Method for preparing metasurface structure based on silicon dioxide microspheres and DNA origami technology

Abstract

The invention relates to a method for preparing a metasurface structure based on silicon dioxide microspheres and a DNA origami technology, which comprises the following steps: carrying out DNA modification on a gold film used in an experiment, and depositing a layer of ssDNA on the surface of the gold film; the preparation method comprises the following steps: forming a single-layer SiO2 microsphere structure on a gold film substrate modified with ssDNA through a Czochralski method, performing plasma treatment after the substrate is completely dried, putting the substrate into a constant-temperature and constant-humidity chamber for incubation, performing ultrasonic stripping on SiO2 microspheres in ultrapure water to form regular ssDNA array sites, depositing a pre-formed DNA origami structure or metal nanoparticles on the surface of a gold film, and drying the gold film to obtain the single-layer single-layer SiO2 microsphere structure. Under the action of complementary base pairing, the origami structure or the metal nanoparticles are accurately adsorbed on the array sites, and the surface of the gold film is cleaned to remove the non-specific binding origami structure or the metal nanoparticles, so that the metasurface structure is formed. The method is simple in process, low in equipment and environment requirements and low in preparation cost, and a paper folding structure can form various nano structures or various metal particles on the surface to form various complex metasurface structures such as a plasma structure and a chiral structure.

Description

Technical Field

[0001] The present invention relates to a method for preparing a metasurface, and in particular, to a method for preparing various metasurface structures based on silica microspheres and DNA origami method. Background Art

[0002] A metasurface is a two-dimensional planar structure composed of artificial crystals with special electromagnetic properties arranged in a specific manner, which can flexibly control the amplitude, phase, and polarization of incident light, thereby achieving a powerful light field manipulation ability. Due to its unique two-dimensional planar structure, the metasurface not only breaks through the electromagnetic property limitations of traditional materials but also overcomes the problem of difficult processing of the three-dimensional structure of metamaterials, providing convenience for the integration and miniaturization of nano-optical devices. The metasurface has broad application prospects in polarization conversion, holographic imaging, ultra-thin lenses, and beam deflection, etc., and thus has received extensive attention and gradually become a hot research field.

[0003] The preparation of metasurfaces is one of the key technological processes in the optoelectronic and semiconductor fields. Traditional methods usually rely on top-down lithography techniques. However, this method faces problems such as high cost and time consumption. As mentioned in the existing literature, superstructures and array structures are usually prepared by electron beam lithography to form a substrate, and then nanoparticles are added on it. However, the cost of electron beam lithography is high and it is not suitable for large-scale applications. Summary of the Invention

[0004] The present invention aims to solve the technical problems in the preparation of metasurface structures and proposes a new method based on silica microspheres and DNA origami method. By forming array sites with silica microspheres and utilizing the precise programming ability of DNA origami technology, various nano-scale structures can be prepared. Depositing these origami structures on the array sites can form a metasurface structure. By adjusting the origami structure and connecting metal nanoparticles, superstructures with different properties can be achieved. This method effectively solves the problems of high preparation cost, complex synthesis conditions, and insufficient structural accuracy in traditional methods.

[0005] A method for preparing a metasurface structure based on silica microspheres and DNA origami method, which is simple, low-cost, and can fabricate various complex superstructures. It includes the following steps:

[0006] Step S1: Immerse a glass slide with a gold film coating in a mixed solution of thiol-modified ssDNA, TCEP, TE buffer solution, and NaCl solution, then transfer it to pure water for rinsing to remove excess ssDNA and buffer solution, and finally, dry it with nitrogen;

[0007] Step S2: Add ultrapure water into a clean beaker and place it on a heating platform for heating. Place the treated gold film glass slide at the bottom of the beaker so that the ultrapure water completely covers the glass slide. Use a pipette to suck up the SiO2 microsphere emulsion and slowly inject the emulsion. After the n-butanol volatilizes, a film will form on the liquid surface. When this phenomenon is observed, use tweezers to slowly lift the glass slide at the bottom of the water out of the liquid surface, and transfer the monolayer SiO2 sphere array on the liquid surface to the gold film;

[0008] Step S3: After the gold film is completely dried, move it to a small petri dish and place it in a plasma cleaner for treatment for a period of time;

[0009] Step S4: Place the treated gold film in a thermostatic and humidostatic chamber and incubate it at a certain temperature and humidity for a period of time;

[0010] Step S5: Ultrasonic in ultrapure water until the SiO2 spheres completely fall off and the glass slide presents a clean state, and blow dry the surface moisture with nitrogen;

[0011] Step S6: Design and anneal to form an origami structure or metal nanoparticles, purify the structure through gel electrophoresis, and deposit the purified origami structure metal nanoparticles on the surface of the substrate for incubation;

[0012] Step S7: Wash the surface of the substrate with origami buffer solution to remove the excess origami structure or metal nanoparticles, blow dry with nitrogen, and prepare for SEM testing.

