CN117904747B - Preparation method of hydrogel superfine fiber material with gradient layered structure - Google Patents

Abstract

The invention discloses a method for preparing a hydrogel ultrafine fiber material with a gradient hierarchical structure, comprising the following steps: 1. dissolving an oligomer with high biocompatibility in a hydrochloric acid solution, and then adding thioglycolic acid to obtain a hydrogel precursor solution, wherein the mass ratio of the oligomer to the thioglycolic acid is 1-10:1-5; 2. grafting an acrylate group onto a hydrogel precursor to obtain a modified hydrogel precursor dispersion; 3. transferring the modified hydrogel precursor dispersion to a plurality of electrostatic spinning syringes placed side by side, setting ultraviolet light, and each syringe needle is at a different distance from the ultraviolet light irradiation, and spraying the modified hydrogel precursor dispersion onto a dynamic conveyor belt to obtain a hydrogel ultrafine fiber with a gradient hierarchical structure. The method has simple steps, a continuous spinning process, and can be applied on a large scale, and has good universality; the hydrogel ultrafine fiber material with a gradient hierarchical structure obtained using the method has high porosity, high swelling rate, and good mechanical properties.

Description

A method for preparing a hydrogel ultrafine fiber material with a gradient layered structure

Technical Field

The invention relates to the technical field of preparation of novel functional textile materials, and in particular to a method for preparing a gradient layered structure hydrogel ultrafine fiber membrane.

Background technique

In recent years, hydrogels have shown good prospects in the research and development of advanced dressings. Due to their strong hygroscopicity, high water content, large drug loading and good biocompatibility, they are particularly suitable for the development of chronic wound dressings. However, there are still some difficulties in the controllable molding of hydrogel fibers. Due to their highly cross-linked structural characteristics, it is difficult to prepare fibers through post-processing. Early methods for preparing hydrogel fibers include template method, wire drawing method and cutting method, and these non-continuous molding methods cannot achieve large-scale manufacturing. Subsequently, researchers used 3D printing, microfluidic spinning and wet spinning methods to achieve continuous molding of hydrogel fibers, but only ion-crosslinked or hydrogen-bonded cross-linked hydrogel fibers could be obtained, which resulted in poor mechanical properties of the fibers. Recently, some researchers have developed a "dynamic polymerization spinning" method based on wet spinning, using polyethylene glycol diacrylate (PEGDA) as the raw material and combining photocrosslinking technology to achieve the continuous preparation of covalently cross-linked hydrogel fibers. This strategy couples the two processes of fiber drawing and polymer cross-linking and curing, which has inspired subsequent related research. However, after the hydrogel fibers are formed, they still need to rely on weaving technology to obtain fiber aggregates, and the process is relatively complicated.

From the perspective of fiber refinement and the regulation of the spatial geometric structure of fiber aggregates, electrospinning shows unique advantages. This method can not only obtain continuously formed ultrafine/nanofibers, but also construct fiber aggregates with adjustable porosity in one step. However, the research on the preparation of hydrogel ultrafine fibers by electrospinning is still in the exploratory stage, and there are still bottlenecks in fiber forming that have not been broken through. In view of this, some researchers used gelatin-hydroxyphenylpropionic acid (Gel-HPA) as raw material for spinning, and then achieved enzymatic covalently cross-linked hydrogel single ultrafine fibers through impregnation treatment. However, this method of separating fiber forming from cross-linking process can only achieve a lower cross-linking density, and due to the single structure, the fiber is prone to deformation and the morphology will be destroyed during post-processing.

The gradient hierarchical structure of hydrogel ultrafine fibers is composed of hydrogel fibers with different diameters, and has excellent performance in porosity, swelling rate and mechanical properties.

However, there is no method in the prior art that can directly utilize electrospinning to obtain a hydrogel ultrafine fiber material with a stable structure and a gradient layered structure.

The present application achieves in-situ assembly of fiber aggregates and obtains a structurally stable gradient hierarchical hydrogel ultrafine fiber membrane by breaking the dynamic bonds between hydrogel precursors under the action of electric polarization and thermal induction, and simultaneously rapidly cross-linking and polymerizing the precursors under light/heat regulation.

