阅读说明：本技术 一种壳聚糖基纳米纤维及其制备方法 (Chitosan-based nanofiber and preparation method thereof ) 是由 胡俊丽 刘益春 张慧 于 2021-07-22 设计创作，主要内容包括：本发明提供一种壳聚糖基纳米纤维及其制备方法,属于高分子纤维领域。该制备方法将壳聚糖溶解到稀酸水溶液中,处理后得到壳聚糖酸盐；将得到的壳聚糖酸盐与水溶性柔性高分子共同溶解于水,静电纺丝,得到纺丝纤维；最后将纺丝纤维进行加热处理,得到壳聚糖基纳米纤维。本发明还提供上述制备方法得到的壳聚糖基纳米纤维,本发明的制备方法简单、快捷、成本低、静电纺丝步骤之后无液相后处理,也不引入毒性试剂。该壳聚糖基纳米纤维能够耐受水相环境,在生理的水相条件下具有良好的结构稳定性,可生物医用。(The invention provides chitosan-based nano-fibers and a preparation method thereof, belonging to the field of polymer fibers. The preparation method comprises the steps of dissolving chitosan into dilute acid water solution, and treating to obtain chitosan acid salt; dissolving the obtained chitosan acid salt and the water-soluble flexible polymer in water together, and performing electrostatic spinning to obtain spinning fibers; finally, the spinning fiber is heated to obtain the chitosan-based nanofiber. The invention also provides the chitosan-based nanofiber prepared by the preparation method, and the preparation method is simple, quick and low in cost, and has no liquid-phase post-treatment after the electrostatic spinning step and no toxic reagent introduced. The chitosan-based nanofiber can resist an aqueous phase environment, has good structural stability under physiological aqueous phase conditions, and can be used for biomedical applications.)

1. A preparation method of chitosan-based nanofibers is characterized by comprising the following steps:

the method comprises the following steps: dissolving chitosan into dilute acid water solution, and treating to obtain chitosan acid salt;

step two: dissolving the chitosan acid salt obtained in the step one and a water-soluble flexible polymer in water together, and performing electrostatic spinning to obtain a spinning fiber;

step three: and (4) heating the spinning fiber obtained in the step (II) to obtain the chitosan-based nanofiber.

2. The method for preparing chitosan-based nanofiber according to claim 1, wherein the concentration of the dilute acid aqueous solution is 0.1-10%, and the acid in the dilute acid aqueous solution is acetic acid, formic acid, lactic acid, hydrochloric acid, nitric acid, sulfuric acid, trifluoroacetic acid or phosphoric acid.

3. The method for preparing chitosan-based nanofiber according to claim 1, wherein the treatment process of the first step is as follows: dissolving under stirring, dialyzing with water, lyophilizing, or precipitating with alcohol solvent, washing, and vacuum drying.

4. A method for preparing chitosan-based nano-fiber according to claim 1, wherein the water-soluble flexible polymer in the second step is polyethylene oxide, polyvinyl alcohol or polyvinylpyrrolidone.

5. The method for preparing chitosan-based nanofiber according to claim 1, wherein the mass ratio of the chitosan acid salt to the water-soluble flexible polymer in the second step is 70: 30-95: 5.

6. a method for preparing chitosan-based nanofiber according to claim 1, wherein the temperature of the heating treatment in the third step is 100-240 ℃ and the heating time is 0-2 hours.

7. The method for preparing chitosan-based nanofiber according to claim 1, wherein the step three further comprises washing the product after the heat treatment to remove polyethylene oxide, so as to obtain pure chitosan nanofiber.

8. A chitosan-based nanofiber obtained by the production method according to any one of claims 1 to 7.

Technical Field

The invention belongs to the field of polymer fibers, and particularly relates to chitosan-based nanofibers and a preparation method thereof.

