Magnetic field driven chain-shaped micro motor and preparation method thereof

Abstract

The invention belongs to the technical field of micro-nano robots, and relates to a magnetic field driven chain-shaped micro motor and a preparation method thereof. The invention discloses a magnetic field driving chain-shaped micro motor, which comprises a rigid magnetic field driving chain-shaped micro motor and / or a flexible magnetic field driving chain-shaped micro motor, according to the rigid magnetic field driven chain-shaped micromotor, magnetic micro-nano particles which are arranged into micron wires by utilizing an external magnetic field are used as an inner core, a silicon dioxide layer is used as a middle layer, and a polymer layer is used as a shell; the magnetic field driven chain-shaped micro motor realizes driving motion through self-responsive rotation under the driving of an external magnetic field.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-nano robots and relates to a magnetic field driven chain micro motor and a preparation method thereof. Background Art

[0002] Micro-nano motors are a type of micro-nano devices that can convert chemical energy, light energy, electrical energy, magnetic energy, ultrasonic energy and other forms of energy in the environment into their own mechanical motion. Thanks to their small size and driven motion, micro-nano motors have high spatial freedom and super-redundant dexterity, and are expected to overcome the low drug delivery efficiency of existing nanocarriers and achieve active targeted drug delivery. They have become one of the frontier hotspots in multidisciplinary cross-disciplinary research such as chemistry, physics, materials, robotics, and biomedicine. Among them, chain-shaped micromotors can not only maintain a stable shape in complex environments and are not easily affected by the external environment, but also combine the high aspect ratio and high specific surface area of ​​one-dimensional materials, and have unique advantages in motion and task execution in complex environments. At present, traditional micromotors often have problems such as fixed size and single function, which cannot meet the increasingly diverse market needs, and their application space has certain limitations. Therefore, how to achieve the batch and simplified preparation of micromotors with adjustable scale is one of the key scientific issues that need to be solved urgently. Summary of the invention

[0003] The purpose of the present invention is to address the above problems existing in the prior art and propose a magnetic field driven chain micro motor that realizes driving motion by self-responsive rotation under the drive of an external magnetic field. The micro motor has magnetic micro-nano particles arranged into micrometer lines by utilizing an external magnetic field as the core and a polymer layer as the shell. The purpose of the present invention can be achieved by the following technical solutions:

[0004] A magnetic field driven chain micro motor, comprising a rigid magnetic field driven chain micro motor and / or a flexible magnetic field driven chain micro motor;

[0005] The rigid magnetic field driven chain micro motor has magnetic micro-nano particles arranged into micrometer lines by using an external magnetic field as a core, a silicon dioxide layer as an intermediate layer, and a polymer layer as an outer shell;

[0006] The flexible magnetic field driven chain micro motor has magnetic micro-nano particles arranged into micrometer lines by utilizing an external magnetic field as a core and a polymer layer as a shell.

[0007] Preferably, the polymer in the polymer layer is one or both of a positively charged polymer and a negatively charged polymer, wherein the positively charged polymer includes one or more of chitosan, polyimine, polyacrylamine hydrochloride, and polydiallyldimethylammonium; the negatively charged polymer includes one or more of sodium alginate, hyaluronic acid, tannic acid, polyacrylic acid, and polypropylene sulfonate.

[0008] Further preferably, the polymers in the polymer layer are positively charged polymers and negatively charged polymers, the positively charged polymers include one or more of chitosan, polyimine, polyacrylamine hydrochloride, polydiallyldimethylammonium, etc.; the negatively charged polymers include one or more of sodium alginate, hyaluronic acid, tannic acid, polyacrylic acid, polypropylene sulfonate, etc.

[0009] Further preferably, when the polymer in the polymer layer is a negatively charged polymer, the polymer layer also includes a trivalent iron compound; the negatively charged polymer includes one or more of sodium alginate, hyaluronic acid, tannic acid, polyacrylic acid, and polypropylene sulfonate, and the trivalent iron compound includes one or more of ferric chloride, ferric nitrate, iron oxide, and iron sulfide.

[0010] More preferably, the raw materials in the polymer layer include tannic acid and trivalent iron compounds.

[0011] Preferably, there is a cavity between the core and the shell of the flexible magnetic field driven chain micromotor.

[0012] Preferably, the particle size of the magnetic micro-nanoparticles is 30 to 200 nm.

[0013] Preferably, the length of the magnetic field driven chain micro motor is 1 to 100 nm.

[0014] More preferably, the length of the magnetic field driven chain micro motor is 5 to 50 nm.

