Construction method of controllable micro-nano array based on 3D printing

Abstract

The invention discloses a construction method of a controllable micro-nano array based on 3D printing, which comprises the following steps: synthesizing gold nanorods by a seed crystal growth method and a dual-surfactant method, and modifying the surfaces of the gold nanorods to effectively synthesize gold-silver core-shell nano bricks with solid morphology and uniform size. A simple and effective self-assembly and nanometer manufacturing method is combined with ligand modification, particles are controllably synthesized, the synthesized high-concentration gold and silver core-shell structure nanometer brick solution is used as a spraying material, and the printing process of micro-droplets is controlled through a micro-scale high-precision spraying controllable micro-nano array preparation technology; and micro-nano-scale ordered arrangement of the gold-core silver-shell bimetallic nano bricks is controlled, so that the controllable micro-nano array with macroscopic large scale and microscopic ordered is prepared.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of 3D printing, micro-nano manufacturing and surface-enhanced Raman scattering, in particular to a method for constructing controllable micro-nano array based on 3D printing. BACKGROUND

[0002] Surface-enhanced Raman scattering (SERS) is a spectroscopic technique based on the localized surface plasmon resonance (LSPR) effect of noble metal nanostructures, which can significantly enhance the Raman signal of molecules. Compared with the traditional Raman spectrum with weak signal and low detection sensitivity, SERS can enhance the Raman signal of target molecules by 10 6 to 10 14 times, thus showing a wide application prospect in the fields of chemical analysis, biological detection and environmental monitoring.

[0003] The enhancement mechanism of SERS signal mainly includes electromagnetic enhancement and chemical enhancement, of which the electromagnetic mechanism is dominant. The core of the electromagnetic mechanism is the high-intensity local electric field "hot spot" formed on the surface of nanostructures (such as nanorods, nanostars, nanocubes, etc.), which significantly improves the Raman scattering intensity of molecules adsorbed on the surface. However, the current large-scale preparation of SERS substrates with high enhancement effect and good uniformity still faces many challenges. In the assembly process of noble metal nanoparticles, there are complex interactions such as van der Waals force, electrostatic force, dipole-dipole interaction and steric hindrance between particles, which easily lead to unstable self-assembly structure or disordered arrangement.

[0004] The traditional strategies for self-assembly realized by electromagnetic field guidance or fluid force often cannot form large-area regular arrangement. While the micro-nano processing technology (such as photolithography, soft printing, etc.) has complex process, high cost, and strict requirements for equipment and environment, which is difficult to meet the application demand of rapid and controllable construction of complex array structure. At the same time, 3D micro-scale printing technology has developed rapidly in recent years, especially the electroblotting method as a new high-precision material deposition method, which shows great potential in the construction of micro-nano structure. It has the advantages of being suitable for various solution systems, high printing precision, relatively low equipment requirements, etc., which provides a new solution for the construction of controllable micro-nano array.

[0005] The application discloses a controllable micro-nano array construction method using gold-silver nano bricks as raw materials, which regulates gold core-silver shell bimetallic nano bricks of core-shell structure based on a polymer-based ligand modification method, and controllably synthesizes gold core-silver shell bimetallic nano bricks with neat arrangement and uniform morphology. Based on the electroblotting method in the 3D micro-scale printing technology, the high-precision spraying controllable micro-nano array preparation technology is improved, so that the gold-silver nano bricks are prepared into an array pattern with uniform order under high-precision spraying from top to bottom, the array pattern size can be between 200-500 microns, and the controllable micro-nano array based on the gold-silver nano bricks has uniform nano-particle spacing distribution characteristics, and can be applied to high-sensitivity detection of trace chemical molecular residues. SUMMARY

[0006] The application aims to provide a controllable micro-nano array construction method based on 3D printing to solve the problems in the background art.

[0007] Firstly, the application controllably synthesizes gold nanorods with different length-diameter ratios: among numerous synthesis of gold nanorods, the seed growth method and the double surfactant method are selected to synthesize gold nanorods, the seed growth method is used to effectively grow short gold nanorods with a length-diameter ratio of 650-700 nm and a short diameter of about 515 nm, and then the NaOL / CTAB double surfactant method is used to grow long gold nanorods with a length-diameter ratio of 700-1200 nm. In the double surfactant method, by changing the addition amount of gold seeds, silver nitrate and hydrochloric acid, comparative tests are conducted, and the ultraviolet-visible spectrophotometer is used to explore the spectral change trend of the gold nanorods.