[0013] Adopting the above technical solution, the beneficial effects of the present invention are as follows:

[0014] The present invention provides a method for preparing a metasurface structure based on silica microspheres and DNA origami technology, including the following steps: DNA-modify the gold film used in the experiment, and deposit a layer of ssDNA on the surface of the gold film by using a gold-sulfur bond. The gold film substrate modified with ssDNA forms a dense monolayer SiO2 microsphere structure by the dip-coating method. After waiting for the substrate to be completely dried, perform plasma treatment, and then place it in a thermostatic and humidostatic chamber for incubation. After that, ultrasonically peel off the SiO2 microspheres in ultrapure water to form regular ssDNA array sites. Deposit the pre-formed DNA origami structure or metal nanoparticles on the surface of the gold film. Under the action of base complementary pairing, the origami structure or metal nanoparticles are accurately adsorbed on the array sites. Wash the surface of the gold film to remove the non-specifically bound origami structure or metal nanoparticles to form a metasurface structure. The advantages are that the requirements for equipment and environment are low, the preparation cost is low, the origami structure can form various nanostructures or various metal particles can be connected to the surface to form a variety of complex metasurface structures such as plasma structures and chiral structures, etc.

[0015] Compared with the prior art, the advantages of the present invention are as follows:

[0016] 1) The operation steps are simple and the applicability is strong.

[0017] 2) The experimental cost is reduced while ensuring high precision.

[0018] 3) By adjusting the combination of the origami structure and metal nanoparticles, various metasurface structures with different functions can be fabricated. Description of the Drawings

[0019] Figure 1 It is a scanning electron microscope photograph of the self-assembly of silica microspheres on the substrate surface obtained by the method provided in Embodiment 1 of the present invention.

[0020] Figure 2 It is a scanning electron microscope photograph of gold nanoparticles hybridized at specific positions obtained by the method provided in Embodiment 1 of the present invention.

[0021] Figure 3 It is a scanning electron microscope photograph of the self-assembly of the origami and nanoparticle hybrid structure on the substrate surface obtained by the method provided in Embodiment 2 of the present invention (8.6 mm × 9.00 k).

[0022] Figure 4 It is a scanning electron microscope photograph of the self-assembly of the origami and nanoparticle hybrid structure on the substrate surface obtained by the method provided in Embodiment 2 of the present invention (9.6 mm × 10.0 k).

[0023] Figure 5 It is a scanning electron microscope photograph of the self-assembly of hexamers on the substrate surface obtained by the method provided in Embodiment 3 of the present invention. Detailed Embodiments

[0024] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] A method for preparing a metasurface structure based on silica microspheres and DNA origami method, comprising the following steps:

[0026] Step S1: Place a glass slide with a gold film coating in a mixed solution of mercapto-modified ssDNA, TCEP, TE buffer, and NaCl solution for soaking, then transfer it to pure water for rinsing to remove excess ssDNA and buffer, and finally, dry it with nitrogen;

[0027] Step S2: Add ultrapure water into a clean beaker and place it on a heating platform for heating. Place the treated gold film glass slide at the bottom of the beaker so that the ultrapure water completely covers the glass slide. Use a pipette to aspirate the SiO2 microsphere emulsion and slowly inject the emulsion. After the n-butanol volatilizes, a film will form on the liquid surface. When observing this phenomenon, use tweezers to slowly lift the glass slide at the bottom of the water out of the liquid surface, and transfer the monolayer SiO2 sphere array on the liquid surface to the gold film;

[0028] Step S3: After the gold film is completely dried, move it to a small petri dish and place it in a plasma cleaner for treatment for a period of time;

[0029] Step S4: Place the treated gold film in a thermostatic and humidostatic chamber and incubate it at a certain temperature and humidity for a period of time;

[0030] Step S5: Sonicate in ultrapure water until the SiO2 spheres completely fall off and the glass slide presents a clean state, and blow dry the surface moisture with nitrogen;

[0031] Step S6: Design and anneal to form an origami structure or metal nanoparticles, purify the structure through gel electrophoresis, and deposit the purified origami structure metal nanoparticles on the substrate surface for incubation;

[0032] Step S7: Wash the substrate surface with origami buffer solution to remove the excess origami structure or metal nanoparticles, blow dry with nitrogen, and prepare for SEM testing.

