Space-engineered microsphere array, preparation method and SERS (Surface Enhanced Raman Scattering) application thereof

Abstract

The invention discloses a space-engineered microsphere array, a preparation method and SERS application of the space-engineered microsphere array, and belongs to the technical field of nano materials, the space-engineered microsphere array comprises a polystyrene compound eye array type structure and a gold nano single layer deposited on the polystyrene compound eye array type structure; the polystyrene compound eye array type structure is a polystyrene single-layer film and is composed of polystyrene microspheres, and a plurality of pits which are not overlapped with one another are distributed on each polystyrene microsphere; the particle size of the polystyrene microspheres is 1-5 [mu] m, the depth of each pit is 50-250 nm, and the diameter of each pit opening is 100-500 nm; and the thickness of the gold nano single layer is 50-200 nm. The space-engineered microsphere array can overcome the defects that a traditional SERS sensor is prone to deformation interference and limitation of a laser angle in the aspect of SERS detection, and has the advantages of being high in sensitivity, stability and reflection resistance, capable of achieving omnidirectional light capture and the like.

Description

Technical Field

[0001] The invention relates to the technical field of nanomaterials, and in particular to a spatially engineered microsphere array, a preparation method and SERS application thereof. Background Art

[0002] The compound eye structure plays a vital role in surface enhanced Raman scattering (SERS) detection and has great application potential. From the perspective of substrate construction, its unique structure composed of numerous small eyes can generate a large number of localized surface plasmon resonance "hot spots", which not only significantly improves the sensitivity of SERS detection, but also excels in stability and repeatability. For example, by organically integrating the artificial compound eye architecture with the nanoparticle array, the SERS substrate can efficiently enrich the target molecules to be detected, laying the foundation for accurate detection; at the same time, the bionic compound eye structure patch effectively overcomes the problems of traditional SERS sensors being susceptible to deformation interference and laser angle constraints, ensuring the stability of signal output. The SERS detection of compound eye structure has shown extremely significant advantages in interdisciplinary application fields: in the field of biology, it can perform highly sensitive detection of disease markers in biological samples to assist in early diagnosis of diseases, and can also provide a powerful tool for the study of molecular interactions on the cell surface, promoting the development of cell biology; in the field of environmental science, with its high sensitivity and high selectivity, it can achieve accurate and rapid monitoring of various environmental pollutants, including heavy metal ions, organic pollutants, etc., as well as key water quality indicators, providing key technical support for environmental protection; in terms of food safety assurance, it can quickly and accurately identify harmful substances such as pathogenic bacteria, toxins, illegal additives in food, and can also perform quantitative analysis of food nutrients to protect the public's dietary health; in addition, in the fields of cultural heritage protection and drug research and development testing, the SERS detection technology of compound eye structure also has its unique microscopic detection capabilities and high sensitivity characteristics, which has opened up new ways for the analysis of cultural relics materials, the exploration of drug molecular action mechanisms and quality control, greatly expanding the application boundaries of SERS technology.

[0003] A Chinese patent document with publication number CN110726711A discloses a metal-modified semiconductor-based bionic compound eye bowl structure SERS substrate and construction method. The invention is based on a multiple interface self-assembly method. First, a small ball template is constructed by utilizing a gas-liquid interface assembly process. Then, the template induces the formation of a semiconductor bowl structure array by utilizing a solid-liquid interface assembly process. Subsequently, the semiconductor bowl is assembled to the surface of a pyramid-shaped cone by utilizing a transfer process to form a bionic compound eye structure. Finally, a layer of uniformly distributed metal particles is modified on the surface of the bionic compound eye structure by physical deposition or chemical deposition, thereby obtaining a metal-modified semiconductor-based bionic compound eye bowl structure SERS substrate.

