Natural polymer-based quantum dot micro-robot and preparation method thereof

Abstract

The invention relates to a natural polymer-based quantum dot micro-robot and a preparation method thereof. The micro-robot comprises a long-strip-shaped robot body, the robot body is formed by laminating a fluorescent material layer and a magnetic material layer, raw materials of the fluorescent material layer comprise a first natural polymer, quantum dots and a cross-linking agent, raw materials of the magnetic material layer comprise a second natural polymer, a magnetic material and a cross-linking agent, the swelling coefficient of the fluorescent material layer is different from that of the magnetic material layer, and the robot body is self-curled in a solution containing an initiator to form a spiral three-dimensional structure. The quantum dots are loaded by natural polymers, so that the quantum dots can be effectively isolated from the outside, and the biotoxicity of the quantum dots is reduced. And meanwhile, different swelling coefficients of the two natural polymers are ingeniously utilized, so that the robot body is self-curled into a three-dimensional spiral structure from a two-dimensional planar material in a solution containing an initiator.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-robots, and in particular to a natural polymer-based quantum dot micro-robot and a preparation method thereof. Background Art

[0002] The concept of microrobots was first proposed by Feynman at the 1959 American Physical Society Conference. It refers to microstructures with sizes ranging from micrometers to nanometers that can convert different forms of energy such as magnetic energy, chemical energy, and light energy into kinetic energy to drive their own movement. Microrobots are extremely small in size and can pass through surfaces such as skin and blood vessel walls without damaging the organism, reach small spaces in the body, and complete operations such as delivering medicines, taking samples, and killing cancer cells. The emergence of microrobots also provides a new platform for the study of microscale physics and dynamics.

[0003] The precise positioning of microrobots is a prerequisite for precise control and fine manipulation in vivo. Currently, the positioning of microrobots mainly includes ultrasound, optics, magnetism and ionizing radiation technologies. Among them, the optical positioning method is divided into optical reflection imaging and fluorescence imaging. The optical reflection imaging method emits incident light to the sample through a light source, and detects the reflection and scattering state of the incident light for positioning. This method is only suitable for areas with low tissue scattering. The fluorescence imaging method adds fluorescent materials to the microrobot and detects the fluorescence it emits for positioning.

[0004] There are many kinds of fluorescent materials available, and one of the most popular ones is quantum dots. Quantum dots are nanoscale semiconductor materials with a physical size no greater than twice the Bohr radius of the corresponding exciton. They are usually spherical or quasi-spherical with a diameter of less than 10 nanometers. When quantum dots are excited by light, the electrons in their valence band absorb energy and are excited to transition to the conduction band to generate corresponding holes. When the excited electrons transition back to the valence band in the form of radiation, they can emit photons to generate fluorescence. Compared with other existing fluorescent materials, quantum dots are larger in size and have good fluorescence and stable brightness. However, through in vitro studies, some quantum dots have been shown to cause significant damage to cells. Studies have also found that since quantum dots are usually composed of II-VI, III-V or IV-VI elements, such as CdTe, GaN and PbSe, these elements are usually highly biotoxic, which greatly limits the application of quantum dots in the field of biomedicine (fluorescent labeling and living cell imaging). Summary of the invention

[0005] The purpose of the present invention is to disclose a natural polymer-based quantum dot microrobot and a preparation method thereof, so as to solve one or more technical problems existing in the prior art and provide at least one beneficial option or create conditions.

[0006] The first aspect of the present invention is to provide a micro robot with a size ranging from micrometer to nanometer.

[0007] The second aspect of the present invention is to provide a method for preparing the microrobot.

