SERS detection chip as well as preparation method and application thereof

Abstract

The invention relates to the technical field of surface enhanced Raman detection, and discloses an SERS (Surface Enhanced Raman Scattering) detection chip as well as a preparation method and application thereof. The SERS detection chip comprises: a substrate having a groove; the groove is formed in the substrate, and the silver nanowires are located in the groove and form a loose net-shaped structure. After the SERS detection chip is in contact with a to-be-detected solution, the silver nanowire net structure can rapidly absorb a target solution, collapse occurs, target molecules are fixed in nano gaps of the silver nanowires, the target molecules are effectively fixed in an electromagnetic field enhancement area under the condition that modification molecules do not need to be introduced, and amplification of Raman signals of the target molecules is achieved. The SERS detection chip is suitable for detecting various environmental pollutants such as polycyclic aromatic hydrocarbon and petroleum which are difficult to be directly adsorbed to the surface of an SERS substrate.

Description

Technical Field

[0001] The present invention relates to the technical field of surface-enhanced Raman detection, and particularly relates to a SERS detection chip, a preparation method thereof, and an application thereof. Background Art

[0002] Surface Enhanced Raman Spectroscopy (SERS) is a non-destructive and non-invasive technique that can amplify the Raman signal intensity of target molecules, provide chemical bond fingerprint information of the molecules to be detected without sample pretreatment, and is applicable to various detection targets such as large and small biomolecules, microorganisms, and environmental pollutants. Due to the excellent sensitivity and unique molecular vibration fingerprint recognition function of the SERS technique, it has been widely applied in analytical fields such as disease diagnosis, environmental monitoring, and food safety.

[0003] The key to SERS detection lies in the SERS substrate composed of metal nanoparticles. The SERS enhancement principle can be understood in two steps. When the target molecule is adsorbed on the surface of the metal nanoparticles, the first step is the generation of a local electromagnetic field enhancement effect around the metal nanoparticles under the action of incident light; the second step is that the metal nanoparticles act as optical antennas to transmit the Raman signal from the near field to the far field, improving the Raman signal intensity of the target molecule. At present, SERS substrates are mainly composed of metal nanoparticles such as gold and silver. Moreover, there is basically no binding force between the metal particles and substances such as polycyclic aromatic hydrocarbons in petroleum substances. Generally, polycyclic aromatic hydrocarbons are fixed on the SERS substrate by adding modifier molecules such as thiols and graphene. However, the introduction of these modifier molecules will, on the one hand, increase the preparation difficulty of the SERS substrate, and on the other hand, the characteristic peaks of the modifier molecules may also affect the detection of target molecules. Therefore, how to prepare a suitable SERS substrate and adsorb petroleum molecules such as polycyclic aromatic hydrocarbons into the nanogaps is a problem worthy of research.

[0004] Patent application CN 108333009 A provides a flexible sodium alginate-gold nanoparticle composite material. Gold nanorods are doped and mixed into sodium alginate gel, and through the method of freeze-drying and the cross-linking effect of calcium chloride, a surface-enhanced Raman active substrate of gold nanorod-calcium alginate sponge is constructed. Patent application CN 111053921 A discloses a freeze-dried preparation of Raman positioning nanoparticles. The freeze-dried preparation of Raman positioning nanoparticles includes the following components calculated by mass: 80-100 parts of core-shell structured gold nanoparticles wrapped with a mesoporous silica layer; 0.1-20 parts of freeze-drying protectant; 0-10 parts of acid-base regulator; 0-10 parts of isotonic regulator. The freeze-dried preparation of Raman positioning nanoparticles has high stability and safety, can be stored for a long time, the preparation process is simple and feasible, and is suitable for large-scale production. Patent application CN 102608093A synthesized a core-shell type Fe3O4@Ag magnetic nanoparticle, and modified the surface of the nanoparticle with thiol. The modified magnetic nanoparticle was used as a surface-enhanced Raman active substrate for the enrichment of polycyclic aromatic hydrocarbons (PAHs), and the Raman characteristic peaks of PAHs were observed by a portable Raman spectrometer. It can not only realize the rapid detection of a single PAH, but also be used for the detection of a mixed solution of polycyclic aromatic hydrocarbons. Summary of the Invention

[0005] The object of the present invention is to overcome the problems existing in the prior art, such as the existing SERS substrates have insufficient enhancement ability, low adsorption efficiency for target molecules, and the need to introduce adsorption molecules such as thiol and graphene to achieve the adsorption of target molecules, and to provide a SERS detection chip, its preparation method and application.