[0033] A method for preparing a metasurface structure based on silica microspheres and DNA origami technology, using a glass slide with a gold film coating as the substrate, constructing a metasurface structure by using silica microspheres and DNA self-assembly technology, modifying nanoparticles or nanorods with DNA, and hybridizing the DNA-modified nanoparticles or nanorods with the above-mentioned triangular tile DNA and cylindrical DNA tiles to form a metasurface structure.

[0034] Further, the above-mentioned substrate is a glass slide with a gold film coating immersed in a mixed solution of mercapto-modified ssDNA, TCEP, TE buffer solution, and NaCl solution to modify ssDNA.

[0035] Further, the above-mentioned SiO2 microsphere emulsion is an emulsion in which SiO2 microspheres are uniformly dispersed in n-butanol, and the configured concentration is 1.5 - 4 mg / ml.

[0036] Further, after the gold film is dried, it also includes the processes of plasma cleaner treatment and incubation in a thermostatic and humidostatic chamber.

[0037] Further, the origami structure includes triangular DNA tiles and cylindrical DNA tiles.

[0038] The triangular DNA tile is characterized by containing a 7259-base linear single-stranded template DNA extracted from the m13mp18 virus, which forms a triangular topological structure with 210 functional short-chain components through nested base complementary pairing, where the lengths of the auxiliary strands are non-uniformly distributed (the number of bases in each strand is different); the capture strand contains two functional modules, the S1 pairing sequence for template binding and the S2 sticky end, and the S2 sticky end realizes the directional capture of nanoparticles or nanorods through asymmetric restriction sites; in addition, 14 DNA ligation strands are required to assemble the triangular DNA tiles into polymeric DNA origami.

[0039] The cylindrical DNA tile is characterized by containing a 7259-base linear single-stranded template DNA extracted from the m13mp18 virus, which forms a cylindrical topological structure with 148 functional short-chain components through nested base complementary pairing, where the lengths of the auxiliary strands are non-uniformly distributed (the number of bases in each strand is different); the capture strand contains two functional modules, the S1 pairing sequence for template binding and the S2 sticky end, and the S2 sticky end realizes the directional capture of nanoparticles or nanorods through asymmetric restriction sites.

[0040] Furthermore, the nanoparticles are gold nanoparticles, and the nanorods are gold nanorods.

[0041] Furthermore, after completing the modification of the nanoparticles or nanorods with DNA, it also includes the step of removing the excess DNA.

[0042] Furthermore, the step of removing the excess DNA includes removing the excess DNA by 1% agarose electrophoresis.

[0043] Furthermore, hybridize the DNA-modified nanoparticles or nanorods with the DNA tiles.

[0044] Furthermore, deposit the hybridization structure of DNA and nanoparticles or metal particles on the substrate, and the deposition temperature is room temperature.

[0045] Example 1

[0046] 1. Modify the substrate with DNA

[0047] Place the glass slide with a gold film coating in a mixed solution of mercapto-modified ssDNA, TCEP, TE buffer, and NaCl solution and soak for 24 h to deposit a layer of ssDNA on the gold film surface, then transfer it to pure water for rinsing to remove the excess ssDNA and buffer, and finally, dry it with nitrogen;

[0048] 2. Self-assembly of silica microspheres on the substrate

[0049] Add 20 ml of ultrapure water to a clean beaker and place it on a heating plate to heat to 60 °C. Place the treated gold film glass slide at the bottom of the beaker so that the ultrapure water completely covers the glass slide. Use a pipette to aspirate 500 μl of SiO2 microsphere emulsion and slowly inject the emulsion. After the n-butanol in the emulsion volatilizes, a film will form on the liquid surface. After observing this phenomenon, use tweezers to slowly lift the glass slide at the bottom of the water out of the liquid surface, and transfer the monolayer SiO2 sphere array on the liquid surface to the gold film;