[0008] The micro robot described in the first aspect of the present invention includes a long strip robot body, the robot body is formed by stacking a fluorescent material layer and a magnetic material layer, the raw materials of the fluorescent material layer include a first natural polymer, quantum dots, a cross-linking agent, an acrylamide monomer and an initiator, the raw materials of the magnetic material layer include a second natural polymer, a magnetic material, a cross-linking agent, an acrylamide monomer and an initiator, the swelling coefficient of the fluorescent material layer is different from the swelling coefficient of the magnetic material layer, and the robot body self-curls in a solution containing an initiator to form a spiral three-dimensional structure. By using natural polymers to load quantum dots, the quantum dots can be effectively isolated from the outside world, thereby reducing their biological toxicity. At the same time, the different swelling coefficients of the two natural polymers are cleverly utilized to make the robot body self-curl into a three-dimensional spiral structure from a two-dimensional planar material in a solution containing an initiator, and the fluorescent material layer and the magnetic material layer support each other, so that the rigidity strength of the micro robot is guaranteed.

[0009] In some application embodiments of the first aspect of the present invention, the first natural polymer and the second natural polymer are the same or different natural polymer materials, and the natural polymer materials are selected from one or more of chitosan and its derivatives, water-soluble cellulose and its derivatives, sodium alginate and its derivatives, hyaluronic acid and its derivatives. The main sources of cellulose include vegetables, grains, etc. in food, and chitosan is mainly extracted from the exoskeletons of crustaceans, such as crabs, lobsters and other marine organisms. Compared with the metal-based robots or robots made of photoresist commonly used in the prior art, the microrobot prepared by the present invention using natural polymers as the main material has very good biocompatibility and effectively avoids the harm of toxic materials to the human body.

[0010] In some application embodiments of the first aspect of the present invention, the swelling coefficient of the first natural polymer is greater than the swelling coefficient of the second natural polymer.

[0011] In some application embodiments of the first aspect of the present invention, the cross-linking agent includes a first cross-linking agent and a second cross-linking agent, the first cross-linking agent is selected from N,N'-methylenebisacrylamide (MBA), and the second cross-linking agent is selected from aluminum chloride, glutaraldehyde or oxalaldehyde. Acrylamide monomers and the first cross-linking agent can produce a synergistic effect during the cross-linking process, making the cross-linked network denser and more stable. This synergistic effect comes from the complementarity of the molecular structures of the two and their different active sites in the cross-linking reaction. When used together as a cross-linking agent, the number of cross-linking points can be increased, thereby increasing the cross-linking density. The second cross-linking agent promotes cross-linking again after the fluorescent material layer and the magnetic material layer are superimposed, which helps to improve the mechanical strength, heat resistance and solvent resistance of the reinforced material.

[0012] In some application embodiments of the first aspect of the present invention, the quantum dots are quantum dots with quantum confinement effect, including ZnS, ZnSe, ZnTe, CdTe or CdS, preferably non-biotoxic ZnS quantum dots.

[0013] In some application embodiments of the first aspect of the present invention, the magnetic material is ferromagnetic nanoparticles selected from ferroferric oxide (Fe 3 O 4 ), cobalt tetraoxide ferrite (CoFe 2 O 4 ), nickel ferrite (NiFe 2 O 4 ), any one or more of Fe-Cr-Co alloy and Nd-Fe-B alloy, preferably Fe 3 O 4 .

[0014] In some application embodiments of the first aspect of the present invention, the nanoparticles of the magnetic material have a particle size of 10 to 100 nm, preferably 10 to 80 nm.

[0015] In some application embodiments of the first aspect of the present invention, the concentration of the first natural polymer is 1-5wt%, preferably 1.5-2.5wt%.

[0016] In some application embodiments of the first aspect of the present invention, the concentration of the second natural polymer is 1-5wt%, preferably 1.5-2.5wt%.

[0017] In some application embodiments of the first aspect of the present invention, the mass ratio of the magnetic material to the second natural polymer is (1-20):1, preferably 5:1.

[0018] In some application embodiments of the first aspect of the present invention, the solvent of the magnetic material layer includes any one of water, acetic acid aqueous solution and ethanol, preferably acetic acid aqueous solution. The concentration of the acetic acid aqueous solution is 0.5-5wt%, preferably 2wt%.

