Preparation method of three-dimensional structure AuNPs / PS composite array structure and application thereof

Abstract

The application discloses a preparation method of a three-dimensional structure AuNPs / PS composite array structure and application thereof, relates to the technical field of three-dimensional composite array, and has the technical scheme as follows: different particle sizes of gold nanoparticles are deposited on a PS microsphere array by adopting an interface self-assembly method, and a three-dimensional (3D) nanostructure surface enhanced Raman scattering (SERS) substrate with controllable particle gaps is prepared. Through modification of the PS microsphere array, the AuNPs array structure can be more stably fixed on the surface of the PS microsphere. Meanwhile, the AuNPs form controllable nano gaps under the adjustment of the PS microsphere curved surface, a larger specific surface area is provided, and target molecules are more easily diffused into the nano gaps. Compared with a traditional two-dimensional plane structure, the unique composite 3D nano structure and nano gaps can generate stronger electromagnetic field enhancement, and the composite nano structure is beneficial to application in the SERS field.

Description

Technical Field

[0001] This invention relates to the field of three-dimensional composite array technology, and more specifically, to a method for fabricating a three-dimensional AuNPs / PS composite array structure and its application. Background Technology

[0002] Surface-enhanced Raman scattering (SERS) spectroscopy has attracted much attention due to its high sensitivity and unique fingerprint specificity, and has been widely used in life sciences, environmental analysis, food safety, and other fields. However, ordinary two-dimensional gold nanofilms suffer from poor film stability and the fact that SERS enhancement hotspots are confined to the two-dimensional plane, resulting in unsatisfactory enhancement effects.

[0003] Therefore, fabricating stable and efficient three-dimensional SERS substrates and obtaining high-density SERS hotspots is a current research direction. Currently, various methods have been explored to fabricate three-dimensional SERS substrates. For example, a sunflower-shaped 3D periodic array was fabricated using spin coating and plasma etching techniques, and then a silver nanofilm was deposited on it using magnetron sputtering to obtain a uniform 3D SERS substrate. A series of polyacrylonitrile nanopillars were fabricated using template transfer technology, and then high-density, small-sized silver nanoparticles were sputtered onto these nanopillars as a metallic nanostructure, also yielding a flexible three-dimensional SERS substrate. Furthermore, based on a particle-film plasmon coupling plasma system, AuNPs films were designed on Ag-coated nanosphere (FON) substrates, and compared to bare Ag FON substrates, this composite structure showed a 233-fold increase in SERS factor. In general, these 3D structured substrates not only possess high SERS enhancement sensitivity but also achieve a good balance between uniformity and repeatability. However, these methods either rely on expensive equipment or involve time-consuming and complex fabrication processes. Therefore, these methods struggle to achieve a good balance between manufacturing efficiency and construction accuracy. Summary of the Invention

[0004] The purpose of this invention is to provide a method for fabricating a three-dimensional AuNPs / PS composite array structure and its application, which is characterized by convenient operation, simple process and no need for expensive equipment.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a method for fabricating a three-dimensional AuNPs / PS composite array structure, comprising the following steps:

[0006] S1. Using chloroauric acid and sodium citrate as raw materials, nano-gold seeds were prepared by chemical synthesis, and then monodisperse nano-gold particles were prepared by seed growth method.

[0007] S2. Using the gold nanoparticles obtained in S1 as the base material, prepare a gold nanofilm using a liquid-liquid interface self-assembly method;

[0008] S3. Polystyrene microsphere arrays were fabricated using a gas-liquid interface self-assembly method with polystyrene microspheres as raw materials.

[0009] S4. The gold nanofilm prepared in S2 was transferred to the modified polystyrene microsphere array by the interface transfer method, and finally a three-dimensional AuNPs / PS composite array structure was obtained.