[0050] 3. Treatment of the substrate with a plasma cleaner

[0051] After the gold film is completely dried, transfer it to a small petri dish and place it in a plasma cleaner for treatment at a power of 11 w for 15 min to remove the ssDNA in the unshielded part of the SiO2 microspheres;

[0052] 4. Incubation of the sample in a constant temperature and humidity chamber

[0053] Put the treated gold film into a constant temperature and humidity chamber and incubate it at a temperature of 60 °C and a humidity of 90% for 48 h to inactivate the hydroxyl groups generated by the plasma cleaner treatment;

[0054] 5. Cleaning of the substrate

[0055] Ultrasonic in ultrapure water for 30 s until the silica spheres completely fall off and the glass slide presents a clean state, and blow dry the surface moisture with nitrogen;

[0056] 6. Modifying the nanoparticles with DNA

[0057] Mix DNA and TCEP in a molar ratio of 1:200 and let it stand for 30 min. Then centrifuge the 40 nm nanoparticles synthesized with sodium citrate (centrifugation rate: 6500 rpm, centrifugation time: 5 minutes). After centrifugation, discard the supernatant, then add ultrapure water and centrifuge again (centrifugation rate: 6500 rpm, centrifugation time: 5 minutes) to remove the excess ligands of the nanoparticles. Then add the above mixed solution of DNA and TCEP to make the molar ratio of gold nanoparticles to DNA reach 1:1000. Then add 9 times the volume of n-butanol, shake to make the solution clear, and then add 2 times the volume of 0.5×TBE to transfer the DNA-modified nanoparticles from the n-butanol phase to the TBE phase. After shaking, let it stand until the solution is stratified, and take the lower layer liquid. Remove the excess DNA from the DNA-modified nanoparticles by 1% agarose electrophoresis, cut the required band for concentration, and measure its concentration by UV spectroscopy to prevent the excess DNA from affecting the precise positioning of the nanoparticles in the subsequent hybridization steps.

[0058] In this example, the DNA used to modify the nanoparticles is preferably thiol DNA, so as to realize the binding between DNA and nanoparticles by using the covalent bond formed between the thiol group and the nanorod.

[0059] In this embodiment, the nanoparticles are preferably gold nanoparticles.

[0060] 7. Deposit the DNA-modified gold nanoparticles on the substrate

[0061] Drop the purified gold nanoparticles onto the above-mentioned substrate. The deposition buffer is 0.5×TBE Na + (250 mM), and place it in an environment at 28°C for 3 hours for assembly. Here, it is necessary to ensure that the gold nanoparticle solution does not dry during the assembly process. Then, use the buffer (0.5×TBE) to wash away the excess unassembled gold nanoparticles; it can be understood that the hybridization temperature for hybridizing the DNA-modified gold nanoparticles with the substrate is lower than the DNA melting temperature; the determination of the position of the gold nanoparticles is achieved by modifying ssDNA on the substrate to extend and pair with the DNA sequences on the surface of the gold nanoparticles.

[0062] Please refer to Figures 1 to 2 , where Figure 1 is a scanning electron microscope photograph of the self-assembly of silica microspheres on the substrate surface obtained by the method provided in Embodiment 1 of the present invention. The silica microspheres are arranged neatly in the closest packing on the substrate; Figure 2 is a scanning electron microscope photograph of the hybridization of gold nanoparticles at specific positions obtained by the method provided in Embodiment 1 of the present invention. The 40-nm gold nanoparticles modified with DNA specifically bind to the sites.