[0006] To achieve the above object, the first aspect of the present invention provides a SERS detection chip, including:

[0007] A bottom plate with grooves; and

[0008] Silver nanowires located in the grooves, and the silver nanowires form a loose network structure.

[0009] Preferably, the diameter of the silver nanowires is 15-65 nm, and the length is 12-40 μm.

[0010] Preferably, the bottom area of the groove is 2-15 mm 2 , and the height is 4-8 mm.

[0011] The second aspect of the present invention provides a method for preparing a SERS detection chip, which includes the following steps:

[0012] (1) Provide a bottom plate with grooves;

[0013] (2) Inject the silver nanowire solution into the groove, then place it in liquid nitrogen, and then perform freeze-drying;

[0014] Among them, the concentration of silver nanowires in the silver nanowire solution is 25 - 65 mg / mL.

[0015] Preferably, the bottom area of the groove is 2 - 15 mm 2 , and the height is 4 - 8 mm.

[0016] Preferably, the material of the bottom plate is a polymer material, silicon nitride, glass, silicon wafer or metal;

[0017] Preferably, the polymer material is selected from PMMA, PC, PVC or PET.

[0018] Preferably, the diameter of the silver nanowires is 15 - 65 nm, and the length is 12 - 40 μm.

[0019] Preferably, the injection volume of the silver nanowire solution is in a volume ratio of 0.4 - 0.8:1 to the volume of the groove.

[0020] Preferably, the conditions for freeze-drying include: the pressure is 4 - 40 Pa, and the time is 5 - 25 h.

[0021] The third aspect of the present invention provides a SERS detection chip prepared by the method described above.

[0022] The fourth aspect of the present invention provides the application of the SERS detection chip described above in the detection of petroleum substances.

[0023] Preferably, the detection concentration of polycyclic aromatic hydrocarbons by the SERS detection chip is ≥10 -9 mol / L.

[0024] The fifth aspect of the present invention provides a method for detecting the concentration of petroleum substances in a solution, the method comprising: dropping the solution to be measured into the groove of the SERS detection chip described above, and performing SERS detection using a Raman spectrometer.

[0025] Preferably, the volume of the solution to be measured is 4 - 8 μL.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The SERS detection chip of the present invention can detect petroleum substances without introducing modifier molecules. Specifically, the SERS detection chip includes a bottom plate with grooves and silver nanowires located in the grooves, and the silver nanowires form a loose network structure. After the SERS detection chip contacts the solution to be detected, the silver nanowire network structure can quickly absorb the target solution, and then collapse, fixing the target molecules in the nano-gaps of the silver nanowires.

[0028] 2. The preparation method of the SERS detection chip of the present invention has the characteristics of simple steps and does not require the use of large and expensive instruments. Combining with the freeze-drying technology, the silver nanowires self-assemble into a network structure, which is convenient for adsorbing the molecules to be detected in the solution.

[0029] 3. The SERS detection chip of the present invention is convenient for storage and transportation, and is suitable for detecting trace petroleum substances in various water quality detection fields such as refinery sewage and domestic sewage. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic flow chart of processing the solution to be detected using the SERS detection chip of the present invention;

[0031] Figure 2 is a characterization result diagram of the product prepared in Example 1 taken by a microscope;

[0032] Figure 3 is a characterization result diagram of the product prepared in Example 1 by SEM;

[0033] Figure 4 is a Raman signal diagram of anthracene at different concentrations under the SERS detection chip;

[0034] Figure 5 is a relationship diagram between the concentration of anthracene and the Raman signal intensity. DETAILED DESCRIPTION OF THE INVENTION

[0035] The following will describe the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining and illustrating the present invention, and are not used to limit the present invention.

[0036] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0037] The first aspect of the present invention provides a SERS detection chip, comprising:

[0038] A bottom plate having a groove; and

[0039] Silver nanowires located in the groove, and the silver nanowires form a loose network structure.

[0040] In the present invention, the silver nanowires located in the groove form a network structure, which can adsorb target molecules into the nano-gaps without introducing modifier molecules, realizing highly sensitive detection of target molecules.

[0041] In a preferred embodiment, the diameter of the silver nanowires is 15 - 65 nm, more preferably 20 - 60 nm; and the length is 12 - 40 μm, more preferably 20 - 35 μm.

[0042] In a preferred embodiment, the bottom area of the groove is 2 - 15 mm 2 , and the height is 4 - 8 mm.