[0008] Secondly, gold-silver core-shell structure nano bricks are controllably synthesized: the gold nanorods synthesized by the seed growth method are used as crystal nuclei, the replacement effect of the surfactant adsorbed on the gold nanorods is used to grow a controllable thickness Ag shell on the surface of the gold nanorods, and the influence of various factors in the growth process on the morphology and plasmon resonance of the nano bricks is explored, including the influence of gold nanorods with different length-diameter ratios as cores and the addition amount of AgNO3 in the system, so that gold-silver core-shell structure metal nano bricks with high length-diameter ratio and controllable performance are effectively synthesized.

[0009] Then, the micro-nano array construction based on the micro-scale 3D printing: the gold-silver core-shell structure nano bricks with different length-diameter ratios synthesized above are used as nano elements, the micro-scale orientation of micro-droplets is controlled through the micro-scale 3D printing technology from top to bottom, and the nano-scale ordered arrangement of the nano bricks is controlled through the evaporation self-assembly technology based on the flexible ligand guidance from bottom to top, so that the controllable micro-nano array with macro-scale and micro-order is prepared, and can be applied to high-sensitivity detection of trace chemical residues and specific proteins.

[0010] To achieve the above object, the present application provides the following technical solutions.

[0011] The present application provides a controllable micro-nano array construction method based on 3D printing, comprising the following steps:

[0012] S1, preparation of gold-silver core-shell structure nanobrick, synthesis of gold nanorod (AuNRs) by seed growth method, synthesis of gold-silver nanobrick (AuNBs) with core-shell structure by taking gold nanorod as core and taking surfactant hexadecyl trimethyl ammonium chloride as ligand in L-ascorbic acid and silver nitrate solution;

[0013] S2, the gold-silver nanobrick prepared in step S1 is washed with water and concentrated to obtain a high-concentration gold-silver nanobrick solution which is used as a printing reagent;

[0014] S3, spraying on a substrate by using a high-precision material printer (WE-HMP Pro, Suzhou Micro-Science Electronics Technology) to obtain a micro-nano array.

[0015] Further, in step S2, the concentration of the high-concentration gold-silver nanobrick solution is 1 mM-3 mM.

[0016] Further, in step S3, the parameters of spraying on the substrate by using the high-precision material printer are as follows: printer ambient temperature: 40.3℃, printer internal ambient humidity: 61%, atomization temperature: 28-34℃, hot table temperature: 92℃, printing speed: 10 mm / s, layer number: 1 layer, and substrate: silicon wafer or glass wafer.

[0017] Further, in step S3, the micro-nano array comprises a straight line array, a straight line cross grid array, and a circular array.

[0018] Further, the spacing of the straight line array is 200-500 μm, the spacing of the straight line cross grid array is 200-500 μm, and the diameter of the circle in the circular array is 400-800 μm.

[0019] Further, the preparation of the gold-silver core-shell structure nanobrick in step S1 specifically comprises the following steps:

[0020] S1-1, preparation of gold nanorod: hexadecyl trimethyl ammonium chloride and sodium oleate are dissolved in 50℃ hot water, AgNO3 aqueous solution and HAuCl4 aqueous solution are added, the solution is slowly changed from gold color to colorless; then concentrated HCl is added to adjust the pH of the system, L-ascorbic acid aqueous solution is added, seed solution is added, the system is thoroughly mixed, and then the system is placed in a 30℃ water bath overnight for growth; then the supernatant is removed by centrifugation, ultrapure water is added, and gold nanorod aqueous solution is obtained;

[0021] S1-2, Preparation of gold-silver nanobrick with core-shell structure: centrifugal supernatant of gold nanorod aqueous solution, add cetyltrimethylammonium chloride aqueous solution, shake uniformly, stand for more than 12 hours overnight; place in 65 DEG C water bath, stirring, heat preservation 3 min, then add AgNO3 solution and L-ascorbic acid solution, continue 60 DEG C water bath stirring 3 hours, after reaction, use ultrapure water to clean, obtain gold-silver nanobrick solution with core-shell structure.

[0022] Seed solution preparation: take 5mL 0.2M CTAB aqueous solution in beaker, add 5mL 1mM HAuCl4 solution (or 0.25mL 10mM HAuCl4 aqueous solution is mixed with 4.75mL ultrapure water), high-speed stirring 2min, after mixing quickly add 0.6mL freshly prepared 0.01M NaBH4, high-speed stirring 2min after placing in room temperature and standing 1h for standby.

