Anisotropic three-dimensional polymer with magnetic driving form adaptability and preparation method and application thereof

Abstract

The application discloses an anisotropic three-dimensional polymer with magnetic driving form adaptability and a preparation method and application thereof. The three-dimensional polymer network is embedded with pre-prepared magnetic microfibers with high length-diameter ratio and anisotropic characteristics. Under the action of a dynamic external magnetic field such as an alternating or rotating magnetic field, the internal magnetic microfiber network can generate high-efficiency mechanical torque and anisotropic driving force, and endow the macroscopic polymer with extremely sensitive motion deformation capability and local mechanical force output. The application breaks the mechanical isotropy limitation caused by the random dispersion of nanoparticles in traditional magnetic polymers, and can prepare macroscopic gel patches, injectable microfluidic microspheres and flexible elastomers across scales, and has extremely high commercial and scientific research conversion value in the fields of micro-nano soft robot driving, biomimetic dynamic tissue engineering scaffolds, cell mechanical culture matrix and intelligent drug delivery carriers.

Description

Technical Field

[0001] This invention belongs to the fields of intelligent polymer materials, bionics, and soft robotics, specifically relating to an anisotropic three-dimensional polymer with magnetically driven morphological adaptability. This three-dimensional polymer (such as a hydrogel, microsphere, or elastomer) embeds anisotropic magnetic microfibers. The invention also relates to corresponding preparation processes and applications. This polymer possesses both excellent magnetophysical and mechanical manipulation properties and a highly ordered, topologically guided microenvironment. Background Technology

[0002] Magnetically responsive smart polymers have attracted considerable attention in soft robotics, tissue engineering, and controlled drug delivery. However, existing magnetic three-dimensional polymers are typically prepared by directly doping zero-dimensional superparamagnetic nanoparticles. This approach has significant drawbacks: the nanoparticles are isotropically distributed in the matrix and can only generate weak in-situ spins under dynamic magnetic fields, making it difficult to output macroscopic directional driving forces or produce sufficient micron-level mechanical deformation.

[0003] Dong Xiangting et al. prepared a step-shaped Janus film with up-conversion luminescence, magnetic multiple anisotropic conductivity (CN111267438A). The preparation method includes four steps: (1) preparing spinning solution; (2) preparing [NaGdF4:Yb 3+ Er 3+ (2) Anisotropic conductive magnetic green upconversion fluorescent Janus microfiber array film of [Eu(TTA)3(TPPO)2 / PMMA] / / [PANI / PMMA] was prepared by conjugate electrospinning technology; (3) Anisotropic conductive red fluorescent Janus nanoribbon array film of [Eu(TTA)3(TPPO)2 / PMMA] / / [PANI / PMMA] was prepared by parallel electrospinning technology; (4) Upconversion luminescent magnetic multi-anisotropic conductive stepped Janus film was prepared.

[0004] Furthermore, natural biological tissues (such as muscle fibers, nerve bundles, and tendons) often exhibit highly ordered anisotropic morphologies. Existing isotropic magnetic polymers cannot simulate this natural tissue structure and are unable to provide the topological physical cues required for directed cell migration and proliferation. At the same time, traditional magnetic polymers often exhibit bottlenecks such as low mechanical conduction efficiency and slow response when facing the urgent needs of micro-soft robots for complex directional motion and high output torque.

[0005] Therefore, developing an anisotropic three-dimensional polymer that possesses both efficient macroscopic / microscopic magnetic driving torque and a highly ordered topological structure, along with its preparation method, has significant technological innovation and enormous clinical and engineering application prospects. Summary of the Invention

[0006] One of the technical problems to be solved by the present invention is to provide an anisotropic three-dimensional polymer system with high mechanical conductivity, directional driving capability and controllable topology.

[0007] Another technical problem to be solved by the present invention is to provide a method for preparing the above-mentioned three-dimensional polymer.

[0008] In a first aspect, the present invention provides an anisotropic three-dimensional polymer.

[0009] The anisotropic three-dimensional polymer of the present invention embeds pre-prepared magnetic microfibers with anisotropic characteristics within a three-dimensional polymer network. These magnetic microfibers are typically elongated, with a length greater than their diameter, for example, exhibiting a high aspect ratio. A high aspect ratio refers to a large ratio of the length to the diameter of an object, commonly used to describe elongated columnar, fibrous, or rod-like structures. In the present invention, the diameter-to-length ratio is typically no greater than 1:3, and can be 1:5-1:20, preferably 1:8-1:15. More preferably, it is 1:10-1:12. For example, in a preferred embodiment of the present invention, the magnetic microfibers used have a length of approximately 20 μm and a diameter of approximately 2 μm, with an aspect ratio of 10:1.

