SERS (Surface Enhanced Raman Scattering) substrate for nano plastic detection based on metal nanoparticle domain aggregation and preparation method of SERS substrate

Abstract

The invention discloses an SERS (Surface Enhanced Raman Scattering) substrate for nano plastic detection based on metal nanoparticle domain aggregation and a preparation method of the SERS substrate, and belongs to the technical field of nanomaterial science and optical analysis. And the two layers of noble metal nanoparticles are successively deposited in a designated area of the hydrophilic microporous polymer film through suction filtration to obtain the nano plastic detection SERS substrate. According to the present invention, the hydrophilic and hydrophobic polymer film and the microporous structure thereof are utilized to sequentially aggregate the silver nanoparticle domains with different sizes to the surface of the hydrophilic polymer film, such that the high-sensitivity detection of the nano-plastic in the aqueous solution is achieved, and the problem of the large nano-plastic detection difficulty caused by the small size is overcome;

Description

Technical Field

[0001] The invention belongs to the field of nanomaterials and optical analysis technology, and particularly relates to a SERS substrate for nanoplastic detection based on metal nanoparticle domain aggregation and a preparation method thereof. Background Art

[0002] Plastic pollution has become a global environmental threat. Nanoplastics are produced by the decomposition of plastic products and are between 1 and 1000 nm in size. Due to their extremely small size, nanoplastics are difficult to detect and are potentially dangerous. Existing studies have shown that nanoplastics can not only enter the human body through diet, breathing, and skin contact, but can even penetrate the placental barrier and enter fetal tissue, affecting the life and health of the next generation. However, due to their small size, low content, and non-specificity, little is known about the source, distribution, and environmental abundance of nanoplastics. Developing a method suitable for the quantitative assessment of nanoplastics is of great significance for the study of human life and health protection.

[0003] Surface enhanced Raman scattering (SERS) uses the localized surface plasmon resonance (LSPR) of nanoscale rough metal to amplify Raman signals. It has both non-destructive analysis and "fingerprint" characteristics, and significantly improves detection sensitivity. It has been proven to be a powerful analytical method for the determination of trace substances. Metal nanoarrays are efficient SERS enhancement substrates obtained by uniformly dispersing or densely stacking metal nanoparticles on the surface of a carrier. By reducing the distance between particles to increase LSPR coupling, a hot spot amplification area is formed at the gap to better enhance the Raman signal. However, it is still challenging to complete high-sensitivity detection of nanoplastics in actual samples based on metal nanoarray SERS substrates. Therefore, it is very important to develop a SERS substrate for nanoplastic detection based on metal nanoparticle domain aggregation. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0006] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a nanoplastic detection SERS substrate based on metal nanoparticle domain aggregation, wherein the nanoplastic detection SERS substrate is a double-layer noble metal nanoparticle structure;

[0007] Among them, the lower layer is precious metal nanoparticle A, and the upper layer is precious metal nanoparticle B; the size of the precious metal nanoparticle A is 150nm~500nm, and the size of the precious metal nanoparticle B is 10nm~200nm; the size of the metal nanoparticle A is larger than the size of the metal nanoparticle B.

[0008] As a preferred solution of the nano-plastic detection SERS substrate based on metal nanoparticle domain aggregation described in the present invention, wherein: the described.

[0009] As a preferred solution of the nano-plastic detection SERS substrate based on metal nanoparticle domain aggregation described in the present invention, wherein: the noble metal includes one of gold or silver.

[0010] As a preferred solution of the nanoplastic detection SERS substrate based on metal nanoparticle domain aggregation described in the present invention, the shape of the nanoparticles includes one of nanospheres, nanorods, nanocubes or nanostars.

[0011] As a preferred solution of the nanoplastic detection SERS substrate based on metal nanoparticle domain aggregation of the present invention, wherein: the volume ratio of the noble metal nanoparticle A to the noble metal nanoparticle B is 1-20:12-25

[0012] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a nano-plastic detection SERS substrate based on metal nanoparticle domain aggregation.

