Shape memory microtopology nanofiber membrane, preparation method and application thereof

Abstract

The application belongs to the technical field of intelligent nanometer materials, and relates to a shape memory micro-topological structure nanometer fiber membrane as well as a preparation method and application thereof. The preparation method is as follows: a fiber membrane is prepared through electrostatic spinning with trifluoroethanol as a solvent; after the fiber membrane is stretched and fixed, in-situ polymerization is carried out in a tris-hydroxymethyl aminomethane buffer to obtain a left-handed polylactic acid / polyhydroxybutyrate valerate@polydopamine fiber membrane; and the surface micro-topological structure is regulated by controlling the temperature to make the fiber retract. The nanometer fiber membrane prepared by the application has both shape memory performance and a regulatable surface micro-topological structure, and the process is simple and the cost is controllable, so the application is suitable for the fields of biomedicine, intelligent materials and the like.

Description

Technical Field

[0001] This invention belongs to the field of intelligent nanomaterials technology, and relates to a shape memory microtopological structure nanofiber membrane, its preparation method and application. Background Technology

[0002] Shape memory materials, capable of recovering their pre-defined shape under external stimuli, hold broad application prospects in fields such as bioengineering scaffolds, smart sensors, and drug delivery carriers. Nanofiber membranes, with their superior mechanical properties, have become an important carrier form for shape memory materials. Among these, the micro-topological structure of the fiber surface, a key characteristic of nanofiber membrane materials, refers to the microscopic morphology on the fiber surface at the micrometer to nanometer scale, including but not limited to grooves, protrusions, pores, wrinkles, and nanoparticle modifications. This structure can significantly optimize the surface properties of nanofiber membranes. Its core advantages are evident in biomedical applications: on the one hand, it can simulate the microenvironment of natural biological tissues, enhancing cell adhesion, proliferation, and differentiation capabilities, providing more suitable interfacial conditions for cell growth, and facilitating the functional realization of bioengineering scaffolds; on the other hand, it can increase the specific surface area of ​​fibers, enhancing the material's adsorption capacity for biomolecules, optimizing the drug loading efficiency and controlled release performance of drug delivery carriers, while also improving the surface hydrophilicity and hydrophobicity of the material, improving biocompatibility and blood compatibility, further expanding the application potential of shape memory nanofiber membranes in the biomedical field.

[0003] Polylactic acid (PLLA) and polyhydroxybutyrate valerate (PHBV) are both biocompatible and biodegradable polyester materials, often used in the preparation of biomedical materials. However, single polymer nanofiber membranes lack sufficient shape memory properties and surface structure controllability. Dopamine (DA) can be polymerized in situ under weakly alkaline conditions to form polydopamine (PDA). PDA exhibits good adhesion and bioactivity, and can optimize composite material properties through interaction with polyester materials. Compared to conventional modification methods such as physical coating, blending, and template methods, in-situ polymerization of dopamine does not require complex templates and harsh post-treatments. It can generate uniform and continuous functional coatings on the fiber surface in situ, and simultaneously induce the formation of micro-topological structures such as wrinkles and particles. Without additional etching or molding steps, it is an ideal approach to achieve precise, mild, and efficient control of micro-topological structures. This makes in-situ polymerization technology irreplaceable in the surface modification of shape memory nanofiber membranes.

[0004] In existing technologies, the preparation of shape memory nanofiber membranes often relies on complex template methods or post-processing techniques, which suffer from problems such as difficulty in precisely controlling the surface micro-topology, cumbersome processes, and high costs. These methods cannot achieve precise construction of specific micro-topologies such as grooves and pores, nor can they guarantee structural uniformity, thus limiting the optimization of material surface properties and the improvement of application effects. Furthermore, some preparation methods use solvents with high toxicity, limiting the application of materials in the biomedical field. In contrast, dopamine in-situ polymerization has significant advantages: mild reaction conditions, environmentally friendly and non-toxic, and can be carried out in aqueous solutions at room temperature and pressure; strong adhesion to the substrate, with coatings that are not easily detached and are uniformly distributed, significantly improving interfacial stability; and simultaneously endowing the material with multiple functions such as hydrophilicity, antioxidant properties, reactive oxygen species scavenging, and bioadhesion, forming a synergistic effect with the micro-topology, thus simultaneously solving the shortcomings of existing technologies from both structural construction and functional endowment perspectives. Therefore, developing a simple, environmentally friendly method for preparing shape memory nanofiber membranes based on dopamine in-situ polymerization with controllable surface micro-topology has significant practical application value. Summary of the Invention

[0005] The purpose of this invention is to provide a shape memory microtopological structure nanofiber membrane, its preparation method, and its application. This shape memory microtopological structure nanofiber membrane possesses both excellent shape memory properties and a tunable surface microtopological structure. It exhibits high shape memory recovery rate and good stability, and can recover a preset shape in response to external stimuli.