[0043] The second aspect of the present invention provides a method for preparing a SERS detection chip, the method comprising the following steps:

[0044] (1) Providing a bottom plate having a groove;

[0045] (2) Injecting a silver nanowire solution into the groove, then placing it in liquid nitrogen, and then performing freeze-drying;

[0046] Wherein, the concentration of silver nanowires in the silver nanowire solution is 25 - 65 mg / mL.

[0047] In the method of the present invention, by injecting the silver nanowire solution into the groove of the bottom plate, the ultra-low temperature of liquid nitrogen can quickly turn the solution into a solid state, and then through the freeze-drying technology, the solvent can be sublimated without destroying the structure formed by the silver nanowires. The present invention can obtain a network structure assembled by silver nanowires in combination with the freeze-drying technology, without involving large and expensive instruments such as vacuum coating machines and electron beam etching machines, which is convenient for further popularization and application.

[0048] In the present invention, the concentration of silver nanowires in the silver nanowire solution is reasonably controlled. If the concentration is too low, the network structure is prone to collapse during freeze-drying; if the concentration is too high, the cost will increase. Therefore, the present invention limits the concentration of the silver nanowire solution to 25 - 65 mg / mL, which can not only form a stable network structure to ensure that target molecules can be distributed in the nano-gaps of the entire silver nanowires, but also ensure the economic practicality of the method and effectively improve the detection sensitivity.

[0049] In a preferred embodiment, the bottom area of the groove is 2 - 15 mm 2, with a height of 4 - 8 mm; specifically, the bottom area of the groove can be 2 mm 2 , 3 mm 2 , 4 mm 2 , 5 mm 2 , 6 mm 2 , 7 mm 2 , 8 mm 2 , 9 mm 2 , 10 mm 2 , 11 mm 2 , 12 mm 2 , 13 mm 2 , 14 mm 2 or 15 mm 2 ; the height of the groove can be 4 mm, 5 mm, 6 mm, 7 mm or 8 mm.

[0050] In the present invention, there are no special requirements for the choice of the bottom surface shape of the groove, and it can be various common shapes, such as triangular, circular or quadrilateral.

[0051] In a preferred embodiment, the thickness of the negative film can be 5 - 15 mm.

[0052] In the present invention, there are no special requirements for the choice of the material of the negative film, and it can be the negative films of various materials commonly used in the art. Preferably, the material of the negative film is a polymer material, silicon nitride, glass, silicon wafer or metal; more preferably, the polymer material is selected from polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinyl chloride (PVC) or polyethylene terephthalate (PET).

[0053] In a preferred embodiment, the diameter of the silver nanowires is 15 - 65 nm, more preferably 20 - 60 nm; the length is 12 - 40 μm, more preferably 20 - 35 μm.

[0054] Preferably, the injection volume of the silver nanowire solution is in a volume ratio of 0.4 - 0.8:1 to the volume of the groove, more preferably 0.55 - 0.7:1.

[0055] In the method of the present invention, the silver nanowires can be commercially available products or prepared in the laboratory. The solvent used in the silver nanowire solution can be water.

[0056] According to some specific embodiments of the present invention, the silver nanowires can be prepared according to the following process:

[0057] S1: Mix polyvinylpyrrolidone with water, and then add silver nitrate for mixing to obtain a mixture;

[0058] S2: Hydrothermally react the mixture, and then perform solid-liquid separation.

[0059] Preferably, the conditions for the hydrothermal reaction include: a temperature of 120 - 180 °C and a time of 4 - 10 h.

[0060] Preferably, the solid-liquid separation can be carried out by centrifugation. Specifically, the rotation speed of centrifugation can be 2000 - 5000 rpm, the time can be 5 - 10 min, and it can be repeated 2 - 5 times.

[0061] Preferably, the weight ratio of the amount of polyvinylpyrrolidone (PVP) to silver nitrate is 1:0.05 - 0.15.

[0062] In a preferred embodiment, the conditions for freeze-drying include: a pressure of 4 - 40 Pa and a time of 5 - 25 h.

[0063] The third aspect of the present invention provides a SERS detection chip prepared by the method described above.

[0064] The fourth aspect of the present invention provides the application of the SERS detection chip described above in the detection of petroleum substances.

[0065] Referring to Figure 1 , the process of treating the test solution during Raman detection using the SERS detection chip of the present invention includes: dropping the test solution into the groove, the test solution quickly fills the entire groove, and as the solvent volatilizes, the silver nanowire network structure will collapse, and the target molecules are wrapped in the nano-gaps of the silver nanowires.

[0066] Preferably, the petroleum substances are selected from anthracene, phenanthrene, pyrene, benzo[a]pyrene, etc.