[0013] In order to solve the above technical problems, the present invention provides the following technical solutions: comprising:

[0014] preparing noble metal nanoparticle solutions of different sizes;

[0015] stacking the punched hydrophobic microporous polymer membrane and the hydrophilic microporous polymer membrane on the filter support in sequence;

[0016] The metal nanoparticle A solution is sampled by a capillary onto a hydrophilic microporous polymer membrane, and water in the solution is filtered out by suction at the overlapping position of the openings of the hydrophilic microporous polymer membrane and the hydrophobic microporous polymer membrane;

[0017] The capillary sampling metal nanoparticle B solution is dripped onto the aggregation area of ​​the metal nanoparticle A domain, and the water in the solution is filtered out again by suction at the overlapping position of the openings of the hydrophilic microporous polymer membrane and the hydrophobic microporous polymer membrane to obtain a SERS substrate for nanoplastic detection.

[0018] As a preferred solution of the method for preparing the nanoplastic detection SERS substrate based on metal nanoparticle domain aggregation of the present invention, the microporous polymer membrane includes one of a polyvinylidene fluoride filter membrane, a polytetrafluoroethylene filter membrane or a polyethersulfone filter membrane.

[0019] As a preferred solution of the method for preparing the nanoplastic detection SERS substrate based on metal nanoparticle domain aggregation of the present invention, the pore size of the opening of the hydrophobic microporous polymer membrane is 1 mm to 5 mm.

[0020] As a preferred solution of the method for preparing the nanoplastic detection SERS substrate based on metal nanoparticle domain aggregation of the present invention, the micropore size of the hydrophilic microporous polymer membrane is 0.1 μm to 0.45 μm.

[0021] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a SERS substrate based on metal nanoparticle domain aggregation for use in nanoplastic detection.

[0022] Beneficial effects of the present invention:

[0023] (1) The present invention adopts the suction filtration technology to sequentially deposit metal nanoparticles of different sizes on the surface of the hydrophilic microporous polymer membrane, thereby improving the enhancement effect of metal nanoparticles of a single size and making it possible to detect nanoplastics with high sensitivity.

[0024] (2) The present invention confines metal nanoparticles to the open-pore region of the hydrophobic microporous polymer membrane by stacking an open-pore hydrophobic microporous polymer membrane with a hydrophilic microporous polymer membrane, thereby reducing metal nanoparticle consumption and improving metal nanoparticle aggregation efficiency.

[0025] (3) The present invention is simple to operate, low in cost, high in sensitivity, and good in uniformity, and provides a simple and efficient method for obtaining a SERS substrate for nanoplastic detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0027] Figure 1 This is a real picture of the SERS substrate for nanoplastic detection based on silver nanoparticle domain aggregation prepared in Example 1 of the present invention.

[0028] Figure 2This is the Raman spectrum of polystyrene nanoplastic measured using the SERS substrate prepared in Example 1 of the present invention as a Raman signal enhancement substrate.

[0029] Figure 3 This is a SEM image of the SERS substrate prepared in Example 9 of the present invention.

[0030] Figure 4 The Raman spectrum of polystyrene nanoplastic measured using the substrate prepared in Comparative Example 1 as a Raman signal enhancement substrate. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0032] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0033] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0034] The raw materials used in the present invention are all commercially available unless otherwise specified.

[0035] The performance of the material prepared in the embodiment of the present invention was tested as follows: After sampling the nanoplastic onto the SERS substrate using a capillary tube with an inner diameter of 0.5 mm, the SERS spectrum intensity of the nanoplastic was tested under 633 nm laser excitation using a Raman spectrometer (Horiba T64000).

[0036] The hydrophobic microporous polymer membrane used in the embodiment of the present invention is a hydrophobic polyvinylidene fluoride filter membrane; the hydrophilic microporous polymer membrane used is a hydrophilic polyvinylidene fluoride filter membrane, and the hydrophilic polyvinylidene fluoride filter membrane has micropores of 0.1 μm.