Summary of the invention

In order to solve the problems that a hydrogel ultrafine fiber material with a gradient layered structure cannot be continuously formed, has a low cross-linking density, and is easy to deform during its preparation, the present invention provides a hydrogel ultrafine fiber material with a gradient layered structure and a preparation method thereof.

The technical solution adopted by the present invention is:

A method for preparing a hydrogel ultrafine fiber material with a gradient layered structure comprises the following steps:

(1) dissolving polysaccharides, polypeptides or synthetic oligomers as raw materials of hydrogel precursors in a hydrochloric acid solution to obtain a mixed solvent with a mass-volume concentration of 2-100 g/L, and then adding thioglycolic acid to the mixed solvent for thiolation reaction to obtain a hydrogel precursor solution, wherein the mass ratio of the oligomer to the thioglycolic acid in the thiolation reaction is 1-10:1-5;

(2) using a silane coupling reaction to graft an acrylate group onto the hydrogel precursor in step (1), so that the hydrogel precursor obtains a cross-linking group, thereby obtaining a modified hydrogel precursor dispersion;

(3) The modified hydrogel precursor dispersion in step (2) is transferred to a plurality of electrospinning syringes placed side by side in an electrospinning machine for electrospinning. An external ultraviolet light is set between the syringe needle and the dynamic receiving conveyor belt to irradiate the modified hydrogel precursor dispersion ejected from the syringe needle. The distance between each syringe needle and the ultraviolet light irradiation is different. The syringe needle ejects the modified hydrogel precursor dispersion. The dispersion is irradiated with ultraviolet light at different positions to form hydrogel fibers with different diameters. The hydrogel fibers with different diameters are stacked on the dynamic receiving conveyor belt to form hydrogel ultrafine fibers with a gradient layered structure.

The reason why the hydrogel fibers prepared by the above method can form a gradient layered structure is that the ultraviolet light irradiation and the injection positions of each syringe are different, which makes the dispersion curing speed different, resulting in different fiber diameters formed by each injector, and therefore different pore sizes of the film; in addition, the conveyor belt is always in motion, and finally a gradient layered structure of hydrogel ultrafine fibers can be obtained, wherein the addition of thioglycolic acid solvent is to introduce thiol dynamic bond groups into the hydrogel precursor.

Furthermore, the oligomer is selected from one or more combinations of hyaluronic acid, cellulose, alginate, chitosan, collagen, poly-L-glutamic acid, polyvinyl alcohol, and polyacrylate.

Furthermore, in step (1), the thiolation reaction is carried out under constant temperature conditions, the constant temperature reaction temperature is 40-60° C., and the reaction time is 2-8 hours.

Furthermore, in step (2), the silane coupling reaction uses silane coupling agent G-570, and the mass ratio of the silane coupling agent G-570 to the hydrogel precursor in step (1) is 1:30~50.

Furthermore, in step (2), the silane coupling reaction is carried out under constant temperature conditions, the constant temperature reaction temperature is 30-80° C., and the reaction time is 20-60 min.

Furthermore, in step (3), the external ultraviolet light is provided by an ultraviolet lamp, the wavelength of the ultraviolet light is 365nm, and the power of the ultraviolet lamp is 30~75W.

Furthermore, in step (3), there are three electrospinning syringes; the distance between the first syringe needle and the ultraviolet light is L, the distance between the second syringe needle and the ultraviolet light is 2L, and the distance between the third syringe needle and the ultraviolet light is 3L, 8cm≥L>0cm, and the distance between the syringe needle and the ultraviolet light is less than the distance between the syringe needle and the receiving conveyor belt.

Furthermore, in step (3), the electrospinning parameters are: spinning speed 1.5~20 μm/min, applied voltage 10~20 kV, distance between syringe needle and collecting conveyor belt 10~30 cm, and receiving conveyor belt speed 100~300 rad/min.

The present invention also provides a hydrogel ultrafine fiber material with a gradient layered structure, which is obtained by any one of the above preparation methods.

Beneficial effects of the present invention:

The present invention can prepare hydrogel fibers with stable gradient hierarchical structures. The hydrogel fibers have high porosity, high swelling rate and good mechanical properties. The preparation method of the present invention is simple, the spinning process is continuous, and it can be applied on a large scale, with good universality.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a microscopic morphology of the gradient hierarchical structure hydrogel fiber prepared in Example 1 under a scanning electron microscope.