[0010] The present invention is further configured such that the specific operation flow of S1 is as follows:

[0011] (1) Add 50 mL of ultrapure water to a double-necked flask and heat to boiling; then add 0.5 mL of 25 mM chloroauric acid solution and stir evenly at 300 r / min for 10 min while lowering the temperature to 90℃; then add 1.5 mL of 1% (w / w) sodium citrate solution and stir evenly for 30 min until the color changes from the initial light yellow to wine red to obtain nano gold seeds;

[0012] (2) First growth process: 40 ml of ultrapure water was added to a double-necked flask and brought to a boil. Then, 10 ml of nano gold seed solution was added and stirred evenly at 300 r / min. At the same time, 1 ml of 1% (w / w) sodium citrate solution was added. After stirring for 3 min, 0.2 ml of 10 mM chloroauric acid aqueous solution was added five times every 8 min. After the last addition, the reaction was carried out for 25 min to finally obtain AuNPs-1st.

[0013] Second growth process: 40 ml of ultrapure water was added to a double-necked flask and brought to a boil. Then, 10 ml of AuNPs-1st was added as seed and stirred evenly at 300 r / min. At the same time, 1 ml of 1% (w / w) sodium citrate solution was added. After stirring for 3 min, 0.2 ml of 10 mM chloroauric acid aqueous solution was added five times every 8 min. After the last addition, the reaction was carried out for 25 min to obtain AuNPs-2nd.

[0014] Third growth process: 40 ml of ultrapure water was added to a double-necked flask and brought to a boil. Then, 10 ml of AuNPs-2nd was added as seed and stirred evenly at 300 r / min. At the same time, 1 ml of 1% (w / w) sodium citrate solution was added. After stirring for 3 min, 0.2 ml of 10 mM chloroauric acid aqueous solution was added four times every 8 min. After the last addition, the reaction was carried out for another 25 min to obtain AuNPs-3rd.

[0015] Fourth growth process: 40 ml of ultrapure water was added to a double-necked flask and brought to a boil. Then, 10 ml of AuNPs-3rd was added as seed and stirred evenly at 300 r / min. At the same time, 1 ml of 1% (w / w) sodium citrate solution was added. After stirring for 3 min, 0.2 ml of 10 mM chloroauric acid aqueous solution was added four times every 8 min. After the last addition, the reaction was carried out for 25 min to obtain AuNPs-4th grown in the fourth stage.

[0016] The present invention is further configured such that the specific operation process of S3 is as follows: First, take 5 mL of 10 wt% polystyrene solution and disperse it in a 1:1 H2O / ethanol solvent to obtain a 5 wt% polystyrene microsphere suspension; second, slowly inject the polystyrene microsphere suspension into the water interface of a glass culture dish filled with water using a syringe pump; the polystyrene microspheres are dispersed along the edge of the liquid surface and eventually cover the entire liquid surface. After standing for about 10 minutes, a large-area uniform and ordered polystyrene monolayer membrane is obtained; finally, the polystyrene microsphere monolayer membrane is transferred to a modified hydrophilic glass slide by a dip-coating method and naturally dried to obtain a polystyrene microsphere array.

[0017] The present invention is further configured as follows: the specific operation process of S4 is as follows: 3 mL of AuNPs solution is added to a 10 mL beaker, diluted with water to 5 mL, and then 1 mL of 10 mM PFT-n-hexane mixed solution is added. When obvious stratification occurs, 3 mL of anhydrous ethanol is immediately added to the solution. Under the action of PFT superhydrophobic properties and the surface tension of anhydrous ethanol, AuNPs migrate and remain at the water / n-hexane interface, thereby self-assembling into a film within 8 s. When n-hexane is completely evaporated at room temperature, the AuNPs monolayer film can be easily transferred to the modified glass slide and the modified polystyrene microsphere array, thereby obtaining a two-dimensional AuNPs monolayer film and a three-dimensional AuNPs / PS composite array structure.

[0018] The present invention further provides the application of the three-dimensional AuNPs / PS composite array structure prepared by the above method. Based on the three-dimensional AuNPs / PS composite array structure, SERS detection of toxic and harmful substances including Rhodamine 6G, crystal violet, malachite green, methylene blue and melamine is obtained.