[0019] In some application embodiments of the first aspect of the present invention, the viscosity of the chitosan at 20° C. is 0-400 mPa·s, preferably 100-200 mPa·s.

[0020] In some application embodiments of the first aspect of the present invention, the viscosity of the cellulose at 20° C. is 0 to 330 mPa·s, preferably 45 to 55 mPa·s.

[0021] In some application embodiments of the first aspect of the present invention, the deacetylation degree of the chitosan is 80-95%, preferably 95%.

[0022] In some application embodiments of the first aspect of the present invention, the acrylamide monomer is selected from any one or more of acrylamide derivative monomers such as acrylamide (AM), methacrylamide (MA), N-ethylacrylamide (NEA), N-hydroxyethylacrylamide (HEAA), and N-isopropylacrylamide (NIPAM).

[0023] In some application embodiments of the first aspect of the present invention, the concentration of the cross-linking agent is 0.5-4.5wt%, preferably 2.2wt%.

[0024] In some application embodiments of the first aspect of the present invention, the concentration of the acrylamide monomer is 5-15wt%, preferably 10wt%.

[0025] In some application embodiments of the first aspect of the present invention, the initiator includes one or more of persulfides such as potassium persulfate and ammonium persulfate, peroxides, bisulfites, and azo compounds.

[0026] In some application implementations of the first aspect of the present invention, the average thickness of the magnetic material layer is 2-12 μm.

[0027] In some application implementations of the first aspect of the present invention, the average thickness of the robot body is 10-50 μm.

[0028] In some application embodiments of the first aspect of the present invention, the helical angle of the helical three-dimensional structure formed by self-curling of the robot body is 25°~35°.

[0029] The preparation method described in the second aspect of the present invention includes the following steps: 1) preparing a fluorescent material solution and a magnetic material solution respectively; 2) coating a release coating on a supporting substrate and forming a release layer after drying; 3) coating the release layer with a magnetic material solution and forming a magnetic material layer after drying; 4) coating the magnetic material layer with a fluorescent material solution and forming a fluorescent material layer after drying; 5) separating the supporting substrate by peeling off the release layer, cutting it into a rectangle to obtain the robot body, placing the robot body in a solution containing a cross-linking agent, causing it to cross-link and self-curl to form a spiral three-dimensional structure, thereby obtaining the micro robot.

[0030] In some application embodiments of the second aspect of the present invention, the cross-linking agent in step 5) is a second cross-linking agent having a cross-linking effect on natural polymers, including aluminum chloride, glutaraldehyde or oxalaldehyde; preferably, the solution containing the cross-linking agent is AlCl 3 Solution.

[0031] In some application embodiments of the second aspect of the present invention, the release coating in step (2) is a starch aqueous solution.

[0032] In some application embodiments of the second aspect of the present invention, step (2) prepares the release layer by spin coating; preferably, the spin coating speed for preparing the release layer is 1500~3500 rpm, and the spin coating time is 20~40 seconds; preferably, the forming is carried out by baking, the baking temperature is 80~100°C, and the baking time is 45~75 seconds.

[0033] In some application embodiments of the second aspect of the present invention, step 3) prepares the magnetic material layer by spin coating; preferably, the spin coating speed for preparing the magnetic material layer is 150~2000 rpm, and the spin coating time is 30~60 seconds; preferably, the forming is carried out by baking, the baking temperature is 80~120℃, and the baking time is 45~75 seconds.

[0034] In some application embodiments of the second aspect of the present invention, step 4) prepares the fluorescent material layer by spin coating; preferably, the spin coating speed for preparing the fluorescent material layer is 500~3500 rpm, and the spin coating time is 30~60 seconds; preferably, the forming is carried out by baking, the baking temperature is 80~120℃, and the baking time is 45~75 seconds.