[0067] Preferably, the detection concentration of polycyclic aromatic hydrocarbons by the SERS detection chip is ≥10 -9 mol / L.

[0068] The fifth aspect of the present invention provides a method for detecting the concentration of petroleum substances in a solution, the method comprising: dropping the test solution into the groove of the SERS detection chip described above, and performing SERS detection using a Raman spectrometer.

[0069] Preferably, the volume of the test solution is 4 - 8 μL.

[0070] In a specific embodiment, quantitative detection of petroleum substances can be carried out. The test process includes the following steps:

[0071] L1: Drop the standard solution of petroleum substances into the groove of the SERS detection chip, dry it, and after the solvent has completely volatilized, perform SERS detection using a Raman spectrometer and record the peak intensity;

[0072] L2: Taking the negative of the logarithm of the concentration as the abscissa and the peak intensity as the ordinate for fitting to obtain the relationship between the concentration and the peak intensity;

[0073] L3: Drop the solution to be measured into the groove of the SERS detection chip, dry it, and after the solvent has completely evaporated, then perform SERS detection using a Raman spectrometer, record the peak intensity, and then substitute the peak intensity into the relationship formula for calculation to obtain the concentration of petroleum substances in the solution to be measured.

[0074] The following further illustrates the SERS detection chip and its preparation method of the present invention through examples. The examples are implemented on the premise of the technical solution of the present invention, and the detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0075] Example 1

[0076] Preparation of silver nanowire solution:

[0077] S1: Add 0.25 g of polyvinylpyrrolidone (PVP, MW = 55000) to 50 mL of deionized water, stir for 40 minutes to form a clear solution, and then add 0.02 g of AgNO3 and stir vigorously for 10 minutes to obtain a mixture;

[0078] S2: Transfer the mixture to a hydrothermal reactor (with a volume of 50 mL) and seal it at 160 °C for 7 hours; after the reaction, take out the suspension, centrifuge it at 3500 rpm for 8 minutes, repeat 3 times, remove the unreacted substances, and dilute it to obtain a silver nanowire (with a length of 28 μm and a diameter of 25 nm) solution with a concentration of 45 mg / mL.

[0079] Preparation of SERS detection chip:

[0080] (1) Provide a negative film with a groove. The shape of the negative film is square, the thickness of the negative film is 6 mm, and the bottom area of the groove is 3.5 mm 2 , and the height is 5 mm;

[0081] (2) Use a pipette gun with a tip diameter of 5 mm to take 12 μL of the silver nanowire suspension, drop it into the groove, then place the negative film in liquid nitrogen, and then transfer it to a freeze dryer and place it for 20 h under the condition of a pressure of 15 Pa to obtain the SERS detection chip.

[0082] Example 2

[0083] S1: Add 0.25 g of polyvinylpyrrolidone (PVP, MW = 55000) to 50 mL of deionized water. After stirring for 40 minutes to form a clear solution, then add 0.02 g of AgNO3 and stir vigorously for 10 minutes to obtain a mixture.

[0084] S2: Transfer the mixture to a hydrothermal reactor (with a volume of 50 mL) and seal it at 160 °C for 7 hours. After the reaction, take out the suspension, centrifuge it at 3500 rpm for 8 minutes, repeat 3 times to remove the unreacted substances, and then dilute it to obtain a silver nanowire (with a length of 28 μm and a diameter of 25 nm) solution with a concentration of 30 mg / mL.

[0085] Preparation of SERS detection chip:

[0086] (1) Provide a negative film with grooves. The shape of the negative film is square, the thickness of the negative film is 6 mm, and the bottom area of the groove is 3.5 mm 2 , with a height of 5 mm;

[0087] (2) Use a pipette with a tip diameter of 5 mm to take 12 μL of the silver nanowire suspension, drop it into the groove, then put the negative film into liquid nitrogen, and then transfer it to a freeze dryer and place it for 20 h under the condition of a pressure of 15 Pa to obtain the SERS detection chip.

[0088] Example 3

[0089] S1: Add 0.25 g of polyvinylpyrrolidone (PVP, MW = 55000) to 50 mL of deionized water. After stirring for 40 minutes to form a clear solution, then add 0.02 g of AgNO3 and stir vigorously for 10 minutes to obtain a mixture.

[0090] S2: Transfer the mixture to a hydrothermal reactor (with a volume of 50 mL) and seal it at 160 °C for 7 hours. After the reaction, take out the suspension, centrifuge it at 3500 rpm for 8 minutes, repeat 3 times to remove the unreacted substances, and then dilute it to obtain a silver nanowire (with a length of 28 μm and a diameter of 25 nm) solution with a concentration of 55 mg / mL.