[0004] A Chinese patent document with publication number CN110735131A discloses a bionic SERS substrate with a metal-based compound eye bowl structure, a construction method and an application. The bionic SERS substrate with a metal-based compound eye bowl structure of the invention is composed of an ordered hierarchy of a metal bowl and a conical structure substrate; the metal bowl is a single-layer bowl structure arranged continuously and closely, the height of the metal bowl is 0.01 to 10 μm, and the diameter of the bowl mouth is 0.01 to 10 μm; the cone is a micron pyramid cone, and the height of the micron pyramid cone is 1 to 100 μm.

[0005] However, the SERS substrate prepared by the above method is susceptible to deformation interference, is restricted by the laser angle, and its stability and repeatability need to be further improved. Summary of the invention

[0006] The present invention provides a spatially engineered microsphere array, which can overcome the shortcomings of traditional SERS sensors such as susceptibility to deformation interference and laser angle constraints in SERS detection, and has the characteristics of high sensitivity, high stability, high anti-reflection and omnidirectional light capture, and has a wide range of applications in surface enhanced Raman, environmental science, food safety and other fields.

[0007] The specific technical solutions adopted are as follows:

[0008] A spatially engineered microsphere array comprises a polystyrene compound eye array structure and a gold nano-monolayer deposited thereon; the polystyrene compound eye array structure is a polystyrene monolayer film, which is composed of polystyrene microspheres, and each polystyrene microsphere is provided with a plurality of non-overlapping pits;

[0009] The particle size of the polystyrene microspheres is 1-5 μm, the depth of the pits is 50-450 nm, and the diameter of the pit mouth is 100-500 nm; the thickness of the gold nano-monolayer is 50-200 nm.

[0010] Preferably, the particle size of the polystyrene microspheres is 2-4 μm, the depth of the pits is 50-250 nm, and the diameter of the pit mouth is 100-500 nm.

[0011] The spatially engineered microsphere array obtained by the method of the present invention includes a polystyrene compound eye array structure and a gold nanomonolayer deposited thereon. The polystyrene compound eye array structure is highly ordered, and the diameter of the pits thereon can be precisely adjusted within the range of 100-500nm, and the depth of the pits can be precisely adjusted within the range of 50-250nm, thereby enabling SERS detection of different molecules.

[0012] The present invention also provides a method for preparing the spatially engineered microsphere array, comprising the following steps:

[0013] (1) forming a polystyrene monolayer substrate from polystyrene microspheres by an interfacial self-assembly method;

[0014] (2) loading silica nanospheres onto a polystyrene monolayer substrate, heating and etching to remove the silica nanospheres to obtain a polystyrene compound eye array structure;

[0015] (3) Preparing a gold nanoparticle monolayer on a polystyrene compound eye array structure to obtain the spatially engineered microsphere array.

[0016] The diameter and depth of the pits on the surface of polystyrene microspheres can be changed by changing the particle size of silica nanospheres and changing the heating time, thereby achieving the regulation of the microstructure of the spatially engineered microsphere array.

[0017] Preferably, in step (1), an ethanol suspension of polystyrene microspheres is used to self-assemble at a gas-liquid interface, and an auxiliary agent, sodium dodecyl sulfate, is added to prepare a polystyrene monolayer substrate.

[0018] More preferably, the mass concentration of the ethanol suspension of polystyrene microspheres is 1.25 wt %.

[0019] Optionally, in step (2), the polystyrene monolayer substrate is loaded with silica nanospheres in one of the following ways:

[0020] Method 1: Transferring a single layer of silicon dioxide film onto a single layer of polystyrene substrate;

[0021] Method 2: coating the silica suspension onto a polystyrene monolayer substrate;

[0022] Method 3: Transferring a polystyrene monolayer substrate to a monolayer silica film, and then coating the silica suspension onto the polystyrene monolayer substrate.

[0023] After the polystyrene monolayer substrate is loaded with silica nanospheres, the silica nanospheres are partially embedded in the polystyrene microspheres by heating. Preferably, in step (2), the heating condition is 100-150° C. for 5-10 min.

[0024] Preferably, in step (2), hydrofluoric acid is used to etch away the silicon dioxide nanospheres to form pits, and the etching conditions are 2-8 wt % hydrofluoric acid etching for 20-60 min.