[0037] Example 1

[0038] This embodiment provides a method for preparing a nano-plastic detection SERS substrate based on metal nanoparticle domain aggregation, specifically:

[0039] Step 1: Prepare 150 nm silver nanosphere solution and 10 nm silver nanosphere solution according to the method of Lixiang Xing in "Size Control Synthesis of Monodisperse, Quasi-Spherical Silver Nanoparticles To Realize Surface-Enhanced Raman Scattering Uniformity and Reproducibility";

[0040] Step 2: A circular array of holes with a diameter of 1 mm is opened on the hydrophobic polyvinylidene fluoride filter membrane, and the hydrophobic polyvinylidene fluoride filter membrane and the hydrophilic polyvinylidene fluoride filter membrane are stacked in sequence on a filter holder made of sintered glass;

[0041] Step 3: Capillary sampling of a 150 nm silver nanosphere solution onto a hydrophilic polyvinylidene fluoride filter membrane, and suction filtration to remove water from the silver nanosphere solution at the overlapped position of the openings of the hydrophilic polyvinylidene fluoride filter membrane and the hydrophobic polyvinylidene fluoride filter membrane;

[0042] Step 4: Capillary sampling of 10nm silver nanosphere solution was dripped onto the 150nm silver nanosphere area, and the water was filtered out again to obtain the nanoplastic detection SERS substrate. The capillary sampling volume ratio of 150nm silver nanosphere to 10nm silver nanosphere was 1:12.

[0043] Figure 1 This is a SERS substrate image of nanoplastic detection based on domain aggregation of silver nanoparticles prepared in this embodiment. It can be seen that the silver nanoparticles have achieved domain aggregation on the hydrophilic polyvinylidene fluoride filter membrane.

[0044] Figure 2 This is the Raman spectrum of polystyrene nanoplastics measured using the SERS substrate prepared in this example as a Raman signal enhancement substrate. It can be seen that the nanoplastic detection SERS substrate based on metal nanoparticle domain aggregation can sensitively detect 0.1 mg / mL polystyrene nanoplastics with a size as low as 100 nm.

[0045] Example 2

[0046] The difference between this embodiment and embodiment 1 is that the sampling volume ratio of noble metal nanoparticles A and noble metal nanoparticles B is adjusted to 1:25, and the rest of the preparation process is the same as that of embodiment 1 to prepare a nano-plastic detection SERS substrate.

[0047] The SERS substrate prepared in this example can sensitively detect 0.5 mg / mL polystyrene nanoplastics with a size as low as 500 nm.

[0048] Example 3

[0049] The difference between this embodiment and embodiment 1 is that the sampling volume ratio of noble metal nanoparticles A and noble metal nanoparticles B is adjusted to 20:12, and the rest of the preparation process is the same as that of embodiment 1 to prepare a nano-plastic detection SERS substrate.

[0050] The SERS substrate prepared in this example can sensitively detect 0.5 mg / mL polystyrene nanoplastics with a size as low as 300 nm.

[0051] Example 4

[0052] The difference between this embodiment and embodiment 1 is that the sampling volume ratio of noble metal nanoparticles A and noble metal nanoparticles B is adjusted to 20:25, and the rest of the preparation process is the same as that of embodiment 1 to prepare a nano-plastic detection SERS substrate.

[0053] The SERS substrate prepared in this example can sensitively detect 0.1 mg / mL polystyrene nanoplastics with a size as low as 200 nm.

[0054] It can be seen from the above embodiments that adjusting the volume ratio of noble metal nanoparticles A and noble metal nanoparticles B has a significant impact on the performance of the SERS substrate. This is because the local surface electromagnetic field coupling effects of noble metal nanoparticles of different sizes with different volume ratios are different. According to the results, the best technical effect can be obtained when the volume ratio of noble metal nanoparticles A and noble metal nanoparticles B in the present invention is 1:12.

[0055] Example 5

[0056] The difference between this embodiment and embodiment 1 is that the opening size of the hydrophobic filter membrane is adjusted to 5 mm, and the rest of the preparation process is the same as that of embodiment 1 to prepare a nano-plastic detection SERS substrate.

[0057] The SERS substrate prepared in this example can sensitively detect 0.5 mg / mL polystyrene nanoplastics with a size as low as 500 nm.

[0058] Example 6

[0059] The difference between this embodiment and embodiment 1 is that the opening size of the hydrophobic filter membrane is adjusted to 3 mm, and the rest of the preparation process is the same as that of embodiment 1 to prepare a nano-plastic detection SERS substrate.