[0010] Anisotropy refers to the property of a substance where its physical and chemical properties differ with changing orientation, as opposed to isotropy. Typically, the atoms within a single crystal are arranged in the same direction, but the atomic density and bonding forces differ in different crystal orientations, leading to variations in properties across directions. This invention uses Solidworks to model the structure of the obtained fibrous-structured hydrogel. The finite element method is then used to perform coupled calculations of solid mechanics and electromagnetics on the modeled fibrous-structured hydrogel.

[0011] Test results show that the anisotropic three-dimensional polymer of the present invention possesses sensitive motion deformation capability and local mechanical force output, and can be used to construct anisotropic compositions with sensitive motion deformation capability or local mechanical force output capability. The present invention also compared the shear force changes of oriented / parallel-arranged anisotropic fibers and randomly arranged fibers within a hydrogel. The results show that oriented anisotropic fibers exhibit greater instantaneous shear force under a 1-5Hz magnetic field. Furthermore, the shear force of the anisotropic three-dimensional polymer of the present invention can significantly enhance the expression of the M1 polarization marker CD86, promoting macrophage polarization.

[0012] Preferably, the anisotropic three-dimensional polymer is used to construct macroscopic gel patches, injectable microfluidic microspheres, flexible elastomers, micro / nano soft robot actuators, biomimetic dynamic tissue engineering scaffolds, cell mechanomechanical culture media, or intelligent drug delivery carriers. It can also be used for tissue repair, cell culture media, or drug delivery, etc.

[0013] Secondly, the present invention provides a method for preparing anisotropic three-dimensional polymers, comprising the following steps: S1, Preparation of anisotropic magnetic microfibers: The anisotropic magnetic microfibers are long and thin and have biomolecular activity. The anisotropic magnetic microfibers contain magnetic nanoparticles or microparticle units inside and are coated with a polymer layer on the outside. S2, Mixing and dispersing the polymer precursor: The magnetic microfibers from step S1 are uniformly dispersed in the polymer precursor solution at a concentration of 0.1–10 mg / mL; S3, constructing the morphology and magnetic field-induced orientation of anisotropic three-dimensional polymer: Before molding and curing, a static magnetic field with a preset direction and intensity is applied to the outside of the polymer precursor obtained in the predetermined morphology fixing step S2, so that the magnetic microfibers in the system overcome the fluid viscous resistance and align in a paramagnetic orientation. S4, Solidification of Network and Locking Morphology: The precursor network is solidified while maintaining the applied magnetic field.

[0014] The magnetic nanoparticles or micron-sized particles are selected from, but are not limited to, one or more of iron(II,III) oxide, neodymium iron boron, and iron-cobalt alloys. Preferably, the anisotropic magnetic microfibers are selected from materials similar to Fe3O4-PAA, Fe3O4@SiO2, Fe3O4@PDA, HFe3O4, Fe3O4@Au, γ-Fe2O3, NdFeB, MnFe2O4, and ZnFe2O4.

[0015] Preferably, the anisotropic magnetic microfibers can be prepared by the following method: dispersing trivalent inorganic iron salts and surfactants in a liquid containing ethylene glycol and dissolving them completely; then placing them in a reaction vessel with a polytetrafluoroethylene liner and heating overnight at a temperature not lower than 200°C to prepare a superparamagnetic core by a one-pot hydrothermal synthesis method; and preparing magnetic composite microspheres containing Fe3O4 magnetic cores based on the cores; placing the magnetic composite microspheres in a solution containing protein and incubating for at least 5 minutes; placing the mixture obtained above in an external magnetic field for at least 2 minutes, removing the magnetic field, redispersing, and allowing it to stand for at least 10 minutes to obtain a self-assembled magnetic composite microsphere.

