A SERS label with fabry-perot optical cavity and localized surface plasmon resonance coupling interaction, and a preparation method and application thereof

Abstract

The application discloses a preparation method of a SERS label with Fabry-Perot optical cavity and localized surface plasmon resonance coupling effect, which comprises the following steps: depositing a copper film on the surface of a polymethyl methacrylate (PMMA) film by using a thermal evaporation technology, generating copper oxide nano spicules by reacting with a sodium hypochlorite solution, depositing silver nanoparticles on the surface of the copper oxide spicules by using a magnetron sputtering technology, and re-depositing a gold layer by using the thermal evaporation technology, so as to obtain a gold@silver nanoparticle / copper oxide spicule / PMMA flexible SERS substrate; and then the substrate is folded, heated and pressed to obtain the SERS label with Fabry-Perot optical cavity and localized surface plasmon resonance coupling effect. The SERS label provided by the application comprehensively integrates capillary action, Fabry-Perot optical cavity and localized surface plasmon resonance, effectively excites a high-intensity and large-volume hotspot, and makes trace biomarkers in a complex solution more easily captured by the large-volume hotspot, so that the in-situ SERS detection performance is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of the manufacturing method of surface enhanced Raman scattering (SERS) labels, and particularly relates to a SERS label with Fabry-Perot optical cavity and localized surface plasmon resonance coupling action and a preparation method and application thereof. BACKGROUND

[0002] Surface enhanced Raman scattering (SERS) is a phenomenon that the Raman signal of a substance to be detected is greatly enhanced when the substance is adsorbed on the surface of a metal sol (such as gold, silver, copper) or a rough metal surface, and has been applied in the fields of food safety, disease diagnosis and environmental pollution detection. In these practical application fields, the trace analyte to be detected is dispersed in water and organic liquid, attached to a solid surface, or dispersed in a gas mixture. In order to realize the detection of the trace analyte in the aqueous solution environment, various SERS substrates with dense hot spots (usually located in a gap of less than ~10 nm) have been integrated with microfluidic chip systems. However, the liquid environment in the aqueous solution is very complex, and the trace analyte is affected by other molecules in the overall environment, so it is difficult to be captured by the limited hot spots, and due to the fluidity of the medium, it is difficult to read out the signal with high intensity and high signal-to-noise ratio. In order to reduce the influence of Brownian motion on the metal plasmonic nanostructure, the microfluidic system involves advanced technology to fix the structure in a small area, which requires professional operation of complex procedures and expensive equipment. Therefore, it is urgent to develop a rapid and ultra-sensitive in-situ SERS detection method which can make the laser, plasmonic structure and trace analyte interact more effectively, and is simple, convenient and low-cost.

[0003] As an optical resonant cavity, the Fabry-Perot cavity is usually composed of two parallel facing mirrors, can effectively absorb and store laser photons in the electromagnetic field, and is one of the important optical phenomena, and has been applied in high-precision spectroscopy, light emission and detection, optical fiber sensors and the like. Due to the optical interference supporting the far-field effect in the Fabry-Perot cavity, strong volume hot spots can be induced, so the Fabry-Perot cavity is expected to provide more sensitive SERS detection. However, there are still few studies on the detection of water pollutants and markers in biological fluids by using the Fabry-Perot cavity, and it is still urgent to obtain an in-situ SERS sensor with Fabry-Perot cavity and localized surface plasmon resonance coupling by a low-cost and simple method. SUMMARY

[0004] In order to overcome the above problems, the present application provides a SERS label with Fabry-Perot optical cavity and localized surface plasmon resonance coupling action and a preparation method and application thereof.

