] The metal nanoparticles are immersed in a 3,3',5,5'-tetramethylbenzidine monoxide solution for modification to obtain metal nanoparticles modified with oxidized benzidine compounds; the metal nanoparticles modified with oxidized benzidine compounds are immersed in a 1H,1H,2H,2H-perfluoro-1-decanethiol solution for hydrophobic modification to obtain the hydrophobic nanoparticles, and the hydrophobic nanoparticles are dispersed in an oil phase to obtain an oil phase dispersion;

[0038] The toxin antigen is fixed, and different concentrations of toxin solution and toxin primary antibody are added, and after washing, alkaline phosphatase-labeled toxin secondary antibody is added thereto; after the reaction is completed, trisodium L-ascorbic acid-2-phosphate (AAP) is added, and the above reaction solution is further mixed with tri(2-carboxyethyl)phosphine (TCEP) to form an aqueous dispersion;

[0039] The above aqueous dispersion is dropped into the oil dispersion, microcapsules are prepared according to the conditions in the second aspect of the present invention, and SERS spectra of the microcapsules are collected.

[0040] More preferably, the toxin in the toxin solution is T-2 toxin.

[0041] The beneficial effects of the present invention are:

[0042] The present invention provides a microcapsule, which is composed of a capsule wall and a chamber, wherein the capsule wall is self-assembled by hydrophobic nanoparticles, and the chamber is filled with an analyte, which can effectively combine a SERS substrate and a target molecule. The microcapsule has a high hot spot density on all spatial planes and has a strong tolerance for laser focus misalignment, and is expected to be used to construct a high-reproducibility SERS sensing platform. In addition, microcapsules have obvious advantages in encapsulating active substances and have been applied to drug delivery, two-phase catalysis, and chemical reaction monitoring. The hydrophobic nanoparticles in the microcapsule of the present invention are prepared by hydrophobic modification of metal nanoparticles using fluorinated organic thiols. The constructed microcapsules can integrate recognition enrichment with SERS label-free detection for highly Raman active molecules to improve the sensitivity of detection; the present invention has high sensitivity and high reproducibility, and is easy to operate and low in price. The entire detection process can be completed within 10 minutes, effectively solving the problems of poor reproducibility and limited sensitivity of SERS detection.

[0043] Specifically, compared with the prior art, the present invention also has the following advantages:

[0044] (1) The microcapsules of the present invention can also perform SEBS detection on compounds with low content and small Raman scattering cross section. The hydrophobic nanoparticles are prepared by hydrophobic modification of metal nanoparticles modified with oxidized benzidine compounds using fluorinated organic thiols. The prepared microcapsules can also achieve ultra-sensitive detection of the target by integrating recognition enrichment with SERS sensing detection.

[0045] (2) The microcapsules of the present invention can tightly encapsulate the analytes inside, thereby avoiding sample leakage and mutual interference between samples; in addition, the microcapsules are reasonably designed, and their size and structure meet the application requirements of SERS detection. From the perspective of application scenarios, microcapsules can not only construct a method that integrates identification and enrichment with SERS label-free detection, but also a method that integrates identification and enrichment with SERS sensing detection. In addition, the microcapsules in the present invention have negligible SERS background interference and a stable size, and can enrich samples, thereby showing excellent SERS signal reproducibility and detection sensitivity.

[0046] (3) The microcapsule preparation method of the present invention is to form the microcapsules through emulsification of water and oil phases and self-assembly at the interface. Not only is the preparation method simple, but it can also be used to prepare microcapsules for water-soluble analyte molecules in the fields of chemical analysis, environmental monitoring, biomedicine or food safety, and is applicable to a wide range of analytes. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The process flow chart of preparing microcapsules (A) and the actual pictures (B) and SEM pictures (C) of microcapsules prepared with various oil phases;

[0048] Figure 2 SERS spectra of MB-encapsulated microcapsules prepared with different silver / water ratios;

[0049] Figure 3 Repeatability (A) and reproducibility test diagram (B) of the microcapsules prepared in Example 1;

[0050] Figure 4 The SERS spectrum (A) and standard curve (B) of the identification, enrichment and SERS label-free detection of MB by the microcapsules in Example 1;

[0051] Figure 5 The SERS spectrum (A) and working curve (B) of the microcapsule in Example 2 for the identification, enrichment and SERS sensing detection of T-2 toxin;

[0052] Figure 6 The SERS spectra of the microcapsules in Example 2 for identifying, enriching and SERS sensing detection of T-2 toxin in peanuts (A) and corn (B). DETAILED DESCRIPTION

[0053] The present invention is further described in detail below through specific examples. The raw materials used in the following examples, unless otherwise specified, can be obtained from conventional commercial sources or prepared and separated by simple synthesis; the processes used, unless otherwise specified, are conventional processes in the art.