[0091] Preparation of SERS detection chip:

[0092] (1) Provide a negative film with grooves. The shape of the negative film is square, the thickness of the negative film is 6 mm, and the bottom area of the groove is 3.5 mm 2 , with a height of 5 mm;

[0093] (2) Use a pipette with a tip diameter of 5 mm to take 12 μL of the silver nanowire suspension, drop it into the groove, then place the negative film in liquid nitrogen, and then transfer it to a freeze dryer and place it for 20 h under the condition of a pressure of 15 Pa to obtain the SERS detection chip.

[0094] Example 4

[0095] Preparation of silver nanowire solution:

[0096] S1: Add 0.25 g of polyvinylpyrrolidone (PVP, MW = 55000) to 50 mL of deionized water, stir for 40 minutes to form a clear solution, and then add 0.02 g of AgNO3 and stir vigorously for 10 minutes to obtain a mixture.

[0097] S2: Transfer the mixture to a hydrothermal reactor (with a volume of 50 mL) and seal it at 160 °C for 7 hours; after the reaction, take out the suspension, centrifuge it at 3500 rpm for 8 minutes, repeat 3 times to remove the unreacted substances, and dilute it to obtain a silver nanowire (with a length of 28 μm and a diameter of 25 nm) solution with a concentration of 45 mg / mL.

[0098] Preparation of SERS detection chip:

[0099] (1) Provide a negative film with a groove. The shape of the negative film is square, the thickness of the negative film is 6 mm, and the bottom area of the groove is 5 mm 2 , and the height is 4 mm;

[0100] (2) Use a pipette with a tip diameter of 5 mm to take 12 μL of the silver nanowire suspension, drop it into the groove, then place the negative film in liquid nitrogen, and then transfer it to a freeze dryer and place it for 20 h under the condition of a pressure of 15 Pa to obtain the SERS detection chip.

[0101] Example 5

[0102] Preparation of silver nanowire solution:

[0103] S1: Add 0.25 g of polyvinylpyrrolidone (PVP, MW = 55000) to 50 mL of deionized water, stir for 40 minutes to form a clear solution, and then add 0.02 g of AgNO3 and stir vigorously for 10 minutes to obtain a mixture.

[0104] S2: Transfer the mixture to a hydrothermal reactor (with a volume of 50 mL) and seal it at 160 °C for 7 hours; after the reaction, take out the suspension, centrifuge it at 3500 rpm for 8 minutes, repeat 3 times to remove the unreacted substances, and dilute it to obtain a silver nanowire (with a length of 28 μm and a diameter of 25 nm) solution with a concentration of 45 mg / mL.

[0105] Preparation of SERS detection chip:

[0106] (1) Provide a negative film with grooves. The negative film is square in shape, with a thickness of 6 mm and the bottom area of the groove is 3.5 mm 2 , and the height is 5 mm;

[0107] (2) Use a pipette gun with a tip diameter of 5 mm to take 9 μL of silver nanowire suspension, drop it into the groove, then put the negative film into liquid nitrogen, and then transfer it to a freeze dryer, and place it for 25 h under the condition of a pressure of 10 Pa to obtain the SERS detection chip.

[0108] Example 6

[0109] Preparation of silver nanowire solution:

[0110] S1: Add 0.25 g of polyvinylpyrrolidone (PVP, MW = 55000) to 50 mL of deionized water, stir for 40 minutes to form a clear solution, and then add 0.025 g of AgNO3 and stir vigorously for 10 minutes to obtain a mixture;

[0111] S2: Transfer the mixture to a hydrothermal reactor (with a volume of 50 mL) and seal it at 160 °C for 7 hours; after the reaction, take out the suspension, centrifuge it at 3500 rpm for 8 minutes, repeat 3 times to remove the unreacted substances, and dilute it to obtain a silver nanowire (length 33 μm, diameter 35 nm) solution with a concentration of 50 mg / mL.

[0112] Preparation of SERS detection chip:

[0113] (1) Provide a negative film with grooves. The negative film is square in shape, with a thickness of 6 mm and the bottom area of the groove is 3.5 mm 2 , and the height is 5 mm;

[0114] (2) Use a pipette gun with a tip diameter of 5 mm to take 12 μL of silver nanowire suspension, drop it into the groove, then put the negative film into liquid nitrogen, and then transfer it to a freeze dryer, and place it for 20 h under the condition of a pressure of 15 Pa to obtain the SERS detection chip.