[0006] In a first aspect, the present invention provides a method for preparing a shape memory microtopological structure nanofiber membrane, the method comprising the following steps:

[0007] S1. Add polyhydroxybutyrate valerate to trifluoroethanol, stir to dissolve, then add L-polylactic acid and dopamine, stir overnight at room temperature to prepare a mixture;

[0008] S2. The mixture is electrospun to obtain a polylactic acid / polyhydroxybutyrate valerate / dopamine fiber membrane;

[0009] S3. The L-polylactic acid / polyhydroxybutyrate valerate / dopamine fiber membrane is uniaxially stretched and kept in a constant stretched state;

[0010] S4. Immerse the stretched and fixed fiber membrane in tris(hydroxymethyl)aminomethane buffer solution and let it stand to allow dopamine to polymerize in situ to form polydopamine, thus obtaining a polylactic acid / polyhydroxybutyrate valerate@polydopamine fiber membrane.

[0011] S5. Immerse the L-polylactic acid / polyhydroxybutyrate valerate@polydopamine fiber membrane in water and allow it to shrink back to obtain a shape memory nanofiber membrane with a specific microtopology.

[0012] Furthermore, the mass ratio of polylactic acid, polyhydroxybutyrate valerate and dopamine is 8:12:(5-15).

[0013] Furthermore, the concentration of polylactic acid (PLA) in the mixture is (0.06-0.08) g / mL.

[0014] Furthermore, in step S2, the electrospinning process parameters are: voltage 15-25 kV, receiving distance 10-15 cm, and spinning solution propulsion speed 1-1.5 ml / h.

[0015] Furthermore, in step S4, the pH value of the tris(hydroxymethyl)aminomethane buffer is 8.5–8.8.

[0016] Furthermore, in step S3, the stretching ratio is 0.5 to 1.5 times.

[0017] Furthermore, in step S4, the standing time is: standing at room temperature for 10 to 12 hours.

[0018] Furthermore, in step S5, the water temperature is 37–46°C.

[0019] In a second aspect, the present invention provides a shape memory microtopological nanofiber membrane prepared by the above-described preparation method.

[0020] In a third aspect, the present invention provides an application of the above-described shape memory microtopology nanofiber membrane in the repair of peripheral nerve injury.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) This invention uses polylactic acid (PLLA), polyhydroxybutyrate valerate (PHBV), and dopamine (DA) as core raw materials and low-toxicity trifluoroethanol as solvent. All three main raw materials have excellent biocompatibility and complete biodegradability, and their metabolites are safe and leave no residue. Combined with the low-toxicity solvent system, the risk of toxic substance residue is avoided from the source. The overall material is environmentally friendly and has high biosafety, strictly meeting the stringent standards for implantable and contact materials in the biomedical field, and can be widely used in various biomedical scenarios.

[0023] (2) This invention adopts an integrated composite process combining electrospinning with stretching-in-situ polymerization-retraction, breaking through the technical bottleneck of traditional surface modification. In-situ polymerization is the core and necessary step to achieve uniform coating and regular wrinkles: in-situ polymerization under pre-stretched fiber conditions allows polydopamine to be fully wetted, uniformly coated, and form a strong interfacial bond with the matrix; after stress release, the coating naturally forms a highly uniform wrinkled microtopology as the fiber retracts, without the need for templates, etching, or complex post-processing, fundamentally solving the problems of uneven topological structure, weak bonding force, and easy detachment in traditional processes. Electrospinning can quickly prepare nanofiber matrices with uniform diameter, with mild subsequent process conditions, strong equipment versatility, and simple operation, significantly reducing preparation costs and production difficulty, and ensuring stable and controllable product quality, facilitating large-scale production.