[0005] To achieve the above technical purposes, the present application adopts the following technical solutions:

[0006] The first aspect of the present application provides a preparation method of a SERS label with Fabry-Perot optical cavity and localized surface plasmon resonance coupling, comprising the following steps:

[0007] (1) spin coating a toluene solution of polymethyl methacrylate (PMMA) on the surface of a copper foil substrate, naturally drying, and then etching the copper foil substrate with a FeCl3 solution to obtain a PMMA flexible film substrate;

[0008] (2) depositing a copper film on the surface of the PMMA flexible film substrate by a thermal evaporation technique, and then immersing in a sodium hypochlorite solution to react to form copper oxide nanospikes, thereby forming a copper oxide spike / PMMA flexible substrate;

[0009] (3) depositing silver nanoparticles on the surface of the copper oxide spikes by a magnetron sputtering technique, thereby forming a silver nanoparticle / copper oxide spike / PMMA flexible substrate, depositing gold on the surface of the silver nanoparticle / copper oxide spike / PMMA by a thermal evaporation technique, thereby obtaining a gold@silver nanoparticle / copper oxide spike / PMMA flexible SERS substrate;

[0010] (4) folding the gold@silver nanoparticle / copper oxide spike / PMMA flexible SERS substrate in half, heating, and pressing to obtain a SERS label with Fabry-Perot optical cavity and localized surface plasmon resonance coupling.

[0011] The second aspect of the present application provides a SERS label with Fabry-Perot optical cavity and localized surface plasmon resonance coupling obtained by the above preparation method.

[0012] The third aspect of the present application provides application of the above SERS label with Fabry-Perot optical cavity and localized surface plasmon resonance coupling to detection of biomarkers in a solution.

[0013] The fourth aspect of the present application provides a method for detecting biomarkers in a solution, comprising the following steps:

[0014] immersing the above SERS label with Fabry-Perot optical cavity and localized surface plasmon resonance coupling in a solution to be detected for a period of time, irradiating the outer surface of the SERS label with a probe of a portable Raman spectrometer, and collecting in-situ Raman spectrum.

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

[0016] (1) The application fully combines and plays the advantages of gold / silver nanoparticles, copper oxide spikes and PMMA flexible substrate: due to the local surface plasmon resonance effect, gold / silver nanoparticles can produce high-intensity local hot spots under laser excitation; the copper oxide spikes are vertical or inclined, similar to the shape of a tree trunk, and have a large specific surface area to provide abundant attachment sites for gold / silver nanoparticles; in addition, after the gold / silver nanoparticles / copper oxide spikes / PMMA flexible substrate is folded, the gold / silver nanoparticles / copper oxide spikes intersect, similar to a mirror surface, and each pair of gold / silver nanoparticles / copper oxide spikes can form a small optical cavity, forming a Fabry-Perot optical cavity as a whole, which can efficiently absorb photon energy after being trapped in the Fabry-Perot optical cavity through multiple reflections, forming a high-intensity large-volume hot spot; with the excellent flexibility of the PMMA film, the substrate can be folded, and the PMMA film also has high transmittance, so that the laser can pass through the PMMA into the Fabry-Perot optical cavity, and the Fabry-Perot optical cavity can be encapsulated inside to protect the plasmonic structure from damage and improve the SERS label life.

[0017] (2) The SERS label provided by the application solves the problem of integrating microfluidic technology and SERS platform for detection of trace markers in solution, and combines capillary action, Fabry-Perot optical cavity and local surface plasmon resonance, effectively exciting high-intensity, large-volume hot spots, so that trace biomarkers in complex solutions are more easily captured by large-volume hot spots, improving the performance of in-situ SERS detection.

[0018] (3) The SERS label provided by the application is easy to operate and can quickly extract the solution to be detected to complete the detection on site. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 The preparation of the SERS label provided by the application and the schematic diagram of in-situ detection thereof;

[0021] Figure 2a is a scanning electron microscope picture of the gold@silver nanoparticles / copper oxide spike / PMMA flexible SERS substrate prepared in Example 1 of the present application; b is a cross-sectional side view of the SERS label of the Fabry-Perot optical cavity and localized surface plasmon resonance coupling effect prepared in Example 1 of the present application; c is a transmission electron microscope picture of the gold@silver nanoparticles / copper oxide spike structure prepared in Example 1 of the present application;

