Surface-enhanced Raman spectroscopy detection method based on small gaps between multilayer nanoparticle films

Abstract

The present invention discloses a surface enhanced Raman spectroscopy detection method based on a small gap between multilayer nanoparticle membranes, which is to repeatedly fix a single layer of nanoparticle membranes self-assembled at a liquid-liquid interface on a perforated flat plate material to form a multilayer nanoparticle membrane, and then cover it on a solution containing target molecules, and use the capillary force of a small gap of 1-6 nanometers formed between the multilayer nanoparticle membranes to introduce the target molecules into the small gaps of the nanoparticles, and then detect the target signal under a Raman spectrometer. The present invention can achieve highly sensitive and stable detection of surface enhanced Raman spectroscopy by constructing a multilayer nanoparticle membrane and using the 1-6 nanometer gap formed inside the nanoparticle membrane layers.

Description

Technical Field

[0001] The invention relates to a construction and analysis detection method of a multi-layer nanoparticle film, and discloses a surface enhanced Raman spectroscopy detection method based on small gaps between layers of the multi-layer nanoparticle film. Background Art

[0002] The stability and sensitivity of surface enhanced Raman spectroscopy (SERS) signals are hot topics and difficult issues in the scientific community today. Designing and fabricating SERS substrates with maximum enhancement has become a major research interest in this field. Since the earliest discovery of strong Raman signals generated by molecules adsorbed on rough silver electrodes, we have now gained a deeper understanding of the causes of Raman scattering enhancement on nanoscale metal surfaces, especially Raman scattering at SERS hotspots (usually referring to protruding cracks and gaps). In the past decade, a variety of anisotropic nanoparticles have been developed with high application potential in SERS sensing and imaging. In general, the generation of hotspots usually uses two nanofabrication strategies, bottom-up and top-down, to construct two-dimensional or three-dimensional hotspots. All these studies aim to design nanoparticles with different morphologies to obtain better SERS enhancement. However, for some target molecules with weak affinity to the substrate (such as some non-adsorbed molecules, neurotransmitters, etc.), the design of different structures is meaningless. Therefore, it is necessary to design and construct substrates that can interact with target molecules to achieve highly sensitive SERS detection. Although a lot of efforts have been made to improve the sensitivity of SERS detection by constructing various SERS substrates or designing probes to improve the affinity of SERS substrates, there is still a problem of poor reproducibility of active SERS hotspots. The emergence of randomly distributed activation hotspots (usually due to changes in particle distance, surface and shape, and molecular diffusion) leads to a wide distribution of electromagnetic enhancement factor values. There is currently no research on how to actually control or guide molecules into hotspots. Summary of the invention

[0003] Based on the problems existing in the background technology, the present invention proposes a surface enhanced Raman spectroscopy detection method based on small gaps between multilayer nanoparticle films, which has simple steps and can achieve the sensitivity of surface enhanced Raman spectroscopy detection. The method of the present invention is also conducive to the wide application of surface enhanced Raman spectroscopy detection for detection objects.

[0004] The present invention proposes a surface enhanced Raman spectroscopy detection method based on small gaps between multilayer nanoparticle films. The single-layer nanoparticle film self-assembled at the liquid-liquid interface is repeatedly fixed on a flat material with regular or irregular through holes to form a multilayer nanoparticle film, which is then covered on a solution containing target molecules. The capillary force of small gaps of 1-6 nanometers formed between the multilayer nanoparticle films is used to introduce the target molecules into the small gaps between the nanoparticles, and then the target signal is detected under a Raman spectrometer.

[0005] The monolayer nanoparticle film is obtained by conventional liquid-liquid interface self-assembly. Generally, the following scheme can be adopted:

[0006] The metal nanosol is centrifuged to collect the concentrated nanosol at the bottom; distilled water and cyclohexane are taken in a container to form a water / cyclohexane interface; the concentrated nanosol is dispersed in ethanol to form an ethanol sol of nanoparticles, and the ethanol sol of nanoparticles is added to the water / cyclohexane interface to form a film at the interface. The metal nanosol includes but is not limited to silver nanosol, gold nanosol, copper nanosol, nickel nanosol, and palladium nanosol. The metal nanosol can be commercially available such as products of Xianfeng Nano Company, etc., or can also be prepared by conventional sodium citrate method.