Background

Chitosan, namely chitosan, is a product of removing partial acetyl groups of natural polysaccharide chitin, is a high molecular polymer only with positive charges in nature, has excellent biocompatibility and biodegradability, and has unique Biological functions of bacteriostasis, cancer resistance, lipid reduction, immunity enhancement and the like (Cai Lingke et al, antibacterial activity and applications of cancer, Polymers 2021,13, 904-. Electrostatic spinning is a new material preparation technology, high-voltage electric field is applied to enable a high-molecular solution to be charged and stretched to form jet flow, and superfine fibers with nanometer-level diameters are formed along with volatilization of a solvent. The nano-fibers can form a nano-porous film or a three-dimensional material with high specific surface area and high porosity by random, ordered or specific mode accumulation, and has significant advantages in the medical fields of wound repair, tissue regeneration, drug delivery and the like (Seema agar et al use of electrophoretic technology for biological applications Polymer 2008,49, 5603-. In view of the advantages of chitosan materials and electrospun nanofiber structures, research institutions at home and abroad are devoted to developing chitosan nanofiber medical materials in recent years. Since chitosan is insoluble in organic solvents and insoluble in water under neutral conditions, electrostatic spinning of chitosan is often carried out by first dissolving chitosan using an aqueous acid solution (e.g., acetic acid, trifluoroacetic acid) or the like (Kousaku Ohkawa, et al. Chitosan Nanofiber, Biomacromolecules 2006,7, 3291-3294; Sander De Vries, et al. electrospraying of chitosan nanoparticles structures: ease of spinning study. journal of Material Science 2007,42, 8029-8034; Mehdi Pakravana, et al. A fundamental study of chitosan/PEO electrospraying. Polymer 2011,52, 4813-4824). However, these acid solvents cannot be completely volatilized in the spinning process, and a part of the acid solvents can be remained in the formed chitosan nano-fiber, so that the fiber can be quickly dissolved in water and cannot be used as a material in a physiological water phase environment; therefore, in order to improve the water resistance of chitosan nanofibers, people often wash them with alkali (such as sodium carbonate, sodium hydroxide) solution to remove acid (Jae-Min park, et al. movement of chitosan-CLEA on electrochemical chitosan nanofibers nanoparticles for effective antimicrobial applications 2013,54, 37-43; Jian Du, et al. comprehensive evaluation of chitosan, cellulose acetate, and polymeric Carbohydrate nanoparticles for chemical reactions, Carbohydrate Polymers, 99,483, or glutaraldehyde cross-linking (surface Kalalinia, molecular weight of cellulose of Biological reaction, particle of molecular reaction, particle of Biological reaction, particle of molecular reaction, particle of 1, particle of Biological reaction, particle of molecular reaction, particle of molecular reaction, particle of 1, particle of molecular reaction, particle of molecular reaction, particle of molecular reaction, molecular reaction of molecular reaction, molecular reaction of molecular reaction, molecular reaction of molecular reaction, molecular reaction of molecular reaction. However, these liquid phase post-treatment processes are cumbersome and may introduce toxic agents, which are very disadvantageous for mass production and medical applications of chitosan nanofibers.

Disclosure of Invention

The invention aims to provide chitosan-based nano fiber and a preparation method thereof, wherein a liquid-phase post-treatment process is not required, and the obtained nano fiber has good water resistance.

The invention firstly provides a preparation method of chitosan-based nano-fiber, which comprises the following steps:

the method comprises the following steps: dissolving chitosan into dilute acid water solution, and treating to obtain chitosan acid salt;

step two: dissolving the chitosan acid salt obtained in the step one and a water-soluble flexible polymer in water together, and performing electrostatic spinning to obtain a spinning fiber;

step three: and (4) heating the spinning fiber obtained in the step (II) to obtain the chitosan-based nanofiber.

Preferably, the concentration of the dilute acid water solution is 0.1-10%, and the acid in the dilute acid water solution is acetic acid, formic acid, lactic acid, hydrochloric acid, nitric acid, sulfuric acid, trifluoroacetic acid or phosphoric acid.

Preferably, the processing procedure of the first step is as follows: dissolving under stirring, dialyzing with water, lyophilizing, or precipitating with alcohol solvent, washing, and vacuum drying.

Preferably, the water-soluble flexible polymer in the second step is polyethylene oxide, polyvinyl alcohol or polyvinylpyrrolidone.

Preferably, in the second step, the mass ratio of the chitosan acid salt to the water-soluble flexible polymer is 70: 30-95: 5.

preferably, the temperature of the heating treatment in the third step is 100-240 ℃, and the heating time is 0-2 hours.