[0054] Example 1

[0055] This embodiment provides a method for preparing microcapsules whose analyte is methylene blue (MB). The schematic diagram of the preparation process is shown in FIG. Figure 1 As shown in A, the specific steps are as follows:

[0056] (1) Preparation of silver nanoparticles: AgNO3 (0.125 g) and PVP (0.625 g) were dissolved in 50 mL of ethylene glycol. The mixture was then transferred to an oil bath and heated to 130°C with vigorous stirring. Stirring was then stopped and the mixture was kept at 130°C for 1 h. Finally, the mixture was washed and purified with a large amount of acetone and ethanol to obtain 100 mg of silver nanoparticles.

[0057] (2) Preparation of hydrophobic silver nanoparticles: 20 mg of purified silver nanoparticles were soaked in 10 mL of isopropanol / n-hexane solution (1:1, v / v) containing 0.1 mmol / L PFDT at room temperature for 6 h. They were then washed with a large amount of ethanol and decane and then dispersed in 1.0 mL of decane to obtain hydrophobic silver nanoparticles (PFDT-AgNPs) with a concentration of 20 mg / mL.

[0058] (3) Preparation of microcapsules: Microcapsules were prepared by manipulating the mass of PFDT-AgNPs and the volume of water (silver / water ratio) during the emulsification process. The preparation of microcapsules with a silver / water ratio of 70 mg / mL was taken as an example. 14 μL of 20 mg / mL PFDT-AgNPs was diluted 10 times with decane and ultrasonicated to obtain a brown transparent suspension. Subsequently, 4.0 μL of MB with different concentrations (10 -5 mol / L、10 -6 mol / L、10 -7 mol / L、10 -8 mol / L、10 -9 mol / L and 10 -10 mol / L) aqueous solution, ultrasonic emulsification to obtain microcapsules, the ultrasonic frequency is 30-100kHz; the ultrasonic time is 1-5min.

[0059] For comparison, 4 μL, 8 μL, 12 μL and 16 μL of 20 mg / mL PFDT-AgNPs were diluted 10 times with decane and treated with ultrasound to obtain a brown transparent suspension. -7mol / L MB solution, and microcapsules with silver / water ratios of 20 mg / mL, 40 mg / mL, 60 mg / mL and 80 mg / mL were obtained.

[0060] It should be noted that microcapsules can be prepared with any two immiscible phases, such as mixing an aqueous phase with several common oil phases. These oil phases include chloroform, carbon tetrachloride, ethyl bromide, dichloromethane, pentamethylheptane, decane, hexane and hexadecane. If the oil phase is lighter than water (such as decane, pentamethylheptane, hexane and hexadecane), the microcapsules will sink to the bottom of the container ( Figure 1 B1-B4), and the corresponding SEM results of the prepared microcapsules are as follows Figure 1 In contrast, if the oil phase is heavier than water (e.g., chloroform, carbon tetrachloride, ethyl bromide, and dichloromethane), the microcapsules will float on the surface of the oil phase ( Figure 1 C1-C4), and the corresponding SEM results of the prepared microcapsules are as follows Figure 1 Their SEM results also show that the method for preparing microcapsules is universal, and any two immiscible phases can be used to prepare microcapsules.

[0061] Example 2

[0062] This embodiment provides a method for preparing microcapsules containing T-2 toxin as an analyte, and the specific steps are as follows:

[0063] (1) Under acidic conditions of pH 3.0 to 6.0, TMB and H2O2 were subjected to a solvothermal reaction at 25 to 50°C for 0.5 to 2 h using horseradish peroxidase (HRP) as a catalyst to obtain the oxidation product of TMB, TMB OX , wherein the molar ratio of TMB, H2O2 and HRP is (30~110):(2~8):1.

[0064] (2) Disperse 20 mg of purified silver nanoparticles in 20 mL of isopropanol / hexane mixed solution (1:1, v:v). Then, add 1 mL of TMB to the above solution. OX (5mmol / L) solution, magnetically stirred for 10h, and then centrifuged and discarded the supernatant to obtain Ag@TMB OX . Ag@TMB OX Dispersed in 20 mL of isopropanol / hexane mixed solution containing 0.1 mmol / L PFDT, stirred for 10 h. Finally, washed with a large amount of ethanol and decane to obtain PFDT-Ag-TMB OX The suspension was dispersed in 1.0 mL of decane to obtain PFDT-Ag@TMB with a concentration of 20 mg / mL. OX .