[0019] In summary, this invention offers the following advantages: The three-dimensional gold nanoparticle / polystyrene (AuNPs / PS) composite array structure prepared by this invention exhibits good stability and excellent SERS detection performance. The preparation method is convenient, simple, and requires no expensive equipment. The obtained three-dimensional gold nanoparticle / polystyrene (AuNPs / PS) composite array structure features a large area, dense SERS active hotspots, and a high SERS enhancement factor. The prepared three-dimensional gold nanoparticle / polystyrene (AuNPs / PS) composite array structure can sensitively detect toxic and harmful substances such as Rhodamine 6G (R6G), crystal violet (CV), malachite green (MG), methylene blue (MB), and melamine via SERS. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the implementation of the present invention;

[0021] Figure 2 The images show the SEM, UV-vis spectra, and XRD patterns of the gold nanoparticles prepared in this invention, where a is the SEM image of gold nanoseeds and gold nanoparticles with different growth cycles, b is the UV-vis spectrum of colloidal solutions of gold nanoparticles of different sizes, and c is the X-ray diffraction pattern of the gold nanofilm.

[0022] Figure 3 Scanning electron microscope (SEM) images and elemental distribution diagrams of the three-dimensional gold nanoparticles and polystyrene (AuNPs / PS) composite array structure prepared in this invention are shown. In the figure, a is a polystyrene monolayer film, b and c are SEM images of the AuNPs / PS composite array structure at different magnifications, and ef is the elemental distribution diagram of gold and PS microspheres represented by carbon.

[0023] Figure 4 The image shows the detection effect of the three-dimensional gold nanoparticle and polystyrene (AuNPs / PS) composite array structure prepared in this invention on R6G. a represents the detection effect on 10... -7 -10 -11 SERS detection of molar R6G: b is the correlation curve between concentration and enhancement intensity, c is the SERS intensity distribution map within a range of 10 × 10 square micrometers, and d is the intensity statistics of R6G at 613 cm⁻¹ wavenumber.

[0024] Figure 5 The three-dimensional gold nanoparticle and polystyrene (AuNPs / PS) composite array structure prepared for this invention is effective against different concentrations (e.g., 10). -7 -10 -12 CV (a) of M), (e.g., 10) -7 -10-11 M)MG(b) and (e.g., 10) -7 -10 -12 MB (c) of M), and SERS detection spectra of the mixed solution of R6G and MG (d);

[0025] Figure 6 The SERS spectra of the three-dimensional gold nanoparticles and polystyrene (AuNPs / PS) composite array structure prepared in this invention were tested in pure milk with different concentrations of melamine doping. Detailed Implementation

[0026] The following is in conjunction with the appendix Figure 1-6 The present invention will be described in further detail below.

[0027] Example: A method for fabricating a three-dimensional AuNPs / PS composite array structure, comprising the following steps:

[0028] S1. Using chloroauric acid and sodium citrate as raw materials, nano-gold seeds were prepared by chemical synthesis, and then monodisperse nano-gold particles were prepared by seed growth method.

[0029] (1) Add 50 mL of ultrapure water to a double-necked flask and heat to boiling; then add 0.5 mL of 25 mM chloroauric acid solution and stir evenly at 300 r / min for 10 min while lowering the temperature to 90℃; then add 1.5 mL of 1% (w / w) sodium citrate solution and stir evenly for 30 min until the color changes from the initial light yellow to wine red to obtain nano gold seeds;

[0030] (2) First growth process: 40 ml of ultrapure water was added to a double-necked flask and brought to a boil. Then, 10 ml of nano gold seed solution was added and stirred evenly at 300 r / min. At the same time, 1 ml of 1% (w / w) sodium citrate solution was added. After stirring for 3 min, 0.2 ml of 10 mM chloroauric acid aqueous solution was added five times every 8 min. After the last addition, the reaction was carried out for 25 min to finally obtain AuNPs-1st.

[0031] Second growth process: 40 ml of ultrapure water was added to a double-necked flask and brought to a boil. Then, 10 ml of AuNPs-1st was added as seed and stirred evenly at 300 r / min. At the same time, 1 ml of 1% (w / w) sodium citrate solution was added. After stirring for 3 min, 0.2 ml of 10 mM chloroauric acid aqueous solution was added five times every 8 min. After the last addition, the reaction was carried out for 25 min to obtain AuNPs-2nd.

[0032] Third growth process: 40 ml of ultrapure water was added to a double-necked flask and brought to a boil. Then, 10 ml of AuNPs-2nd was added as seed and stirred evenly at 300 r / min. At the same time, 1 ml of 1% (w / w) sodium citrate solution was added. After stirring for 3 min, 0.2 ml of 10 mM chloroauric acid aqueous solution was added four times every 8 min. After the last addition, the reaction was carried out for another 25 min to obtain AuNPs-3rd.

