A natural polymer-based quantum dot micro-robot and a preparation method thereof

Abstract

The application relates to a natural high-molecular quantum dot micro robot and a preparation method thereof. The micro robot comprises a long strip-shaped robot body, the robot body is composed of a fluorescent material layer and a magnetic material layer, raw materials of the fluorescent material layer comprise a first natural high molecule, quantum dots and a crosslinking agent, raw materials of the magnetic material layer comprise a second natural high molecule, a magnetic material and a crosslinking agent, a swelling coefficient of the fluorescent material layer is different from that of the magnetic material layer, and the robot body is self-crimped to form a helical three-dimensional structure in a solution containing an initiator. Quantum dots can be effectively isolated from the outside world by using natural high molecules to load the quantum dots, so that the biological toxicity of the quantum dots is reduced. Meanwhile, the swelling coefficients of the two natural high molecules are different, so that the robot body is self-crimped from a two-dimensional planar material into a three-dimensional helical structure in a solution containing an initiator.

Description

TECHNICAL FIELD

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

[0002] The concept of micro-robot was first proposed by Feynman at the American Physical Society meeting in 1959, which refers to a micro-structure with a size of microns to nanometers, capable of converting different forms of energy such as magnetic energy, chemical energy and light energy into kinetic energy to drive its movement. The micro-robot is extremely small, and can reach the narrow space in the body through the surface such as the skin and the blood vessel wall without damaging the biological body, and complete the operation of drug delivery, sampling and killing cancer cells. The emergence of micro-robot also provides a new platform for the research of micro-scale physics and dynamics.

[0003] The accurate positioning of micro-robot is the premise of completing accurate control and fine operation in the body. At present, the positioning of micro-robot mainly includes ultrasonic, optical, magnetic and ionizing radiation technology, wherein the optical positioning method is divided into optical reflection imaging method and fluorescence imaging method. The optical reflection imaging method emits incident light to the sample through a light source, detects the reflection and scattering state of the incident light to position, and this method is only suitable for the position with low tissue scattering. The fluorescence imaging method adds fluorescent material to the micro-robot, and detects the fluorescence emitted thereby to position.

[0004] There are many existing fluorescent materials, one of which is most concerned is quantum dots. Quantum dots are a kind of nanometer semiconductor material, whose physical size is not more than twice the corresponding exciton Bohr radius, they are usually spherical or quasi-spherical, and the diameter is less than 10 nanometers. When the quantum dots are excited by light, the electrons on the valence band absorb energy and are excited to the conduction band to produce corresponding holes, and when the excited electrons jump back to the valence band in the form of radiation, photons are emitted to produce fluorescence. Compared with other existing fluorescent materials, quantum dots have larger size, good fluorescence and brightness stable fluorescence characteristics. However, through in vitro research, it has been proved that some quantum dots can cause significant damage to cells. It has also been 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 usually have strong biological toxicity, which greatly limits the application of quantum dots in the field of biological medicine (fluorescent labeling and in vivo cell imaging). SUMMARY

[0005] The present application aims to disclose a natural polymer-based quantum dot micro-robot and a preparation method thereof, to solve one or more technical problems existing in the prior art, and to provide at least one beneficial option or create conditions.

[0006] The first aspect of the present application provides a micro robot with a size ranging from microns to nanometers.

[0007] The second aspect of the present application provides a preparation method of the micro robot.

[0008] The micro robot of the first aspect of the present application comprises a long strip-shaped robot body, which is composed of a fluorescent material layer and a magnetic material layer, the raw material of the fluorescent material layer comprises a first natural polymer, quantum dots, a crosslinking agent, an acrylamide monomer and an initiator, the raw material of the magnetic material layer comprises a second natural polymer, a magnetic material, a crosslinking 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 is self-crimped to form a spiral three-dimensional structure in a solution containing an initiator. 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 ingeniously used, so that the robot body is self-crimped from a two-dimensional planar material to a three-dimensional spiral structure in a solution containing an initiator, and the fluorescent material layer and the magnetic material layer support each other, so that the rigidity of the micro robot is guaranteed.

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

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

[0011] In some embodiments of the first aspect of the present application, the cross-linking agent comprises a first cross-linking agent selected from N,N'-methylenebisacrylamide (MBA) and a second cross-linking agent selected from aluminum chloride, glutaraldehyde or oxaldehyde. The acrylamide monomer and the first cross-linking agent can produce a synergistic effect in the cross-linking process, making the cross-linking network more compact and stable. This synergistic effect is derived from the complementarity of the molecular structures of the two and their different active sites in the cross-linking reaction. When used as a cross-linking agent, it can increase the number of cross-linking points, thereby increasing the cross-linking density. The second cross-linking agent promotes re-cross-linking after the combination of the fluorescent material layer and the magnetic material layer, which helps to enhance the mechanical strength, heat resistance and solvent resistance of the material.