[0024] (3) The L-polylactic acid / polyhydroxybutyrate valerate@polydopamine nanofiber membrane prepared in this invention achieves dual optimization of shape memory performance and surface microtopology by relying on the strong interfacial bonding and uniform coating of in-situ polymerization. The material has a high shape memory recovery rate and excellent cycling stability, and can accurately recover the preset shape under external field stimulation; the wrinkled topology structure constructed by in-situ polymerization and retraction has a large specific surface area and a uniform and adjustable morphology, which significantly improves cell adhesion, spreading and proliferation ability, and optimizes drug loading capacity and sustained release uniformity. With the combination of shape response, surface functionalization, biocompatibility and degradability, this nanofiber membrane has outstanding application advantages and broad industrialization prospects in multiple biomedical fields such as tissue engineering scaffolds, intelligent sensing, and drug sustained release carriers. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the present invention, the accompanying drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0026] Figure 1 Scanning electron microscope image of a shape memory microtopological nanofiber membrane;

[0027] Figure 2 This describes the stretch recovery process of shape memory microtopological nanofiber membranes. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some 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 scope of protection of this application.

[0029] In a first aspect, the present invention provides a method for preparing a shape memory microtopological structure nanofiber membrane, the method comprising the following steps:

[0030] S100. Polyhydroxybutyrate valerate (PHBV) is dissolved in trifluoroethanol by stirring, followed by the addition of polylactic acid (PLLA) and dopamine. The mixture is stirred overnight at room temperature to prepare a homogeneous solution. This step ensures that the polymer is fully dissolved and forms a stable and homogeneous system, while also achieving uniform dispersion of dopamine, thus guaranteeing the smooth progress of subsequent electrospinning.

[0031] S200. Electrospin the mixture and collect the fiber membrane to obtain a composite nanofiber membrane with uniform structure and good mechanical properties and bioactivity.

[0032] S300. The composite fiber membrane is uniaxially stretched and held in a stretched state so that the fibers are aligned along the direction of force to improve the mechanical properties of the fiber membrane and stabilize its microstructure.

[0033] S400. The stretched and fixed fiber membrane is immersed in tris(hydroxymethyl)aminomethane buffer solution to allow dopamine to polymerize in situ on the fiber surface and form a polydopamine layer, thereby improving the hydrophilicity, biocompatibility and structural stability of the fiber membrane.

[0034] S500. Immerse L-polylactic acid / polyhydroxybutyrate valerate@polydopamine fiber membrane in water to construct a specific micro-topology using the shape memory effect, while ensuring the integrity of the polydopamine active layer and fiber structure.

[0035] For example, in step S100, the mass ratio of L-polylactic acid, polyhydroxybutyrate valerate and dopamine is 8:12:(5-15).

[0036] For example, in step S100, the heating and stirring is: heating to 60-65°C and stirring for 15-20 minutes.

[0037] For example, in step S100, the concentration of polylactic acid (PLA) in the mixture is (0.06-0.08) g / mL.

[0038] For example, in step S200, the electrospinning process parameters are: voltage 15-25 kV, receiving distance 10-15 cm, and spinning solution propulsion speed 1-1.5 ml / h, so as to ensure stable spinning jet and sufficient solvent evaporation, and obtain a composite nanofiber membrane with uniform morphology and no adhesion.

[0039] For example, in step S300, a tris(hydroxymethyl)aminomethane buffer system with pH 8.5–8.8 and a concentration of 10 mmol / L is used, and the reaction is allowed to proceed at room temperature for 10–12 h to provide a suitable environment for in-situ self-polymerization of dopamine, so as to form a uniform and stable polydopamine coating.

[0040] For example, in step S300, the stretching ratio is 0.5 to 1.5 times.

[0041] For example, in step S500, the water temperature is 37–46°C.

[0042] To further illustrate the embodiments of this application, the following description, in conjunction with specific examples and accompanying drawings, will be provided. Figure 1 , Figure 2 This application provides a detailed description of the shape memory microtopology nanofiber membrane for smart nanomaterials and its preparation method, based on embodiments of this application.

[0043] Example 1

[0044] Weigh 1.2 g of polyhydroxybutyrate valerate (PHBV) and add it to 10 ml of trifluoroethanol. Stir at 65°C for 20 min, then add 0.8 g of polylactic acid (PLLA) and 0.5 g of dopamine (DA) and stir at room temperature for 12 h to obtain a uniform spinning solution. Set the electrospinning parameters to 15 kV voltage, 10 cm receiving distance, and 1 ml / h feed speed for electrospinning. Collect the polylactic acid / polyhydroxybutyrate valerate@polydopamine fiber membrane. Stretch and fix it at 1x ratio, immerse it in 10 mmol / L, pH=8.5 tris(hydroxymethyl)aminomethane buffer solution, let it stand at room temperature for 12 h, and dry it at room temperature to obtain the sample of Example 1.