[0023] Compared with prior art, the beneficial effects of the present application are:

[0024] The present application is synthesized gold nanorod by seed growth method and double surfactant method, and the surface is modified, and gold-silver core-shell nanobrick with uniform solid morphology and size is effectively synthesized, and the particle is controllably synthesized by simple and effective self-assembly and nanofabrication method combined with ligand modification on microscale.

[0025] When ligand modification and assembly are carried out on gold nanorod, based on the characteristic of nanomaterial surface resonance, the addition amount of related factors is compared, and the regulation of gold-silver core-shell nanobrick on microscale is realized, and the aspect ratio is changed.

[0026] The present application is based on the micro-nano array construction of high-precision spraying controllable micro-nano array preparation technology, the high-concentration gold-silver core-shell structure nanobrick solution synthesized above is used as spraying material, the printing process of microdroplet is controlled by high-precision spraying controllable micro-nano array preparation technology of microscale, the micro-nano scale ordered arrangement of gold core-silver shell bimetallic nanobrick is controlled, and therefore the controllable micro-nano array with macro large scale and micro order is prepared. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is the TEM diagram of AuNBs;

[0028] Figure 2 It is a) straight line array micrograph; b)-d) straight line array SEM diagram of different magnification;

[0029] Figure 3 It is a)-b) straight line cross grid array micrograph of different magnification; c)-d) straight line cross grid array SEM diagram of different magnification;

[0030] Figure 4 For a) - b): Micrographs of the circular array at different magnifications; c) - d): SEM images of the circular array at different magnifications. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0032] The raw materials used in the embodiments are shown in Table 1.

[0033] Table 1

[0034]

[0035] Seed solution preparation: 5 mL of 0.2M CTAB aqueous solution was taken in a beaker, 5 mL of 1 mM HAuCl4 solution (or 0.25 mL of 10 mM HAuCl4 aqueous solution was mixed with 4.75 mL of ultrapure water) was added, and high-speed stirring was performed for 2 min. After thorough mixing, 0.6 mL of freshly prepared 0.01M NaBH4 was quickly added, high-speed stirring was performed for 2 min, and then the solution was placed at room temperature for 1 h and was ready for use.

[0036] Example 1

[0037] (1) Preparation of large system 180 mL AuNRs: 8.4 g of CTAB and 1.4808 g of NaOL were dissolved in 600 mL of 50°C hot water, and after complete dissolution, the solution was divided into 3 groups of 180 mL system in conical flasks, and then the conical flasks were placed in a 30°C water bath. 8.64 mL of 4 mM AgNO3 aqueous solution was added, and the solution was slowly stirred at 300 rpm for 15 min. Then, 3.6 mL of 25 mM HAuCl4 aqueous solution was added, and the solution was stirred at 500 rpm for 30 min, and the solution slowly changed from gold to colorless. Subsequently, 1.020 mL of concentrated HCl was added to adjust the pH of the system, and the solution was slowly stirred at 300 rpm for 15 min. 450 μL of 0.064M AA aqueous solution was added, and after the solution was stirred at 900 rpm for 30 s, 288 μL of seed solution was added. After thorough mixing, the system was placed in a 30°C water bath overnight for growth. Then, the grown AuNRs were divided into 15 mL centrifuge tubes, 10 mL of AuNBs was added to each tube, and then the solution was centrifuged at 6500 rpm for 25 min, and the supernatant was removed. 10 mL of ultrapure water was added to obtain an AuNRs aqueous solution.

[0038] (2) Preparation of high-concentration AuNBs solution: 30 mL of the prepared AuNRs aqueous solution was divided into three centrifuge tubes with a capacity of 15 mL, 10 mL of the solution was added to each tube, and then centrifugation was performed at 6500 rpm for 25 min, and the supernatant was removed. 10 mL of 80 mM CTAC aqueous solution was added to each tube, and the solution was shaken uniformly and left to stand overnight for more than 12 h. The AuNRs-CTAC after standing was introduced into a conical flask, 30 mL of AuNRs-CTAC was introduced into each conical flask, and the conical flask was placed in a 65°C water bath and stirred at a speed of 400 rpm for 3 min. Then 4320 μL of 0.01M AgNO3 and 2160 μL of 0.1M AA were added in sequence, and the water bath was continued at 60°C and stirred at a speed of 400 rpm for 3 h. After 3 h, the reaction was stopped, and the system was cooled to room temperature to obtain 30 mL of AuNBs aqueous solution. The AuNBs was washed twice with ultrapure water, and the 30 mL of AuNBs aqueous solution was concentrated to 1.5 mL of AuNBs solution.