[0035] Compared with the existing detection technology, the present invention has the following advantages: The microrobot is mainly composed of natural polymers, has very good biocompatibility, has a low risk of use in the human body, and is suitable for application in the biomedical field. At the same time, natural polymers have the advantage of being easier to attach and modify functional groups compared to traditional microrobots made of materials such as metals and carbon tubes, and can easily add groups such as those used to detect lesions or encapsulate drugs to the microrobot. In addition, the microrobot uses two natural polymers with different swelling coefficients to stack and cross-link together and support each other, solving the problem of insufficient rigidity strength of a single natural polymer. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of the double-layer membrane curling of the microrobot; Figure 2 is a photograph of the microrobot prepared in Example 3, with a scale of 200 μm; Figure 3 is the EDS detection image of the microrobot prepared in Example 3, with a scale of 500 μm; Figure 4 It is a relationship diagram of the micro robot on the x-axis, y-axis and composite speed and the rotation frequency of the rotating magnetic field. DETAILED DESCRIPTION

[0037] The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the spirit and essence of the present invention, modifications and substitutions made to the methods, steps or conditions of the present invention all belong to the scope of the present invention.

[0038] Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0039] Example 1: Preparation method for constructing natural polymer-based quantum dot microrobot ZnS quantum dots were selected, combined with cellulose and chitosan to prepare a microrobot that self-curled to form a spiral three-dimensional structure. The preparation method is as follows: Prepare fluorescent material solution: prepare ZnS quantum dot aqueous dispersion, add cellulose powder and stir evenly until it becomes a gel, then add AM and MBA and stir evenly, and finally add initiator ammonium persulfate (APS); Preparation of magnetic material solution: Dissolve chitosan powder in acetic acid solution, stir until it becomes a gel, then add AM, MBA and Fe 3 O 4 Stir well and finally add APS; Forming of the robot body: coating a release coating on the supporting substrate to form a release layer after drying, spin coating the magnetic material solution on the surface of the release layer, drying after confirming that the spin coating is uniform to obtain a magnetic material layer, and then spin coating the fluorescent material solution on the surface of the magnetic material solution layer, drying after confirming that the spin coating is uniform to obtain the robot body composed of the magnetic material layer and the fluorescent material layer; Self-curling molding: The robot body was peeled off from the release layer and cut into 5000 μm × 500 μm strips and placed in AlCl 3 The solution is cross-linked and self-curled to form a spiral three-dimensional structure to obtain the microrobot. Figure 1 As shown, when curling to form a spiral or cylindrical shape, the radius of each turn is R 0 , the perimeter is L 0 . W is the width of the rectangle, when W<L 0 When the coil is rolled up, a spiral structure is formed. c is the characteristic folding angle, when the angle θ between the direction of curling and the long side of the rectangle is less than θ c When curled, a tubular structure with multiple turns is formed.

[0040] Example 2: Optimization of the preparation method of microrobots (1) Optimization of the preparation of ZnS quantum dot aqueous dispersion.

[0041] 1) Take 3.66 g of zinc acetate granules and 0.54 g of manganese acetate powder to prepare 20 mL of zinc acetate and manganese acetate mixed solution, and take 2.4 g of sodium sulfide powder to prepare 20 mL of sodium sulfide solution. Take 260 mL of ultrapure water in a three-necked flask, heat it to 180°C in an oil bath, and stir the mixture at 700 rpm. Pour the prepared zinc acetate and manganese acetate mixed solution into the three-necked flask. After stirring for ten minutes, add the prepared sodium sulfide solution dropwise into the three-necked flask. When the sodium sulfide solution is dripped, obvious floccules are produced. After all the sodium sulfide solution is dripped, continue to maintain 180°C and the stirring rod speed is 700 rpm for two hours. After the stirring is completed, a large amount of precipitation occurs. Under 365 nm wavelength light, the precipitation has obvious orange fluorescence, and the supernatant has no obvious fluorescence.