[0060] The SERS substrate prepared in this example can sensitively detect 0.25 mg / mL polystyrene nanoplastics with a size as low as 200 nm.

[0061] It can be seen from the above embodiments that adjusting the pore size of the hydrophobic filter membrane has a significant effect on the performance of the SERS substrate. This is because the smaller the pore size of the hydrophobic filter membrane, the smaller the distance between the metal nanoparticles, and the stronger the electromagnetic field coupling effect. According to the results, the best technical effect can be obtained when the pore size of the hydrophobic filter membrane in the present invention is 1 mm.

[0062] Example 7

[0063] The difference between this embodiment and embodiment 1 is that the 150nm silver nanosphere solution and the 10nm silver nanosphere are adjusted to 150nm gold nanosphere solution and 10nm gold nanosphere, and the rest of the preparation process is the same as that of embodiment 1 to prepare a nano plastic detection SERS substrate.

[0064] The SERS substrate prepared in this example can sensitively detect 0.5 mg / mL polystyrene nanoplastics with a size as low as 500 nm.

[0065] Example 8

[0066] The difference between this embodiment and embodiment 1 is that the 150nm silver nanosphere solution and the 10nm silver nanosphere are adjusted to 150nm gold nanosphere solution and 10nm silver nanosphere, and the rest of the preparation process is the same as that of embodiment 1 to prepare a nano plastic detection SERS substrate.

[0067] The SERS substrate prepared in this example can sensitively detect 0.1 mg / mL polystyrene nanoplastics with a size as low as 200 nm.

[0068] Example 9

[0069] The difference between this embodiment and embodiment 1 is that the 150nm silver nanosphere solution and the 10nm silver nanosphere are adjusted to 250nm gold nanosphere solution and 100nm silver nanosphere, and the rest of the preparation process is the same as that of embodiment 1 to prepare a nanoplastic detection SERS substrate.

[0070] The SERS substrate prepared in this example can sensitively detect 0.2 mg / mL polystyrene nanoplastics with a size as low as 200 nm.

[0071] Figure 3 This is a SEM image of the SERS substrate prepared in this example. It can be seen that the small-sized silver nanosphere layer is distributed above the large-sized silver nanosphere layer.

[0072] It can be seen from the above embodiments that adjusting the type of precious metal has a significant impact on the performance of the SERS substrate. This is because when the size of the precious metal nanoparticles remains unchanged, the precious metal silver has a stronger electromagnetic field enhancement effect than the precious metal gold. According to the results, the best technical effect can be obtained when both of the two precious metal nanoparticles in the present invention are precious metal silver.

[0073] Comparative Example 1

[0074] This comparative example provides a method for preparing a nanoplastic detection SERS substrate based on silver nanowires, specifically:

[0075] Step 1: Add 0.16 g polyvinyl pyrrolidone (MW ~ 1.3 million) and 0.16 g polyvinyl pyrrolidone (MW ~ 55000) to 44 mL ethylene glycol respectively.

[0076] Step 2: After polyvinyl pyrrolidone is fully melted, quickly pour 5 ml of 600 μM ferric chloride solution and 6 ml of 0.35 M silver nitrate solution into the above solvent.

[0077] Step 3: Heat at 140°C for 2h in an oil base, and the color of the solution after the reaction changes to bright yellow to gray. Then wash with deionized water three times, and disperse the solution in 50ml of deionized water by ultrasound to obtain silver nanowires.

[0078] Step 4: Sample 1 mL of silver nanowire solution onto the surface of the cellulose membrane, remove water from the solution by suction, and obtain a nanoplastic detection SERS substrate.

[0079] Figure 4 The Raman spectrum of polystyrene nanoplastics measured by using the substrate prepared in this comparative example as a Raman signal enhancement substrate shows that it can sensitively detect 5 mg / mL nanoplastics at 630 nm.