[0039] (3) The 30 mL system AuNBs in step (2) was repeatedly synthesized, and the 30 mL AuNBs was concentrated to 1.5 mL AuNBs, and finally the high-concentration AuNBs solution 60 mL (1.5 mM) was obtained. The microstructure is shown in Figure 1

[0040] Example 2

[0041] Meanwhile, two glass sheets and a 5 cm*5 cm silicon wafer were prepared, and alcohol was used to clean the glass sheets and the silicon wafer, and the glass sheets and the silicon wafer were dried and stored to prepare a high-precision sprayable controllable micro-nano array.

[0042] Linear array

[0043] 1. The related item parameters of the spraying printing track of the high-precision material printer (WE-HMP Pro, Suzhou Weiknow Electronics Technology) in spraying the linear array were determined, as shown in Table 2.

[0044] 2. The high-concentration AuNB solution prepared in Example 1 was used as a printing reagent.

[0045] 3. The silicon wafer was sprayed, and the linear array interval was 500 μm.

[0046] Table 2

[0047] Item Value Ambient temperature in printer 40.3℃ Ambient humidity in printer 61％ Atomization temperature 28-34℃ Hotplate temperature ～92℃ Printing speed 10 mm / s Number of layers 1 Substrate Silicon wafer

[0048] The linear array printed by the high-precision material printer is shown in Figure 2 Figure 2 ​​Figure 2a is a microscopic magnification of the straight line array, from which it can be found that, using high-precision controllable micro-nano array preparation technology, the straight line array is macroscopically regular and orderly, the column spacing is clear and uniform, and the straight line is coherent. In SEM figures b-d, it can be observed that a large number of AuNB particles are distributed in each straight line in the straight line array, indicating that high-precision spraying technology can realize the micro-nano array construction of AuNBs.

[0049] Example 3

[0050] Meanwhile, two glass sheets and a 5cm*5cm silicon wafer were prepared and cleaned with alcohol, and were kept dry and dust-free for the preparation of high-precision controllable micro-nano array.

[0051] Straight line cross grid array

[0052] 1. The related item parameters of the high-precision material spraying printer in the spraying printing track of the straight line cross grid array are shown in Table 2;

[0053] 2. The high-concentration AuNB solution prepared by the method of Example 1 is used as the printing reagent;

[0054] 3. Spraying is performed on the surface of the silicon wafer, and the spacing of the straight line cross grid array is 500μm.

[0055] Table 3

[0056] Item Value Ambient temperature in printer 40.3℃ Ambient humidity in printer 61％ Atomization temperature 28-34℃ Hotplate temperature ～92℃ Printing speed 10 mm / s Number of layers 1 Substrate Silicon wafer

[0057] The straight line cross grid array printed by high-precision spraying printing technology is shown in Figure 3a, Figure 3 Figure 3 Figure 2a is a microscopic magnification of the straight line cross grid array, from which it can be found that, using high-precision controllable micro-nano array preparation technology, the straight line cross grid array is macroscopically regular and orderly, and the line is basically stable and coherent.

[0058] Figure b is a microscopic magnification of the grid array of large size, from which it can be found that the length of each square in the grid array is basically around 500μm, indicating that the spacing of the array printed by the high-precision material printer will have a small difference compared with the set spacing, but this difference is within the allowable range. In figure b, it can also be observed that the width of the straight line is basically 50μm, which further realizes the size requirement of the micro-nano array.

[0059] In SEM figures c-d, it can be observed that a large number of AuNB particles are distributed in each straight line in the straight line cross grid array, indicating that high-precision spraying technology can realize the micro-nano array construction of AuNB particles. However, the printing solution concentration of AuNBs needs to be improved in the later stage. ​

[0060] Example 4

[0061] Meanwhile, 2 glass sheets and 5cm*5cm silicon wafers are prepared and cleaned with alcohol, and are stored in a dustproof and dry environment for the preparation of high-precision controllable micro-nano array by spraying.

[0062] Circular array

[0063] 1. The relevant project parameters of the high-precision material spraying printer in the spraying printing track of the circular array are shown in Table 3.

[0064] 2. The high-concentration AuNB solution prepared by the method of Example 1 is used as a printing reagent.