[0042] 2) Prepare ZnS quantum dot aqueous dispersion, take 1.83 g zinc acetate particles and 0.27 g manganese acetate powder to prepare 20 mL zinc acetate manganese acetate mixed solution, and take 1.2 g sodium sulfide powder to prepare 20 mL sodium sulfide solution. Take 260 mL ultrapure water in a three-necked flask, heat it to 180°C in an oil bath, and stir the bar at 700 rpm. Inject the prepared zinc acetate manganese acetate mixed solution into the three-necked flask, continue stirring for ten minutes, and then add the prepared sodium sulfide solution dropwise into the three-necked flask; there is no obvious phenomenon when the sodium sulfide solution is dripped in. After all the sodium sulfide solution is dripped in, continue to maintain 180°C and the stirring bar at 700 rpm for two hours. After the stirring is completed, no precipitation is produced, and no fluorescence is produced under 365 nm wavelength light irradiation.

[0043] 3) Take 3.66 g zinc acetate granules and 0.54 g manganese acetate powder to prepare 20 mL zinc acetate manganese acetate mixed solution, and take 1.2 g sodium sulfide powder to prepare 20 mL sodium sulfide solution. Take 260 mL ultrapure water in a three-necked flask, heat it to 180°C in an oil bath, and stir the bar at 700 rpm. Pour the prepared zinc acetate manganese acetate mixed solution into the three-necked flask. After stirring for ten minutes, add the prepared sodium sulfide solution drop by drop into the three-necked flask. When the sodium sulfide solution is dripped, obvious floccules are produced. After all the sodium sulfide solution is dripped, continue to maintain 180°C and the stirring bar at 700 rpm for two hours to obtain a relatively uniform milky white turbid liquid. Under 365 nm wavelength light, the upper clear liquid has obvious orange fluorescence.

[0044] Comparative Example 1) The results show that adding a sodium sulfide solution with too high a concentration to a three-necked flask will cause zinc sulfide to precipitate and aggregate quickly, and it is impossible to obtain a uniformly dispersed quantum dot dispersion. Therefore, the concentration of the sodium sulfide solution is set to 0.75 mol / L. Comparative Example 2) The results show that no zinc sulfide quantum dots are produced in the final product, from which it can be concluded that when the concentrations of zinc acetate and manganese acetate are insufficient, zinc sulfide quantum dots cannot be produced. Therefore, the concentration of zinc acetate is finally set to 0.85 mol / L, and the concentration of manganese acetate is set to 0.15 mol / L.

[0045] (2) Optimization of chitosan dosage.

[0046] Dispersing Fe in chitosan solution with different concentrations 3 O 4 Particles, the specific steps are as follows: Chitosan solutions with concentrations of 1wt%, 2wt%, and 5wt% were prepared with 2wt% acetic acid solution, and equal amounts of Fe 3 O 4 Particles, including Fe 3 O 4The mass ratio of Fe to chitosan is 5:1, and the mixture is evenly mixed to obtain Fe 3 O 4 Then, a microrobot was prepared according to the method in Example 1.

[0047] The results showed that Fe 3 O 4 Chitosan acetic acid solution was prepared and spin-coated. Due to the small amount of chitosan, Fe 3 O 4 When a 5wt% chitosan solution is used, the chitosan solution will precipitate and stratify, and cannot be effectively dispersed; when a 5wt% chitosan solution is used, the chitosan solution concentration is too high, and agglomerates will form, which is not conducive to uniform spin coating and the preparation of magnetically controlled microrobots. Therefore, the chitosan solution concentration should be set in the range of greater than 1~5wt%.

[0048] (3) Fe 3 O 4 Optimization of dosage.

[0049] The concentration of chitosan solution was fixed at 2wt%, and different masses of Fe 3 O 4 , the specific steps are as follows: A 2wt% chitosan solution was prepared with a 2wt% acetic acid solution, and different masses of Fe 3 O 4 Particles, including Fe 3 O 4 The mass ratio of Fe to chitosan was 1:1, 5:1, and 20:1, respectively, and the mixture was uniformly mixed to obtain Fe 3 O 4 Then, a microrobot was prepared according to the method in Example 1.