[0012] In some embodiments of the first aspect of the present application, the quantum dots are quantum dots with quantum confinement effect, including ZnS, ZnSe, ZnTe, CdTe or CdS, preferably ZnS quantum dots with no biological toxicity.

[0013] In some embodiments of the first aspect of the present application, the magnetic material is a ferromagnetic nanoparticle selected from any one or more of ferriferrous oxide (Fe3O4), cobalt ferrite (CoFe2O4), nickel ferrite (NiFe2O4), iron-chromium-cobalt alloy, and neodymium-iron-boron alloy, preferably Fe3O4.

[0014] In some embodiments of the first aspect of the present application, the nanoparticle size of the magnetic material is 10-100 nm, preferably 10-80 nm.

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

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

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

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

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

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

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

[0022] In some application embodiments of the first aspect of the present application, the acrylamide monomer is selected from any one or more of acrylamide (AM), methacrylamide (MA), N-ethyl acrylamide (NEA), N-hydroxyethyl acrylamide (HEAA), N-isopropyl acrylamide (NIPAM), and other acrylamide derivative monomers.

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

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

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

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

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

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

[0029] The preparation method of the second aspect of the application comprises 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 drying to form a release layer; 3) coating the magnetic material solution on the release layer, and drying to form a magnetic material layer; 4) coating the fluorescent material solution on the magnetic material layer, and drying to form a fluorescent material layer; 5) separating the supporting substrate from the release layer by peeling, cutting into a rectangle to obtain the robot body, and placing the robot body in a solution containing a crosslinking agent, so that the robot body is crosslinked and self-coiled to form a spiral three-dimensional structure, thereby obtaining the micro robot.

[0030] In some application embodiments of the second aspect of the application, the crosslinking agent in step 5) is a second crosslinking agent having a crosslinking effect on natural polymers, and the crosslinking agent includes aluminum chloride, glutaraldehyde or oxaldehyde, etc.

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

[0032] In some application embodiments of the second aspect of the application, the release layer in step (2) is prepared 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 release layer is dried and formed by baking at a temperature of 80-100℃ for 45-75 seconds.

[0033] In some application embodiments of the second aspect of the application, the magnetic material layer in step 3) is prepared 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 magnetic material layer is dried and formed by baking at a temperature of 80-120℃ for 45-75 seconds.

[0034] In some application embodiments of the second aspect of the application, the fluorescent material layer in step 4) is prepared 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 fluorescent material layer is dried and formed by baking at a temperature of 80-120℃ for 45-75 seconds.

[0035] Compared with the existing detection technology, the application has the following advantages:

[0036] The micro robot is mainly composed of natural polymers, has very good biocompatibility, has very low risk in the human body, and is suitable for application in the biomedical field. Meanwhile, compared with the micro robot prepared by using traditional materials such as metal and carbon tube, the natural polymer has the advantage of being easier to attach a functional group, and the micro robot can be easily added with a group such as a group for detecting a lesion or a group for encapsulating a drug. In addition, the micro robot solves the problem of insufficient rigidity of a single natural polymer by using two natural polymers with different swelling coefficients to be laminated and crosslinked to support each other. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a double-layer film rolling schematic diagram of the micro robot;

[0038] Figure 2 is a photo of the micro robot prepared in Example 3, and the scale is 200 μm;

[0039] Figure 3 is an EDS detection diagram of the micro robot prepared in Example 3, and the scale is 500 μm;

[0040] Figure 4 is a diagram of the relationship between the x-axis, y-axis and composite velocity of the micro robot and the rotating frequency of the rotating magnetic field. DETAILED DESCRIPTION

[0041] The following examples further illustrate the content of the present application, but should not be understood as limiting the present application. Modifications and replacements of the method, steps or conditions of the present application without departing from the spirit and essence of the present application all belong to the scope of the present application.

[0042] If not specifically indicated, the technical means used in the examples is the conventional means familiar to those skilled in the art.