[0016] The polymer encapsulation layer contains biological macromolecules. Biological macromolecules refer to organic molecules with molecular weights reaching tens of thousands or more in living organisms; they are the basic building blocks of life and mainly include proteins, nucleic acids, and polysaccharides. The unit of protein is amino acid, the unit of nucleic acid is nucleotide, and the unit of polysaccharide is monosaccharide. Preferably, the polymer encapsulation layer of the present invention contains one or more of the following: fibronectin, collagen, fibrin, fibrinogen, laminin, hyaluronic acid, sodium alginate, chitosan, PEG, or DNA. A precursor is a substance that exists before the target product is obtained and can be transformed into the target material during chemical or material synthesis. It typically exists as an organic-inorganic complex, a mixture of solids, or a sol. Precursors generally include, but are not limited to, one or more of the following: photocrosslinked hydrogels, thermocrosslinked hydrogels, chemically crosslinked hydrogels, thermosensitive polymers, pH-sensitive polymers, and flexible elastomers. Preferably, photo / thermal / chemically crosslinked hydrogels include, but are not limited to, GelMA, PEGDA, gelatin, alginate, and hyaluronic acid; flexible elastomer precursor solutions include, but are not limited to, polydimethylsiloxane (PDMS) and Ecoflex.

[0017] Elastomer materials commonly used in soft robotics and biomedical engineering can be divided into two main categories: "biohydrogels" and "silicone rubber".

[0018] Biological hydrogels are characterized by their hydrophilicity, allowing them to hold a large amount of water and form a moist 3D network. Therefore, they are naturally compatible with biological tissues, making them particularly suitable for applications in medicine, tissue engineering, cell culture, and for simulating soft tissues such as muscle and skin in soft robotics. Examples include GelMA (methacrylated gelatin), PEGDA (polyethylene glycol diacrylate), gelatin, and alginate.

[0019] GelMA is made by grafting photosensitive methacrylate groups onto natural gelatin molecules. It exhibits excellent biocompatibility, photocurability, and modifiability. Derived from gelatin, it retains natural cell adhesion sites (RGD sequences), allowing cells to grow and migrate effectively. With the addition of a photoinitiator, it rapidly solidifies from a liquid state into a gel upon exposure to ultraviolet or blue light. This greatly facilitates 3D printing. Its mechanical properties (hardness / softness) can be adjusted by changing the light intensity or the degree of chemical modification.

[0020] PEGDA (polyethylene glycol diacrylate) is a completely synthetic polymer. It consists of hydrophilic polyethylene glycol (PEG) segments and acrylate groups at both ends. It can be photocured, avoiding non-specific adhesion such as protein adsorption and cell adhesion. It can be used to manufacture microfluidic chip channels or as a basic framework for constructing complex soft robots.

[0021] Gelatin, the precursor to GelMA, is a natural polymer obtained by partially hydrolyzing collagen from the skin and bones of animals (such as pigs and cows). It is thermally reversible, dissolving in hot water and forming a gel when cooled to below about 30°C, and then remelting upon heating.

[0022] Alginate is a natural polysaccharide extracted from seaweed such as brown algae. It exhibits mild gel-forming conditions, enabling ionic cross-linking without the need for light or heat; it forms a gel instantly upon contact with calcium ions. It can be used to produce bio-inks, and its calcium-curing property allows for rapid, non-destructive 3D printing to create drug delivery carriers or soft actuators.

[0023] Silicone elastomers are hydrophobic and anhydrous, with their main chain primarily composed of silicon-oxygen bonds. They possess extremely high elasticity, thermal stability, and chemical inertness, including PDMS (polydimethylsiloxane) and Ecoflex.

[0024] PDMS (polydimethylsiloxane) is one of the most widely used organosilicon polymer materials. It possesses excellent light transmittance, chemical inertness, hydrophobicity, and air permeability. Through casting and thermosetting, it can precisely replicate micron-scale channel structures. It can be used to manufacture structures requiring a certain shape retention capability, such as pneumatic soft robots.

[0025] Ecoflex is a stackable biodegradable copolyester with ultra-high elasticity, much softer than PDMS, and better mimics the feel of skin. It can be used to make the flexible parts of soft grippers or the body of soft crawling robots.

[0026] The concentration of the precursor fluid can be 10–1000 mg / mL; preferably, the concentration of the precursor fluid is 20–100 mg / mL.

[0027] The final concentration of anisotropic magnetic microfibers in the precursor fluid can be 0.1–10 mg / mL, preferably 0.5–10 mg / mL; more preferably, 1–5 mg / mL.

[0028] The method for curing the precursor network is selected from one or more of ultraviolet / visible light initiation, thermal initiation, enzymatic crosslinking, or chemical crosslinking. The ultraviolet light irradiation time is 1 s to 5 min, preferably 5 to 30 s.

[0029] A static magnetic field, also known as a constant magnetic field, refers to a magnetic field that does not change with time and has a frequency of 0 Hz. It is usually generated by a steady current or a permanent magnet, and the magnetic field distribution remains stable. In this invention, the strength of the static magnetic field can be 0.1–200 mT, preferably 0.5–100 mT, more preferably 1–100 mT, for example 10–100 mT.