[0063] Example 2

[0064] 1. Modify the substrate with DNA

[0065] Place the glass slide with a gold film coating in a mixed solution of thiol-modified ssDNA, TCEP, TE buffer, and NaCl solution and soak for 24 hours to deposit a layer of ssDNA on the surface of the gold film. Then, transfer it to pure water for rinsing to remove the excess ssDNA and buffer. Finally, dry it with nitrogen;

[0066] 2. Self-assembly of silica microspheres on the substrate

[0067] Add 20 ml of ultrapure water to a clean beaker and heat it to 60°C on a heating platform. Place the treated gold film glass slide at the bottom of the beaker so that the ultrapure water completely covers the glass slide. Use a pipette to aspirate 500 microliters of the SiO2 microsphere emulsion and slowly inject the emulsion. After the n-butanol in the emulsion volatilizes, a film will form on the liquid surface. When this phenomenon is observed, use tweezers to slowly lift the glass slide at the bottom of the water out of the liquid surface, and transfer the monolayer SiO2 sphere array on the liquid surface to the gold film;

[0068] 3. Plasma Cleaner Treatment of the Substrate

[0069] After the gold film is completely dry, transfer it to a small petri dish and place it in a plasma cleaner for treatment at a power of 11 w for 15 min to remove the ssDNA in the unblocked part of the SiO2 microspheres;

[0070] 4. Incubation of the Sample in a Thermostatic and Humidostatic Chamber

[0071] The treated gold film is placed in a thermostatic and humidostatic chamber and incubated at a temperature of 60 °C and a humidity of 90% for 48 h to inactivate the hydroxyl groups generated by the plasma cleaner treatment;

[0072] 5. Cleaning of the Substrate

[0073] Ultrasonic in ultrapure water for 30 s until the silica spheres completely fall off and the glass slide presents a clean state, and blow dry the surface moisture with nitrogen;

[0074] 6. Modification of Nanoparticles with DNA

[0075] Mix DNA and TCEP in a molar ratio of 1:200 and let stand for 30 min. Then centrifuge the 20 nm nanoparticles synthesized by sodium citrate (centrifugation rate: 9000 rpm, centrifugation time: 5 min). After centrifugation, discard the supernatant, then add ultrapure water and centrifuge again (centrifugation rate: 9000 rpm, centrifugation time: 5 min) to remove the excess ligands of the nanoparticles. Then add the above mixed solution of DNA and TCEP to make the molar ratio of gold nanoparticles to DNA reach 1:1000. Then add 9 times the volume of n-butanol, shake to make the solution clear, and then add 2 times the volume of 0.5×TBE to transfer the DNA-modified nanoparticles from the n-butanol phase to the TBE phase. After shaking, let stand until the solution is stratified, and take the lower layer liquid. The DNA-modified nanoparticles are electrophoresed with 1% agarose to remove the excess DNA, cut out the required band for concentration, and measure its concentration with UV spectroscopy to prevent the excess DNA from affecting the precise positioning of the nanoparticles in the subsequent hybridization step.

[0076] In this example, the DNA used to modify the nanoparticles is preferably thiol-DNA, so as to realize the binding between DNA and nanoparticles by using the covalent bond formed between the thiol group and the nanorod.

[0077] In this example, the nanoparticles are preferably gold nanoparticles.

[0078] 7. Preparation of a Hybrid Structure of Cylindrical DNA Tiles and 20 nm Gold Nanoparticles Using DNA Self-Assembly Technology

[0079] A set of auxiliary strands with a concentration of 100 μM was mixed with the long single-stranded DNA of m13mp18 virus at a molar ratio of 20:1; then a short-chain DNA for capturing nanoparticles, namely the capture strand, was added. The sticky end S2 of this short-chain DNA paired with the single-stranded DNA on the surface of the nanoparticles, and another sequence S1 participated in the pairing with the long single-stranded DNA of m13mp18 virus, forming a part of the cylindrical DNA tile. Then, the Mg concentration in the solution was adjusted to 12.5 mM with TE solution and MgCl2, and the mixed solution was annealed with a PCR instrument, cooling from 85 °C to 25 °C to form the required cylindrical DNA tile. The excess DNA was removed from the cylindrical DNA tile by 1% agarose electrophoresis, the required band was cut out and concentrated, and its concentration was measured with B-500. Then, the above-mentioned 20 nm gold nanoparticles were added at a molar ratio of 10:1, and the mixed solution was annealed with a PCR instrument, slowly cooling from 45 °C to 25 °C. Then, the solution was subjected to 1% agarose electrophoresis to remove the excess structure, and the required band was cut out and concentrated to obtain the hybrid structure of the required cylindrical DNA tile and 20 nm gold nanoparticles. 2+ In this example, the cylindrical DNA tile is characterized by containing a 7259-base linear single-stranded template DNA extracted from m13mp18 virus, which forms a cylindrical topological structure with 148 functional short-chain components through nested base complementary pairing. Among them, the lengths of the auxiliary strands are non-uniformly distributed (the number of bases in each strand is different); the capture strand contains two functional modules, the S1 pairing sequence for template binding and the S2 sticky end. The S2 sticky end realizes the directional capture of nanoparticles or nanorods through asymmetric restriction sites.