[0050] The results show that after spin coating with a dispersion of mass ratio of 1:1, the Fe 3 O 4 The low content results in insufficient magnetism and poor movement performance of the prepared microrobot (it can hardly move in a magnetic field); after spin coating with a dispersion liquid with a mass ratio of 20:1, visible aggregation occurs due to the high concentration, which is not suitable for the subsequent preparation of robots. In order to enable the robot to obtain excellent movement performance, a mass ratio of 5:1 is preferred.

[0051] Example 3: Preparation of microrobots The natural polymer quantum dot microrobot was prepared according to the optimized preparation method of Example 2. The specific steps are as follows: (1) Prepare 20 mL of zinc acetate and manganese acetate mixed solution with 3.66 g of zinc acetate granules and 0.54 g of manganese acetate powder, and prepare 20 mL of sodium sulfide solution with 1.2 g of sodium sulfide powder. Place 260 mL of ultrapure water in a three-necked flask, heat to 180°C in an oil bath, and set the stirring rod speed at 700 rpm. Pour the prepared zinc acetate and manganese acetate mixed solution into the three-necked flask, continue stirring for ten minutes, and then add the prepared sodium sulfide solution dropwise into the three-necked flask.

[0052] (2) After all the sodium sulfide solution has been dropped in, continue to maintain 180°C and a stirring rod speed of 700 rpm for two hours to obtain a relatively uniform milky white turbid liquid, which is purified using a centrifuge at a speed of 1500 rpm and a centrifugal time of 2 minutes.

[0053] (3) Take 0.4 g of cellulose powder and dissolve it in 16.12 g of ZnS quantum dot aqueous dispersion, stir continuously until the uniform solution becomes a gel, add 2 g of AM and 0.44 g of MBA mixed powder, continue stirring until the powder is completely dissolved, and add 1 g of APS to obtain a fluorescent material solution.

[0054] (4) Preparation of magnetic materials: 0.4 g chitosan powder was dissolved in 14.16 g acetic acid solution with a mass fraction of 2%. The mixture was stirred until the solution became a gel with no obvious powder particles. 2 g AM, 0.44 g MBA and 2 g Fe 3 O 4 Mix the powders, continue stirring until the powders are completely dissolved, and add 1 g of APS to obtain a magnetic material solution.

[0055] (5) Select a silicon wafer of appropriate size as a supporting substrate, treat its surface, and remove impurities on the silicon wafer surface. Use a starch film as a sacrificial film to adhere to the surface of the silicon wafer, and spin-coat a layer of magnetic material solution on the starch film surface at a spin-coating speed of 200 rpm for 30 seconds. After confirming that the spin coating is uniform, place the silicon wafer on a 100°C hot plate to dry to form a magnetic material layer. Use a spin coater to spin-coat a layer of fluorescent material solution on the magnetic material layer at a spin-coating speed of 1000 rpm for 30 seconds, and continue to place it on a 100°C hot plate to dry to obtain the robot body composed of a magnetic material layer and a fluorescent material layer.

[0056] (6) The robot body was cut into a 5000 μm × 500 μm rectangle and placed in 2 mol / L AlCl 3 The microrobot is prepared by placing the microrobot in a solution, cross-linking the microrobot and self-curling the microrobot to form a spiral three-dimensional structure. Figure 2 shown.

[0057] Energy Dispersive Spectroscopy (EDS) was used to detect the distribution of each element in the microrobot. 3+ It plays the role of cross-linking the two layers of materials during the preparation process. Figure 3 The red dots representing Al are distributed throughout the microrobot, indicating that the two layers of materials have been tightly cross-linked. Zn and S, as the main elements of quantum dot fluorescent materials, are distributed throughout the microrobot, proving that the fluorescent materials are evenly distributed. Fe is evenly distributed on the microrobot, proving that the magnetic materials are evenly distributed, further indicating that precise control under magnetic field can be achieved.

[0058] The obtained microrobot was placed in deionized water and a three-dimensional uniform rotating magnetic field was applied to carry out a motion performance test. Specifically, the magnetic field intensity was controlled to remain constant at 12 mT, and the rotation frequency of the magnetic field was changed. The rotation frequency range was 0.5~4.5 Hz, with an increase of 0.5 Hz each time.

