Hydroxybutyl chitosan, hydroxybutyl chitosan hydrogel and preparation method thereof

Abstract

The invention discloses a hydroxybutyl chitosan, a hydroxybutyl chitosan hydrogel and a preparation method. The final product hydroxybutyl chitosan is obtained by crushing, dissolving, butylene oxide modification and purification of chitosan. The hydroxybutyl chitosan prepared by the method has good solubility in purified water and can form a hydrogel with a low solid content. The hydroxybutyl chitosan hydrogel may have broad application prospects in the fields of biomedicine, absorbable materials, etc.

Description

Technical Field

[0001] The invention belongs to the technical field of materials and relates to a hydroxybutyl chitosan hydrogel and a preparation method thereof. Background Art

[0002] Chitosan is a linear polysaccharide natural polymer, and its repeating unit is 2-acetylamino-(1,4)-β-glucose. Chitosan is widely present in nature, and its sources are mainly concentrated in the shells of animals such as fish, shrimp and crabs and the cell walls of fungi. Chitosan is the most abundant nitrogen-containing organic matter in nature and one of the most abundant polymers in nature. Chitosan has many excellent properties, such as excellent biocompatibility, low immunogenicity, good hemostasis, etc., and has broad application prospects in the fields of biomedicine, absorbable materials, etc.

[0003] Chitosan derivative hydrogel is a kind of excellent absorbable material. Due to the sugar interactions and hydrogen bonds within or between chitosan molecules, as well as the linear molecular structure that easily causes dense molecular stacking, chitosan has poor solubility and is mostly a structural material of crustaceans in nature. Chitosan is modified by using some reagents, and the molecular dense stacking ability of the obtained chitosan derivatives is reduced and the water solubility is improved. By changing the type and amount of reagents, the balance between the hydrophilicity and hydrophobicity of chitosan derivative molecules can be adjusted to obtain chitosan derivative hydrogels. There are two common chitosan modification reagents, one is halogenated hydrocarbon reagents and the other is epoxy reagents. Halogenated hydrocarbon reagents include chloroacetic acid, chloroethanol, etc., and carboxymethyl chitosan and hydroxyethyl chitosan are obtained through the substitution reaction of chitosan hydroxyl groups. Common epoxy reagents include propylene oxide, etc., and the resulting derivatives are hydroxypropyl chitosan. The above chitosan derivatives can form hydrogels through physical crosslinking, which has become one of the current research hotspots. Summary of the invention

[0004] The purpose of the present invention is to discover new chitosan derivatives and explore new chitosan hydrogels. The prepared hydroxybutyl chitosan has good dispersibility in water phase and can be prepared as physical hydrogels, which have broad application prospects in tissue engineering, cell culture, Class III medical devices, etc. To this end, the inventor proposes the following technical solutions based on research and experimental results:

[0005] According to the first aspect of the present invention, the present invention adopts the following technical solution:

[0006] A method for preparing hydroxybutyl chitosan, characterized in that it comprises the following steps:

[0007] (1) Chitosan is dispersed in an alkaline aqueous solution at low temperature;

[0008] (2) adding butylene oxide or diluted butylene oxide to the chitosan aqueous phase system and stirring for reaction;

[0009] (3) After the reaction is completed, hydroxybutyl chitosan is obtained through dialysis and freeze-drying.

[0010] On the basis of adopting the above technical solutions, the present invention may also adopt or combine the following further technical solutions to form various further optimized technical solutions:

[0011] In step (1), the chitosan powder is added to an alkaline aqueous solution and then treated at -20°C to room temperature for 1 to 30 days.

[0012] In step (2), before being added to the alkaline aqueous solution of chitosan, epoxybutane is diluted by a mixed reagent to adjust the gel effect of hydroxybutyl chitosan; the mixed reagent includes: one or more of methanol, ethanol, isopropanol, and n-butanol (the volume fraction of all alcohol reagents in the mixed reagent is preferably 20%-80%); purified water (the volume fraction of the mixed reagent is preferably 20%-80%); one or more of sodium dodecyl sulfate, sodium iodide, and potassium iodide (the total concentration of the mixed reagent is preferably 0-0.1g / mL); one or more of lithium chloride, sodium chloride, potassium chloride, and cesium chloride (the total concentration of the mixed reagent is preferably 0-0.1g / mL). Its preparation method is: in epoxybutane, add alcohol reagents, purified water, and salt reagents in order, stir evenly, and use.