[0030] Preferably, the three-dimensional polymer in step S4 includes, but is not limited to, bulk gels, microfluidic microspheres, or bulk elastomers.

[0031] Specifically, this invention provides a method for preparing anisotropic three-dimensional polymers with magnetically driven morphological adaptability, comprising the following steps: (1) Preparation of anisotropic magnetic microfibers: Anisotropic magnetic microfibers with high aspect ratio and surface biomolecular activity are prepared in advance. The fibers contain magnetic nanoparticles or microparticle units (such as iron(II,III) oxide, neodymium iron boron, iron-cobalt alloy, etc.) inside and are coated with a polymer layer on the outside. The biomolecular components include fibronectin, collagen, fibrin, fibrinogen, laminin, hyaluronic acid, sodium alginate, chitosan, PEG, and DNA, etc.

[0032] (2) Polymer precursor mixing and dispersion: The magnetic microfibers from step (1) are uniformly dispersed in the polymer precursor solution at a specific concentration (0.1-10 mg / mL). The precursor includes, but is not limited to, photo / thermal / chemical cross-linked hydrogels (such as GelMA, PEGDA, gelatin, alginate, hyaluronic acid), or temperature-sensitive / pH-sensitive polymer materials, or flexible elastomer precursor solutions (such as polydimethylsiloxane PDMS, Ecoflex).

[0033] (3) Morphology construction and magnetic field-induced orientation: The above-mentioned hybrid system is placed in a specific mold, or extruded into droplets by a microfluidic chip device, or extruded by 3D printing. Before curing, a static magnetic field (0.1~200 mT) with a preset direction and intensity is applied to the outside of the system, so that the magnetic microfibers in the system overcome the fluid viscosity resistance and align in a paramagnetic orientation, thus constructing an anisotropic morphology inside.

[0034] (4) Network solidification and morphology locking: While maintaining an external magnetic field, the precursor network is solidified by means of ultraviolet / visible light initiation, thermal initiation, enzymatic crosslinking or chemical crosslinking. The solidification process permanently locks the anisotropic magnetic fiber network inside the three-dimensional polymer (bulk gel, microfluidic microsphere or bulk elastomer). After the magnetic field is removed, the anisotropic three-dimensional polymer is obtained.

[0035] The technical features and beneficial effects of this invention are as follows: This invention breaks through the isotropic limitations of nanoparticles. The torque generated by the pre-embedded high aspect ratio micron-sized fibers under alternating or rotating dynamic magnetic fields is geometrically amplified. This structure enables the polymer to efficiently convert magnetic field energy into mechanical energy, possessing excellent soft robotic actuation characteristics such as macroscopic bending, swimming, grasping, and microscopic deformation. The polymer after curing exhibits a highly ordered microscopic anisotropic structure. In tissue engineering, this structure can perfectly simulate the anisotropic characteristics of natural tissues such as muscles and nerves, providing natural ECM-like topological guidance cues for fibroblasts, neurons, and cardiomyocytes, inducing directional cell alignment and differentiation. The preparation process of this invention has strong versatility, capable of preparing macroscopic 3D hydrogels for in vitro culture or skin dressings, as well as microsphere formulations suitable for minimally invasive injection into deep tissues by combining microfluidic technology, and tough elastomers for engineering instruments.

[0036] In the description of this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a reference structure" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0037] It should be noted that in this article, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0038] As used herein, the term “about” typically means + / - 5% of the value, more typically + / - 4% of the value, more typically + / - 3% of the value, more typically + / - 2% of the value, more typically + / - 1% of the value, and even more typically + / - 0.5% of the value. As used herein, “1E5”, “1E7”, “1E8”, and “1E10” refer to 1x10^5, 1x10^7, 1x10^8, and 1x10^10, respectively.

[0039] Throughout this disclosure, certain embodiments may be disclosed in a range format. It should be understood that the range format is merely for convenience and brevity and should not be construed as a limitation on the scope of protection of the disclosed range. Therefore, the range description should be considered to specifically disclose all possible subranges and the individual values ​​within those ranges. For example, a description of a range such as 1 to 6 should be considered to have specifically disclosed subranges, such as 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, etc., and the individual numbers within those ranges, such as 1, 2, 3, 4, 5, and 6. The range is not limited to integers and may include decimal measurements. This applies regardless of the width of the range. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, each drawing described below is for a part of the embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0041] Figure 1 An optical microscope image of the prepared anisotropic magnetic microfiber.