[0025] Preferably, in step (3), a gold nano-monolayer is prepared on the polystyrene compound eye array structure by physical sputtering, a gold target is selected for sputtering, and the sputtering time is 5-60 min.

[0026] The present invention also provides the application of the spatially engineered microsphere array in SERS detection. As a SERS substrate, the microsphere array has the characteristics of high sensitivity, high stability, high anti-reflection and omnidirectional light capture, and has broad application prospects in SERS detection.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The method of the present invention first forms a polystyrene monolayer substrate from polystyrene microspheres, and then uses the polystyrene monolayer substrate, a monolayer silica film, and a silica suspension to prepare a polystyrene compound eye array structure, wherein the arrangement of the structural units is long-range orderly, the pit diameter is in the range of 100-500nm, and the depth is precisely adjustable in the range of 50-250nm. After further sputtering of a gold nano monolayer, a spatially engineered microsphere array is obtained. The spatially engineered microsphere array has the characteristics of high sensitivity, high stability, high anti-reflection, and omnidirectional light capture, and has a wide range of applications in the fields of surface enhanced Raman, early disease diagnosis, environmental science, and food safety.

[0029] (2) The spatially engineered microsphere array provided by the method of the present invention includes a polystyrene compound eye array structure and a gold nanolayer deposited thereon. The surface pits of the polystyrene compound eye array structure are evenly distributed, and the surface pits and the gold nanolayer provide a large number of "hot spot" areas, thereby enabling high-sensitivity detection of different molecules. At the same time, it exhibits high anti-reflection ability, which can overcome the shortcomings of traditional SERS sensors such as susceptibility to deformation interference and laser angle constraints, and further improve the intensity of SERS signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the preparation process of the spatially engineered microsphere array.

[0031] Figure 2 This is the SEM image of the polystyrene PS single-layer substrate prepared in Example 1.

[0032] Figure 3 This is the SEM image of the polystyrene compound eye array structure prepared in Example 2.

[0033] Figure 4 This is the SEM image of the spatially engineered microsphere array prepared in Example 2.

[0034] Figure 5 This is a reflection spectrum diagram of the spatially engineered microsphere array prepared in Examples 1-3.

[0035] Figure 6 This is a statistical graph of the SERS signal intensity of the spatially engineered microsphere array prepared in Example 2 under different incident laser angles. DETAILED DESCRIPTION

[0036] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the following is a detailed description through specific embodiments. In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below. The technical features in each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0037] The operating methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. The contents not described in detail in this specification belong to the prior art known to professionals in the field. The experimental materials used in the following examples, unless otherwise specified, can be purchased from conventional biochemical reagent companies.

[0038] Specifically, the schematic diagram of the preparation process of the spatially engineered microsphere array is as follows: Figure 1 As shown, it includes: (1) forming a polystyrene monolayer substrate from polystyrene microspheres through an interface self-assembly method; (2) loading the polystyrene monolayer substrate with silica nanospheres, heating and etching to remove the silica nanospheres to obtain a polystyrene compound eye array structure; (3) preparing a gold nanomonolayer on the polystyrene compound eye array structure to obtain the spatially engineered microsphere array.

[0039] Example 1

[0040] First, polystyrene PS microspheres (particle size 3 μm) were dispersed in ethanol to obtain a uniform ethanol suspension of polystyrene microspheres with a mass concentration of 1.25 wt%. The ethanol suspension of polystyrene microspheres was injected onto an inclined glass slide (45°) at an injection speed of 10 μL / min using a syringe, and then flowed to the air-water interface for self-assembly. After 30 minutes, 200 μL of sodium dodecyl sulfate SDS (2.5 wt%) was added as a surfactant to further reduce the surface tension of water and change the surface properties of the PS microspheres, which was conducive to the formation of a more stable monolayer. Subsequently, colored diffraction fringes at the air / water interface were observed, and a polystyrene monolayer substrate (such as Figure 2 As shown), the polystyrene monolayer substrate was transferred to an underwater silicon wafer (3 mm × 3 mm, the silicon wafer was treated with 100 mW, 2 min oxygen plasma before use) and then dried at room temperature.