[0007] Furthermore, the small gap formed between the multilayer nanoparticle film is 1-6 nanometers, the multilayer nanoparticle film is preferably 2-3 layers, and the gap between nanoparticles in the same layer is about 8nm. The morphology of the nanoparticles includes but is not limited to nanospheres, nanorods, nanowires, nanopolyhedrons, and the like.

[0008] Furthermore, the flat plate material includes but is not limited to silicon wafer, mica sheet, glass sheet, quartz and other flat surface materials suitable for loading nanoparticles. The flat plate material itself should not have obvious Raman peaks that affect subsequent Raman detection. The thickness of the flat plate material is preferably 100 microns to 500 microns.

[0009] Furthermore, the diameter of the small holes in the perforated plate material is 0.1 mm to 0.5 mm. The plate material can be perforated with holes, which can be regular or irregular.

[0010] Furthermore, the single-layer nanoparticle membrane self-assembled at the liquid-liquid interface is repeatedly fixed on a perforated flat plate material, and the flat plate with perforations on the surface and the nanoparticle membrane self-assembled at the liquid-liquid interface are penetrated at an angle of 30-45° to perform a membrane scooping operation to obtain a layer of nanoparticle membrane in the small pores and gaps. The scooping operation is repeated to obtain a multi-layer nanoparticle membrane.

[0011] Furthermore, a multilayer nanoparticle film is covered on a solution containing target molecules, the solution can move upward through the small holes, and then the target signal can be detected under a Raman spectrometer at room temperature of 25 degrees Celsius.

[0012] Further, the target molecules are mainly adsorbed molecules including but not limited to plasticizers, organic pollutants, anti-tumor drugs, poisons, toxins, pesticide residues, dyes, antibiotics, explosives and amino acids, etc., and the solution can be an aqueous solution or an organic solution. Specifically, the target includes but is not limited to methylene blue (MB), rhodamine 6G (R6G), brilliant green (BG), malachite green (MG), crystal violet (CV), Nile blue (NB), and harmful chemicals in daily life such as Sudan III, o-phenanthroline (phen), p-aminobenzoic acid (PABA), 4-mercaptobenzoic acid (4-MBA), etc. The present invention provides a method for controlling or guiding the target molecules to enter hot spots to achieve the sensitivity of surface enhanced Raman spectroscopy detection. Obviously, those skilled in the art know that the method is naturally not limited to the category of target molecules, and all those based on the mechanism of the present invention and capable of achieving the sensitivity of surface enhanced Raman spectroscopy detection should be included in the protection scope of the method of the present invention.

[0013] Further, the target signal is detected under a Raman spectrometer, and the excitation light wavelength of the Raman spectrometer can be 532nm, 633nm or 785nm. Further, the Raman spectrometer used can be a large Raman spectrometer in a laboratory, or a portable or handheld Raman spectrometer.

[0014] In the multilayer nanoparticle film structure constructed by the present invention, nanoparticles are closely located between layers to form a small gap of 1-6 nanometers. When the multilayer nanoparticle film is covered on a solution containing target molecules, the gap formed between the nanoparticles actively absorbs the target molecules due to capillary suction, and as the solution evaporates, the solution carries the target molecules further to a smaller gap, that is, a small gap of 1-6 nanometers formed between nanoparticle layers. Huge electromagnetic enhancement is formed at the small gap, and the molecules inevitably enter the small gap with the solution, thereby making full use of the spatial hot spots between the multilayer nanoparticle layers to ensure the sensitivity and stability of surface enhanced Raman spectroscopy detection.

[0015] The present invention has the following beneficial effects:

[0016] 1. The idea of ​​constructing hotspots with small gaps of 1-6 nanometers between layers of multilayer nanoparticle membranes is proposed. The single-layer nanoparticle membrane assembled at the liquid-liquid interface is repeatedly fixed on a perforated flat substrate. The nanoparticles are closely placed between layers, forming a small gap of 1-6 nanometers with a huge electromagnetic enhancement effect.

[0017] 2. Utilizing the small gaps formed by multi-layer nanoparticle membranes and the principle of capillary suction, the target molecules are actively introduced into the small gaps of 1-6 nanometers between layers with huge electromagnetic enhancement, and continuous detection can be performed during the diffusion of the target solution, thus achieving the sensitivity and stability of surface enhanced Raman spectroscopy detection.