[0042] Figure 2 Scanning electron microscope (SEM) image of a three-dimensional photocrosslinked hydrogel containing anisotropic magnetic fibers locked internally.

[0043] Figure 3 A confocal microscopy cross-sectional image of a three-dimensional photocrosslinked hydrogel loaded with anisotropic magnetic fibers, showing the high orientation of the internal fibers. This indicates that the three-dimensional photocrosslinked hydrogel of the magnetic fibers of the present invention possesses anisotropy.

[0044] Figure 4 Microscopic images of injectable composite hydrogel microspheres containing an internal network of oriented fibers, prepared using microfluidic technology. The images show the bulk gel group, the HMS-1 mT microsphere group, and the HMS-2 mT microsphere group. Compared with HMS-1 mT, HMS-2 mT can form longer fibers with a larger aspect ratio, which are concentrated on one side of the microsphere.

[0045] Figure 5 This is an optical image showing the deformation of the anisotropic polymer structure under an applied alternating magnetic field. It can be seen that under the action of the anisotropic magnetic fibers, the anisotropic polymer can not only translate but also oscillate in various directions. (Please provide screenshots and indicate which images best demonstrate the sensitive motion deformation capability and localized mechanical force output of the three-dimensional polymer of this invention.) Figure 6This study uses the finite element method to calculate the shear force variation of anisotropic polymer structures (oriented and randomly arranged) under an applied high-frequency magnetic field. The shear force variations of oriented / parallel-arranged anisotropic fibers and randomly arranged fibers within the hydrogel were compared. The results show that oriented anisotropic fibers exhibit greater instantaneous shear force under a 1-5 Hz magnetic field.

[0046] Figure 7 This is a fluorescence staining image of fibroblasts cultured on this anisotropic three-dimensional polymer. This not only demonstrates the anisotropy of the three-dimensional polymer of the present invention, but also shows the highly directional growth and alignment of cells along the fiber direction.

[0047] Figure 8 Scanning electron microscopy images of macrophages cultured on this anisotropic three-dimensional polymer show the adhesion and guidance of fibers to cell pseudopodia. This indicates that the three-dimensional polymer of the present invention not only possesses excellent biocompatibility but also promotes cell adhesion and motility.

[0048] Figure 9 This is a flow cytometry analysis of the expression of CD86, a marker of M1 polarization, in macrophages cultured on an anisotropic three-dimensional polymer under an applied high-frequency magnetic field. This indicates that fiber shear forces can promote macrophage polarization. Detailed Implementation

[0049] This invention discloses an anisotropic three-dimensional polymer with magnetically driven morphological adaptability, in which a network is embedded with pre-prepared magnetic microfibers with high aspect ratio and anisotropic characteristics. Under the action of a dynamic external magnetic field such as alternating or rotating, the internal magnetic microfiber network can generate efficient mechanical torque and anisotropic driving force, endowing the macroscopic polymer with extremely sensitive motion deformation capability and local mechanical force output.

[0050] The preparation method involves uniformly dispersing pre-prepared magnetic microfibers in a polymer precursor and then cross-linking and curing them under an applied directional magnetic field to lock in their biomimetic anisotropic morphology. The method includes the following steps: S1, Preparation of anisotropic magnetic microfibers: The anisotropic magnetic microfibers have biomolecular activity and a length greater than their diameter. The anisotropic magnetic microfibers contain magnetic nanoparticles or microparticle units inside and a polymer coating layer outside, which contains biomolecular molecules. S2, Mixing and dispersing polymer precursors: The anisotropic magnetic microfibers obtained in step S1 are uniformly dispersed in the polymer precursor solution at a concentration of 0.1 to 10 mg / mL to obtain a polymer precursor mixture; S3, constructing the morphology and magnetic field-induced orientation of anisotropic three-dimensional polymer: before molding and curing, a static magnetic field with a preset direction and intensity is applied to the outside of the polymer precursor mixture obtained in step S2 according to the predetermined morphology fixation step, so that the magnetic microfibers in the system overcome the fluid viscous resistance and align in a paramagnetic orientation. S4, Solidification Network and Locking Morphology: While maintaining the applied magnetic field, the polymer precursor network is solidified to form an anisotropic three-dimensional polymer.