[0015] Preferably, the rigid magnetic field driven chain micromotor is obtained by sequentially coating a silicon dioxide layer and a polymer layer on the surface of a magnetic micro-nano particle core arranged into a micrometer line by an external magnetic field. Preferably, the flexible magnetic field driven chain micromotor is obtained by etching the silicon dioxide layer of the rigid magnetic field driven chain micromotor.

[0016] Preferably, the flexible magnetic field driven chain micro motor is obtained by sequentially coating a silicon dioxide layer and a polymer layer on the surface of a magnetic micro-nano particle core arranged into a micrometer line by an external magnetic field, and then removing the silicon dioxide layer by etching. Preferably, the polymer layer is 1 to 40 layers.

[0017] Preferably, the magnetic field driven chain micro motor moves for 10 to 20 seconds and over a distance of 30 to 600 μm under a magnetic field of 15 mT and 5 Hz.

[0018] Further preferably, a rigid magnetic field driven chain micromotor with a length of 30 μm moves for 10 s and a movement distance of >120 μm under a magnetic field of 15 mT and 5 Hz.

[0019] Preferably, the flexible magnetic field driven chain micro motor can pass through a right-angle channel whose width is ≤ its length.

[0020] Further preferably, a 5-50 μm flexible magnetic field driven chain micro motor can pass through a 10 μm wide right angle channel. A method for preparing a magnetic field driven chain micro motor, the method comprising the following steps:

[0021] (1) arranging magnetic micro-nano particles into micrometer wires by using an external magnetic field, and then coating the surface of the magnetic micrometer wires with silica to obtain silica-coated magnetic micrometer wires;

[0022] (2) Immersing the silica-coated magnetic microwires in (1) into a polymer precursor solution to obtain a rigid magnetic field-driven chain micromotor;

[0023] (3) The rigid magnetic field driven chain micromotor obtained in (2) is etched with a hydrofluoric acid solution to remove the silicon dioxide layer, thereby preparing a flexible magnetic field driven chain micromotor.

[0024] Preferably, the method for preparing the silica-coated magnetic microwires in (1) comprises: dispersing magnetic micro-nano particles in a solvent, adding ammonia water and a silicon source in sequence, and then placing an external magnetic field just below the bottom of the reactor, using the external magnetic field to arrange the magnetic micro-nano particles into microwires, and allowing the reaction to stand so that the surface of the magnetic microwires is completely coated with silica, thereby obtaining silica-coated magnetic microwires.

[0025] Preferably, the length of the microwire in (1) is 1 to 100 nm; the length of the magnetic microwire coated with silica is 1 to 100 nm.

[0026] Preferably, the particle size of the magnetic micro-nanoparticles in (1) is 30 to 200 nm.

[0027] Preferably, the magnetic micro-nanoparticles in (1) include magnetic elements such as iron, nickel, cobalt, chromium, manganese, gadolinium and their compounds.

[0028] More preferably, the mass ratio of the magnetic micro-nanoparticles to the silicon source is 1:(5-50).

[0029] More preferably, the static reaction temperature is 20 to 60°C.

[0030] More preferably, the magnetic induction intensity of the external magnetic field is 10 to 100 mT.

[0031] More preferably, the distance between the external magnetic field and the bottom of the reactor is 0 to 10 cm.

[0032] More preferably, the silicon source includes one of an inorganic silicon source or an organic silicon source and a mixture of the two; specifically includes one or more of tetraethyl orthosilicate, 1,2-bis(triethoxysilyl)ethane, and bis(triethoxysilyl)methane.

[0033] Preferably, the concentration of the polymer precursor solution is 1 to 5 mg / mL.

[0034] Preferably, the polymer precursor solution comprises a negatively charged polymer and a trivalent iron compound.

[0035] More preferably, the silica-coated magnetic microwire is immersed in a polymer precursor solution containing a negatively charged polymer and a trivalent iron compound to prepare a rigid magnetic field-driven chain micromotor.

[0036] Preferably, the polymer precursor solution comprises a positively charged polymer solution and a negatively charged polymer solution.

[0037] More preferably, the silicon dioxide coated magnetic microwire is successively immersed in a positively charged polymer solution and a negatively charged polymer solution to obtain a rigid magnetic field driven chain micromotor. An application of a magnetic field driven chain micromotor in the biomedical field.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The magnetic field driven chain micro motor of the present invention has magnetic micro-nano particles arranged into micrometer lines by utilizing an external magnetic field as the core and a polymer layer as the shell, or has magnetic micro-nano particles arranged into micrometer lines by utilizing an external magnetic field as the core, silicon dioxide as the middle layer and a polymer layer as the shell; under the drive of an external magnetic field, the driven movement is achieved through its own responsive rotation.