[0041] Silica nanospheres (particle size 200nm) are dispersed in n-butanol to obtain a n-butanol suspension of silica nanospheres (concentration 2wt%), a single-layer silica film is prepared at the gas-liquid interface using a Langmuir-Blodgett film analyzer, and then the single-layer silica film is transferred to a polystyrene single-layer substrate to load the polystyrene single-layer substrate with silica nanospheres, and further heated at 120°C for 10min, cooled to room temperature after the heating is completed, and then immersed in a 4wt% hydrofluoric acid solution for treatment for 30min, taken out, rinsed with deionized water to remove surface impurities, and finally dried at room temperature to obtain a polystyrene compound eye array structure, which is composed of polystyrene microspheres, each of which is distributed with a number of non-overlapping pits, the depth of the pits is 50-200nm, and the pit mouth diameter is 100-200nm.

[0042] A gold nanolayer was sputtered on the surface of the polystyrene compound eye array structure using a gold target for 15 minutes, so that the surface of the pits was evenly covered with the gold nanolayer to obtain a spatially engineered microsphere array with an average thickness of 200 nm.

[0043] Example 2

[0044] A silica nanosphere ethanol suspension with a mass fraction of 2 wt% was prepared, and 2 μL of the silica nanosphere ethanol suspension was dropwise added to the surface of the polystyrene monolayer substrate prepared in Example 1. The polystyrene monolayer substrate was loaded with silica nanospheres by a doctor blade coating method. The blade angle was set to 8°, and the gap between the blade edge and the substrate was 30 μm. After the doctor blade coating was completed, it was dried, further heated at 120° C. for 10 min, cooled to room temperature after the heating was completed, and then immersed in a 4 wt% hydrofluoric acid solution for treatment for 30 min. After being taken out, it was rinsed with deionized water to remove surface impurities, and finally dried at room temperature to obtain a polystyrene compound eye array structure (such as Figure 3 As shown in the figure, the polystyrene compound eye array structure is composed of polystyrene microspheres, each of which is provided with a number of non-overlapping pits, the depth of the pits being 50-200 nm, and the diameter of the pit opening being 100-200 nm.

[0045] A gold nanolayer was sputtered on the surface of the polystyrene compound eye array structure using a gold target for 15 minutes, so that the surface of the pits was evenly covered with the gold nanolayer to obtain a spatially engineered microsphere array with an average thickness of 200 nm.

[0046] Example 3

[0047] Silica nanospheres (particle size 200 nm) were dispersed in n-butanol to obtain a n-butanol suspension of silica nanospheres (concentration 2 wt%), a single-layer silica film was prepared at the gas-liquid interface using a Langmuir-Blodgett film analyzer, and then the single-layer silica film was transferred to a silicon wafer, and then the polystyrene single-layer substrate prepared in Example 1 was transferred to the single-layer silica film, and then a silica nanosphere ethanol suspension was prepared according to the steps of Example 2, and the silica nanosphere ethanol suspension was coated on the silicon wafer using a doctor blade method under the parameters of Example 2. The surface of the polystyrene single-layer substrate not covered by the silica nanospheres is further heated at 120°C for 10 minutes, cooled to room temperature after the heating is completed, and then immersed in a 4wt% hydrofluoric acid solution for treatment for 30 minutes. After being taken out, it is rinsed with deionized water to remove surface impurities, and finally dried at room temperature to obtain a polystyrene compound eye array structure, which is composed of polystyrene microspheres, each of which is distributed with a number of non-overlapping pits, the depth of the pits is 50-200nm, and the pit mouth diameter is 100-200nm.

[0048] A gold nanoparticle monolayer was sputtered on the surface of the polystyrene compound eye array structure. A gold target was used for sputtering for 15 min, so that the surface of the pit was evenly covered with the gold nanoparticle monolayer to obtain a spatially engineered microsphere array (such as Figure 4 As shown), the average thickness of the gold nanolayer is 200 nm.