[0043] Example 1: Preparation method of natural polymer-based quantum dot micro robot

[0044] ZnS quantum dots are selected, and cellulose and chitosan are combined to prepare a micro robot with a self-rolled spiral three-dimensional structure. The preparation method is as follows:

[0045] Preparation of fluorescent material solution: prepare ZnS quantum dot aqueous dispersion, add cellulose powder and stir until it becomes gelatinous, then add AM and MBA and stir until they are uniform, and finally add initiator ammonium persulfate (APS);

[0046] Preparation of magnetic material solution: dissolve chitosan powder in acetic acid solution, stir until it becomes gelatinous, then add AM, MBA and Fe3O4 and stir until they are uniform, and finally add APS;

[0047] The robot body is formed by coating a release agent on a supporting base, drying to form a release layer, spin-coating the magnetic material solution on the surface of the release layer, drying after confirming uniform spin-coating to obtain a magnetic material layer, spin-coating the fluorescent material solution on the surface of the magnetic material layer, drying after confirming uniform spin-coating to obtain the robot body composed of the magnetic material layer and the fluorescent material layer.

[0048] Self-coiling formation: the robot body is peeled off from the release layer, cut into a long strip of 5000 μm x 500 μm, placed in an AlCl3 solution, cross-linked and self-coiled to form a spiral three-dimensional structure to obtain the micro robot. The principle of coiling formation is shown in Figure 1 When coiling occurs to form a spiral or a cylindrical shape, the radius of each turn is R0, and the circumference is L0. W is the width of the rectangle, and when W < L0, the spiral structure is formed after coiling. c is the folding characteristic angle, and when the direction of coiling is less than θ c than the angle θ of the long side of the rectangle, the multi-turn tubular structure is formed after coiling.

[0049] Example 2: Optimization of the preparation method of the micro robot

[0050] (1) Optimization of the preparation of ZnS quantum dot aqueous dispersion.

[0051] 1) 3.66 g of zinc acetate particles and 0.54 g of manganese acetate powder were prepared to prepare 20 mL of zinc acetate manganese acetate mixed solution, and 2.4 g of sodium sulfide powder was prepared to prepare 20 mL of sodium sulfide solution. 260 mL of ultrapure water was taken in a three-necked flask, heated to 180℃ in an oil bath, and the stirring speed of the stirring rod was 700 rpm. The zinc acetate manganese acetate mixed solution prepared above was injected into the three-necked flask, and the stirring was continued for ten minutes. Then, the sodium sulfide solution prepared above was added dropwise into the three-necked flask. When the sodium sulfide solution was added dropwise, there were obvious flocculent substances. After the sodium sulfide solution was completely added, the temperature was maintained at 180℃ and the stirring speed of the stirring rod was maintained at 700 rpm for two hours. After stirring, a large amount of precipitate was obtained, which had obvious orange fluorescence under 365 nm light. The fluorescence of the upper clear liquid was not obvious.

[0052] 2) Preparation of 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, take another 1.2 g sodium sulfide powder to prepare 20 mL sodium sulfide solution. Take 260 mL ultrapure water into a three-necked flask, heat the oil bath to 180℃, the stirring speed of the stirring rod is 700 rpm, inject the above prepared zinc acetate manganese acetate mixed solution into the three-necked flask, continue to stir for ten minutes, then add the above prepared sodium sulfide solution dropwise into the three-necked flask; no obvious phenomenon occurs when the sodium sulfide solution is added dropwise, after the sodium sulfide solution is completely added, continue to maintain 180℃ and the stirring speed of the stirring rod at 700 rpm for two hours, no precipitate is generated after stirring, and no fluorescence is generated under 365 nm wavelength light irradiation.

[0053] 3) Take 3.66 g zinc acetate particles and 0.54 g manganese acetate powder to prepare 20 mL zinc acetate manganese acetate mixed solution, take another 1.2 g sodium sulfide powder to prepare 20 mL sodium sulfide solution. Take 260 mL ultrapure water into a three-necked flask, heat the oil bath to 180℃, the stirring speed of the stirring rod is 700 rpm, inject the above prepared zinc acetate manganese acetate mixed solution into the three-necked flask, continue to stir for ten minutes, then add the above prepared sodium sulfide solution dropwise into the three-necked flask; obvious flocculent material is generated when the sodium sulfide solution is added dropwise, after the sodium sulfide solution is completely added, continue to maintain 180℃ and the stirring speed of the stirring rod at 700 rpm for two hours, a relatively uniform milky white turbidity is obtained, and the upper clear liquid has obvious orange fluorescence under 365 nm wavelength light irradiation.

[0054] The results of Comparative Example 1 show that adding a sodium sulfide solution with too high a concentration dropwise into the three-necked flask can cause zinc sulfide to precipitate rapidly and aggregate, and a uniformly dispersed quantum dot dispersion cannot be obtained. Therefore, the concentration of the sodium sulfide solution is set to 0.75 mol / L. The results of Comparative Example 2 show that no zinc sulfide quantum dots are generated in the final product, and thus it can be concluded that when the concentrations of zinc acetate and manganese acetate are insufficient, zinc sulfide quantum dots cannot be prepared. 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.