[0040] 2. The magnetic field driven chain micromotor of the present invention has 1 to 40 polymer layers. The number of polymer layers will affect the flexibility and toughness of the motor. By controlling the number of polymer layers, the overall strength and wear resistance of the material can be improved; and by selecting polymers with different functional groups, specific functionalization of the surface of the nanomaterial can be achieved, including improving its biocompatibility, enhancing the ability of drug carriers, or giving the nanomaterial specific biorecognition functions.

[0041] 3. In the preparation method of the magnetic field driven chain micromotor of the present invention, silicon dioxide is used as a template to form a magnetic micrometer wire, i.e., a rigid magnetic field driven chain micromotor. By removing the middle silicon dioxide layer and combining it with polymer coating, it is further generated into a flexible magnetic field driven chain micromotor.

[0042] 4. The magnetic field driven chain micro motor of the present invention is of adjustable size and can precisely control the size and arrangement of its internal structure.

[0043] 5. The preparation method of the magnetic field driven chain micromotor of the present invention is controllable, the process is simple and the biocompatibility is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The figure is a flow chart of the preparation of the magnetic chain micromotor of the present invention;

[0045] Figure 2 is a scanning electron microscope image of the rigid magnetic field driven chain micromotor prepared in Example 1;

[0046] Figure 3 is a fluorescence microscope photograph of the rigid magnetic field driven chain micromotor prepared in Example 2;

[0047] Figure 4 This is a real-time motion picture of the rigid magnetic field driven chain micromotor prepared in Example 2 under a magnetic field of 15mT and 5Hz;

[0048] Figure 5 is a statistical diagram of the movement speed of the rigid magnetic field driven chain micro motor prepared in Example 2 at different frequencies under a magnetic field of 15 mT;

[0049] Figure 6 This is a real-time motion picture of the rigid magnetic field driven chain micro motor prepared in Example 3 under a magnetic field;

[0050] Figure 7 It is a statistical diagram of the movement speed of the chain micromotors driven by the rigid magnetic field of different lengths in Example 3 under the magnetic field of 15mT and 5Hz;

[0051] Figure 8 This is a real-time motion picture of the flexible magnetic field driven chain micro motor prepared in Example 4 under a magnetic field of 15 mT and 5 Hz;

[0052] Fig. 9 It is a comparison chart of the movement speed statistics of the rigid magnetic field driven chain micro motor prepared in Example 2 and the flexible magnetic field driven chain micro motor prepared in Example 4 under a magnetic field of 15mT and 5Hz. DETAILED DESCRIPTION

[0053] The following are specific embodiments of the present invention, which further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0054] The magnetic field driven chain micro motor includes a rigid magnetic field driven chain micro motor and a flexible magnetic field driven chain micro motor;

[0055] The rigid magnetic field driven chain micro motor has magnetic micro-nano particles arranged into micrometer lines by using an external magnetic field as a core, a silicon dioxide layer as an intermediate layer, and a polymer layer as an outer shell;

[0056] The flexible magnetic field driven chain micro motor has magnetic micro-nano particles arranged into micrometer lines by using an external magnetic field as the core and a polymer layer as the shell;

[0057] The number of the polymer layers is 1 to 40.

[0058] A method for preparing a magnetic field driven chain micromotor, comprising:

[0059] (1) Preparation of magnetic micro-nanoparticles

[0060] Magnetic micro-nanoparticles can be made in-house or purchased commercially.

[0061] The particle size of the magnetic micro-nano particles is 30 to 200 nm, preferably 50 to 100 nm.

[0062] (2) Preparation of silica-coated magnetic microwires

[0063] The magnetic micro-nano particles in (1) are dispersed in a reactor containing anhydrous ethanol and dispersed by ultrasound; ammonia water is added, and a silicon source is added while mechanically stirring; an external magnetic field is placed just below the bottom of the reactor, and the magnetic micro-nano particles are arranged into micrometer wires by the external magnetic field; silicon dioxide is then coated on the surface of the magnetic micrometer wires, and the reaction is allowed to stand until the surface of the magnetic micrometer wires is completely coated with silicon dioxide, thereby obtaining silicon dioxide-coated magnetic micrometer wires;

[0064] The silicon source is one of an inorganic silicon source, an organic silicon source and a mixture of the two; the silicon source includes one or more of tetraethyl orthosilicate, 1,2-bis(triethoxysilyl)ethane, and bis(triethoxysilyl)methane;

[0065] The feed ratio of magnetic micro-nano particles to silicon source is 1:(5-50), and the static reaction temperature is 20-60°C;

[0066] The magnetic induction intensity of the external magnetic field is 10 to 100 mT, and the distance is 0 to 10 cm.