[0013] In step (2), butylene oxide or diluted butylene oxide is added to the alkaline aqueous solution of chitosan, and the mixture is stirred at 0° C. to 45° C. for 1 to 7 days.

[0014] In step (3), the reaction system is diluted 1-20 times with purified water, dialyzed, and freeze-dried.

[0015] According to the second aspect of the present invention, the present invention adopts the following technical solution:

[0016] A method for preparing hydroxybutyl chitosan hydrogel, characterized in that it comprises the following preparation steps:

[0017] The hydroxybutyl chitosan prepared by any of the above preparation methods is added to purified water, stirred at 0°C-30°C, and after being completely dissolved, a hydroxybutyl chitosan hydrogel is formed.

[0018] According to the third aspect of the present invention, the present invention adopts the following technical solution:

[0019] A hydroxybutyl chitosan is characterized in that it is hydroxybutyl chitosan prepared by a preparation method comprising the above preparation steps.

[0020] According to a fourth aspect of the present invention, the present invention adopts the following technical solution:

[0021] A hydroxybutyl chitosan hydrogel is characterized in that it is the hydroxybutyl chitosan hydrogel prepared by the preparation method comprising the above steps.

[0022] The inventor attempts to modify chitin with butylene oxide in the present invention, and prepares hydroxybutyl chitin and its hydrogel. Compared with the chitin modification reagent reported, butylene oxide is more hydrophobic, suitable for modifying polymers (such as chitosan, etc.) that are more hydrophilic than chitin, and there will be more difficulties in chitin modification reaction and product purification, such as phase separation in reaction, uncontrollable precipitation in purification, etc. However, considering the adjustment of the hydrophilicity / hydrophobicity balance of chitin derivatives, hydroxybutyl chitin and its hydrogel will show new properties. The research and development of hydroxybutyl chitin and its hydrogel is of great significance for further exploring the gel mechanism of physical hydrogels, exploring new chitin modification methods, and discovering new chitin derivative hydrogel properties.

[0023] The hydroxybutyl chitosan product of the present invention is a white sponge-like solid that is easy to absorb moisture. Experiments have shown that the hydroxybutyl chitosan of the present invention has good dispersibility in purified water, and its solid content can be between 2.0% and 2.5%.

[0024] The present invention is further described below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the infrared spectrum of hydroxybutyl chitosan prepared by the present invention.

[0026] Figure 2 This is a diagram of the effect of the aqueous phase system of four hydroxybutyl chitosans at 1% mass fraction. From left to right, they are hydroxybutyl chitosan 1, hydroxybutyl chitosan 2, hydroxybutyl chitosan 3, and hydroxybutyl chitosan 4.

[0027] Figure 3 This is a diagram of the effect of the aqueous phase system of four hydroxybutyl chitosans at a mass fraction of 2%. From left to right, they are hydroxybutyl chitosan 1, hydroxybutyl chitosan 2, hydroxybutyl chitosan 3, and hydroxybutyl chitosan 4.

[0028] Figure 4 This is a diagram of the effect of the aqueous phase system of four hydroxybutyl chitosans at a mass fraction of 2.5%. From left to right, they are hydroxybutyl chitosan 1, hydroxybutyl chitosan 2, hydroxybutyl chitosan 3, and hydroxybutyl chitosan 4. DETAILED DESCRIPTION

[0029] In order to further understand the present invention, the following is a specific description of a method for preparing chitosan highly dispersed in an aqueous phase provided by the present invention in conjunction with the embodiments. However, the present invention is not limited to these embodiments, and non-essential improvements and adjustments made by technicians in this field under the core guiding ideology of the present invention still fall within the scope of protection of the present invention.

[0030] Example 1, Preparation of Chitosan Solution

[0031] (1) Preparation of chitosan powder. Weigh 20.00 g of chitosan and place it in a traditional Chinese medicine grinder for 2-5 minutes. Take out the ground chitosan and pass it through a 20-mesh and 50-mesh sieves in turn to obtain chitosan powder.

[0032] (2) Preparation of alkaline aqueous solution. Accurately weigh 129.42 g of NaOH and slowly add it to 1 L of purified water several times. After the NaOH is completely dissolved and the system temperature drops to room temperature, add 47.06 g of urea to the solution, stir to dissolve, and cool to room temperature.

[0033] (3) Dissolution and dispersion of chitosan powder. Take 1.85g chitosan powder, add it to 1L alkaline aqueous solution, and stir to disperse it. Immerse the entire system in a -20℃ low-temperature medium and treat it for 24 hours. After taking it out, return it to room temperature, stir it for 1 hour, and immerse it in a -20℃ low-temperature medium again, and let it stand at low temperature for 20 days. After taking it out, return it to room temperature to obtain a chitosan alkaline aqueous solution with better dispersion and higher viscosity.