Preferably, the third step further comprises washing the heat-treated product to remove polyethylene oxide, so as to obtain pure chitosan nanofiber.

The invention also provides the chitosan-based nanofiber prepared by the preparation method.

The invention has the advantages of

The invention provides a chitosan-based nanofiber and a preparation method thereof, the method comprises the steps of firstly preparing chitosan acid salt, then dissolving the chitosan acid salt and flexible water-soluble polymers into water for electrostatic spinning, then heating the obtained fiber, and in the spinning and/or heating process, acid radicals are separated from chitosan, thus obtaining the chitosan-based nanofiber with water resistance. The preparation method is simple and rapid, has low cost, does not have liquid phase post-treatment after the electrostatic spinning step, and does not introduce toxic reagents.

The invention also provides the chitosan-based nanofiber prepared by the preparation method, and the chitosan-based nanofiber can resist an aqueous phase environment, has good structural stability under physiological aqueous phase conditions, and can be used for biomedical applications.

Drawings

FIG. 1 is a scanning electron micrograph of chitosan-based nanofibers obtained in example 1 of the present invention and a scanning electron micrograph (a) and a quality maintenance (b) after immersion in a simulated body fluid at 37 ℃.

FIG. 2 is a SEM photograph of chitosan-based nanofibers obtained in example 2 of the present invention.

FIG. 3 is a scanning electron microscope photograph of chitosan-based nanofibers obtained in example 3 of the present invention initially and after being soaked in a simulated body fluid at 37 ℃ for 1 week.

FIG. 4 is a SEM photograph of chitosan-based nanofibers obtained in example 4 of the present invention initially and after 1 week of soaking in a simulated body fluid.

Detailed Description

The invention firstly provides a preparation method of chitosan-based nano-fiber, which comprises the following steps:

the method comprises the following steps: dissolving chitosan into dilute acid water solution, and treating to obtain chitosan acid salt; the treatment process preferably comprises: stirring for dissolving, dialyzing with water, lyophilizing, or precipitating with alcohol solvent, washing, and vacuum drying; the alcohol solvent is preferably ethanol, the concentration of the dilute acid aqueous solution is preferably 0.1-10%, more preferably 0.5-2%, the selection of acid in the dilute acid aqueous solution directly influences the subsequent heat treatment step, the acid is preferably acetic acid, formic acid, lactic acid, hydrochloric acid, nitric acid, sulfuric acid, trifluoroacetic acid or phosphoric acid, when the acid is acetic acid, the chitosan salt is easy to decompose due to weak acidity of the acetic acid, heat treatment is not needed, and the fiber directly obtained by electrospinning has water resistance;

step two: dissolving the chitosan acid salt obtained in the step one and a water-soluble flexible polymer in water together, and performing electrostatic spinning to obtain a spinning fiber; the water-soluble flexible polymer is preferably polyethylene oxide, polyvinyl alcohol or polyvinylpyrrolidone, more preferably polyethylene oxide, and due to the characteristic of molecular chain flexibility of polyethylene oxide, the water-soluble flexible polymer is combined with the chitosan acid salt to play a role in promoting molecular chain entanglement of the chitosan acid salt, so that the effect of forming fibers by electrospinning is achieved; the mass ratio of the chitosan acid salt to the water-soluble flexible polymer is preferably 70: 30-95: and 5, the electrostatic spinning conditions are preferably 6-30 kV voltage and 10-30 cm distance between a spinning nozzle and a receiver.

Step three: and (4) heating the spinning fiber obtained in the step (II) to obtain the chitosan-based nanofiber.

The temperature of the heating treatment is preferably 100-240 ℃, more preferably 120-160 ℃, and the heating time is preferably 0-12 hours, more preferably 30 minutes-2 hours.

According to the invention, the third step also comprises the step of washing the product after the heat treatment with water to remove polyoxyethylene, so as to obtain the pure chitosan nano fiber.

The invention also provides the chitosan-based nanofiber prepared by the preparation method.

The present invention is further illustrated by the following specific examples, but the present invention is not limited thereto.

Example 1: acetic acid is used as acid, and polyoxyethylene is used as flexible water-soluble polymer to prepare the chitosan/polyoxyethylene nano-fiber.