[0115] Example 7

[0116] Preparation of silver nanowire solution:

[0117] S1: Add 0.25 g of polyvinylpyrrolidone (PVP, MW = 55000) to 50 mL of deionized water, stir for 40 minutes to form a clear solution, and then add 0.018 g of AgNO3 and stir vigorously for 10 minutes to obtain a mixture;

[0118] S2: Transfer the mixture to a hydrothermal reactor (with a volume of 50 mL), seal it at 160 °C for 7 hours; after the reaction, take out the suspension, centrifuge it at 3500 rpm for 8 minutes, repeat 3 times to remove the unreacted substances, and dilute it to obtain a silver nanowire (with a length of 20 μm and a diameter of 22 nm) solution with a concentration of 30 mg / mL.

[0119] Prepare the SERS detection chip:

[0120] (1) Provide a negative film with grooves. The shape of the negative film is square, the thickness of the negative film is 6 mm, and the bottom area of the groove is 3.5 mm 2 , and the height is 5 mm;

[0121] (2) Use a pipette gun with a tip diameter of 5 mm to take 12 μL of the silver nanowire suspension, drop it into the groove, then put the negative film into liquid nitrogen, and then transfer it to a freeze dryer and place it for 20 h under the condition of a pressure of 15 Pa to obtain the SERS detection chip.

[0122] Example 8

[0123] Prepare the silver nanowire solution:

[0124] S1: Add 0.25 g of polyvinylpyrrolidone (PVP, MW = 55000) to 50 mL of deionized water, stir for 40 minutes to form a clear solution, and then add 0.02 g of AgNO3 and stir vigorously for 10 minutes to obtain a mixture;

[0125] S2: Transfer the mixture to a hydrothermal reactor (with a volume of 50 mL), seal it at 160 °C for 7 hours; after the reaction, take out the suspension, centrifuge it at 3500 rpm for 8 minutes, repeat 3 times to remove the unreacted substances, and dilute it to obtain a silver nanowire (with a length of 28 μm and a diameter of 25 nm) solution with a concentration of 38 mg / mL.

[0126] Prepare the SERS detection chip:

[0127] (1) Provide a negative film with grooves. The shape of the negative film is square, the thickness of the negative film is 6 mm, and the bottom area of the groove is 3.5 mm 2 , and the height is 5 mm;

[0128] (2) Use a pipette gun with a tip diameter of 5 mm to take 14 μL of the silver nanowire suspension, drop it into the groove, then put the negative film into liquid nitrogen, and then transfer it to a freeze dryer and place it for 20 h under the condition of a pressure of 15 Pa to obtain the SERS detection chip.

[0129] Example 9

[0130] Preparation of silver nanowire solution:

[0131] S1: Add 0.25 g of polyvinylpyrrolidone (PVP, MW = 55000) to 50 mL of deionized water. After stirring for 40 minutes to form a clear solution, then add 0.023 g of AgNO3 and stir vigorously for 10 minutes to obtain a mixture.

[0132] S2: Transfer the mixture to a hydrothermal reactor (with a volume of 50 mL) and seal it at 160 °C for 7 hours. After the reaction, take out the suspension, centrifuge it at 3500 rpm for 8 minutes, repeat 3 times to remove the unreacted substances, and then dilute it to obtain a silver nanowire (with a length of 30 μm and a diameter of 29 nm) solution with a concentration of 45 mg / mL.

[0133] Preparation of SERS detection chip:

[0134] (1) Provide a bottom plate with grooves. The shape of the bottom plate is circular, the thickness of the bottom plate is 6 mm, and the bottom area of the groove is 3.5 mm 2 , and the height is 5 mm;

[0135] (2) Use a pipette gun with a tip diameter of 5 mm to take 13 μL of the silver nanowire suspension, drop it into the groove, then put the bottom plate into liquid nitrogen, and then transfer it to a freeze dryer and place it for 20 h under a pressure of 15 Pa to obtain the SERS detection chip.

[0136] Comparative Example 1

[0137] Preparation of silver nanowire solution:

[0138] S1: Add 0.25 g of polyvinylpyrrolidone (PVP, MW = 55000) to 50 mL of deionized water. After stirring for 40 minutes to form a clear solution, then add 0.02 g of AgNO3 and stir vigorously for 10 minutes to obtain a mixture.