[0034] Example 2, Preparation of Hydroxybutyl Chitosan

[0035] By changing the volume ratio of butylene oxide to the mixed reagent, four chitin modification reagents were prepared. The four reagents are: modification reagent 1 (butylene oxide volume is 100%, and the mixed reagent volume accounts for 0%), modification reagent 2 (butylene oxide volume is 75%, and the mixed reagent volume accounts for 25%), modification reagent 3 (butylene oxide volume is 25%, and the mixed reagent volume accounts for 75%), and modification reagent 4 (butylene oxide volume is 0%, and the mixed reagent volume accounts for 100%).

[0036] The components and proportions of the mixed reagent are as follows: the volume ratio of alcohol reagent to the mixed reagent is 60% (the following are the volume ratios of each reagent to the mixed reagent), of which isopropanol is 20%, ethanol is 20%, and methanol is 20%. The volume ratio of purified water is 40%. The concentration of sodium chloride is 0.01g / mL, and the concentration of sodium iodide is 0.01g / mL.

[0037] Taking modified reagent 2 as an example, its preparation method is as follows: accurately measure 30 mL of butylene oxide, add 2 mL of isopropanol, 2 mL of ethanol, and 2 mL of methanol thereto in sequence, and stir evenly. Weigh 0.1 g of sodium chloride and 0.1 g of sodium iodide, add 4 mL of purified water in sequence, and stir to dissolve. Add the purified aqueous solution of sodium chloride and sodium iodide dropwise to the mixed solution of butylene oxide and alcohols, and stir evenly to obtain mixed reagent 2. Prepare modified reagents 1-4 according to the above method.

[0038] Take 4 kinds of modification reagents (each reagent is 5 mL), respectively drip into 50 mL of the chitosan solution prepared in Example 1, and stir and react for 2 days at 4°C. The corresponding relationship between the modification reaction and the obtained product is as follows: the product modified by modification reagent 1 is hydroxybutyl chitosan 1, the product modified by modification reagent 2 is hydroxybutyl chitosan 2, the product modified by modification reagent 3 is hydroxybutyl chitosan 3, and the product modified by modification reagent 4 is hydroxybutyl chitosan 4.

[0039] Example 3, Purification of Hydroxybutyl Chitosan

[0040] (1) Take out the aqueous phase system in Example 2, add 150 mL of purified water, and stir evenly.

[0041] (2) Filter out the insoluble matter in the system and dialyze with a 5000 cellulose ester dialysis bag. The amount of purified water for each dialysis is 5 L. Change the water every 4 hours for 4 consecutive times; then change the water every 12 hours for 6 consecutive times.

[0042] (3) After the dialysis is completed, the liquid in the bag is taken out and freeze-dried to obtain hydroxybutyl chitosan. The infrared data of hydroxybutyl chitosan 2 is as follows Figure 1 shown.

[0043] Example 4, Preparation of Hydroxybutyl Chitosan Hydrogel

[0044] Weigh a certain amount of 4 kinds of hydroxybutyl chitosan, and then add 3.5mL purified water. Prepare 4 kinds of hydroxybutyl chitosan systems at 1%, 2%, and 2.5% mass fractions respectively. Shake at room temperature for 3 minutes and place in a 4°C refrigerator for 0.5 hours. Take out the sample and stir at 4°C for 15 hours to obtain a stable hydroxybutyl chitosan aqueous phase system. Among them, the dissolution and dispersion time of hydroxybutyl chitosan 1 requires more than 12 hours, and the dissolution and dispersion time of other hydroxybutyl chitosans is 5-8 hours.

[0045] like Figure 2 As shown, at 1% mass fraction, hydroxybutyl chitosan 1 forms a viscous liquid, and hydroxybutyl chitosan 2, 3, and 4 form solutions with good fluidity. After being placed at room temperature for 14 days, flocculent precipitation appeared in the hydroxybutyl chitosan 4 system.

[0046] like Figure 3As shown, at 2% mass fraction, hydroxybutyl chitosan 1 and 2 form hydrogels, and hydroxybutyl chitosan 3 and 4 form solutions with good fluidity. Hydroxybutyl chitosan 1 requires a long dispersion time (about 12 hours). After being placed at room temperature for 14 days, the hydroxybutyl chitosan 1 hydrogel will ooze out a small amount of purified water, and the gel stability is not high; flocculent precipitation appears in the hydroxybutyl chitosan 4 system.