[0018] 3. This surface-enhanced Raman spectroscopy detection method based on the small gaps between multi-layer nanoparticle films has a simple, efficient and scientific preparation method. It has good application effects for different types of molecules and different scenarios, and is a universal (widespread) surface-enhanced Raman detection method. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0020] Figure 1 A scanned image of a layer of silver nanoparticle film being constructed.

[0021] Figure 2 A scanning image of the constructed two-layer silver nanoparticle film.

[0022] Figure 3 This is a scanned image of the constructed three-layer silver nanoparticle film.

[0023] Figure 4 In order to detect the SERS spectrum of the target molecule crystal violet (CV) by using the constructed three-layer silver nanoparticle film covered on the solution, the crystal violet molecule 10 -12 M-level effective detection. In the figure, 2500 is the intensity scale, and the four spectral lines correspond to 10 -9 M, 10 -10 M, 10 -11 M, 10 -12 M.

[0024] Figure 5 In order to detect the SERS spectrum of the target molecule malachite green (MG) solution by using the constructed three-layer silver nanoparticle film, the malachite green molecule 10 -12 M-level effective detection.

[0025] Figure 6 In order to detect the SERS spectrum of the target molecule Nile blue (NB) solution by using the constructed three-layer silver nanoparticle film, the Nile blue molecule 10 -11 M-level effective detection. In the figure, the concentration range of Nile blue solution is 10-8 -10 - 11 M.

[0026] Figure 7 Comparison of the dry film-forming surface enhanced Raman spectroscopy detection method and the surface enhanced Raman spectroscopy detection method of the small gaps between the layers of the multilayer nanoparticle film of the present invention for detecting CV solutions. a1-a3, the dry film-forming method is used to detect CV solutions of different concentrations of single-layer, two-layer and three-layer AgNPs films; b1-b3, the surface enhanced Raman spectroscopy detection method of the small gaps between the layers of the multilayer nanoparticle film is used to detect CV solutions of different concentrations of one-layer, two-layer and three-layer AgNPs films. Figure 7 In a1-a3, the concentration range of CV solution is 10 -6 -10 -9 M; in Figure b1-b3, the CV solution concentration range is 10 -9 -10 -12 M.

[0027] Figure 8 Comparison of the dry film-forming surface-enhanced Raman spectroscopy detection method and the surface-enhanced Raman spectroscopy detection method of small gaps between multilayer nanoparticle membranes of the present invention for MG solutions. Comparison of the dry film-forming method and the surface-enhanced Raman spectroscopy detection method of small gaps between multilayer nanoparticle membranes. a1-a3, the dry film-forming method is used to detect MG solutions of different concentrations of single-layer, two-layer and three-layer AgNPs membranes; b1-b3, the surface-enhanced Raman spectroscopy detection method of small gaps between multilayer nanoparticle membranes is used to detect MG solutions of different concentrations of one-layer, two-layer and three-layer AgNPs membranes. Figure 8 In a1, the concentration range of MG solution is 10 -6 -10 -8 M; Figure 8 In a2-a3, the concentration range of MG solution is 10 -6 -10 -9 M; in Figure b1-b3, the concentration range of MG solution is 10 -9 -10 -12 M.

[0028] Fig. 9 The surface enhanced Raman spectroscopy of the small gaps between the layers of the multilayer nanoparticle film of the present invention detects the CV solutions of one, two, three, four, and five layers of AgNPs film with different concentrations and the same concentration. ae, the surface enhanced Raman spectroscopy of the small gaps between the layers of the multilayer nanoparticle film is used to detect the CV solutions of one, two, three, four, and five layers of AgNPs film with different concentrations; f, the surface enhanced Raman spectroscopy of the small gaps between the layers of the multilayer nanoparticle film is used to detect the CV solutions of different concentrations of AgNPs film with different layers. -9SERS spectrum of M CV. According to the method of the present invention, as the concentration of the target changes, the consistency of the two-layer and three-layer Raman detection results is better and more stable than that of the one-layer, four-layer and five-layer detection results; according to the method of the present invention, when the concentration of the target is the same, the two-layer and three-layer detection are more sensitive (signal intensity is large); in the figure, the concentration range of CV solution is 10 -9 -10 -12 M. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Example 1

[0031] Step 1, take 1-10 ml of silver nanosol in a centrifuge tube, put it in a centrifuge, centrifuge it at 6000-8000 rpm for 10-20 minutes, take it out, remove the supernatant, and collect the concentrated nanosol at the bottom of the centrifuge tube for later use;