[0139] S2: Transfer the mixture to a hydrothermal reactor (with a volume of 50 mL) and seal it at 160 °C for 7 hours. After the reaction, take out the suspension, centrifuge it at 3500 rpm for 8 minutes, repeat 3 times to remove the unreacted substances, and then dilute it to obtain a silver nanowire (with a length of 28 μm and a diameter of 25 nm) solution with a concentration of 45 mg / mL.

[0140] Preparation of SERS chip:

[0141] (1) Provide a bottom plate with grooves. The shape of the bottom plate is square, the thickness of the bottom plate is 6 mm, and the bottom area of the groove is 3.5 mm 2 , and the height is 5 mm;

[0142] (2) Use a pipette with a tip diameter of 5 mm to take 12 μL of the silver nanowire suspension, and drop it into the groove. After the solvent has completely evaporated, the SERS detection chip D1 is obtained.

[0143] Comparative Example 2

[0144] Prepare the silver nanowire solution:

[0145] S1: Add 0.25 g of polyvinylpyrrolidone (PVP, MW = 55000) to 50 mL of deionized water, stir for 40 minutes to form a clear solution, and then add 0.02 g of AgNO3 and stir vigorously for 10 minutes to obtain a mixture.

[0146] S2: Transfer the mixture to a hydrothermal reactor (volume: 50 mL), seal it at 160 °C for 7 hours. After the reaction, take out the suspension, centrifuge it at 3500 rpm for 8 minutes, repeat 3 times to remove the unreacted substances, and dilute it to obtain a silver nanowire (length: 28 μm, diameter: 25 nm) solution with a concentration of 15 mg / mL.

[0147] Prepare the SERS detection chip:

[0148] (1) Provide a bottom plate with a groove. The bottom plate is square in shape, with a thickness of 6 mm and the bottom area of the groove is 3.5 mm 2 , and the height is 5 mm;

[0149] (2) Use a pipette with a tip diameter of 5 mm to take 12 μL of the silver nanowire suspension, drop it into the groove, then place the bottom plate in liquid nitrogen, and then transfer it to a freeze dryer and place it for 20 h under the condition of a pressure of 15 Pa. During the placement process, it is observed that the silver nanowires collapse at the bottom of the groove. This may be due to the too low concentration of the silver nanowire solution, resulting in insufficient supporting force of the formed network structure.

[0150] Test Example 1

[0151] Use an Olympus CX31 microscope to take pictures of the chip prepared in Example 1, and the results are as Figure 2 shown; use SEM to characterize the chip prepared in Example 1, and the results are as Figure 3 shown.

[0152] It can be observed from Figure 3 that the silver nanowires can intertwine with each other to form a loose network structure.

[0153] Test Example 2

[0154] Test the performance of the products prepared in the examples and comparative examples. The test process is as follows:

[0155] Add 6 μL of an ethanol solution of anthracene with a concentration of 10 -6 M (i.e., 10 -6 mol / L) dropwise onto the chip to be tested. After the solvent has evaporated completely, use a Horiba Xplus microscopic confocal Raman spectrometer to test the substrate. Select a laser with a wavelength of 633 nm, a power of 0.5 mW, an integration time of 40 s, and an integration number of 2 times. Taking the intensity of anthracene molecules at 1403 cm -1 as an example, the results are shown in Table 1.

[0156] Table 1

[0157] Number Strength Number Strength Example 1 10231 Example 6 11042 Example 2 9932 Example 7 9456 Example 3 10312 Example 8 9905 Example 4 9785 Example 9 10135 Example 5 9821 Comparative Example 1 7415

[0158] As can be seen from Table 1, the SERS detection chip prepared in the example has good signal amplification ability when applied to surface-enhanced Raman detection. The signal intensity of the SERS detection chip prepared in Comparative Example 1 is significantly lower than that of the example. This may be because in this SERS detection chip, the silver nanowires in the grooves are closely packed. After adding the solution to be tested, the target molecules can only adsorb on the surface of the silver nanowires, and the number of molecules entering the nanogaps decreases, resulting in a decrease in the Raman signal.

[0159] Test Example 3

[0160] Prepare standard solutions with anthracene concentrations of 10 -9 mol / L, 10 -8 mol / L, 10 -7 mol / L, 10 -6 mol / L, 10 -5 mol / L respectively. Drop the above standard solutions onto 6 SERS detection chips prepared according to the method described in Example 1. After the solvent has evaporated completely, perform SERS detection using a Raman spectrometer. The corresponding Raman signal diagrams are as shown in Figure 4 . As can be seen from the figure, the characteristic peaks of anthracene molecules are mainly at 391 cm -1 , 754 cm -1 , 1403 cm -1 and 1562 cm -1 . It can be seen from the intensity of the characteristic peaks that as the concentration gradually decreases, the intensity of the characteristic peaks also gradually decreases. Thus, it can be seen that the SERS detection chip described in the present invention can achieve qualitative detection of anthracene molecules with a concentration ≥ 10 -9 mol / L.