[0022] Figure 3 a is a picture of the SERS label of the Fabry-Perot optical cavity and localized surface plasmon resonance coupling effect prepared in Example 1 of the present application and in-situ SERS detection by means of a portable Raman spectrometer; b is a schematic diagram of the binding of the aptamer and the biomarker of the gold@silver nanoparticles / copper oxide spike structure in the capillary SERS label prepared in Example 1 of the present application and the capture by a large volume hotspot; c is a Raman spectrum of the in-situ detection of a microcystin (MC-LR) aqueous solution with a concentration of 5 x 10 –6 μg / L ~ 5 x 10 –2 μg / L by the capillary SERS label prepared in Example 1 of the present application; d is a Raman spectrum of the in-situ detection of an adenine nucleoside aqueous solution with a concentration of 10 –11 M ~ 10 –5 M by the capillary SERS label prepared in Example 1 of the present application; e is a Raman spectrum of the in-situ detection of a malachite green (MG) solution with a concentration of 10 –11 M ~ 10 –5 M by the capillary SERS label prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0023] It should be noted that the following detailed description is merely exemplary in nature and is intended to provide further description of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0024] It is also important to note that the terms used herein are not intended to limit the particular embodiments of the present application to the preferred embodiments described. Rather, the terms are used only to describe specific embodiments of the present application. As used herein, unless otherwise expressly specified, all ranges are inclusive and combinable. Furthermore, it should be understood that where the terms "comprise", "comprises", "comprising", "include", "includes", "including" are used, they are used to indicate that the item(s) listed after the term is inclusive and does not exclude the addition of one or more other non-specified items.

[0025] In a first exemplary embodiment of the present application, a method for preparing a SERS label of a Fabry-Perot optical cavity and localized surface plasmon resonance coupling effect is provided, the method comprising:

[0026] (1) spin-coat a toluene solution of polymethyl methacrylate (PMMA) on the surface of a copper foil substrate, and after natural drying, etch away the copper foil substrate using a FeCl3 solution to obtain a PMMA flexible film substrate;

[0027] (2) deposit a copper film on the surface of the PMMA flexible film substrate using a thermal evaporation technique, and then immerse the copper film in a sodium hypochlorite solution to react to form copper oxide nanospikes, thereby forming a copper oxide spike / PMMA flexible substrate;

[0028] (3) deposit silver nanoparticles on the surface of the copper oxide spikes using a magnetron sputtering technique, thereby forming a silver nanoparticle / copper oxide spike / PMMA flexible substrate, and then deposit gold on the surface of the silver nanoparticle / copper oxide spike / PMMA using a thermal evaporation technique to obtain a gold@silver nanoparticle / copper oxide spike / PMMA flexible SERS substrate;

[0029] (4) fold the gold@silver nanoparticle / copper oxide spike / PMMA flexible SERS substrate in half, heat, and press to obtain a SERS label with the effects of a Fabry-Perot optical cavity and localized surface plasmon resonance coupling.

[0030] In one or more embodiments, the thickness of the copper foil substrate in step (1) is 20-30 μm, preferably 25 μm.

[0031] In one or more embodiments, the rotation speed during the spin-coating process in step (1) is 5 rpm-20 rpm, preferably 10 rpm; and the time is 5 s-10 s, preferably 10 s.

[0032] In one or more embodiments, the concentration of the toluene solution of polymethyl methacrylate (PMMA) in step (1) is 0.70 g / L-0.80 g / L, preferably 0.75 g / L, i.e. 0.75 g of polymethyl methacrylate is dissolved in 1 L of toluene.

[0033] In one or more embodiments, the concentration of the FeCl3 solution in step (1) is 250-300 g / L, preferably 270 g / L, i.e. 270 g of FeCl3 is dissolved in 1 L of deionized water.

[0034] In one or more embodiments, the etching time in step (1) is 5 h-10 h, preferably 5 h.

[0035] In one or more embodiments, the thickness of the PMMA film in step (1) is 1-5 μm, preferably 3 μm.