[0045] To verify whether wrinkles formed on the shape memory microtopological nanofiber membrane due to polydopamine, the sample from Example 1 was unconstrained and immersed in a 46°C water bath to retract naturally, then dried at room temperature. Scanning electron microscopy (SEM) was used to photograph the sample. The actual electron microscope image is provided by [source missing]. Figure 1 As can be seen, the polydopamine coating of the sample in Example 1 exhibits rich wrinkles and clustered microstructures as the fiber shrinks in the retracted state, and the coating is uniformly coated on the fiber surface with complete fiber outline, indicating that the shape memory recovery process can effectively induce the polydopamine coating to form structured wrinkles.

[0046] Example 2

[0047] Weigh 1.5 g of polyhydroxybutyrate valerate (PHBV) and add it to 10 ml of trifluoroethanol. Stir at 65°C for 20 min, then add 1 g of polylactic acid (PLLA) and 0.625 g of dopamine (DA) and stir at room temperature for 12 h to obtain a uniform spinning solution. Set the electrospinning parameters to 15 kV voltage, 10 cm receiving distance, and 1 ml / h feed speed for electrospinning. Collect the polylactic acid / polyhydroxybutyrate valerate@polydopamine fiber membrane. Stretch and fix it at 1x ratio, immerse it in 10 mmol / L, pH=8.5 tris(hydroxymethyl)aminomethane buffer, let it stand at room temperature for 12 h, and dry it at room temperature to obtain the sample of Example 2.

[0048] To verify the shape controllability of the shape memory microtopology nanofiber membrane, the initial length of the sample from Example 2 was measured and recorded. After stretching it 1.5 times and recording the stretched length, it was immersed in water. The length of the sample from Example 2 at this point was then recorded. The change process of the sample from Example 2 is as follows: Figure 2 As shown, this illustrates that the sample in Example 2 still retains a certain shape memory effect after being stretched.

Claims

1. A method for preparing a shape memory microtopological structure nanofiber membrane, characterized in that, The preparation method includes the following steps: S1. Add polyhydroxybutyrate valerate to trifluoroethanol, stir to dissolve, then add L-polylactic acid and dopamine, stir overnight at room temperature to prepare a mixture; S2. The mixture is electrospun to obtain a polylactic acid / polyhydroxybutyrate valerate / dopamine fiber membrane; S3. The L-polylactic acid / polyhydroxybutyrate valerate / dopamine fiber membrane is uniaxially stretched and kept in a constant stretched state; S4. Immerse the stretched and fixed fiber membrane in tris(hydroxymethyl)aminomethane buffer solution and let it stand to allow dopamine to polymerize in situ to form polydopamine, thus obtaining a polylactic acid / polyhydroxybutyrate valerate@polydopamine fiber membrane. S5. Immerse the L-polylactic acid / polyhydroxybutyrate valerate@polydopamine fiber membrane in water and allow it to shrink back to obtain a shape memory nanofiber membrane with a specific microtopology.

2. The preparation method according to claim 1, characterized in that, The mass ratio of L-polylactic acid, polyhydroxybutyrate valerate and dopamine is 8:12:(5-15).

3. The preparation method according to claim 1, characterized in that, The concentration of polylactic acid (PLA) in the mixture is (0.06-0.08) g / mL.

4. The preparation method according to claim 1, characterized in that, In step S2, the electrospinning process parameters are: voltage 15-25 kV, receiving distance 10-15 cm, and spinning solution propulsion speed 1-1.5 ml / h.

5. The preparation method according to claim 1, characterized in that, In step S4, the pH of the tris(hydroxymethyl)aminomethane buffer solution is 8.5–8.

8.

6. The preparation method according to claim 1, characterized in that, In step S3, the stretching ratio is 0.5 to 1.5 times.

7. The preparation method according to claim 1, characterized in that, In step S4, the standing time is: standing at room temperature for 10 to 12 hours.

8. The preparation method according to claim 1, characterized in that, In step S5, the water temperature is 37–46°C.

9. A shape memory microtopological nanofiber membrane is prepared by the preparation method according to any one of claims 1-8.

10. The application of the shape memory microtopology nanofiber membrane as described in claim 9 in the repair of peripheral nerve injury.

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