[0033] Fourth growth process: 40 ml of ultrapure water was added to a double-necked flask and brought to a boil. Then, 10 ml of AuNPs-3rd was added as seed and stirred uniformly at 300 r / min. Simultaneously, 1 ml of 1% (w / w) sodium citrate solution was added. After stirring for 3 min, 0.2 ml of 10 mM chloroauric acid aqueous solution was added four times every 8 min. After the last addition, the reaction was allowed to proceed for another 25 min to obtain the fourth-grown AuNPs-4th. All prepared AuNPs were stored at 4℃ for later use. Table 1 shows the required reagent amounts for preparing AuNPs of different particle sizes through different growth stages.

[0034] Table 1. Summary of reagent amounts and particle sizes required for preparing AuNPs of different sizes.

[0035]

[0036] S2. Using the gold nanoparticles obtained in S1 as the base material, prepare a gold nanofilm using a liquid-liquid interface self-assembly method;

[0037] S3. Polystyrene microsphere arrays were fabricated using a gas-liquid interface self-assembly method with polystyrene microspheres as raw materials.

[0038] First, 5 mL of a 10 wt% polystyrene solution was taken and dispersed in a 1:1 H2O / ethanol solvent to obtain a 5 wt% polystyrene microsphere suspension. Second, the polystyrene microsphere suspension was slowly injected into the water interface of a water-filled glass petri dish using a syringe pump. The polystyrene microspheres were dispersed along the edge of the liquid surface, eventually covering the entire liquid surface. After standing for about 10 minutes, a large-area, uniform, and ordered polystyrene monolayer membrane was obtained. Finally, the polystyrene microsphere monolayer membrane was transferred to a modified hydrophilic glass slide using the dip-coating method, and after natural drying, a polystyrene microsphere array was obtained.

[0039] S4. The gold nanofilm prepared in S2 was transferred to the modified polystyrene microsphere array by the interface transfer method, and finally a three-dimensional AuNPs / PS composite array structure was obtained.

[0040] Add 3 mL of AuNPs solution to a 10 mL beaker, dilute with water to 5 mL, and then add 1 mL of a 10 mM PFT-n-hexane mixture. Once obvious stratification occurs, immediately add 3 mL of anhydrous ethanol. Under the influence of the superhydrophobic properties of PFT and the surface tension of anhydrous ethanol, the AuNPs migrate and remain at the water / n-hexane interface, thus self-assembling into a film within 8 seconds. When the n-hexane completely evaporates at room temperature, the AuNPs monolayer film can be easily transferred to a modified glass slide and a modified polystyrene microsphere array, resulting in a two-dimensional AuNPs monolayer film and a three-dimensional AuNPs / PS composite array structure. By changing the particle size of the gold nanoparticles and PS microspheres, AuNPs monolayer films and AuNPs / PS composite array structures with different particle sizes can be prepared using the same method.

[0041] Application example: The three-dimensional AuNPs / PS composite array structure prepared by the above method is used as a basis to obtain SERS detection applications for toxic and harmful substances including Rhodamine 6G, crystal violet, malachite green, methylene blue and melamine.

[0042] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for fabricating a three-dimensional AuNPs / PS composite array structure, characterized by: Includes the following steps: S1. Using chloroauric acid and sodium citrate as raw materials, nano-gold seeds were prepared by chemical synthesis, and then monodisperse nano-gold particles were prepared by seed growth method. S2. Using the gold nanoparticles obtained in S1 as the base material, prepare a gold nanofilm using a liquid-liquid interface self-assembly method; S3. Polystyrene microsphere arrays were fabricated using a gas-liquid interface self-assembly method with polystyrene microspheres as raw materials. S4. The gold nanofilm prepared in S2 was transferred to the modified polystyrene microsphere array by the interface transfer method, and finally a three-dimensional AuNPs / PS composite array structure was obtained.