[0080] 8. Deposit the hybrid structure of the cylindrical DNA tile and 20 nm gold nanoparticles on the substrate.

[0081] Drop the purified hybrid structure of the cylindrical DNA tile and 20 nm gold nanoparticles on the above-mentioned substrate and place it in an environment at 28 °C for 3 hours for assembly. Here, it is necessary to ensure that the solution does not dry during the assembly process. Then, use buffer 0.5×TAE Mg (6.25 mM) to rinse off the excess unassembled structure; it can be understood that the hybridization temperature for hybridizing the hybrid structure with the substrate is lower than the DNA melting temperature; the position of the hybrid structure is determined by the complementary pairing of the ssDNA modified on the substrate with the strand extending from the bottom of the cylindrical DNA tile.

[0082] Please refer to 2+ (6.25 mM) to rinse off the excess unassembled structure; it can be understood that the hybridization temperature for hybridizing the hybrid structure with the substrate is lower than the DNA melting temperature; the position of the hybrid structure is determined by the complementary pairing of the ssDNA modified on the substrate with the strand extending from the bottom of the cylindrical DNA tile.

[0083] Please refer to Figures 3 to 4 , Figure 3 , Figure 4Scanning electron microscope photograph of the self-assembly of the hybrid structure of origami and nanoparticles on the substrate surface obtained by the method provided in Embodiment 2 of the present invention. The hybrid structure in which the cylindrical origami wraps 20 nm gold nanoparticles specifically binds to the sites on the substrate through the capture chains protruding from the origami; among them Figure 3 The working distance and magnification are 8.6 mm × 9.00 k; Figure 4 The working distance and magnification are 9.6 mm × 10.0 k.

[0084] Embodiment 3

[0085] 1. Modify the substrate with DNA

[0086] Place the glass slide with a gold film coating in a mixed solution of mercapto-modified ssDNA, TCEP, TE buffer, and NaCl solution and soak for 24 h to deposit a layer of ssDNA on the gold film surface. Then move it to pure water for rinsing to remove excess ssDNA and buffer. Finally, dry it with nitrogen;

[0087] 2. Self-assembly of silica microspheres on the substrate

[0088] Add 20 ml of ultrapure water to a clean beaker and place it on a heating platform to heat to 60 °C. Place the treated gold film glass slide at the bottom of the beaker so that the ultrapure water completely covers the glass slide. Use a pipette to aspirate 500 μl of SiO2 microsphere emulsion and slowly inject the emulsion. After the n-butanol in the emulsion volatilizes, a film will form on the liquid surface. When this phenomenon is observed, use forceps to slowly lift the glass slide at the bottom of the water out of the liquid surface and transfer the monolayer SiO2 sphere array on the liquid surface to the gold film;

[0089] 3. Treatment of the substrate with a plasma cleaner

[0090] After the gold film is completely dried, move it to a small petri dish and place it in a plasma cleaner for treatment at a power of 11 w for 15 min to remove the ssDNA in the unblocked part of the SiO2 microspheres;

[0091] 4. Incubate the sample in a constant temperature and humidity chamber

[0092] Put the treated gold film into a constant temperature and humidity chamber and incubate at a temperature of 60 °C and a humidity of 90% for 48 h to inactivate the hydroxyl groups generated by the plasma cleaner treatment;

[0093] 5. Cleaning of the substrate

[0094] Ultrasonic in ultrapure water for 30 s until the silica spheres completely fall off and the glass slide presents a clean state. Dry the surface moisture with nitrogen;

[0095] 6. Modify the nanorods with DNA

[0096] Mix DNA and TCEP in a molar ratio of 1:200 and let it stand for 30 min. Then centrifuge the nanorods protected by cetrimonium bromide (CTAB) twice. For the first centrifugation (9000 rpm, 10 minutes), discard the supernatant and redissolve it with ultrapure water. For the second centrifugation (9000 rpm, 10 minutes) to remove the excess ligands on the nanoparticles. Then add the above mixed solution of DNA and TCEP to make the molar ratio of gold nanorods to DNA reach 1:1000. Then add 9 volumes of n-butanol, shake to make the solution clear. Then add 2 volumes of 0.5×TBE to transfer the DNA-modified nanorods from the n-butanol phase to the TBE phase. After shaking, let it stand until the solution is layered, and take the lower layer liquid. Remove the excess DNA from the DNA-modified nanorods by 1% agarose electrophoresis, cut the required band for concentration, and measure its concentration by UV spectroscopy to prevent the excess DNA from affecting the precise positioning of the nanoparticles in the subsequent hybridization step.