Figure 2 shows the stress-strain curve of the gradient layered hydrogel microfiber membrane under swelling equilibrium (stress peak and strain valley).

Figure 3 shows the stress-strain curve (stress valley value and strain peak value) of the gradient layered hydrogel microfiber membrane under swelling equilibrium.

FIG4 is a stress-strain curve (stress valley value and strain peak value) of the gradient layered hydrogel microfiber membrane after drying.

FIG5 is a stress-strain curve (stress peak and strain valley) of the gradient layered hydrogel microfiber membrane after drying.

FIG6 is a graph showing the swelling performance of the gradient hierarchical structure hydrogel fiber prepared in Example 1.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with a preferred embodiment. The universal tensile testing machine used in the following examples and comparative examples is Instron 3400-10TM.

Example 1

A method for preparing a gradient hierarchical structure hydrogel ultrafine fiber membrane, the specific steps are as follows:

At room temperature, 5 g of chitosan was first dissolved in 100 mL of hydrochloric acid solution, and 1 g of thioglycolic acid was added to carry out thiol reaction, and the temperature was controlled at 50 ° C for 3 h to obtain hydrogel precursor solution A. Then, silane coupling agent G-570 was added to A solution at a mass ratio of 1:30, and the reaction was carried out at 30 ° C for 20 min to obtain modified hydrogel precursor solution B. Next, solution B was transferred to three 5 mL electrospinning syringes, designated as X, Y, and Z respectively; the electrospinning parameters were set as follows: spinning speed of 1.5 μm/min, applied voltage of 10 kV, distance between syringe needle and collection conveyor belt of 20 cm, conveyor belt speed of 100 rad/min, distance between X syringe needle and external ultraviolet light irradiation of 5 cm, distance between Y syringe needle and external ultraviolet light irradiation of 10 cm, distance between Z syringe needle and external ultraviolet light irradiation of 15 cm, ultraviolet light power of 30 W, and dynamic stratified jetting was performed to obtain a hydrogel ultrafine fiber membrane with a gradient stratified structure.

The gradient layered hydrogel ultrafine fiber membrane obtained in Example 1 was scanned by electron microscope, as shown in FIG1 . The gradient layered hydrogel ultrafine fiber membrane has a fiber diameter of 100 to 500 nm and has the advantages of high porosity and high swelling rate.

Mechanical properties test: The hydrogel microfiber membrane with gradient layered structure in Example 1 was made into multiple 50mm*10mm rectangular strips, and the mechanical properties of the samples were tested by a universal tensile testing machine, with a tensile speed of 0.3mm/min and a gauge length of 20mm. The test was divided into two groups, one of which was a hydrogel microfiber membrane with gradient layered structure under swelling equilibrium, with a stress of 2.16~2.88MPa and a strain of 41.76%~52.20% (see Figures 2 and 3 of the specification for details); the other group of hydrogel microfiber membranes with gradient layered structure after drying had a stress of 5.95~7.73MPa and a strain of 2.43%~3.24% (see Figures 4 and 5 of the specification for details).

Swelling rate test: The gradient layered hydrogel microfiber membrane of Example 1 was dried and weighed, recorded as M ₀ , and then the sample was immersed in a PBS solution (10 mL, 0.01 mol/L, pH = 7.4). At different time intervals, the surface water was absorbed with filter paper, and then the weight of the wet fiber hydrogel was accurately weighed, recorded as Mt. The swelling ratio was calculated according to the formula, swelling ratio (%) = (Mt - M ₀ )/M ₀ × 100%. The maximum swelling rate of the gradient layered hydrogel microfiber membrane was 325%, indicating that the swelling rate was good (see Figure 6 of the specification for details).