[0067] (3) Preparation of rigid magnetic field driven chain micromotors

[0068] The silica-coated magnetic microwires in (2) are successively immersed in a polymer precursor solution, and a polymer is assembled on the surface of the silica-coated magnetic microwires. The above-mentioned infiltration process is repeated to modify the polymer layer on the surface of the silica-coated magnetic microwires by a layer-by-layer assembly method;

[0069] The polymer precursor solution includes a negatively charged polymer and a trivalent iron compound, and the silicon dioxide-coated magnetic microwire is immersed in the polymer precursor solution containing the negatively charged polymer and the trivalent iron compound to prepare a rigid magnetic field-driven chain micromotor;

[0070] The polymer precursor solution includes a positively charged polymer solution and a negatively charged polymer solution, and the silicon dioxide-coated magnetic microwire is successively immersed in the positively charged polymer solution and the negatively charged polymer solution to obtain a rigid magnetic field driven chain micromotor; the positively charged polymer includes one or more of chitosan, polyimine, polyacrylamine hydrochloride, polydiallyldimethylammonium, etc.; the negatively charged polymer includes one or more of sodium alginate, hyaluronic acid, tannic acid, polyacrylic acid, polypropylene sulfonate, etc.; the trivalent iron compound includes one or more of ferric chloride, ferric nitrate, iron oxide, and iron sulfide. The polymer precursor solution is 1 to 5 mg / mL; the number of polymer layers is 10 to 40 layers.

[0071] (4) Preparation of flexible magnetic field driven chain micromotors

[0072] The rigid magnetic field driven chain micromotor in (3) is dispersed in an excess amount of hydrofluoric acid solution, and fully oscillated so that the silicon dioxide in the rigid magnetic field driven chain micromotor is completely etched to obtain a flexible magnetic field driven chain micromotor;

[0073] The middle part where silicon dioxide is etched gradually forms a cavity as the etching degree increases.

[0074] The preparation flow chart of magnetic field driven chain micromotors is shown in Figure 1 .

[0075] In this paper, as the number of polymer layers increases, the mechanical strength and toughness of the magnetic field-driven chain micromotor increase, improving its stability and durability in etching processes and harsh environments, and providing additional protection for the micromotor to prevent it from chemical corrosion or physical damage.

[0076] In this article, after the silicon dioxide layer is etched, the magnetic field drives the chain micromotor to change from rigid to flexible, so that it can better respond to external stimuli and thus improve the controllability of the micromotor, and better adapt to complex or restricted environments. For example, when moving in narrow channels or biological tissues, the flexible structure can provide greater flexibility. The magnetic field driven chain micromotor of the present invention is applied to the biomedical field. By selecting suitable polymers and / or loading drugs thereon, an external magnetic field is used to control the flexible chain micromotor to pass through a complex environment and reach a target position, and then treatment is performed to achieve a therapeutic effect.

[0077] Example 1

[0078] (1) Synthesis of magnetic FeO nanoparticles

[0079] Dissolve 0.65g of FeCl3 and 0.20g of trisodium citrate in 20mL of ethylene glycol, and then add 1.20g of sodium acetate while stirring. After continuous vigorous stirring for 30 minutes, transfer the mixed solution into a reactor. Heat the reactor loaded with the mixed solution at 200°C for 10 hours, cool to room temperature, centrifuge at 9000rpm / min to collect the precipitate, and wash it three times with a 1:1 mixed solution of deionized water / ethanol to obtain magnetic ferrosoferric oxide nanoparticles.

[0080] (2) Preparation of silica-coated magnetic microwires

[0081] Disperse 50 mg of the synthesized magnetic ferrosoferric oxide nanoparticles (1) into a three-necked flask containing 60 mL of anhydrous ethanol. After ultrasonic treatment for 30 minutes, add 3 mL of 28-30% ammonia water to the above solution. Mechanically stir the mixed solution for 30 minutes in a 30°C water bath, and then drop 0.3 g of tetraethyl orthosilicate into it. Stop the mechanical stirring after 15 minutes, and then place a magnet with a magnetic induction intensity of 20 mT 5 cm directly below the three-necked flask. After standing at 30°C for 12 hours, collect the solution using a magnetic field and clean it with anhydrous ethanol to obtain magnetic microwires wrapped with silica.

[0082] (3) Preparation of rigid magnetic field driven chain micromotors

[0083] The silica-coated magnetic microwires obtained in (2) were dispersed in water to form a suspension, and 50 μL of 1 mg / mL ferric chloride hexahydrate and 4 mg / mL tannic acid were added to 400 μL of the suspension, and the suspension was immediately mixed vigorously with a vortex mixer for 10 seconds. Subsequently, 0.5 ml of PBS buffer (20 mM, pH 7.4) was added to increase the pH of the suspension. After centrifugation for three minutes, the magnetic microwires were collected by a magnet and washed with deionized water three times, and then dispersed in water to form a suspension. The above layer-by-layer assembly was repeated 10 times to obtain a 10-layer Fe Ⅲ -Tannic acid-modified silica-coated magnetic microwires, rigid magnetic field-driven chain micromotors with polymer as shell and silica-coated magnetic micro-nanoparticles as skeleton core.