[0036] In one or more embodiments, the pressure in the thermal evaporation chamber in step (2) is 8 x 10 -5 Pa-4 x 10 -4 Pa, preferably 2 x 10 -4 Pa; the rate of thermal evaporation is 0.5-2.5 A / s, preferably 1.5 A / s. Preferably, the rate of thermal evaporation is 0.5-2.5 A / s, preferably 1.5 A / s. The rotation speed of the sample tray on which the PMMA flexible substrate is located is 5-20 rpm, preferably 10 rpm.

[0037] In one or more embodiments, the thickness of the copper film deposited by thermal evaporation in step (2) is 50-150 nm, preferably 80 nm.

[0038] In one or more embodiments, the mass fraction of the sodium hypochlorite solution in step (2) is 15-25%, preferably 20%.

[0039] In one or more embodiments, the time of immersion in the sodium hypochlorite solution in step (2) is 20-40 s, preferably 30 s.

[0040] In one or more embodiments, the copper oxide nanospikes in step (2) are similar to the shape of a tree trunk, with a base diameter of 60-180 nm and a height of 500-1500 nm.

[0041] In one or more embodiments, in step (3), the atmosphere for magnetron sputtering is argon, and the pressure for magnetron sputtering is 1 x 10 -4 Pa-4 x 10 -4 Pa, preferably 2 x 10 -4 Pa; the sputtering power is 50-70 W, preferably 60 W; the time for magnetron sputtering is 15-25 s, preferably 20 s.

[0042] In one or more embodiments, the diameter of the silver nanoparticles deposited in step (3) is 15-30 nm.

[0043] In one or more embodiments, the pressure in the thermal evaporation chamber in step (3) is 8 x 10 -5 Pa-4 x 10 - 4 Pa, preferably 2 x 10 -4 Pa; the rate of thermal evaporation is 0.5-2.5 A / s, preferably 1.5 A / s. Preferably, the rate of thermal evaporation is 0.5-2.5 A / s, preferably 1.5 A / s. The rotation speed of the sample tray on which the silver nanoparticle / copper oxide nanospike / PMMA flexible substrate is located is 5-20 rpm, preferably 10 rpm.

[0044] In one or more embodiments, the thickness of the gold film deposited in step (3) is 0.5-2.5 nm, preferably 2 nm.

[0045] In one or more embodiments, the temperature of the heating in step (4) is 60-100°C, preferably 80°C.

[0046] In one or more embodiments, the pressing force in step (4) is 5N-100N, preferably 80N.

[0047] In a second typical embodiment of the present application, a SERS tag with Fabry-Perot optical cavity and localized surface plasmon resonance coupling effect is provided, which is obtained by the above preparation method.

[0048] In a third typical embodiment of the present application, the SERS tag with Fabry-Perot optical cavity and localized surface plasmon resonance coupling effect is applied to detect biomarkers in a solution.

[0049] In one or more embodiments, the biomarker is microcystin (MC-LR), adenine, malachite green.

[0050] In a fourth typical embodiment of the present application, a method for detecting biomarkers in a solution is provided, which comprises:

[0051] The SERS tag with Fabry-Perot optical cavity and localized surface plasmon resonance coupling effect is immersed in the solution to be detected for a period of time, a portable Raman spectrometer probe is used to irradiate the outer surface of the SERS tag, and in-situ Raman spectrum is collected.

[0052] In one or more embodiments, the SERS tag is immersed in the solution to be detected for 4-6min, preferably 5min.

[0053] In one or more embodiments, for microcystin (MC-LR) detection, the SERS tag needs to be bound with a microcystin aptamer through Au-S, and the structure of the microcystin aptamer is 5'-SHC6-GGCGCCAAACAGGACCACCATGACAATTACCCATACC ACCTCATTATGCCCCATCTCCGC-3.

[0054] The present application will be further described in detail below with reference to specific examples, it should be pointed out that the specific examples are an explanation of the present application rather than a limitation.