[0032] Step 2, taking 3-10 ml of distilled water and 1-4 ml of cyclohexane in a container to form a water-oil interface (water / cyclohexane interface); taking 20-80 μl of the concentrated nanosol in step 1, dispersing it in 1-5 ml of ethanol, taking 20-80 μl of the ethanol sol of silver nanoparticles each time and adding it to the water / cyclohexane interface to form a film at the interface;

[0033] Step 3: Cut the silicon wafer into 3 mm × 3 mm pieces, and use a laser to make a 0.2 mm circular hole on the silicon wafer for later use;

[0034] Step 4: Use tweezers to hold the silicon wafer in step 3, and fish out the film at the interface at a depth of 35° to the water / cyclohexane interface to obtain a nanomaterial film structure, such as Figure 1 As shown;

[0035] Step 5: Repeat step 4 to obtain a two-layer nanomaterial film structure, such as Figure 2 As shown;

[0036] Step 6: Repeat step 5 to obtain a three-layer nanomaterial film structure, such as Figure 3 As shown;

[0037] Step 7, Preparation 10 -9 -10 -12 M Crystal violet aqueous solution;

[0038] Step 8: Take 10 from step 7-9 -10 -12 2 μL of crystal violet aqueous solution was dropped on the silicon wafer;

[0039] Step 9, covering the three-layer silver nanoparticle film structure obtained in step 6 on the silicon wafer obtained in step 8;

[0040] Step 10: Based on capillary action, the crystal violet solution will rise from the pores prepared in step 3, and SERS detection will be performed during the process of the target sample solution continuously moving into the small gaps of the multilayer nanoparticle film. The surface enhanced Raman detection results are shown in Figure 1. Figure 4 As shown. The excitation light wavelength of the Raman spectrometer is 633nm.

[0041] Comparative Example 1

[0042] Step 1, take 1-10 ml of silver nanosol into a centrifuge tube, put it into a centrifuge, centrifuge it at 6000-8000 rpm for 10-20 minutes, take it out, remove the supernatant, and obtain the concentrated nanosol at the bottom of the centrifuge tube;

[0043] Step 2, taking 3-10 ml of distilled water and 1-4 ml of cyclohexane in a container to form a water-oil interface (water / cyclohexane interface); taking 20-80 μl of the concentrated nanosol in step 1, dispersing it in 1-5 ml of ethanol, taking 20-80 μl of the ethanol sol of silver nanoparticles each time and adding it to the water / cyclohexane interface to form a film at the interface;

[0044] Step 3, cutting the silicon wafer into 3 mm × 3 mm pieces for later use;

[0045] Step 4: Use tweezers to hold the silicon wafer in step 3, and fish out the film at the interface at a depth of 35° to the water / cyclohexane interface to obtain a nanomaterial film structure, such as Figure 1 As shown;

[0046] Step 5: Repeat step 4 to obtain a two-layer nanomaterial film structure, such as Figure 2 As shown;

[0047] Step 6: Repeat step 5 to obtain a three-layer nanomaterial film structure, such as Figure 3 As shown;

[0048] Step 7, placing the film structure obtained in step 4, 5 or 6 on a silicon wafer, and drying to obtain a SERS substrate on which silver nanoparticles are deposited;

[0049] Step 8, Preparation 10 -6 -10 -9 M Crystal violet aqueous solution;

[0050] Step 9, drop 2 microliters of crystal violet aqueous solution on the SERS substrate obtained in step 7; perform SERS detection. The surface enhanced Raman detection results are as follows Figure 7 As shown in a1-a3, the excitation light wavelength of the Raman spectrometer is 633nm.

[0051] Comparing Example 1 with Comparative Example 1 (dry film-forming drop method), it is found that the detection accuracy of crystal violet in Comparative Example 1 can only reach 10 -9 M, while Example 1 can reach 10 -12 M; Figure 7 , the Raman spectrum of Comparative Example 1 is chaotic compared with that of Example 1. Figure 1 The consistency is poor and the detection is unstable. Figure 7 b1-b3 The Raman detection results of the two-layer film and the three-layer film of the present invention are relatively more stable than those of the single-layer film.