[0084] In this embodiment, the 10 μm rigid magnetic field drives the chain micromotor to move forward 36.14 μm within 10 seconds under a 15 mT, 5 Hz magnetic field.

[0085] The SEM image of the rigid magnetic field driven chain micromotor obtained in this example is shown in Figure 2 .

[0086] Example 2

[0087] (1) Synthesis of magnetic FeO nanoparticles

[0088] Dissolve 0.65g of FeCl3 and 0.20g of trisodium citrate in 20mL of ethylene glycol, and then add 1.20g of sodium acetate while stirring. After continuous vigorous stirring for 30 minutes, transfer the mixed solution into a reactor. Heat the reactor loaded with the mixed solution at 200°C for 10 hours, cool to room temperature, centrifuge at 9000rpm / min to collect the precipitate, and wash it three times with a 1:1 mixed solution of deionized water / ethanol to obtain magnetic ferrosoferric oxide nanoparticles.

[0089] (2) Preparation of silica-coated magnetic microwires

[0090] Disperse 50 mg of the synthesized magnetic ferrosoferric oxide nanoparticles (1) into a three-necked flask containing 60 mL of anhydrous ethanol. After ultrasonic treatment for 30 minutes, add 3 mL of 28-30% ammonia water to the above solution. Mechanically stir the mixed solution for 30 minutes in a 30°C water bath, and then drop 0.3 g of tetraethyl orthosilicate into it. Stop the mechanical stirring after 15 minutes, and then place a magnet with a magnetic induction intensity of 20 mT 5 cm directly below the three-necked flask. After standing at 30°C for 12 hours, collect the solution using a magnetic field and clean it with anhydrous ethanol to obtain magnetic microwires wrapped with silica.

[0091] (3) Preparation of rigid magnetic field driven chain micromotors

[0092] The silica-coated magnetic microwire obtained in (2) was dispersed into a chitosan solution with a concentration of 2 mg / mL, and after oscillation for 15 minutes, it was collected by a magnet and washed with deionized water 3 times, and then dispersed into a sodium alginate solution with a concentration of 2 mg / mL, and after oscillation for 15 minutes, it was collected by a magnet and washed with deionized water 3 times. The above layer-by-layer assembly was repeated 10 times to obtain a silica-coated magnetic microwire with a surface modified by 20 layers of chitosan / sodium alginate layers, that is, a rigid magnetic field driven chain micromotor with a polymer layer as an outer shell and silica-coated magnetic micro-nanoparticles as a skeleton core.

[0093] The fluorescence microscope image of the rigid magnetic field driven chain micromotor obtained in this example is shown in Figure 3 , it can be seen that the polymer layer is successfully coated.

[0094] Figure 4 This is a real-time motion picture of the 10μm rigid magnetic field driven chain micromotor under a magnetic field in this embodiment; in this embodiment, the rigid magnetic field driven chain micromotor moved forward 41.05μm within 10s under a 15mT, 5Hz magnetic field.

[0095] Figure 5This is a statistical diagram of the movement speed of the 20μm rigid magnetic field driven chain micromotor at different frequencies under a magnetic field of 15mT. It can be seen that as the frequency increases, the movement speed of the rigid magnetic field driven chain micromotor first increases and then decreases.

[0096] Example 3

[0097] (1) Synthesis of magnetic FeO nanoparticles

[0098] Dissolve 0.65g of FeCl3 and 0.20g of trisodium citrate in 20mL of ethylene glycol, and then add 1.20g of sodium acetate while stirring. After continuous vigorous stirring for 30 minutes, transfer the mixed solution into a reactor. Heat the reactor loaded with the mixed solution at 200°C for 10 hours, cool to room temperature, centrifuge at 9000rpm / min to collect the precipitate, and wash it three times with a 1:1 mixed solution of deionized water / ethanol to obtain magnetic ferrosoferric oxide nanoparticles.

[0099] (2) Preparation of silica-coated magnetic microwires

[0100] Disperse 50 mg of the synthesized magnetic ferrosoferric oxide nanoparticles (1) into a three-necked flask containing 60 mL of anhydrous ethanol. After ultrasonic treatment for 30 minutes, add 3 mL of 28-30% ammonia water to the above solution. Mechanically stir the mixed solution for 30 minutes in a 30°C water bath, and then drop 0.3 g of tetraethyl orthosilicate into it. Stop the mechanical stirring after 15 minutes, and then place a magnet with a magnetic induction intensity of 40 mT at 0 cm directly below the three-necked flask. After standing at 30°C for 12 hours, collect the solution using a magnetic field and wash it with anhydrous ethanol to obtain magnetic microwires wrapped with silica.