[0055] Example 1

[0056] Preparation of the SERS tag with Fabry-Perot optical cavity and localized surface plasmon resonance coupling effect:

[0057] (1) A 0.75 g / L toluene solution of polymethyl methacrylate (PMMA) was spin-coated on a 10 cm long, 2 cm wide, and 25 μm thick copper foil substrate at a speed of 10 rpm for 10 s. After natural drying, the copper foil substrate was etched away using a 270 g / L FeCl3 solution to obtain a 3 μm thick PMMA flexible substrate film.

[0058] (2) A copper film with a thickness of 100 nm was deposited on the surface of the PMMA flexible substrate film using thermal evaporation technology. The pressure in the thermal evaporation chamber was 2×10 -4 Pa, the rate of thermal evaporation is The sample tray where the PMMA film is located rotates at a speed of 10 rpm.

[0059] The copper film / PMMA flexible substrate was then immersed in a 20% by mass sodium hypochlorite solution for 30 seconds to generate copper oxide nanospikes. The formed copper oxide nanospikes were similar in shape to a tree trunk, with a bottom diameter of 60 to 180 nm and a height of 500 to 1500 nm.

[0060] (3) Silver nanoparticles were deposited on the surface of copper oxide spikes using magnetron sputtering technology. The magnetron sputtering power was 60 W, the magnetron sputtering time was 20 s, the magnetron sputtering atmosphere was argon, and the magnetron sputtering pressure was 2×10 -4 Pa, the size of the obtained silver nanoparticles is 15 to 30 nm.

[0061] Gold was deposited on the surface of silver nanoparticles / copper oxide spikes / PMMA using thermal evaporation technology. The thickness of the deposited gold was 2 nm. The pressure in the thermal evaporation chamber was 2×10 -4 Pa, the rate of thermal evaporation is The sample tray containing the silver nanoparticles / copper oxide spikes / PMMA flexible substrate rotated at a speed of 10 rpm.

[0062] (4) The gold@silver nanoparticles / copper oxide spikes / PMMA flexible substrate was folded in half, heated to 80°C, and pressed with a force of 50N to obtain a SERS tag with the resonance coupling of the Fabry-Perot cavity and the localized surface plasmon.

[0063] pass Figure 1 It can be seen that the present invention provides a method for preparing a SERS tag with resonance coupling effect of a Fabry-Perot cavity and localized surface plasmons.

[0064] The SERS tag produced by the Fabry-Perot cavity and the localized surface plasmon resonance coupling prepared in this embodiment was characterized by scanning electron microscopy and transmission electron microscopy. Figure 2 shown.

[0065] Example 2

[0066] Detection of biomarker in solution by SERS tag prepared in Example 1

[0067] (1) Detection of microcystin

[0068] Firstly, 0.5 mL of 10 mM / L microcystin aptamer solution was taken by a pipette and placed in a centrifuge tube, then the SERS tag prepared in Example 1 was immersed in the aptamer solution, and the SERS tag was adsorbed by capillary phenomenon. After incubation at room temperature for 15 minutes, the aptamer was bound by Au-S bond. The outer surface of the SERS tag was washed with ultrapure water.

[0069] Then, 0.5 mL of 5 x 10 –6 μg / L ~ 5 x 10 –2 μg / L microcystin (MC-LR) aqueous solution was taken and placed in a centrifuge tube. The SERS tag was immersed in the 5 x 10 –6 μg / L microcystin solution for 5 min, and the SERS tag was adsorbed by capillary phenomenon. The outer surface of the SERS tag was washed with ultrapure water. The outer surface of the SERS tag was irradiated by a portable Raman spectrometer probe, and in-situ Raman spectrum was collected. The SERS tag with Fabry-Perot optical cavity and localized surface plasmon resonance coupling was used to detect from low concentration to high concentration according to the above steps, and the experimental results are shown in Fig. c. Figure 3