[0055] (2) Optimization of the amount of chitosan.

[0056] Fe3O4 particles are dispersed in chitosan solutions with different concentrations, and the specific steps are as follows:

[0057] A chitosan solution with a concentration of 1wt%, 2wt%, and 5wt% is prepared using an acetic acid solution with a concentration of 2wt%, and equal mass of Fe3O4 particles is added, wherein the mass ratio of Fe3O4 to chitosan is 5:1, and the chitosan acetic acid solution of Fe3O4 is obtained by mixing uniformly. Then, the micro robot is prepared according to the method in Example 1.

[0058] The results show that the chitosan solution with 1wt% is used to prepare the chitosan acetic acid solution of Fe3O4, and after spin coating, the Fe3O4 is easy to aggregate and stratify due to the small amount of chitosan, and cannot be effectively dispersed; when the chitosan solution is 5wt%, the chitosan solution is too high in concentration, and thus the spin coating is not uniform, and the preparation of the micro robot of magnetic control is not conducive. Therefore, the concentration of the chitosan solution should be set in the range of greater than 1-5wt%.

[0059] (3) Optimization of the amount of Fe3O4.

[0060] The concentration of the chitosan solution is fixed at 2wt%, and different amounts of Fe3O4 are dispersed, and the specific steps are as follows:

[0061] The chitosan solution with a concentration of 2wt% is prepared by using an acetic acid solution with a concentration of 2wt%, and different amounts of Fe3O4 particles are added, and the mass ratio of Fe3O4 to chitosan is 1:1, 5:1, and 20:1, respectively, and the mixture is uniformly mixed to obtain a chitosan acetic acid solution of Fe3O4. Then, the micro robot is prepared according to the method in Example 1.

[0062] The results show that the dispersion liquid with a mass ratio of 1:1 is used for spin coating, and the prepared micro robot has poor magnetic properties and poor movement performance (almost unable to move in the magnetic field) due to the small amount of Fe3O4; the dispersion liquid with a mass ratio of 20:1 is used for spin coating, and the concentration is too high, and the aggregation phenomenon can be seen with the naked eye, which is not suitable for the preparation of the robot in the later stage. In order to make the robot have excellent movement performance, the mass ratio of 5:1 is preferred.

[0063] Example 3: Preparation of a micro robot

[0064] The natural polymer quantum dot micro robot is prepared according to the preparation method optimized in Example 2. The specific steps are as follows:

[0065] (1) 3.66 g of zinc acetate particles and 0.54 g of manganese acetate powder are taken to prepare 20 mL of zinc acetate manganese acetate mixed solution, and 1.2 g of sodium sulfide powder is taken to prepare 20 mL of sodium sulfide solution. 260 mL of ultrapure water is taken in a three-necked flask, and the oil bath is heated to 180℃, and the stirring speed of the stirring rod is 700 rpm. The zinc acetate manganese acetate mixed solution prepared above is injected into the three-necked flask, and the stirring is continued for ten minutes. Then, the prepared sodium sulfide solution is added dropwise into the three-necked flask.

[0066] (2) After the sodium sulfide solution is completely added, the temperature is kept at 180℃ and the stirring speed of the stirring rod is kept at 700 rpm for two hours, and a relatively uniform milky white turbidity is obtained. The turbidity is purified by a centrifuge with a centrifugal speed of 1500 rmp and a centrifugal time of 2 minutes.

[0067] (3) Take 0.4 g of cellulose powder and dissolve it in 16.12 g of ZnS quantum dot water dispersion, continuously stirring until the solution is gelatinous. 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. A fluorescent material solution is obtained.

[0068] (4) Prepare a magnetic material by taking 0.4 g of chitosan powder and dissolving it in 14.16 g of 2% acetic acid solution, continuously stirring until the solution is gelatinous and there are no obvious powder particles. Add 2 g of AM, 0.44 g of MBA, and 2 g of Fe3O4 mixed powder, continue stirring until the powder is completely dissolved, and add 1 g of APS. A magnetic material solution is obtained.

[0069] (5) Select a silicon wafer of appropriate size as a support substrate, treat its surface to remove impurities on the surface of the silicon wafer. Apply a starch film as a sacrificial film to the surface of the silicon wafer, and spin coat a layer of magnetic material solution on the surface of the starch film 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, forming 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, obtaining the robot body composed of a magnetic material layer and a fluorescent material layer.