[0080] Comparative Example 2

[0081] This comparative example provides a method for preparing a nanoplastic detection SERS substrate based on metal nanoparticle domain aggregation, specifically:

[0082] Step 1: preparing a 50 nm silver nanosphere solution and a 10 nm silver nanosphere solution;

[0083] Step 2: stacking a hydrophobic polyvinylidene fluoride filter membrane with a pore size of 1 mm and a hydrophilic polyvinylidene fluoride filter membrane with a pore size of 0.1 μm in sequence on a filter holder made of sintered glass;

[0084] Step 3: Capillary sampling of a 50 nm silver nanosphere solution onto a hydrophilic polyvinylidene fluoride filter membrane, and suction filtration to remove water from the solution at the overlapping position of the openings of the hydrophilic polyvinylidene fluoride filter membrane and the hydrophobic polyvinylidene fluoride filter membrane;

[0085] Step 4: Capillary sampling of 10nm silver nanosphere solution was dripped onto the 50nm silver nanosphere area, and water was filtered out by suction to obtain the nanoplastic detection SERS substrate. The sampling volume ratio of 50nm silver nanosphere to 10nm silver nanosphere was 25:12.

[0086] In this comparative example, since the size of the metal nanoparticles is smaller than the micropore size of the hydrophilic polyvinylidene fluoride filter membrane (0.1 μm), a nanoplastic detection SERS substrate cannot be formed.

[0087] In summary, the present invention utilizes hydrophilic and hydrophobic polymer membranes and their microporous structures to sequentially aggregate silver nanoparticle domains of different sizes onto the surface of the hydrophilic polymer membrane, thereby achieving highly sensitive detection of nanoplastics in aqueous solution and overcoming the difficulty in detecting nanoplastics due to their tiny size.

[0088] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A SERS substrate for nanoplastic detection based on metal nanoparticle domain aggregation, characterized in that: The nanoplastic detection SERS substrate is a double-layer noble metal nanoparticle structure; Among them, the lower layer is precious metal nanoparticle A, and the upper layer is precious metal nanoparticle B; the size of the precious metal nanoparticle A is 150nm~500nm, and the size of the precious metal nanoparticle B is 10nm~200nm; the size of the metal nanoparticle A is larger than the size of the metal nanoparticle B.

2. The SERS substrate for nanoplastic detection based on metal nanoparticle domain aggregation as claimed in claim 1, characterized in that: The precious metal includes one of gold and silver.

3. The SERS substrate for nanoplastic detection based on metal nanoparticle domain aggregation as claimed in claim 1, characterized in that: The shape of the nanoparticles includes one of a nanosphere, a nanorod, a nanocube or a nanostar.

4. The SERS substrate for nanoplastic detection based on metal nanoparticle domain aggregation as claimed in claim 1, characterized in that: The volume ratio of the noble metal nanoparticles A to the noble metal nanoparticles B is 1-20:12-25.

5. The method for preparing a SERS substrate for nanoplastic detection based on metal nanoparticle domain aggregation according to any one of claims 1 to 4, characterized in that: include, preparing noble metal nanoparticle solutions of different sizes; stacking the punched hydrophobic microporous polymer membrane and the hydrophilic microporous polymer membrane on the filter support in sequence; The metal nanoparticle A solution is sampled by a capillary onto a hydrophilic microporous polymer membrane, and water in the solution is filtered out by suction at the overlapping position of the openings of the hydrophilic microporous polymer membrane and the hydrophobic microporous polymer membrane; The capillary sampling metal nanoparticle B solution is added dropwise to the aggregation area of ​​the metal nanoparticle A domain, and the water in the solution is filtered out by suction again to obtain a SERS substrate for nanoplastic detection.

6. The method for preparing a SERS substrate for nanoplastic detection based on metal nanoparticle domain aggregation as claimed in claim 5, characterized in that: The microporous polymer membrane includes one of a polyvinylidene fluoride filter membrane, a polytetrafluoroethylene filter membrane or a polyethersulfone filter membrane.

7. The method for preparing a SERS substrate for nanoplastic detection based on metal nanoparticle domain aggregation as claimed in claim 5, characterized in that: The pore diameter of the opening of the hydrophobic microporous polymer membrane is 1 mm to 5 mm.

8. The SERS substrate for nanoplastic detection based on metal nanoparticle domain aggregation as claimed in claim 5, characterized in that: The micropore size of the hydrophilic microporous polymer membrane is 0.1 μm to 0.45 μm.

9. Application of a SERS substrate based on metal nanoparticle domain aggregation prepared by the method as claimed in claim 5 in the detection of nanoplastics.

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