[0070] (2) Detection of adenine nucleoside

[0071] Then, 0.5 mL of 10 –11 M ~ 10 –5 M adenine nucleoside aqueous solution was taken and placed in a centrifuge tube. The SERS tag was immersed in the 10 –11 M adenine nucleoside solution for 5 min, and the SERS tag was adsorbed by capillary phenomenon. The outer surface of the SERS tag was washed with ultrapure water. The outer surface of the SERS tag was irradiated by a portable Raman spectrometer probe, and in-situ Raman spectrum was collected. The SERS tag with Fabry-Perot optical cavity and localized surface plasmon resonance coupling was used to detect from low concentration to high concentration according to the above steps, and the experimental results are shown in Fig. d. Figure 3

[0072] (3) Detection of malachite green (MG)

[0073] Then, 0.5 mL of 10 –11 M ~ 10 –5 M malachite green (MG) aqueous solution was taken and placed in a centrifuge tube. The SERS tag was immersed in the 10​​–11 The SERS tag was irradiated by a portable Raman spectrometer probe aimed at the outer surface of the SERS tag, and in-situ Raman spectra were collected. The SERS tag with Fabry-Perot optical cavity and localized surface plasmon resonance coupling was used to detect from low concentration to high concentration according to the above steps, and the experimental results are as follows Figure 3 Fig. 2 shows the in-situ Raman spectra of the SERS tag in the microcystin solution with different concentrations.

[0074] From Figure 3 Fig. 2c, d and e, it can be seen that in the complex solution, the microcystin molecular characteristic peaks 1020 cm -1 and 1581 cm -1 were detected, the adenine nucleoside characteristic peaks 723 cm -1 and 1337 cm -1 were detected, the malachite green molecular characteristic peaks 1173 cm -1 and 1616 cm -1 were detected, and such high-performance in-situ SERS rapid detection was mainly attributed to the Fabry-Perot optical cavity and localized surface plasmon resonance coupling. Under laser excitation, the photon energy can be effectively collected, realizing large-volume excitation of high-intensity hot spots, and trace biomarkers are more easily captured in a complex environment.

Claims

1. A method of fabricating a SERS tag with Fabry-Perot optical cavity and localized surface plasmon resonance coupling, characterized in that, The method comprises: (1) spin-coating a toluene solution of polymethyl methacrylate on the surface of a copper foil substrate, naturally drying, and then etching the copper foil substrate with a FeCl3 solution to obtain a PMMA flexible film substrate; (2) depositing a copper film on the surface of the PMMA flexible film substrate by thermal evaporation, and then immersing in a sodium hypochlorite solution to react to form copper oxide nanospikes, thereby forming a copper oxide spike / PMMA flexible substrate; the copper oxide nanospikes are similar to tree trunk shapes, with a bottom diameter of 60-180 nm and a height of 500-1500 nm; (3) depositing silver nanoparticles on the surface of the copper oxide spikes by magnetron sputtering to form a silver nanoparticle / copper oxide spike / PMMA flexible substrate, and then depositing gold on the surface of the silver nanoparticle / copper oxide spike / PMMA by thermal evaporation to obtain a gold@silver nanoparticle / copper oxide spike / PMMA flexible SERS substrate; (4) folding the gold@silver nanoparticle / copper oxide spike / PMMA flexible SERS substrate in half, heating, and pressing to obtain a SERS label with the effects of Fabry-Perot optical cavity and localized surface plasmon resonance coupling; the heating temperature is 60-100℃, and the pressing force is 5N-100N.

2. The production method according to claim 1, wherein The thickness of the copper foil substrate in step (1) is 20-30 μm; Alternatively, in the spin-coating process in step (1), the rotation speed is 5 rpm-20 rpm, and the time is 5 s-10 s; Alternatively, the concentration of the toluene solution of polymethyl methacrylate in step (1) is 0.70 g / L-0.80 g / L; Alternatively, the concentration of the FeCl3 solution in step (1) is 250-300 g / L; Alternatively, the etching time in step (1) is 5 h-10 h; Alternatively, the thickness of the PMMA flexible film substrate in step (1) is 1-5 μm.