[0051] This invention breaks through the mechanical isotropic limitation caused by the random dispersion of nanoparticles in traditional magnetic polymers, enabling the preparation of macroscopic gel patches, injectable microfluidic microspheres and flexible elastomers across scales. It has extremely high commercial and scientific research transformation value in fields such as micro-nano soft robot drive, biomimetic dynamic tissue engineering scaffolds, cell mechanomechanical culture substrates and intelligent drug delivery carriers.

[0052] The technical solution will be clearly and completely described below through embodiments of this application. Obviously, the described embodiments are only some preferred embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0053] Example 1 This embodiment prepares an anisotropic 3D hydrogel patch containing a highly oriented magnetic fiber network, including the following steps: (1) Under an external magnetic field, Fe3O4@SiO2 (the preparation method can be found in CN115888571A) is magnetized and generates a magnetic dipole moment. It connects end to end along the magnetic field lines and densely accumulates into anisotropic layered aggregates, which lock the chain structure through the interaction of fibronectin (Fn). When the magnetic field is removed and a fluid shear force is applied, the weak lateral binding force of the lamellar structure is utilized to tear it along the direction of the magnetic field lines, retaining the tight chain structure in the long axis direction, and finally dispersing it to form micron-sized colloidal fibers. Magnetic microfibers with an average length of about 20 μm and a diameter of about 2 μm are collected.

[0054] (2) Accurately weigh 100 mg of methacrylamide gelatin (GelMA) and an appropriate amount of photoinitiator (LAP) and dissolve them in 1 mL of phosphate buffer (PBS) to obtain GelMA precursor solution. Add the magnetic microfibers obtained in step (1) to the GelMA precursor solution at a concentration of 1 mg / mL and disperse them thoroughly by blowing to obtain a mixed solution.

[0055] (3) Inject the above mixed solution into a rectangular Teflon mold. Place a pair of neodymium iron boron strong magnets on both sides of the mold to generate a uniform parallel static magnetic field of about 10 mT in the central region of the mold. Let it stand for 1 min to allow the magnetic fibers in the system to fully align anisotropically along the direction of the magnetic field lines.

[0056] (4) While maintaining the magnetic field, irradiate the mold with a 365 nm ultraviolet light source for 30 s to cause photocuring and cross-linking of the GelMA solution. Remove the light source and magnet, take out the sample, and you will get an anisotropic 3D hydrogel patch containing a highly oriented magnetic fiber network inside.

[0057] Optical microscope image of the prepared anisotropic magnetic microfibers as shown below Figure 1 As shown.

[0058] A confocal microscopy cross-sectional image of a three-dimensional photocrosslinked hydrogel loaded with anisotropic magnetic fibers is shown below. Figure 3 As shown, the high degree of orientation of the internal fibers is evident. This indicates that the three-dimensional photocrosslinked hydrogel of the magnetic fibers of the present invention possesses anisotropy.

[0059] Example 2 This embodiment prepares anisotropic injectable hydrogel microspheres containing a parallel-oriented fiber backbone, including the following steps: (1) Pretreated anisotropic magnetic microfibers were prepared using the same method as in Example 1.

[0060] (2) Polyethylene glycol diacrylate (PEGDA, molecular weight 4000) and photoinitiator were dissolved in deionized water as the aqueous phase (dispersed phase), and magnetic microfibers were uniformly dispersed in it at a concentration of 5 mg / mL. Fluorinated oil containing surfactants was used as the continuous phase.

[0061] (3) The aqueous phase and the continuous phase are pumped into the droplet microfluidic chip respectively, and PEGDA droplets encapsulating magnetic fibers are generated under the action of fluid shear force.

[0062] (4) A directional static magnetic field (100 mT) is applied outside the collection channel from which the droplets flow out, causing the short-cut magnetic fibers inside each droplet to align in the same direction. The droplets enter the ultraviolet light (365 nm) irradiation zone with the fluid, where they are instantly photocrosslinked and cured. After washing away the oil phase, anisotropic injectable hydrogel microspheres containing a parallel-oriented fiber skeleton are obtained, which have directional orientation.

[0063] Scanning electron microscope (SEM) image of a three-dimensional photocrosslinked hydrogel with internally locked anisotropic magnetic fibers, as shown below. Figure 2 As shown.

[0064] Example 3 Anisotropic injectable hydrogel microspheres containing a parallel-oriented fiber backbone, obtained in Example 2, were placed in 0.1M PBS buffer to obtain a soft robot.

[0065] The soft robot was placed in a 200 mT directional magnetic field, causing the soft robot to be closely oriented along the fiber extension line.