[0047] like Figure 4 As shown, when the mass fraction is further increased to 2.5%, hydroxybutyl chitosan 1, 2, and 3 form hydrogels, and hydroxybutyl chitosan 4 forms a solution with good fluidity. The dispersion time required for hydroxybutyl chitosan 1 is still relatively long (about 12 hours). After being placed at room temperature for 14 days, the hydroxybutyl chitosan 1 hydrogel will ooze out a small amount of purified water, and the gel stability is not ideal; flocculent precipitation appears in the hydroxybutyl chitosan 4 system.

[0048] Taking into account the dispersion time, solid content, and hydrogel stability of hydroxybutyl chitosan, hydroxybutyl chitosan 2 performed better and formed hydroxybutyl chitosan hydrogel within 5-8 hours at a solid content of 2%-2.5%.

[0049] in conclusion:

[0050] The present invention disperses chitosan to obtain a chitosan alkaline aqueous phase system with good dispersibility. Butylene oxide or diluted butylene oxide is added thereto to modify the chitosan. New hydroxybutyl chitosan is obtained by diluting, dialysing and freeze-drying the sample system. Hydroxybutyl chitosan can form a uniform and stable physical cross-linked hydrogel at a solid content of 2%-2.5%. The hydroxybutyl chitosan hydrogel will be further developed into a new type of degradable material such as a tissue engineering scaffold, and play an important role in the field of Class III medical devices.

Claims

1. A method for preparing hydroxybutyl chitosan, characterized in that: The following steps are involved: (1) The preparation of chitosan solution comprises the following steps: (1-1) Preparation of chitosan powder: Weigh 20.00 g of chitosan, place it in a traditional Chinese medicine grinder, and grind it for 2-5 minutes; take out the ground chitosan, and pass it through a 20-mesh and a 50-mesh sieve in sequence to obtain chitosan powder; (1-2) Preparation of alkaline aqueous solution: accurately weigh 129.42 g of NaOH and slowly add it to 1 L of purified water several times; after the NaOH is completely dissolved and the system temperature drops to room temperature, add 47.06 g of urea to the solution, stir to dissolve, and cool to room temperature; (1-3) Dissolution and dispersion of chitosan powder: 1.85 g of chitosan powder was added to 1 L of alkaline aqueous solution and stirred for dispersion; the whole system was immersed in a low-temperature medium at -20°C for 24 hours; after being taken out, the system was restored to room temperature and stirred for 1 hour, and then immersed in a low-temperature medium at -20°C again and allowed to stand at low temperature for 20 days; after being taken out, the system was restored to room temperature, and an alkaline aqueous solution of chitosan with good dispersion and high viscosity was obtained; (2) Preparation of Hydroxybutyl Chitosan Prepare a chitosan modification reagent, wherein the components and proportions of the modification reagent are 75% by volume of butylene oxide and 25% by volume of the mixed reagent; The components and proportions of the mixed reagent are as follows: the volume ratio of alcohol reagent to the mixed reagent is 60%, of which the volume ratio of isopropanol to the mixed reagent is 20%, the volume ratio of ethanol to the mixed reagent is 20%, the volume ratio of methanol to the mixed reagent is 20%, the volume ratio of purified water is 40%, the concentration of sodium chloride is 0.01g / mL, and the concentration of sodium iodide is 0.01g / mL; Take 5 mL of the modification reagent and add it dropwise to 50 mL of the chitosan solution prepared in step (1), and stir and react at 4°C for 2 days; (3) After the reaction is completed, hydroxybutyl chitosan is obtained through dialysis and freeze-drying.

2. The method for preparing hydroxybutyl chitosan according to claim 1, wherein: In step (3), the reaction system is diluted 1-20 times with purified water, dialyzed, and freeze-dried.

3. A method for preparing hydroxybutyl chitosan hydrogel, characterized in that: The method comprises the following preparation steps: The hydroxybutyl chitosan prepared by the preparation method of claim 1 or 2 is added to purified water, stirred at 0°C-30°C, and after being completely dissolved, a hydroxybutyl chitosan hydrogel is formed.

4. A hydroxybutyl chitosan, characterized in that The hydroxybutyl chitosan is prepared by the preparation method described in claim 1 or 2.

5. A hydroxybutyl chitosan hydrogel, characterized in that The hydrogel is a hydroxybutyl chitosan hydrogel prepared by a preparation method comprising the preparation steps described in claim 3.

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