[0070] (6) Cut the robot body into a rectangle of 5000 μm x 500 μm and place it in a 2 mol / L AlCl3 solution to cross-link and self-roll into a helical three-dimensional structure, obtaining the micro robot. The prepared micro robot is as shown in Figure 2 .

[0071] Use EDS (Energy Dispersive Spectroscopy) to detect the distribution of each element in the micro robot. Al 3+ plays a role in cross-linking the two layers of material during preparation, Figure 3 The red dots representing Al are distributed throughout the micro robot, indicating that the two layers of material have been tightly cross-linked. Zn and S, as the main elements of quantum dot fluorescent material, are distributed throughout the micro robot, proving that the fluorescent material is evenly distributed. Fe is evenly distributed on the micro robot, proving that the magnetic material is evenly distributed, and further proving that precise control under a magnetic field can be achieved.

[0072] Place the obtained micro robot in deionized water and apply a three-dimensional uniform rotating magnetic field to test its motion performance. Specifically, control the magnetic field strength to be constant at 12 mT, change the rotating frequency of the magnetic field, and the rotating frequency range is 0.5~4.5 Hz, with an increment of 0.5 Hz each time.

[0073] The experimental results, as shown in Figure 4 Fig. 4, show that when the frequency is less than 4 Hz, the movement speed of the micro robot increases with the increase of the rotating frequency of the magnetic field, and when the rotating frequency of the magnetic field is higher than 4 Hz, the movement speed of the micro robot decreases rapidly. The test proves that the micro robot has good movement performance in deionized water, and further shows that the micro robot can move in the fluid after the magnetic field is applied.

[0074] It is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

Claims

1. A micro-robot, characterized in that, The robot body comprises a long, strip-shaped body, which is composed of a fluorescent material layer and a magnetic material layer stacked together. The fluorescent material layer is made from a first natural polymer, quantum dots, acrylamide monomers, a crosslinking agent, and an initiator. The magnetic material layer is made from 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 self-rolls into a helical three-dimensional structure in a solution containing an initiator. The first and second natural polymers are different natural polymer materials, selected from cellulose, chitosan, or sodium alginate. The swelling coefficient of the first natural polymer is greater than that of the second natural polymer. The crosslinking agent includes a first crosslinking agent and a second crosslinking agent. The first crosslinking agent is selected from N,N'-methylenebisacrylamide, and the second crosslinking agent is selected from aluminum chloride, glutaraldehyde, or oxalaldehyde.

2. The microrobot according to claim 1, characterized in that, The quantum dots are selected from at least one of ZnS, ZnSe, ZnTe, CdTe, or CdS.

3. The microrobot according to claim 1, characterized in that, The magnetic material is selected from at least one of iron(II,III) oxide, cobalt(II,III) ferrite, nickel(II) ferrite, iron-chromium-cobalt alloy, or neodymium-iron-boron alloy.

4. The microrobot according to any one of claims 1 to 3, characterized in that, The spiral angle of the three-dimensional spiral structure formed by the self-curling of the robot body is 25°~35°.

5. A method for manufacturing the microrobot according to any one of claims 1 to 4, characterized in that, Including the following steps: 1) Prepare fluorescent material solutions and magnetic material solutions separately; 2) Apply release coating to the supporting substrate and allow it to dry to form a release layer; 3) A magnetic material solution is applied to the release layer, and after drying, a magnetic material layer is formed; 4) A fluorescent material solution is coated onto the magnetic material layer, and after drying, a fluorescent material layer is formed; 5) The supporting substrate is detached by peeling off the release layer and cut into a rectangle to obtain the robot body. The robot body is placed in a solution containing a crosslinking agent to crosslink and self-curl to form a spiral three-dimensional structure, thus obtaining the microrobot.

6. The preparation method according to claim 5, characterized in that, Step 2) The release coating is an aqueous starch solution.

7. The preparation method according to claim 5, characterized in that, Step 5) The solution containing the crosslinking agent refers to a solution containing a second crosslinking agent; the solution containing the crosslinking agent is an AlCl3 solution.

8. The preparation method according to claim 6, characterized in that, Step 2) and / or Step 3) and / or Step 4) prepare the release layer and / or the magnetic material layer and / or the fluorescent material layer by spin coating; The spin coating speed for preparing the release layer is 1500~3500 rpm, and the spin coating time is 20~40 seconds; The spin coating speed for preparing the magnetic material layer is 150~2000 rpm, and the spin coating time is 30~60 seconds; 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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