[0066] like Figure 5 As shown, the resulting elastic soft robot can output extremely large torque and crawling motion that cannot be achieved by traditional isotropic doped materials under an applied low-frequency rotating magnetic field.

[0067] Example 4 This embodiment prepares injectable hydrogel microspheres containing a randomly oriented fiber backbone, including the following steps: (1) Pretreated anisotropic magnetic microfibers were prepared using the same method as in Example 1.

[0068] (2) Polyethylene glycol diacrylate (PEGDA, molecular weight 4000) and photoinitiator were dissolved in deionized water as the aqueous phase (dispersed phase), and magnetic microfibers were uniformly dispersed in it at a concentration of 5 mg / mL. Fluorinated oil containing surfactants was used as the continuous phase.

[0069] (3) The aqueous phase and the continuous phase are pumped into the droplet microfluidic chip respectively, and PEGDA droplets encapsulating magnetic fibers are generated under the action of fluid shear force.

[0070] (4) The droplets enter the ultraviolet light (365 nm) irradiation area with the fluid and are instantly photocrosslinked and cured. After washing to remove the oil phase, injectable hydrogel microspheres containing a randomly oriented fiber skeleton are obtained.

[0071] The fibrous skeleton hydrogels in Examples 2 and 4 were structurally modeled using Solidworks. Coupled calculations of solid mechanics and electromagnetics were then performed on the modeled fibrous skeleton hydrogels using the finite element method.

[0072] The injectable hydrogel microspheres from Examples 2 (directed group) and 3 (randomized group) were placed under an external high-frequency magnetic field, and their shear force changes were calculated. The results are as follows: Figure 6 As shown, under a 1Hz magnetic field, the shear force changes for the random and oriented groups are approximately 0.33 and 0.48 ΔWSS (Pa), respectively; under a 2Hz magnetic field, the shear force changes for the random and oriented groups are approximately 0.44 and 0.81 ΔWSS (Pa), respectively; and under a 5Hz magnetic field, the shear force changes for the random and oriented groups are approximately 0.59 and 1.22 ΔWSS (Pa), respectively. This indicates that the anisotropic fibers arranged in the oriented group experience greater instantaneous shear force under magnetic fields ranging from 1 to 5Hz.

[0073] Microscopic image of injectable composite hydrogel microspheres containing an internal oriented fiber network, prepared using microfluidic technology, as shown below. Figure 4 As shown in the figure, the block gel group, the microsphere HMS-1 mT group, and the microsphere HMS-2 mT group are displayed. Compared with HMS-1 mT, HMS-2 mT can form longer fibers with a larger aspect ratio, which are concentrated on one side of the microsphere.

[0074] Example 5 The fluorescence staining image of fibroblasts after being seeded and cultured on this anisotropic three-dimensional polymer is shown below. Figure 7 As shown, this not only demonstrates the anisotropy of the three-dimensional polymer of the present invention, but also shows the highly directional growth and arrangement of cells along the fiber direction.

[0075] Example 6 Scanning electron microscope images of macrophages cultured on this anisotropic three-dimensional polymer are shown below. Figure 8 As shown, the adhesion and guidance of fibers to cell pseudopodia are illustrated; this demonstrates that the three-dimensional polymer of the present invention not only possesses excellent biocompatibility but also promotes cell adhesion and movement.

[0076] Example 7 Flow cytometry analysis of CD86, a marker of M1 polarization, expressed in macrophages cultured on anisotropic three-dimensional polymers under an applied high-frequency magnetic field, is shown below. Figure 9 As shown, this indicates that the shear force of the fiber can promote macrophage polarization.

[0077] The embodiments described above are merely specific implementations of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be conceived by those skilled in the art within the scope of the technology disclosed in this application without creative effort should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the claims in this application.

Claims

1. A method for preparing anisotropic three-dimensional polymers, characterized in that, Includes the following steps: S1, Preparation of anisotropic magnetic microfibers: The anisotropic magnetic microfibers have biomolecular activity and a length greater than their diameter. The anisotropic magnetic microfibers contain magnetic nanoparticles or microparticle units inside and a polymer coating layer outside, which contains biomolecular molecules. S2, Mixing and dispersing polymer precursors: The anisotropic magnetic microfibers obtained in step S1 are uniformly dispersed in the polymer precursor solution at a concentration of 0.1 to 10 mg / mL to obtain a polymer precursor mixture. S3, constructing the morphology and magnetic field-induced orientation of anisotropic three-dimensional polymer: before molding and curing, a static magnetic field with a preset direction and intensity is applied to the outside of the polymer precursor mixture obtained in step S2 according to the predetermined morphology fixation step, so that the magnetic microfibers in the system overcome the fluid viscous resistance and align in a paramagnetic orientation. S4, Solidification Network and Locking Morphology: While maintaining the applied magnetic field, the polymer precursor network is solidified to form an anisotropic three-dimensional polymer.