[0101] (3) Preparation of rigid magnetic field driven chain micromotors

[0102] The silica-coated magnetic microwire obtained in (2) was dispersed into a sodium alginate solution with a concentration of 2 mg / mL, and after oscillation for 15 minutes, it was collected by a magnet and washed with deionized water 3 times, and then dispersed into a chitosan solution with a concentration of 2 mg / mL, and after oscillation for 15 minutes, it was collected by a magnet and washed with deionized water 3 times. The above layer-by-layer assembly was repeated 10 times to obtain a silica-coated magnetic microwire with a surface modified by 20 layers of chitosan / sodium alginate layers, that is, a rigid magnetic field driven chain micromotor with a polymer as the shell and magnetic micro-nanoparticles as the skeleton core.

[0103] Compared with Example 2, the average length of the rigid magnetic field driven chain micro motor prepared in this example is longer.

[0104] Figure 6This is a real-time motion picture of the 15μm rigid magnetic field driven chain micromotor prepared in this embodiment under a magnetic field; in this embodiment, the rigid magnetic field driven chain micromotor moved forward 70.73μm within 10s under a 15mT, 5Hz magnetic field.

[0105] Figure 7 This is a statistical chart of the movement speed of rigid magnetic field driven chain micromotors of different lengths made by magnets with different magnetic induction strengths under a magnetic field of 15mT and 5Hz in this embodiment; it can be seen that as the length of the rigid magnetic field driven chain micromotors increases, the movement speed of the rigid magnetic field driven chain micromotors first increases and then decreases.

[0106] In this embodiment, a 5 μm rigid magnetic field drives a right-angle channel with a width of 10 μm through which the chain-like micromotor can pass; in this embodiment, a 15 μm rigid magnetic field drives a right-angle channel with a width of 10 μm through which the chain-like micromotor cannot pass.

[0107] Example 4

[0108] (1) Synthesis of magnetic FeO nanoparticles

[0109] Dissolve 0.65g of FeCl3 and 0.20g of trisodium citrate in 20mL of ethylene glycol, and then add 1.20g of sodium acetate while stirring. After continuous vigorous stirring for 30 minutes, transfer the mixed solution into a reactor. Heat the reactor loaded with the mixed solution at 200°C for 10 hours, cool to room temperature, centrifuge at 9000rpm / min to collect the precipitate, and wash it three times with a 1:1 mixed solution of deionized water / ethanol to obtain magnetic ferrosoferric oxide nanoparticles.

[0110] (2) Preparation of silica-coated magnetic microwires

[0111] Disperse 50 mg of the synthesized magnetic ferrosoferric oxide nanoparticles (1) into a three-necked flask containing 60 mL of anhydrous ethanol. After ultrasonic treatment for 30 minutes, add 3 mL of 28-30% ammonia water to the above solution. Mechanically stir the mixed solution for 30 minutes in a 30°C water bath, and then drop 0.3 g of tetraethyl orthosilicate into it. Stop the mechanical stirring after 15 minutes, and then place a magnet with a magnetic induction intensity of 20 mT 5 cm directly below the three-necked flask. After standing at 30°C for 12 hours, collect the solution using a magnetic field and clean it with anhydrous ethanol to obtain magnetic microwires wrapped with silica.

[0112] (3) Preparation of rigid magnetic field driven chain micromotors

[0113] The silica-coated magnetic microwires obtained in (2) were dispersed in a chitosan solution with a concentration of 2 mg / mL, shaken for 15 minutes, collected by a magnet and washed with deionized water three times, and then dispersed in a sodium alginate solution with a concentration of 2 mg / mL, shaken for 15 minutes, collected by a magnet and washed with deionized water three times. The above layer-by-layer assembly was repeated 10 times to obtain silica-coated magnetic microwires with 20 layers of chitosan / sodium alginate layers on the surface.

[0114] (4) Preparation of a flexible magnetic field driven chain micromotor with a polymer layer as the shell and magnetic micro-nanoparticles as the core

[0115] The silica-coated magnetic microwires with surface modification of chitosan / sodium alginate layer in (3) were dispersed in a 0.1% HF acid solution, wherein the ratio of microwire to HF solution was 1 mg:1 mL. After oscillation for 20 seconds, the microwires were collected by a magnet and washed with deionized water three times to obtain a flexible magnetic field-driven chain micromotor.