[0097] In this example, the DNA used to modify the nanorods is preferably thiol-DNA, so as to utilize the covalent bond formed between the thiol group and the nanorods to achieve the binding between DNA and the nanorods.

[0098] In the example provided by the present invention, the nanorods are preferably gold nanorods.

[0099] 7. Prepare a hexamer of the hybrid structure of triangular DNA tiles and gold nanorods using DNA self-assembly technology

[0100] Mix a group of auxiliary strands with a concentration of 100 μM and the long single-stranded DNA of m13mp18 virus in a molar ratio of 20:1. Then add the short-chain DNA used to capture nanoparticles, that is, the capture strand. The sticky end S2 of this short-chain DNA pairs with the single-stranded DNA on the surface of the nanoparticles, and the other sequence S1 participates in the pairing of the long single-stranded DNA of m13mp18 virus, forming a part of the triangular DNA tile. Then use TE solution and MgCl2 to adjust the Mg in the solution 2+Adjust the concentration to 12.5 mM, anneal the mixed solution with a PCR instrument, cool it from 80 °C to 27 °C to form the required triangular DNA tiles. Remove the excess DNA from the triangular DNA tiles by 1% agarose gel electrophoresis, cut out the required band for concentration, measure its concentration with B-500, and then add the above gold nanorods according to a molar ratio of 5:1. Anneal the mixed solution with a PCR instrument and slowly cool it from 45 °C to 25 °C to form the hybrid structure of the required triangular DNA tiles and 40 nm gold nanorods. Remove the excess structure from the hybrid structure by 1% agarose gel electrophoresis, cut out the required band for concentration, measure its concentration with B-500, and then add the above 14 linker strands according to a molar ratio of 200:1. Anneal the mixed solution with a PCR instrument and slowly cool it from 45 °C to 27 °C. Remove the excess structure from the solution by 1% agarose gel electrophoresis, cut out the required band for concentration, and obtain the hexamer of the hybrid structure of the required triangular DNA tiles and gold nanorods.

[0101] In this embodiment, the triangular DNA tile is characterized by containing a linear single-stranded template DNA of 7259 bases extracted from the m13mp18 virus, which forms a triangular topological structure with 210 functional short-chain components through nested base complementary pairing, where the lengths of the auxiliary strands are non-uniformly distributed (the number of bases in each strand is different); the capture strand contains two functional modules, the S1 pairing sequence for template binding and the S2 sticky end, and the S2 sticky end realizes the directional capture of nanoparticles or nanorods through an asymmetric restriction site; in addition, 14 DNA linker strands are required to assemble the triangular DNA tiles into a polymeric DNA origami.

[0102] Drop the purified hexamer of the hybrid structure of triangular DNA tiles and gold nanorods onto the above substrate and place it in an environment at 28 °C for 3 hours for assembly. Here, it is necessary to ensure that the solution does not dry during the assembly process. Then use buffer 0.5×TAE Mg 2+ (6.25 mM) to rinse off the excess unassembled structure; it can be understood that the hybridization temperature for hybridizing the hexamer with the substrate is lower than the DNA melting temperature; the position of the hexamer is determined by the complementary pairing of the ssDNA modified on the substrate with the strand extending from the gold nanorod connected to the bottom of the hexamer.

[0103] Please refer to Figure 5 , Figure 5 which is a scanning electron microscope photograph of the self-assembly of the hexamer obtained by the method provided in Embodiment 3 of the present invention on the substrate surface. The hexamer structure is specifically bound through the underlying gold nanorods.