[0059] The experimental results are as follows Figure 4 As shown in the figure, it can be seen that when the frequency is less than 4 Hz, the movement speed of the microrobot increases with the increase of the magnetic field rotation frequency, and when the magnetic field rotation frequency is higher than 4 Hz, the movement speed of the microrobot decreases rapidly. This test proves that the microrobot has good movement performance in deionized water, and further shows that after applying a magnetic field, the microrobot can achieve movement in the fluid.

[0060] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A micro robot, It is characterized in that The invention comprises a long strip robot body, which is formed by stacking a fluorescent material layer and a magnetic material layer. The raw materials of the fluorescent material layer include a first natural polymer, quantum dots, acrylamide monomers, a crosslinking agent and an initiator. The raw materials of the magnetic material layer include a second natural polymer, a magnetic material, acrylamide monomers, a crosslinking agent and an initiator. The swelling coefficient of the fluorescent material layer is different from that of the magnetic material layer. The robot body curls itself in a solution containing an initiator to form a spiral three-dimensional structure.

2. The microrobot according to claim 1, It is characterized in that The first natural polymer and the second natural polymer are the same or different natural polymer materials, and the natural polymer material is selected from cellulose, chitosan or sodium alginate.

3. The micro robot according to claim 2, It is characterized in that The swelling coefficient of the first natural polymer is greater than the swelling coefficient of the second natural polymer.

4. The micro robot according to claim 1, It is characterized in that The cross-linking agent comprises a first cross-linking agent and a second cross-linking agent, wherein the first cross-linking agent is selected from N,N'-methylenebisacrylamide, and the second cross-linking agent is selected from aluminum chloride, glutaraldehyde or oxalaldehyde.

5. The micro robot according to claim 1, It is characterized in that The quantum dots are selected from at least one of ZnS, ZnSe, ZnTe, CdTe or CdS.

6. The micro robot according to claim 1, It is characterized in that The magnetic material is selected from at least one of ferroferric oxide, cobalt ferrite, nickel ferrite, iron-chromium-cobalt alloy or neodymium-iron-boron alloy.

7. The microrobot according to any one of claims 1 to 6, It is characterized in that The helical angle of the helical three-dimensional structure formed by the self-curling of the robot body is 25° to 35°.

8. A method for preparing the microrobot according to any one of claims 1 to 7, It is characterized in that Includes steps: 1) preparing a fluorescent material solution and a magnetic material solution respectively; 2) Coating a release coating on the supporting substrate to form a release layer after drying; 3) coating the release layer with a magnetic material solution to form a magnetic material layer after drying; 4) coating the magnetic material layer with a fluorescent material solution and forming a fluorescent material layer after drying; 5) The supporting substrate is separated by peeling off the release layer, and the robot body is obtained by cutting into a rectangle, and the robot body is placed in a solution containing a cross-linking agent to make it cross-linked and self-curled to form a spiral three-dimensional structure, thereby obtaining the micro robot.

9. The preparation method according to claim 8, It is characterized in that The release coating in step (2) is a starch aqueous solution; preferably, the solution containing a crosslinking agent in step 5) is a solution containing a second crosslinking agent; preferably, the solution containing a crosslinking agent is AlCl 3 Solution.

10. The preparation method according to claim 9, It is characterized in that Step (2) and / or step 3) and / or step 4) preparing the release layer and / or the magnetic material layer and / or the fluorescent material layer by spin coating; Preferably, the spin coating speed for preparing the release layer is 1500-3500 rpm, and the spin coating time is 20-40 seconds; preferably, the spin coating speed for preparing the magnetic material layer is 150-2000 rpm, and the spin coating time is 30-60 seconds; Preferably, the spin coating speed for preparing the fluorescent material layer is 500-3500 rpm, and the spin coating time is 30-60 seconds.

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