[0116] Figure 8 This is a real-time motion picture of the 10μm flexible magnetic field driven chain micromotor under a magnetic field in this embodiment; in this embodiment, the flexible magnetic field driven chain micromotor moved forward 30.73μm within 20s under a 15mT, 5Hz magnetic field.

[0117] Fig. 9 It is a comparison chart of the movement speed statistics of the 10μm rigid magnetic field driven chain micromotor (Motor) of Example 2 and the 10μm flexible magnetic field driven chain micromotor (Flexible moter) of this Example 4 under a magnetic field of 15mT, 5Hz; it can be seen that the movement speed of the flexible magnetic field driven chain micromotor is reduced, mainly because the flexible material is more likely to deform during movement, resulting in increased energy dissipation, while its lower bending stiffness and greater deformation capacity make it encounter greater resistance when moving in the fluid, these factors work together to reduce the overall movement speed of the flexible material.

[0118] In this embodiment, the flexible magnetic field driven chain micro motors of 5 to 50 μm can pass through the right-angle channel of 10 μm width.

[0119] Example 5

[0120] Compared with Example 3, the difference is that the rigid magnetic field driven chain micromotor prepared in Example 3 (3) is etched using the method of Example 4 (4) to obtain a flexible magnetic field driven chain micromotor.

[0121] In this embodiment, the 15 μm flexible magnetic field driven chain micro motor moved forward 54.36 μm within 20 seconds under a 15 mT, 5 Hz magnetic field.

[0122] In this embodiment, the 5-50 μm flexible magnetic field driven chain micro motor can pass through a right-angle channel with a width of 10 μm.

[0123] Example 6

[0124] Compared with Example 3, the difference is that in (3):

[0125] The silica-coated magnetic microwire obtained in (2) was dispersed into a hyaluronic acid solution with a concentration of 2 mg / mL, and after oscillation for 15 minutes, it was collected by a magnet and washed with deionized water 3 times, and then dispersed into a polyacrylamine hydrochloride solution with a concentration of 2 mg / mL, and after oscillation for 15 minutes, it was collected by a magnet and washed with deionized water 3 times. The above layer-by-layer assembly was repeated 10 times to obtain a silica-coated magnetic microwire with a surface modified by 20 layers of polyacrylamine hydrochloride / hyaluronic acid layers, that is, a rigid magnetic field driven chain micromotor with a polymer as the shell and magnetic micro-nanoparticles as the skeleton core.

[0126] The method (4) in Example 4 is used for etching to obtain a flexible magnetic field driven chain micromotor.

[0127] In this embodiment, the 15 μm flexible magnetic field driven chain micro motor moved forward 52.59 μm within 20 seconds under a 15 mT, 5 Hz magnetic field.

[0128] In this embodiment, the flexible magnetic field driven chain micro motors of 5 to 50 μm can pass through the right-angle channel of 10 μm width.

[0129] Comparative Example 1

[0130] Compared with Example 3, the difference is that the surface of the magnetic microwires wrapped with silica is not modified with a polymer layer.

[0131] (1) Synthesis of magnetic FeO nanoparticles

[0132] Dissolve 0.65g of FeCl3 and 0.20g of trisodium citrate in 20mL of ethylene glycol, and then add 1.20g of sodium acetate while stirring. After continuous vigorous stirring for 30 minutes, transfer the mixed solution into a reactor. Heat the reactor loaded with the mixed solution at 200°C for 10 hours, cool to room temperature, centrifuge at 9000rpm / min to collect the precipitate, and wash it three times with a 1:1 mixed solution of deionized water / ethanol to obtain magnetic ferrosoferric oxide nanoparticles.

[0133] (2) Preparation of silica-coated magnetic microwires

[0134] Disperse 50 mg of the synthesized magnetic ferrosoferric oxide nanoparticles (1) into a three-necked flask containing 60 mL of anhydrous ethanol. After ultrasonic treatment for 30 minutes, add 3 mL of 28-30% ammonia water to the above solution. Mechanically stir the mixed solution for 30 minutes in a 30°C water bath, and then drop 0.3 g of tetraethyl orthosilicate into it. Stop the mechanical stirring after 15 minutes, and then place a magnet with a magnetic induction intensity of 40 mT at 0 cm directly below the three-necked flask. After standing at 30°C for 12 hours, collect the solution using a magnetic field and wash it with anhydrous ethanol to obtain magnetic microwires wrapped with silica.

[0135] In this comparative example, the 15 μm silica-wrapped magnetic microwire moved forward 97.1 μm within 10 seconds under a 15 mT, 5 Hz magnetic field.

[0136] In this comparative example, the 15 μm silica-wrapped magnetic microwire cannot pass through a right-angle channel with a width of 10 μm.