Claims

1. A method for preparing a metasurface structure based on silica microspheres and DNA origami technology, characterized in that, It includes the following steps: Step S1: Place the glass slide with a gold film coating in a mixed solution of mercapto-modified ssDNA, TCEP, TE buffer, and NaCl solution for soaking, then transfer it to pure water for rinsing to remove excess ssDNA and buffer. Finally, dry it with nitrogen gas. Step S2: Add ultrapure water to a clean beaker and place it on a heating platform for heating. Place the treated gold film glass slide at the bottom of the beaker so that the ultrapure water completely covers the glass slide. Use a pipette to aspirate the SiO2 microsphere emulsion and slowly inject the emulsion. After the n-butanol volatilizes, a film will form on the liquid surface. When this phenomenon is observed, use tweezers to slowly lift the glass slide at the bottom of the water out of the liquid surface and transfer the monolayer SiO2 sphere array on the liquid surface to the gold film. Step S3: After the gold film is completely dried, transfer it to a small petri dish and place it in a plasma cleaner for treatment for a period of time. Step S4: Place the treated gold film in a constant temperature and humidity chamber and incubate it at a certain temperature and humidity for a period of time. Step S5: Sonicate in ultrapure water until the SiO2 spheres completely fall off and the glass slide presents a clean state, and dry the surface moisture with nitrogen gas. Step S6: Design and anneal to form an origami structure or metal nanoparticles, purify the structure through gel electrophoresis, and deposit the purified origami structure metal nanoparticles on the substrate surface for incubation. Step S7: Wash the substrate surface with origami buffer to remove excess origami structure or metal nanoparticles, dry it with nitrogen gas, and prepare for SEM testing.

2. The method for preparing a metasurface structure based on silica microspheres and DNA origami technology according to claim 1, characterized in that: The SiO2 microsphere emulsion used in Step S2 is an emulsion in which SiO2 microspheres are uniformly dispersed in n-butanol, and the configured concentration is 1.5 - 4 mg / ml.

3. A method for preparing a metasurface structure based on silica microspheres and DNA origami technology according to claim 1, characterized in that: The buffer solution used in the deposition process of step S6 is 0.5×TAE Mg 2+ (6.25 mM) or 0.5×TBENa + (250 mM).

4. A method for preparing a metasurface structure based on silica microspheres and DNA origami method according to claim 1, characterized in that: The origami structure in Step S6 includes triangular DNA tiles and cylindrical DNA tiles. The triangular DNA tile is characterized in that it contains a linear single-stranded template DNA of 7259 bases extracted from the m13mp18 virus, forms a triangular topological structure through nested base complementary pairing with 210 functional short-chain components, and the length of the auxiliary chain shows a non-uniform distribution; the capture chain contains two functional modules, the S1 pairing sequence for template binding and the S2 sticky end, and the S2 sticky end realizes the directional capture of nanoparticles or nanorods through an asymmetric restriction site; in addition, 14 DNA ligation chains are required to assemble the triangular DNA tiles into a polymeric DNA origami. The cylindrical DNA tile is characterized in that it contains a linear single-stranded template DNA of 7259 bases extracted from the m13mp18 virus, forms a cylindrical topological structure through nested base complementary pairing with 148 functional short-chain components, and the length of the auxiliary chain shows a non-uniform distribution; the capture chain contains two functional modules, the S1 pairing sequence for template binding and the S2 sticky end, and the S2 sticky end realizes the directional capture of nanoparticles or nanorods through an asymmetric restriction site.

5. A method for preparing a metasurface structure based on silica microspheres and DNA origami method according to claim 1, characterized in that: The gold nanoparticles in Step S6 are gold nanospheres or gold nanorods modified with mercapto-modified ssDNA.

6. A method for preparing a metasurface structure based on silica microspheres and DNA origami method according to claim 1, characterized in that: The gel electrophoresis purification in Step S6 is to use 1% agarose electrophoresis to remove excess origami structure or metal nanoparticles.

7. A method for preparing a metasurface structure based on silica microspheres and DNA origami method according to claim 1, characterized in that: The buffer solution used for the final washing in step S7 is 0.5×TAE Mg 2+ (6.25 mM).

8. A method for preparing a metasurface structure based on silica microspheres and DNA origami method according to claim 1, characterized in that: The stacking methods of the metal nanoparticles connected to the origami include laying flat, cross-stacking, cross-stacking of the upper and lower layers of the origami structure, and multi-layer stacking on one side of the origami, forming various metasurface plasmon array structures.

Images