3. The production method according to claim 2, wherein The thickness of the copper foil substrate in step (1) is 25 μm.

4. The production method according to claim 2, wherein In the spin-coating process in step (1), the rotation speed is 10 rpm, and the time is 10 s.

5. The production method according to claim 2, wherein The concentration of the toluene solution of polymethyl methacrylate in step (1) is 0.75 g / L.

6. The production method according to claim 2, wherein The concentration of the FeCl3 solution in step (1) is 270 g / L.

7. The production method according to claim 2, wherein The etching time in step (1) is 5 h.

8. The production method according to claim 2, wherein The thickness of the PMMA flexible film substrate in step (1) is 3 μm.

9. The production method according to claim 1, wherein The pressure in the thermal evaporation cavity in step (2) is 8x10 -5 Pa~4x10 -4 Pa; the rate of thermal evaporation is 2~10Å / s; the rotation speed of the sample tray where the PMMA flexible film substrate is located is 5rpm~20rpm; Alternatively, the thickness of the copper film deposited by thermal evaporation in step (2) is 50 nm-150 nm; Alternatively, the mass fraction of the sodium hypochlorite solution in step (2) is 15%-25%; Alternatively, the time for immersing in the sodium hypochlorite solution in step (2) is 20 s-40 s.

10. The production method according to claim 9, wherein The pressure in the thermal evaporation cavity in step (2) is 2x10 -4 Pa; the rate of thermal evaporation is 5 A / s; and the rotation speed of the sample holder on which the PMMA flexible film substrate is located is 10 rpm.

11. The production method according to claim 9, wherein The thickness of the copper film deposited by thermal evaporation in step (2) is 100 nm.

12. The production method according to claim 9, wherein The mass fraction of the sodium hypochlorite solution in step (2) is 20%.

13. The production method according to claim 9, wherein The time for immersing in the sodium hypochlorite solution in step (2) is 30 s.

14. The production method according to claim 1, wherein The diameter of the silver nanoparticles deposited in step (3) is 15-30 nm; or, the pressure in the thermal evaporation cavity in step (3) is 8x10 -5 Pa~4x10 -4 Pa; the rate of thermal evaporation is 1~3Å / s; the rotation speed of the sample tray on which the silver nanoparticle / copper oxide spike / PMMA flexible substrate is located is 5rpm~20rpm; Alternatively, the thickness of the gold film deposited in step (3) is 0.5-2.5 nm.

15. The production method according to claim 14, wherein The pressure in the thermal evaporation cavity in step (3) is 2x10 -4 Pa; the rate of thermal evaporation is 1 A / s; the rotation speed of the sample tray where the silver nanoparticle / copper oxide spike / PMMA flexible substrate is located is 10 rpm.

16. The production method according to claim 14, wherein The thickness of the gold film deposited in step (3) is 2 nm.

17. The production method according to claim 1, wherein The heating temperature in step (4) is 80℃. Or, the pressing force in the step (4) is 80N.

18. The SERS tag prepared by the method of any one of claims 1-17.

19. The SERS tag prepared by the method of any one of claims 1-17 is applied to detect biomarkers in a solution.

20. The use according to claim 19 for detecting a biomarker in a solution, wherein The biomarker is microcystin, adenine, malachite green.

21. A method of detecting a biomarker in a solution, characterized by, The method comprises: immersing the SERS tag prepared by the method of any one of claims 1-17 in a solution to be detected for a period of time, aiming the SERS tag outer surface with a portable Raman spectrometer probe, and collecting in-situ Raman spectrum.

22. The method of claim 21, wherein, For microcystin (MC-LR) detection, the SERS tag needs to be bound with microcystin aptamer through Au-S, and the structure of the microcystin aptamer is 5'-SHC6-GGCGCCAAACAGGACCACCATGACAATTACCCATACCACCTCATTATGCCCCATCTCCGC-3'; Or, the SERS tag is immersed in the solution to be detected for 4-6 min.

23. The method of claim 21, wherein, The SERS tag is immersed in the solution to be detected for 5 min.

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