(1) Adding chitosan into water, adding acetic acid, stirring and dissolving for 8 hours to obtain a solution with the acetic acid concentration of 2% and the chitosan concentration of 2%. Transferring the solution into a dialysis bag with molecular weight cutoff of 3500, dialyzing with a large amount of ultrapure water for 8 times, each time for 3 hours, and freeze-drying with a freeze-drying machine to obtain chitosan acetate;

(2) respectively preparing 2.5% of chitosan acetate and 4% of polyoxyethylene (molecular weight is 500 ten thousand) aqueous solution, then mixing the two solutions according to the mass ratio of 80:20 of the chitosan acetate to the polyoxyethylene, uniformly stirring the mixed solution at room temperature, standing overnight to obtain a uniform mixed solution without bubbles, placing the mixed solution in a high-voltage electric field of 20kV for spinning, and collecting fibers at a position 25cm away from a spinning nozzle;

and carrying out appearance test on the obtained material, soaking the material into simulated body fluid, carrying out constant-temperature culture at 37 ℃ for a certain time, representing the appearance and quality of the material, and evaluating the water resistance of the material. As shown in figure 1, the nanofiber has a smooth surface, has a good appearance within 4 weeks of simulated body fluid soaking, and loses less than 30% of mass, indicating that the nanofiber has excellent water resistance.

Example 2: acetic acid is used as acid, and polyvinyl alcohol is used as flexible water-soluble polymer to prepare the chitosan/polyvinyl alcohol nano-fiber.

(1) Preparing chitosan acetate according to the method of example 1, preparing 2.5% solution, preparing 10% polyvinyl alcohol (molecular weight is 10 ten thousand) aqueous solution, mixing the two solutions according to the mass ratio of the chitosan acetate to the polyvinyl alcohol of 40:60, stirring the mixed solution uniformly at room temperature, standing overnight to obtain uniform mixed solution without bubbles, placing the mixed solution in a high-voltage electric field of 25kV for spinning, and collecting fibers at a position 22cm away from a spinning nozzle to obtain the chitosan/polyvinyl alcohol nanofibers. As shown in figure 2, the nanofiber has good appearance, and still maintains 39.2 percent of initial mass after being soaked in simulated body fluid and cultured at constant temperature of 37 ℃ for 1 week, which indicates that the nanofiber has certain water resistance.

Example 3: the chitosan/polyethylene oxide nano-fiber is prepared by using formic acid as acid and polyethylene oxide as flexible water-soluble polymer.

(1) Adding chitosan into water, adding formic acid, stirring and dissolving for 12 hours to obtain a solution with the concentration of 2 percent of formic acid and the concentration of 2 percent of chitosan. Transferring the solution into a dialysis bag with molecular weight cutoff of 3500, dialyzing with a large amount of ultrapure water for 8 times, each time for 3 hours, and freeze-drying with a freeze-drying machine to obtain chitosan formate;

(2) respectively preparing 2.5% of chitosan formate and 4% of polyoxyethylene (molecular weight is 500 ten thousand) aqueous solution, then mixing the two solutions according to the mass ratio of 80:20 of the chitosan formate to the polyoxyethylene, uniformly stirring the mixed solution at room temperature, standing overnight to obtain a uniform mixed solution without bubbles, placing the mixed solution in a high-voltage electric field of 20kV for spinning, and collecting fibers at a position 25cm away from a spinning nozzle;

(3) the resulting nanofibers were placed in an oven and heated at 120 ℃ for 30 minutes.

As shown in figure 3, the obtained nanofibers have good morphology, and the initial mass of the nanofibers and the morphology of the nanofibers are maintained at 62.6% after the nanofibers are soaked in simulated body fluid and cultured at the constant temperature of 37 ℃ for 1 week, which shows that the nanofibers have better water resistance.

Example 4: pure chitosan nano-fiber

The chitosan/polyethylene oxide nanofibers obtained in example 1 were washed with a large amount of pure water to remove polyethylene oxide, and freeze-dried to obtain pure chitosan nanofibers.

As shown in FIG. 4, the obtained nanofibers have good morphology, and the original quality of the nanofibers still maintains 98.9% after being soaked in simulated body fluid and cultured at constant temperature of 37 ℃ for 1 week, which shows that the nanofibers have excellent water resistance.