[0049] Sample analysis

[0050] The reflectance spectra of the spatially engineered microsphere arrays prepared in Examples 1-3 are shown in FIG. Figure 5 As shown, it can be seen that the reflectivity of the spatially engineered microsphere arrays prepared in Examples 1-3 in different wavelength bands is less than 5%, which is much lower than the reflectivity of the PS microsphere array, indicating that the spatially engineered microsphere array has good anti-reflection performance.

[0051] The SERS spectra of the spatially engineered microsphere array prepared in Example 2 with incident lasers at different angles are shown in FIG. Figure 6 As shown, the upper right corner illustration is a schematic diagram of laser incident at different angles. It can be seen that the SERS signal intensity of the spatially engineered microsphere array prepared in Example 2 is basically unchanged when the laser is incident at different angles, indicating that the SERS detection of the spatially engineered microsphere array has the characteristic of not being dependent on the laser incident angle. At the same time, the error bar in the figure is very low, indicating that the structure has high stability in SERS detection.

[0052] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A spatially engineered microsphere array, characterized in that: It includes a polystyrene compound eye array structure and a gold nano-monolayer deposited thereon; the polystyrene compound eye array structure is a polystyrene monolayer film, which is composed of polystyrene microspheres, and each polystyrene microsphere is distributed with a number of non-overlapping pits; The particle size of the polystyrene microspheres is 1-5 μm, the depth of the pits is 50-450 nm, and the diameter of the pit mouth is 100-500 nm; the thickness of the gold nano-monolayer is 50-200 nm.

2. The spatially engineered microsphere array according to claim 1, characterized in that: The particle size of the polystyrene microspheres is 2-4 μm, the depth of the pits is 50-250 nm, and the diameter of the pit mouth is 100-500 nm.

3. The method for preparing a spatially engineered microsphere array according to claim 1 or 2, characterized in that: The following steps are involved: (1) forming a polystyrene monolayer substrate from polystyrene microspheres by an interfacial self-assembly method; (2) loading silica nanospheres onto a polystyrene monolayer substrate, heating and etching to remove the silica nanospheres to obtain a polystyrene compound eye array structure; (3) Preparing a gold nanoparticle monolayer on a polystyrene compound eye array structure to obtain the spatially engineered microsphere array.

4. The method for preparing a spatially engineered microsphere array according to claim 3, characterized in that: In step (1), an ethanol suspension of polystyrene microspheres is self-assembled at a gas-liquid interface, and an auxiliary agent, sodium dodecyl sulfate, is added to prepare a polystyrene monolayer substrate.

5. The method for preparing a spatially engineered microsphere array according to claim 3, characterized in that: In step (2), the polystyrene monolayer substrate is loaded with silica nanospheres by one of the following methods: Method 1: Transferring a single layer of silicon dioxide film onto a single layer of polystyrene substrate; Method 2: coating the silica suspension onto a polystyrene monolayer substrate; Method 3: Transferring a polystyrene monolayer substrate to a monolayer silica film, and then coating the silica suspension onto the polystyrene monolayer substrate.

6. The method for preparing a spatially engineered microsphere array according to claim 3, characterized in that: In step (2), the heating conditions are 100-150° C. for 5-10 min.

7. The method for preparing a spatially engineered microsphere array according to claim 3, characterized in that: In step (2), the silicon dioxide nanospheres are removed by hydrofluoric acid etching to form pits, and the etching conditions are 2-8 wt % hydrofluoric acid etching for 20-60 min.

8. The method for preparing a spatially engineered microsphere array according to claim 3, characterized in that: In step (3), a gold nano-monolayer is prepared on the polystyrene compound eye array structure by physical sputtering, a gold target is selected for sputtering, and the sputtering time is 5-60 minutes.

9. Use of the spatially engineered microsphere array according to claim 1 or 2 in SERS detection.

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