[0065] (3) 100 μL BSA-T2 (5 μg / mL) was added to a 96-well plate and incubated at 4°C overnight, and then BSA (1%, 250 μL) was added and incubated at 37°C for 1 h. Subsequently, 25 μL T-2 toxin standard and 25 μL toxin primary antibody (Ab1, 5 μg / mL) were added and incubated at 37°C for 1 h. Then 50 μL alkaline phosphatase-labeled toxin secondary antibody ALP-Ab2 (0.5 μg / mL) was introduced into the wells and reacted at 37°C for 1 h. After each of the above steps, the wells were carefully washed 3 times with 1× PBST buffer. Subsequently, 100 μL L-ascorbic acid-2-phosphate trisodium salt (AAP, 1.0 mmol / L) was added to the wells and reacted at 37°C for 1 h to obtain the catalytic product ascorbic acid (AA).

[0066] (4) To obtain microcapsules, the catalytic product AA in step (3) was mixed with 100 μL TCEP (thiol reducing agent, 1.2 mmol / L), and 4 μL of the mixed aqueous solution was transferred to 200 μL decane solution. Then, 14 μL PFDT-Ag@TMB was added. OX (20 mg / mL), ultrasonic emulsification to form microcapsules, the ultrasonic frequency is 30-100 kHz; the ultrasonic time is 1-5 min, and microcapsules encapsulating the catalytic product (AA) and TCEP are obtained. Then, the reaction is continued for 9 minutes to allow AA and TCEP to react with the oxidized benzidine compound on the surface of the capsule.

[0067] Example 3

[0068] This embodiment provides an application of a microcapsule whose analyte is T-2 toxin in the field of food safety, and the specific steps are as follows:

[0069] (1) Experimental groups: ① 120 μg / kg T-2 toxin standard; ② crushed peanut sample; ③ 120 μg / kg T-2 toxin spiked with 0.5 g crushed corn sample; ④ 320 μg / kg T-2 toxin standard; ⑤ crushed corn sample; ⑥ 320 μg / kg T-2 toxin spiked with 0.5 g crushed peanut sample.

[0070] The samples of experimental groups ②③⑤⑥ were added into 20 mL of methanol / water extraction solvent (8:2, v / v), respectively, the samples were vortexed for 20 min, and then filtered through glass fiber filter paper.

[0071] (2) 100 μL BSA-T2 (5 μg / mL) was added to a 96-well plate and incubated at 4°C overnight, and then BSA (1%, 250 μL) was added and incubated at 37°C for 1 hour. Subsequently, 25 μL of the above experimental groups ①②③④⑤⑥ and 25 μL of the primary toxin antibody (Ab1, 5 μg / mL) were added respectively and incubated at 37°C for 1 hour. Then 50 μL of alkaline phosphatase-labeled secondary toxin antibody ALP-Ab2 (0.5 μg / mL) was introduced into the wells and reacted at 37°C for 1 hour. After each of the above steps, the wells were carefully washed 3 times with 1× PBST buffer. Subsequently, 100 μL L-ascorbic acid-2-phosphate trisodium salt (AAP, 1.0 mmol / L) was added to the wells and reacted at 37°C for 1 hour to obtain the catalytic product ascorbic acid (AA). The catalytic product AA was then mixed with 100 μL TCEP (1.2 mmol / L), and 4 μL of the mixed aqueous solution was transferred to 200 μL decane solution. Then, 14 μL PFDT-Ag@TMB was added. OX (20 mg / mL) and ultrasonic emulsification to form microcapsules.

[0072] Experimental analysis

[0073] 1. SERS detection method

[0074] Then, 5.0 μL of the microcapsules immersed in decane were dropped onto a 3×3 mm silicon wafer. The laser was focused on the microcapsules. The parameters of the surface enhanced Raman spectrometer were set as follows: 5x objective lens, filter selection was 0.1% (laser power was 100 μW), grating line density was selected as 600 gr / mm, accumulation time was 500 ms, excitation wavelength was 532 nm, and at 200 cm -1 -1800cm -1 Collect data within the scope.

[0075] 2. Test results

[0076] (1) 10 -7 The SERS results of MB encapsulated in microcapsules are shown in Figure 2. Figure 2 As shown, line 1 is the SERS spectrum of MB detected by using silver nanoparticles of the same mass ratio as the SERS substrate, mechanically mixing them with MB and dropping them on a silicon wafer to form a coffee ring, and lines 2-6 are the SERS spectra of MB detected by microcapsules prepared when the silver / water ratio is 20, 40, 60, 70, and 80 mg / mL. It is obvious that MB is enriched when the microcapsules are formed. As the silver / water ratio increases, the 1633 cm -1 The signal at the site also increases. When the silver-water ratio is 70 mg / mL, the confined enrichment effect of the microcapsule is the best. The microcapsule has been successfully prepared.