2. The method for fabricating a three-dimensional AuNPs / PS composite array structure according to claim 1, characterized in that: The specific operation procedure of S1 is as follows: (1) Add 50 mL of ultrapure water to a double-necked flask and heat to boiling; then add 0.5 mL of 25 mM chloroauric acid solution and stir evenly at 300 r / min for 10 min while lowering the temperature to 90℃; then add 1.5 mL of 1% (w / w) sodium citrate solution and stir evenly for 30 min until the color changes from the initial light yellow to wine red to obtain nano gold seeds; (2) First growth process: 40 ml of ultrapure water was added to a double-necked flask and brought to a boil. Then, 10 ml of nano gold seed solution was added and stirred evenly at 300 r / min. At the same time, 1 ml of 1% (w / w) sodium citrate solution was added. After stirring for 3 min, 0.2 ml of 10 mM chloroauric acid aqueous solution was added five times every 8 min. After the last addition, the reaction was carried out for 25 min to finally obtain AuNPs-1st. Second growth process: 40 ml of ultrapure water was added to a double-necked flask and brought to a boil. Then, 10 ml of AuNPs-1st was added as seed and stirred evenly at 300 r / min. At the same time, 1 ml of 1% (w / w) sodium citrate solution was added. After stirring for 3 min, 0.2 ml of 10 mM chloroauric acid aqueous solution was added five times every 8 min. After the last addition, the reaction was carried out for 25 min to obtain AuNPs-2nd. Third growth process: 40 ml of ultrapure water was added to a double-necked flask and brought to a boil. Then, 10 ml of AuNPs-2nd was added as seed and stirred evenly at 300 r / min. At the same time, 1 ml of 1% (w / w) sodium citrate solution was added. After stirring for 3 min, 0.2 ml of 10 mM chloroauric acid aqueous solution was added four times every 8 min. After the last addition, the reaction was carried out for another 25 min to obtain AuNPs-3rd. Fourth growth process: 40 ml of ultrapure water was added to a double-necked flask and brought to a boil. Then, 10 ml of AuNPs-3rd was added as seed and stirred evenly at 300 r / min. At the same time, 1 ml of 1% (w / w) sodium citrate solution was added. After stirring for 3 min, 0.2 ml of 10 mM chloroauric acid aqueous solution was added four times every 8 min. After the last addition, the reaction was carried out for 25 min to obtain AuNPs-4th grown in the fourth stage.

3. The method for fabricating a three-dimensional AuNPs / PS composite array structure according to claim 1, characterized in that: The specific operation procedure of S3 is as follows: First, take 5 mL of 10 wt% polystyrene solution and disperse it in a water / ethanol solvent with a volume ratio of 1:1 to obtain a 5 wt% polystyrene microsphere suspension; second, slowly inject the polystyrene microsphere suspension into the water interface of a glass culture dish filled with water using a syringe pump; the polystyrene microspheres are dispersed along the edge of the liquid surface and eventually cover the entire liquid surface. After standing for about 10 minutes, a large-area uniform and ordered polystyrene monolayer film is obtained; finally, the polystyrene microsphere monolayer film is transferred to a modified hydrophilic glass slide by the dip-coating method and naturally dried to obtain a polystyrene microsphere array.

4. The method for fabricating a three-dimensional AuNPs / PS composite array structure according to claim 1, characterized in that: The specific operation procedure of S4 is as follows: Add 3 mL of AuNPs solution to a 10 mL beaker, dilute with water to 5 mL, and then add 1 mL of 10 mM 1H,1H,2H,2H-perfluorodecylthiol (PFT)-n-hexane mixed solution. When obvious stratification occurs, immediately add 3 mL of anhydrous ethanol to the solution. Under the influence of PFT superhydrophobic properties and the surface tension of anhydrous ethanol, AuNPs migrate and remain at the water / n-hexane interface, thus self-assembling into a film within 8 seconds. When n-hexane is completely evaporated at room temperature, the AuNP monolayer film can be easily transferred to a modified glass slide and a modified polystyrene microsphere array, thus obtaining a two-dimensional AuNPs monolayer film and a three-dimensional AuNPs / PS composite array structure.

5. The application of the three-dimensional AuNPs / PS composite array structure prepared by any one of the methods described in claims 1-4, characterized in that: Based on a three-dimensional AuNPs / PS composite array structure, a SERS detection application was obtained for toxic and hazardous substances including Rhodamine 6G, crystal violet, malachite green, methylene blue, and melamine.

Images