Example 2

A method for preparing a gradient hierarchical structure hydrogel ultrafine fiber membrane, the specific steps are as follows:

At room temperature, 10 g of hyaluronic acid was first dissolved in 200 mL of hydrochloric acid solution, and 1 g of thioglycolic acid was added to carry out thiol reaction, and the temperature was controlled at 70°C for 3 h to obtain hydrogel precursor solution A. Then, silane coupling agent G-570 was added to solution A at a mass ratio of 1:40, and the reaction was carried out at 30°C for 20 min to obtain modified hydrogel precursor solution B. Next, solution B was transferred to three 5 mL electrospinning syringes, designated as X, Y, and Z respectively; the electrospinning parameters were set as follows: spinning speed of 5 μm/min, applied voltage of 15 kV, distance between syringe needle and collection conveyor belt of 20 cm, conveyor belt speed of 100 rad/min, distance between X syringe needle and external ultraviolet light irradiation of 5 cm, distance between Y syringe needle and external ultraviolet light irradiation of 10 cm, distance between Z syringe needle and external ultraviolet light irradiation of 15 cm, ultraviolet light power of 30 W, and dynamic stratified jetting was performed to obtain a hydrogel ultrafine fiber membrane with a gradient stratified structure.

Example 3

A method for preparing a gradient hierarchical structure hydrogel ultrafine fiber membrane, the specific steps are as follows:

At room temperature, 10 g of hyaluronic acid was first dissolved in 200 mL of hydrochloric acid solution, and 1 g of thioglycolic acid was added to carry out thiol reaction, and the temperature was controlled at 70°C for 3 h to obtain hydrogel precursor solution A. Then, silane coupling agent G-570 was added to solution A at a mass ratio of 1:40, and the reaction was carried out at 30°C for 20 min to obtain modified hydrogel precursor solution B. Next, solution B was transferred to three 5 mL electrospinning syringes, designated as X, Y, and Z respectively; the electrospinning parameters were set as follows: spinning speed of 5 μm/min, applied voltage of 15 kV, distance between syringe needle and collection conveyor belt of 30 cm, conveyor belt speed of 100 rad/min, distance between X syringe needle and external ultraviolet light irradiation of 8 cm, distance between Y syringe needle and external ultraviolet light irradiation of 16 cm, distance between Z syringe needle and external ultraviolet light irradiation of 24 cm, ultraviolet light power of 30 W, and dynamic stratified jetting was performed to obtain a hydrogel ultrafine fiber membrane with a gradient stratified structure.

Comparative Example 1

At room temperature, 5g of chitosan was first dissolved in 100mL of hydrochloric acid solution, and 1g of thioglycolic acid was added to carry out thiol reaction. The temperature was controlled at 50°C for 3h to obtain hydrogel precursor A solution. Then, silane coupling agent G-570 was added to A solution at a mass ratio of 1:30, and the reaction was carried out at 30°C for 20min to obtain modified hydrogel precursor solution B. Then, solution B was transferred to a 5mL electrospinning syringe, and the electrospinning parameters were set, with a spinning speed of 1.5μm/min, an applied voltage of 10kV, a distance of 20cm between the syringe needle and the collection conveyor belt, a conveyor belt speed of 100rad/min, and a distance of 10cm between the syringe needle and the external ultraviolet light irradiation to obtain a hydrogel nanofiber membrane.

Mechanical properties test: The hydrogel nanofiber membrane in comparative example 1 was made into a 50mm*10mm rectangular strip, and the mechanical properties of the sample were tested by a universal tensile testing machine, with a tensile speed of 0.3mm/min and a gauge length of 20mm. The test was divided into two groups, one of which was a hydrogel nanofiber membrane under swelling equilibrium, with a stress of 1.52~2.03 MPa and a strain of 32.85%~41.43%; the other group was a hydrogel ultrafine fiber membrane with a gradient layered structure after drying, with a stress of 5.19~6.72 MPa and a strain of 2.16%~2.92%.

Swelling rate test: The hydrogel nanofiber membrane of comparative example 1 was dried and weighed, recorded as M ₀ , and then the sample was immersed in a PBS solution (10 mL, 0.01 mol/L, pH=7.4). At different time intervals, the surface moisture was absorbed by filter paper, and then the weight of the wet fiber hydrogel was accurately weighed, recorded as Mt. The swelling ratio was calculated according to the formula, and the maximum swelling ratio of the hydrogel nanofiber membrane was 220%.