[0052] Example 2

[0053] Step 1, take 1-10 ml of silver nanosol in a centrifuge tube, put it in a centrifuge, centrifuge it at 6000-8000 rpm for 10-20 minutes, take it out, remove the supernatant, and collect the concentrated nanosol at the bottom of the centrifuge tube for later use;

[0054] Step 2, taking 3-10 ml of distilled water and 1-4 ml of cyclohexane in a container to form a water-oil interface; taking 20-80 μl of the concentrated nanosol in step 1, dispersing it in 1-5 ml of ethanol, taking 20-80 μl of the ethanol sol of silver nanoparticles each time and adding it to the water / cyclohexane interface to form a film at the interface;

[0055] Step 3: Cut the silicon wafer into 3 mm × 3 mm pieces, and use a laser to make a 0.2 mm circular hole on the silicon wafer for later use;

[0056] Step 4: Use tweezers to hold the silicon wafer in step 3, and fish out the film at the interface at a depth of 35° to the water / cyclohexane interface to obtain a nanomaterial film structure, such as Figure 1 As shown;

[0057] Step 5: Repeat step 4 to obtain a two-layer nanomaterial film structure, such as Figure 2 As shown;

[0058] Step 6: Repeat step 5 to obtain a three-layer nanomaterial film structure, such as Figure 3 As shown;

[0059] Step 7, Preparation 10 -9 -10 -12 M Malachite green aqueous solution;

[0060] Step 8: Take 10 from step 7 -9 -10 -12 M 2 μl of malachite green aqueous solution was dropped on the silicon wafer;

[0061] Step 9, covering the three-layer silver nanoparticle film structure obtained in step 6 on the silicon wafer in step 8;

[0062] Step 10: Based on the capillary action, the malachite green solution will rise from the pores prepared in step 3, and SERS detection will be performed while the target sample solution is continuously moving into the small gaps of the multilayer nanoparticle film. Figure 5 As shown. The excitation light wavelength of the Raman spectrometer is 633nm.

[0063] Comparative Example 2

[0064] Step 1, take 1-10 ml of silver nanosol into a centrifuge tube, put it into a centrifuge, centrifuge it at 6000-8000 rpm for 10-20 minutes, take it out, remove the supernatant, and obtain the concentrated nanosol at the bottom of the centrifuge tube;

[0065] Step 2, taking 3-10 ml of distilled water and 1-4 ml of cyclohexane in a container to form a water-oil interface (water / cyclohexane interface); taking 20-80 μl of the concentrated nanosol in step 1, dispersing it in 1-5 ml of ethanol, taking 20-80 μl of the ethanol sol of silver nanoparticles each time and adding it to the water / cyclohexane interface to form a film at the interface;

[0066] Step 3, cutting the silicon wafer into 3 mm × 3 mm pieces for later use;

[0067] Step 4: Use tweezers to hold the silicon wafer in step 3, and fish out the film at the interface at a depth of 35° to the water / cyclohexane interface to obtain a nanomaterial film structure, such as Figure 1 As shown;

[0068] Step 5: Repeat step 4 to obtain a two-layer nanomaterial film structure, such as Figure 2 As shown;

[0069] Step 6: Repeat step 5 to obtain a three-layer nanomaterial film structure, such as Figure 3 As shown;

[0070] Step 7, placing the film structure obtained in step 4, 5 or 6 on a silicon wafer, and drying to obtain a SERS substrate on which silver nanoparticles are deposited;

[0071] Step 8, Preparation 10 -6 -10 -9 M Malachite green aqueous solution;

[0072] Step 9, take 2 microliters of malachite green aqueous solution and drop it on the SERS substrate obtained in step 7; perform SERS detection. The surface enhanced Raman detection results are as follows Figure 8 As shown in a1-a3, the excitation light wavelength of the Raman spectrometer is 633nm.

[0073] Comparing Example 2 with Comparative Example 2 (dry film-forming drop method), it is found that the detection accuracy of malachite green in Comparative Example 2 can only reach 10 -9 M even 10 -8 M(such as Figure 8 a1), while Example 1 can reach 10 -12 M; Comparative Example 2 ( Figure 8 a1-a3) compared with Example 2 ( Figure 8 b1-b3) Raman spectra are chaotic and vary with concentration. Figure 1 The consistency is poor and the detection is unstable. Figure 8 b1-b3 The Raman detection results of the two-layer film and the three-layer film of the present invention are relatively more stable than those of the single-layer film.