[0137] In summary, the magnetic field driven chain micromotor of the present invention has magnetic micro-nanoparticles arranged into micrometer lines using an external magnetic field as the core and a polymer layer as the shell, or has magnetic micro-nanoparticles arranged into micrometer lines using an external magnetic field as the core, silicon dioxide as the middle layer and a polymer layer as the shell; under the drive of an external magnetic field, the driven movement is achieved through its own responsive rotation.

[0138] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A magnetic field driven chain micro motor, characterized in that: It includes a rigid magnetic field driven chain micromotor and / or a flexible magnetic field driven chain micromotor; the rigid magnetic field driven chain micromotor has magnetic micro-nano particles arranged into micron lines using an external magnetic field as the core, a silicon dioxide layer as the middle layer, and a polymer layer as the outer shell; the flexible magnetic field driven chain micromotor has magnetic micro-nano particles arranged into micron lines using an external magnetic field as the core, and a polymer layer as the outer shell.

2. The magnetic field driven chain micro motor according to claim 1, characterized in that: The polymer in the polymer layer is one or both of a positively charged polymer and a negatively charged polymer; the positively charged polymer includes one or more of chitosan, polyimine, polyacrylamine hydrochloride, and polydiallyldimethylammonium, and the negatively charged polymer includes one or more of sodium alginate, hyaluronic acid, tannic acid, polyacrylic acid, and polypropylene sulfonate.

3. The magnetic field driven chain micro motor according to claim 1, characterized in that: The polymers in the polymer layer are positively charged polymers and negatively charged polymers, wherein the positively charged polymers include one or more of chitosan, polyimine, polyacrylamine hydrochloride, polydiallyldimethylammonium, etc.; the negatively charged polymers include one or more of sodium alginate, hyaluronic acid, tannic acid, polyacrylic acid, polypropylene sulfonate, etc.; When the polymer in the polymer layer is a negatively charged polymer, the polymer layer also includes a trivalent iron compound; the negatively charged polymer includes one or more of sodium alginate, hyaluronic acid, tannic acid, polyacrylic acid, and polypropylene sulfonate, and the trivalent iron compound includes one or more of ferric chloride, ferric nitrate, iron oxide, and iron sulfide.

4. The magnetic field driven chain micro motor according to claim 1, characterized in that: The particle size of the magnetic micro-nano particles is 30-200 nm; the length of the chain micro-motor driven by the magnetic field is 1-100 nm.

5. The magnetic field driven chain micro motor according to claim 1, characterized in that: The rigid magnetic field driven chain micromotor is obtained by sequentially coating a silicon dioxide layer and a polymer layer on the surface of a magnetic micro-nano particle core arranged into a micron line using an external magnetic field; the flexible magnetic field driven chain micromotor is obtained by sequentially coating a silicon dioxide layer and a polymer layer on the surface of a magnetic micro-nano particle core arranged into a micron line using an external magnetic field, and then removing the silicon dioxide layer by etching.

6. The magnetic field driven chain micro motor according to claim 1, characterized in that: The magnetic field driven chain micro motor has a movement time of 10 to 20 seconds and a movement distance of 30 to 200 μm under a 15 mT, 5 Hz magnetic field.

7. A method for preparing a magnetic field driven chain micromotor as claimed in claim 1, characterized in that ,, the preparation method comprises the following steps: (1) arranging magnetic micro-nano particles into micrometer wires by using an external magnetic field, and then coating the surface of the magnetic micrometer wires with silica to obtain silica-coated magnetic micrometer wires; (2) Immersing the silica-coated magnetic microwires in (1) into a polymer precursor solution to obtain a rigid magnetic field-driven chain micromotor; (3) The rigid magnetic field driven chain micromotor obtained in (2) is etched with a hydrofluoric acid solution to remove the silicon dioxide layer, thereby preparing a flexible magnetic field driven chain micromotor.

8. The method for preparing a magnetic field driven chain micromotor according to claim 7, characterized in that: The method for preparing the silica-coated magnetic microwires in (1) comprises: dispersing magnetic micro-nano particles in a solvent, adding ammonia water and a silicon source in sequence, and then placing an external magnetic field directly below the bottom of a reactor, using the external magnetic field to arrange the magnetic micro-nano particles into microwires, and allowing the reaction to stand so that the surface of the magnetic microwires is completely coated with silica, thereby obtaining silica-coated magnetic microwires.

9. The method for preparing a magnetic field driven chain micromotor according to claim 8, characterized in that: The magnetic induction intensity of the external magnetic field is 10-100 mT; the distance between the external magnetic field and the bottom of the reactor is 0-10 cm.

10. Application of the magnetic field driven chain micromotor according to any one of claims 1 to 6 in the biomedical field.

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