[0077] The repeatability and reproducibility of the microcapsules in Example 1 were tested. The specific test results are as follows: Figure 3 As shown, Figure 3 A is the SERS test response diagram of 15 batches of microcapsules in Example 1, with a relative deviation of 4.8%; Figure 3 B is the SERS test response diagram of the microcapsule in Example 1 after 15 tests, with a relative deviation of 6.9%. Figure 3 It can be seen that the use of the microcapsules in the present invention to test MB has good repeatability and reproducibility.

[0078] (2) SERS detection was performed on the aqueous solution of MB at each concentration in Example 1, and the detection was performed three times to obtain the average intensity.

[0079] Figure 4 A is the SERS spectrum obtained by detecting MB. Figure 4 B is the standard curve of SERS detection of MB, the concentration of MB is 10 - 5 mol / L、10 -6 mol / L、10 -7 mol / L、10 -8 mol / L、10 -9 mol / L and 10 -10 mol / L, indicating that microcapsules can be used to construct a method that integrates identification and enrichment with SERS label-free detection.

[0080] 3. Figure 5 A is a SERS spectrum obtained by integrating identification, enrichment and SERS sensing detection based on microcapsules for T-2 toxin detection, 1609cm -1 The SERS intensity at shows that its signal gradually increases with the increase of T-2 toxin concentration. Figure 5 B shows that the logarithm of T-2 toxin concentration and SERS intensity have a good linear relationship in the range of 0.005-40.0 μg / L. The linear equation is I = 2618.61log C T-2 +8506.31 (R=0.9993), the detection limit of T-2 toxin was 1.64 ng / L.

[0081] 4. Figure 6 This is a SERS spectrum diagram for the detection of T-2 toxin in food based on microcapsules that integrates identification, enrichment and SERS sensing detection. Figure 6 Curves 1-3 in (A) are experimental groups ①②③, Figure 6 The curves 1-3 in (B) are ④⑤⑥ respectively. Figure 6It can be shown that the foods in experimental groups ② and ⑤ are positive samples, in which T-2 toxin is present. The microcapsules prepared by the present invention can detect T-2 toxin in food by integrating identification, enrichment and SERS sensing detection.

[0082] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A microcapsule, characterized in that: The microcapsule consists of a capsule wall and a cavity. The capsule wall is self-assembled from hydrophobic nanoparticles, and the cavity is filled with analytes. The hydrophobic nanoparticles are prepared by hydrophobically modifying metal nanoparticles with fluorinated organic thiol.

2. The microcapsule according to claim 1, characterized in that The fluorinated organic mercaptan is 1H,1H,2H,2H-perfluoro-1-decanethiol; And / or, the hydrophobic nanoparticles are prepared by a preparation method comprising the following steps: immersing metal nanoparticles in a fluorinated organic thiol solution to perform hydrophobic modification to obtain the hydrophobic nanoparticles.

3. The microcapsule according to claim 1, characterized in that The metal nanoparticles are gold nanoparticles or silver nanoparticles; And / or, the particle size of the metal nanoparticles is 25 to 325 nm.

4. The microcapsule according to claim 1, characterized in that The metal nanoparticles are metal nanoparticles modified with an oxidized benzidine compound.

5. The microcapsule according to claim 1, characterized in that The analyte is an organic small molecule or a biological macromolecule.

6. The method for preparing microcapsules according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: dispersing the hydrophobic nanoparticles in an oil phase to obtain an oil phase dispersion; dispersing the analyte in an aqueous phase to obtain an aqueous phase dispersion; and mixing the oil phase dispersion with the aqueous phase dispersion for emulsification to obtain the microcapsule.

7. The method for preparing microcapsules according to claim 6, characterized in that: The oil phase is a long-chain alkane; and / or, the mass volume ratio of the hydrophobic nanoparticles to the oil phase in the oil phase dispersion is (1-100) mg:1 mL; And / or, the volume ratio of the oil phase dispersion to the water phase dispersion is (1.5-200):

1.

8. The method for preparing microcapsules according to claim 6, characterized in that: The emulsification is carried out under ultrasonic conditions.

9. Use of the microcapsule according to any one of claims 1 to 5 in Raman spectroscopy detection.

10. A method for detecting an analyte by Raman spectroscopy, characterized in that: The analyte is made into the microcapsule according to any one of claims 1 to 5, or the analyte is made into the microcapsule according to the preparation method of claims 6 to 8, and the SERS spectrum of the microcapsule is collected.

Images