[0065] 3. Spraying is performed on the surface of the silicon wafer, and the diameter of the circle in the circular array is 600μm.

[0066] Table 4

[0067]

[0068]

[0069] The spraying results are shown in Figure 4 In Figure a, it can be seen that the circular micro-nano array is arranged regularly at the macro scale, and the center-to-center distance is about 1000μm, which is basically consistent with the preset distance, indicating that the spraying positioning has good repeatability and control accuracy. Figure b shows that the diameter of the printed circular pattern is about 700μm, although there is a certain deviation from the set value, but the overall profile remains good, and the pattern is basically in the form of a circle. This shows that the current high-precision spraying technology has a good foundation in constructing micro-nano arrays, and there is still room for optimization in further improving the pattern edge definition and size consistency.

[0070] In SEM images c-d, it can be observed that there are a large number of AuNB particles distributed in each circular edge in the circular array, indicating that high-precision spraying technology can realize the construction of micro-nano array of AuNB particles. However, the printing solution concentration of AuNBs needs to be improved in the later stage.

[0071] In the present application, high-precision controllable micro-nano array preparation technology is used, high-concentration AuNBs are used as raw materials, a high-precision material spraying printer is used, and glass sheets and silicon wafers are used as the bottom sheet. Regular micro-nano structure patterns can be sprayed on the bottom sheet, which can be proved by experiments.

[0072] It is to be noted that the terms such as first and second, etc. are used herein merely to differentiate one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between such entities or operations. Also, the terms "comprising", "containing", or any other variant thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0073] It is to be noted that the above merely illustrates the technical idea of the present application, and cannot limit the protection scope of the present application. For those skilled in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements all fall within the protection scope of the claims of the present application.

Claims

1. A method for constructing a controllable micro-nano array based on 3D printing, characterized in that, The method comprises the following steps: S1, preparation of gold-silver core-shell structure nanobrick, gold nanorod is synthesized by seed growth method, taking gold nanorod as core, and synthesizing gold-silver nanobrick with core-shell structure in L-ascorbic acid and silver nitrate solution by taking surfactant hexadecyl trimethyl ammonium chloride as ligand; S2, the gold-silver nanobrick prepared in step S1 is washed with water and concentrated to obtain a high-concentration gold-silver nanobrick solution which is used as a printing reagent; S3, high-precision material printer is used to spray on a substrate to obtain a micro-nano array.

2. The method according to claim 1, wherein, In step S2, the concentration of the high-concentration gold-silver nanobrick solution is 1 mM-3 mM.

3. The method according to claim 1, wherein, In step S3, the parameters of the high-precision material printer for spraying on the substrate are as follows: printer ambient temperature: 40.3℃, printer internal ambient humidity: 61%, atomization temperature: 28-34℃, hot table temperature: 92℃, printing speed: 10 mm / s, layer number: 1 layer, and substrate: silicon wafer or glass sheet.

4. The method according to claim 1, wherein, In step S3, the micro-nano array comprises a straight line array, a straight line cross grid array, and a circular array.

5. The method according to claim 4, wherein, The pitch of the straight line array is 200-500 μm, the pitch of the straight line cross grid array is 200-500 μm, and the diameter of the circle in the circular array is 400-800 μm.

6. The method according to claim 1, wherein, Step The preparation of gold-silver core-shell structure nanobrick in step S1 comprises the following steps: S1-1, preparation of gold nanorod: hexadecyl trimethyl ammonium chloride and sodium oleate are dissolved in 50℃ hot water, AgNO3 aqueous solution and HAuCl4 aqueous solution are added, the solution is slowly changed from gold color to colorless; then concentrated HCl is added to adjust the pH of the system, L-ascorbic acid aqueous solution is added after the seed solution is added, the system is fully mixed and then placed in a 30℃ water bath overnight; then the supernatant is removed by centrifugation, and ultrapure water is added to obtain a gold nanorod aqueous solution; S1-2, preparation of gold-silver nanobrick with core-shell structure: the gold nanorod aqueous solution is centrifuged to remove the supernatant, hexadecyl trimethyl ammonium chloride aqueous solution is added, and the mixture is shaken and placed overnight for more than 12 h; the mixture is placed in a 65℃ water bath, stirred and incubated for 3 min, then AgNO3 solution and L-ascorbic acid solution are added in sequence, and the mixture is continuously stirred in a 60℃ water bath for 3 h; after the reaction is completed, the mixture is washed with ultrapure water to obtain a gold-silver nanobrick solution with core-shell structure.

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