[0161] Furthermore, in order to achieve quantitative detection of anthracene molecules, according to the data in Figure 4 , select the intensity of the characteristic peak at 1403 cm -1 as the ordinate and the negative logarithm of the concentration as the abscissa to obtain the attached Figure 5 . From the attachedFigure 5 It can be seen that there is a good functional relationship between the intensity of the characteristic peak and the negative logarithm of the concentration. The intensity of the characteristic peak y = -3272.9x + 30441.5, R 2 = 0.9922, where x is the negative logarithm of the concentration (i.e., -lgC). Based on this mathematical relationship, after measuring the intensity of the characteristic peak at 1403 cm -1 , the concentration of the solution can be calculated, thereby realizing the quantitative detection of anthracene molecules.

[0162] Solutions with anthracene molecule concentrations of 10 -5 mol / L, 10 -7 mol / L, and 10 -8 mol / L were prepared as the test solutions. Three SERS detection chips prepared according to the method described in Example 1 were prepared. Then, the above solutions were dropped into the grooves of the SERS detection chips. After the solvent had evaporated completely, the Raman spectra were measured to obtain the intensity of the characteristic peak at 1403 cm -1 . Substituting it into the above relationship formula, the concentration was calculated. The measured results were compared with the theoretical values of the test solutions, and the results are shown in Table 2.

[0163] Table 2

[0164] Theoretical value Characteristic peak intensity Detected value Error <![CDATA[10 -5 mol / L]]> 14175 <![CDATA[10 -4.97 mol / L]]> 7.2％ <![CDATA[10 -7 mol / L]]> 7400 <![CDATA[10 -7.04 mol / L]]> 8.8％ <![CDATA[10 -8 mol / L]]> 4356 <![CDATA[10 -7.97 mol / L]]> 7.2％

[0165] As can be seen from Table 2, the SERS detection chip described in the present invention can accurately measure the anthracene concentration in the solution.

[0166] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A SERS detection chip, characterized in that, Comprising: A bottom film having grooves; And Silver nanowires located in the grooves, and the silver nanowires form a loose network structure.

2. The SERS detection chip according to claim 1, wherein, The diameter of the silver nanowires is 15 - 65 nm, and the length is 12 - 40 μm.

3. The SERS detection chip according to claim 1 or 2, characterized in that, The bottom area of the groove is 2-15 mm 2 , and the height is 4-8 mm.

4. A method for preparing an SERS detection chip, characterized in that, The method comprises the following steps: (1) Providing a bottom film having grooves; (2) Injecting a silver nanowire solution into the grooves, then placing it in liquid nitrogen, and then performing freeze-drying; Wherein, the concentration of silver nanowires in the silver nanowire solution is 25 - 65 mg / mL.

5. The method according to claim 4, characterized in that, The bottom area of the groove is 2 - 15 mm 2 , and the height is 4 - 8 mm.

6. The method according to claim 4 or 5, characterized in that The material of the bottom film is a polymer material, silicon nitride, glass, silicon wafer or metal; Preferably, the polymer material is selected from PMMA, PC, PVC or PET.

7. The method according to any one of claims 4-6, characterized in that, The diameter of the silver nanowires is 15 - 65 nm, and the length is 12 - 40 μm.

8. The method according to any one of claims 4 to 7, characterized in that The injection volume of the silver nanowire solution is in a volume ratio of 0.4 - 0.8:1 to the volume of the grooves.

9. The method according to claim 4, characterized in that, The conditions for freeze-drying include: the pressure is 4 - 40 Pa, and the time is 5 - 25 h.

10. A SERS detection chip prepared by the method according to any one of claims 4 - 9.

11. The application of the SERS detection chip according to any one of claims 1 - 3 and 10 in the detection of petroleum substances.

12. According to the application described in claim 11, the detection concentration of polycyclic aromatic hydrocarbons by the SERS detection chip is ≥ 10 -9 mol / L.

13. A method for detecting the concentration of petroleum substances in a solution, characterized in that, The method includes: dropping a test solution into the grooves of the SERS detection chip according to any one of claims 1 - 3 and 9, and performing SERS detection using a Raman spectrometer.

14. The method according to claim 13, wherein The volume of the test solution is 4 - 8 μL.

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