Test results analysis

Compared with comparative example 1, in terms of mechanical properties, Example 1 has the following characteristics: the stress of the hydrogel ultrafine fiber with gradient layered structure under swelling equilibrium is about 29% higher than that of the hydrogel nanofiber membrane, and the strain is increased by about 21%; the stress of the hydrogel ultrafine fiber with gradient layered structure after drying is about 13% higher than that of the hydrogel nanofiber membrane, and the strain is increased by about 10%. In terms of water absorption performance, the maximum swelling rate of the hydrogel ultrafine fiber membrane with gradient layered structure is about 33% higher than that of the hydrogel nanofiber membrane. This shows that the mechanical properties and water absorption properties of the hydrogel ultrafine fiber material with gradient layered structure in Example 1 are better than those of the hydrogel nanofiber membrane in the comparative example.

The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications are also within the protection scope of the present invention.

Claims (8)

1. The preparation method of the hydrogel superfine fiber material with the gradient layered structure is characterized by comprising the following steps of:

(1) Polysaccharide, polypeptide or artificially synthesized oligomer is taken as a hydrogel precursor raw material to be dissolved in hydrochloric acid solution to obtain a mixed solvent with the mass-volume concentration of 2-100g/L, and thioglycollic acid is added into the mixed solvent to carry out a thiolation reaction to obtain a hydrogel precursor solution, wherein the mass ratio of the oligomer to the thioglycollic acid in the thiolation reaction is 1-10:1-5;

(2) Grafting an acrylic ester group onto the hydrogel precursor obtained in the step (1) by utilizing a silane coupling reaction, so that the hydrogel precursor obtains a crosslinking group, and a modified hydrogel precursor dispersion liquid is obtained;

(3) Transferring the modified hydrogel precursor dispersion liquid in the step (2) to a plurality of electrostatic spinning injectors which are arranged side by side of an electrostatic spinning machine respectively, carrying out electrostatic spinning, arranging ultraviolet irradiation between an injector needle and a dynamic receiving conveyor belt, and irradiating the modified hydrogel precursor dispersion liquid ejected by the injector needle, wherein the irradiation distance between each injector needle and the ultraviolet irradiation distance is different; the syringe needle sprays the modified hydrogel precursor dispersion liquid, the dispersion liquid is irradiated by ultraviolet light at different positions to form hydrogel fibers with different diameters, and the hydrogel fibers with different diameters are stacked on a dynamic receiving conveyor belt to form hydrogel superfine fibers with a gradient layered structure;

the oligomer is selected from hyaluronic acid or chitosan.

2. The preparation method according to claim 1, wherein in the step (1), the sulfhydrylation reaction is performed under a constant temperature condition, the constant temperature reaction temperature is 40-60 ℃, and the reaction time is 2-8 hours.

3. The preparation method of claim 1, wherein in the step (2), the silane coupling reaction adopts a silane coupling agent G-570, and the mass ratio of the silane coupling agent G-570 to the hydrogel precursor in the step (1) is 1:30-50.

4. The preparation method according to claim 1, wherein in the step (2), the silane coupling reaction is performed under a constant temperature condition, the constant temperature reaction temperature is 30-80 ℃, and the reaction time is 20-60 min.

5. The method according to claim 1, wherein in the step (3), the ultraviolet light is provided by an ultraviolet lamp, the wavelength of the ultraviolet light is 365nm, and the power of the ultraviolet lamp is 30-75 w.

6. The method according to claim 1, wherein in the step (3), there are 3 electrospinning injectors; the first syringe needle is L with ultraviolet irradiation distance, the second syringe needle is 2L with ultraviolet irradiation distance, the third syringe needle is 3L with ultraviolet irradiation distance, 8cm is greater than or equal to L >0cm, and the syringe needle is less than the syringe needle with receiving conveyor.

7. The method according to claim 6, wherein in the step (3), the electrospinning parameters are as follows: the spinning speed is 1.5-20 mu m/min, the applied voltage is 10-20 kV, the distance between the needle of the injector and the receiving conveyor belt is 10-30 cm, and the rotating speed of the collecting conveyor belt is 100-300 rad/min.

8. A hydrogel ultrafine fibrous material having a gradient layered structure, characterized in that it is produced by the production method according to any one of claims 1 to 7.