[0074] Example 3

[0075] Step 1, take 1-10 ml of nanosol in a centrifuge tube, put it in a centrifuge, centrifuge it at 6000-8000 rpm for 10-20 minutes, take it out, remove the supernatant, and collect the concentrated nanosol at the bottom of the centrifuge tube for later use;

[0076] Step 2, taking 3-10 ml of distilled water and 1-4 ml of cyclohexane in a container to form a water-oil interface; taking 20-80 μl of the concentrated nanosol in step 1, dispersing it in 1-5 ml of ethanol, taking 20-80 μl of the ethanol sol of gold / silver nanoparticles each time and adding it to the water / cyclohexane interface to form a film at the interface;

[0077] Step 3: Cut the mica sheet into 3 mm × 3 mm pieces, and use a laser to make a 0.2 mm circular hole on the mica sheet for later use;

[0078] Step 4: Use tweezers to hold the mica sheet in step 3, and fish out the film at a depth of 35° to the water / cyclohexane interface to obtain a nanomaterial film structure, such as Figure 1 As shown;

[0079] Step 5: Repeat step 4 to obtain a two-layer nanomaterial film structure, such as Figure 2 As shown;

[0080] Step 6: Repeat step 5 to obtain a three-layer nanomaterial film structure, such as Figure 3 As shown;

[0081] Step 7, Preparation 10 -8 -10 -11 M Nile blue aqueous solution;

[0082] Step 8: Take 10 from step 7 -8 -10 -11 2 μL of Nile blue aqueous solution was dropped on the silicon wafer;

[0083] Step 9, covering the three-layer silver nanoparticle film structure obtained in step 6 on the silicon wafer in step 8;

[0084] Step 10: Based on the capillary action, the Nile blue solution will rise from the pores prepared in step 3, and SERS detection will be performed while the target sample solution is continuously moving into the small gaps of the multilayer nanoparticle film. Figure 6 As shown. The excitation light wavelength of the Raman spectrometer is 633nm.

[0085] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A surface enhanced Raman spectroscopy detection method based on small gaps between multilayer nanoparticle films, characterized in that: A single-layer nanoparticle film is repeatedly fixed on a flat material with regular or irregular through holes to form a multi-layer nanoparticle film, and then the multi-layer nanoparticle film is placed on a solution containing a target object. The target object solution will rise from the through holes and move to the small gaps in the multi-layer nanoparticle film, and then the target object signal is detected under a Raman spectrometer; the through holes have a diameter of 0.1 mm to 0.5 mm; and small gaps of 1 to 6 nanometers are formed between the layers of the multi-layer nanoparticle film.

2. The detection method according to claim 1, characterized in that: The single-layer nanoparticle film is obtained by a liquid-liquid interface self-assembly method.

3. The detection method according to claim 2, characterized in that: The liquid-liquid interface self-assembly method comprises the steps of: centrifuging the metal nanosol to collect the concentrated nanosol at the bottom; taking distilled water and cyclohexane in a container to form a water / cyclohexane interface; taking the concentrated nanosol and dispersing it in ethanol to form an ethanol sol of nanoparticles; taking the ethanol sol of nanoparticles and adding it to the water / cyclohexane interface to form a film at the interface.

4. The detection method according to claim 3, characterized in that: The metal nano-sol includes at least one of silver nano-sol, gold nano-sol and copper nano-sol.

5. The detection method according to claim 1, characterized in that: The flat plate material is a planar material with a flat surface suitable for loading nanoparticles, including at least one of a silicon sheet, a mica sheet, and a glass sheet.

6. The detection method according to claim 1, characterized in that: The method of repeatedly fixing a single-layer nanoparticle film on a flat plate material with regular or irregular through holes to form a multi-layer nanoparticle film is to penetrate the flat plate material and the nanoparticle film self-assembled at the liquid-liquid interface at an angle of 30-45°, perform a film scooping operation, obtain a layer of nanoparticle film at the through hole, and repeat the scooping operation to obtain a multi-layer nanoparticle film.

7. The detection method according to claim 1, characterized in that: The target object includes at least one of plasticizers, anti-tumor drugs, poisons, pesticide residues, dyes, antibiotics, explosives and amino acids, and the solution of the target object is an aqueous solution or an organic solution.

8. The detection method according to claim 7, characterized in that: The target object is a dye.

9. The detection method according to claim 8, characterized in that: The target substance includes at least one of crystal violet, malachite green, Nile blue, methylene blue, rhodamine, and brilliant green.

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