2. The preparation method according to claim 1, characterized in that, In step S1, the magnetic nanoparticles or microparticles are selected from, but not limited to, one or more of iron(II,III) oxide, neodymium iron boron, and iron-cobalt alloys; the ratio of the diameter to the length of the anisotropic magnetic microfiber is 1:3 to 1:

20. In step S2, the precursors include, but are not limited to, photo / thermal / chemical cross-linked hydrogels, temperature-sensitive / pH-sensitive polymer materials, and flexible elastomer precursor solutions; In step S3, the strength of the static magnetic field is 0.1–200 mT; In step S4, the method for curing the precursor network is selected from one or more of ultraviolet / visible light initiation, thermal initiation, enzymatic crosslinking, or chemical crosslinking.

3. The preparation method according to claim 1, characterized in that, In step S1, the polymer coating layer contains one or more of the following: fibronectin, collagen, fibrin, fibrinogen, laminin, hyaluronic acid, sodium alginate, chitosan, PEG, or DNA. In step S2, the photo / thermal / chemical cross-linked hydrogel includes, but is not limited to, GelMA, PEGDA, gelatin, alginate, and hyaluronic acid; the flexible elastomer precursor liquid includes, but is not limited to, polydimethylsiloxane (PDMS) and Ecoflex. In step S3, the strength of the static magnetic field is 0.5–150 mT; In step S4, the anisotropic three-dimensional polymer includes, but is not limited to, bulk gels, microfluidic microspheres, or bulk elastomers.

4. The preparation method according to claim 1, characterized in that, The anisotropic magnetic microfibers are selected from at least one of Fe3O4-PAA, Fe3O4@SiO2, Fe3O4@PDA, HFe3O4, Fe3O4@Au, γ-Fe2O3, NdFeB, MnFe2O4, and ZnFe2O4; The concentration of the precursor fluid is 10–1000 mg / mL; The final concentration of anisotropic magnetic microfibers in the precursor fluid is 0.5–10 mg / mL; The strength of the static magnetic field is 1–100 mT; The ultraviolet light irradiation time is 1 second to 5 minutes.

5. The preparation method according to claim 1, characterized in that, The concentration of the precursor fluid is 20–100 mg / mL; The final concentration of anisotropic magnetic microfibers in the precursor fluid is 1–5 mg / mL; The strength of the static magnetic field is 10–100 mT; The irradiation time of the ultraviolet light source is 5 to 30 seconds.

6. The preparation method according to claim 1, characterized in that, The method for preparing the anisotropic magnetic microfiber includes the following steps in sequence: Trivalent inorganic iron salts and surfactants were dispersed in a liquid containing ethylene glycol and fully dissolved. Then, the mixture was placed in a reaction vessel with a polytetrafluoroethylene liner and heated overnight at a temperature not lower than 200°C. A superparamagnetic core was prepared by a one-pot hydrothermal synthesis method. Based on this core, magnetic composite microspheres containing Fe3O4 magnetic cores were prepared. Place the magnetic composite microspheres in a solution containing protein and incubate for at least 5 minutes. The mixture obtained above was placed in an external magnetic field and magnetically attracted for at least 2 minutes. After the magnetic field was removed, the mixture was redispersed and allowed to stand for more than 10 minutes to obtain a self-assembled magnetic composite microsphere.

7. An anisotropic three-dimensional polymer, characterized in that, Pre-prepared magnetic microfibers with anisotropic characteristics are embedded within a three-dimensional polymer network.

8. The anisotropic three-dimensional polymer according to claim 7, characterized in that, Obtained using the preparation method described in any one of claims 1 to 6.

9. The application of the anisotropic three-dimensional polymer according to claim 7, characterized in that, Construct an anisotropic composition that possesses sensitive motion deformation capabilities or local mechanical force output capabilities.

10. The application according to claim 9, characterized in that, The anisotropic three-dimensional polymers described herein are used to construct macroscopic gel patches, injectable microfluidic microspheres, flexible elastomers, micro / nano soft robot actuators, biomimetic dynamic tissue engineering scaffolds, cell mechanomechanical culture media, or intelligent drug delivery carriers.

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