Hydroxybutyl / N-carboxymethyl chitosan derivative as well as preparation method and application thereof

Abstract

The invention discloses a hydroxybutyl / N-carboxymethyl chitosan derivative as well as a preparation method and application thereof, and belongs to the field of biomedical materials. The chitosan derivative can be obtained by firstly carrying out carboxymethylation modification on chitosan and then carrying out hydroxybutylation modification. Or the chitosan is firstly subjected to hydroxybutylation modification and then subjected to carboxymethyl modification. The hydroxybutyl / N-carboxymethyl chitosan derivative disclosed by the invention can be compatible with an osmotic pressure regulator of a strong-polarity ionic compound to obtain a temperature-sensitive solution with good performance, the solution is uniform and transparent at low temperature, the gel is also uniform at body temperature, the transparency is very high, the gel strength is relatively large, the problems of whitening and fragmentation do not exist, and the application prospect is wide. And the method can be well matched with the human physiological environment. The material can be used as a temperature-sensitive cell carrier, a tissue engineering scaffold material, a drug controlled release material and a body surface superficial layer and deep layer tissue or in-vivo implant material.

Description

Technical Field

[0001] The invention belongs to the field of biomedical materials, and specifically relates to a hydroxybutyl / N-carboxymethyl chitosan derivative and a preparation method and application thereof. Background Art

[0002] Chitosan is a natural high molecular weight cationic polysaccharide with the advantages of good biocompatibility, no immunogenicity, no toxic side effects, and good biosafety. It also has multiple functions such as hemostasis, analgesia, antibacterial, and anti-infection, and can promote wound healing. It is easy to make into membranes and has good performance for preparing various dressings. After decades of continuous development, chitosan materials have gone through the first three generations of materials and have now developed to the fourth stage.

[0003] The first generation of chitosan materials is chitin extracted from the shells of crustaceans such as shrimps and crabs, and chitosan obtained by further deacetylation. Chitin is insoluble in general common solvents, and chitosan is soluble in some dilute acid solutions, but both are insoluble in neutral aqueous solutions. The second generation of chitosan materials is made into water-soluble materials by grafting soluble groups on the molecules of chitosan or chitosan. Representative materials are derivatives such as carboxymethyl chitosan, carboxymethyl chitosan, and chitosan quaternary ammonium salts. This type of material solves the problem that the first generation of chitosan materials are insoluble in water. In the medical field, it solves the problem that the acidic solution of the first generation of chitosan materials cannot enter the body for use, greatly expanding the application of chitosan materials in the human body.

[0004] The third generation of chitosan materials is made by grafting intelligent groups on the molecules of chitin or chitosan to make it an intelligent chitosan biomaterial, including temperature-sensitive intelligent materials, pH-sensitive biomaterials, pressure-sensitive biomaterials, magnetic-sensitive biomaterials, etc. Among them, the chitosan material obtained by grafting hydroxybutyl has been widely used for its excellent temperature sensitivity. Hydroxybutyl chitosan material not only solves the problem of water insolubility of the first generation of biomaterials, but also has temperature-sensitive properties. That is, its aqueous solution is in a solution state at low temperature (lower than its gel temperature), and after gradually heating up, it can be converted into a non-flowing gel state after being higher than its gel temperature, such as reaching body temperature of 37°C. This feature allows the material to be fixed and play a role for a long time after acting on the affected area. It can be used on wounds of almost any shape, including flat, wrinkled, gap-shaped, etc. After use, it is converted into a non-flowing gel attached to the wound surface, and will not be lost due to changes in body position, thereby achieving a long-term treatment effect, solving the problem that the second generation of carboxymethyl chitosan and other materials have high fluidity and are easy to leave the wound area that needs a barrier. Therefore, hydroxybutyl chitosan material has good wound healing and other biological activities.

[0005] The invention patent application with publication number CN 113908329 A discloses a hydroxybutyl chitosan hydrogel dressing and a preparation method thereof, wherein the auxiliary materials used in combination with hydroxybutyl chitosan are polyols containing three or more hydroxyl groups, such as glycerol, mannitol, sorbitol, etc., while highly polar ionic osmotic pressure regulators commonly used in pharmacopoeias, such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride, potassium nitrate, sodium sulfate, etc., cannot be used in combination with hydroxybutyl chitosan preparations under normal conditions. This is because hydroxybutyl chitosan is compatible with the above-mentioned highly polar substances, and is a uniform and transparent flowing solution at low temperature, but becomes a white opaque gel when heated. The gel strength is low, and it is easy to break under the action of external force, and will not solidify again unless it is homogenized again at low temperature.

[0006] And if only aqueous solution is used, or the solution prepared by the compatibility of polyols such as glycerol and mannitol, it can reach low temperature and be easy to flow, and after being warmed up to near body temperature, it is converted into a non-flowing gel, and the gel strength is relatively large, and the gel is not scattered. But after the hydroxybutyl chitosan hydrogel dressing using this type of formula is used for human body, especially in the position with more body fluids, such as the peritoneal cavity and the wound surface position with more exudate, it will gradually shrink and precipitate, and can only play a short-term gel effect. And when used as a cell culture medium, the phenomenon of precipitation will also occur, that is, the matching degree of the hydroxybutyl chitosan hydrogel dressing and the physiological environment of human body also has certain defects. Summary of the invention

[0007] In view of the above problems, an object of the present invention is to provide a chitosan derivative grafted with hydroxybutyl and carboxymethyl groups at the same time, which can be compatible with an osmotic pressure regulator of a strongly polar ionic compound (such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride, potassium nitrate, sodium sulfate, etc.) to obtain a temperature-sensitive solution with good performance, and when forming a gel at body temperature, it also presents a uniform and transparent state, has high gel strength, does not have the problem of whitening and fragmentation, and can be well matched with the physiological environment of the human body.

[0008] The hydroxybutyl / N-carboxymethyl chitosan derivative of the present invention has the following structure:

[0009]

[0010] Wherein, R1, R2, R3, and R4 are one of the following groups:

[0011] H, hydroxybutyl, carboxymethyl, acetyl.

[0012] Furthermore, R1 is hydroxybutyl, R2 is hydroxybutyl or H; R3 is H, acetyl or hydroxybutyl, and R4 is H or carboxymethyl.

[0013] The structural formula of the group is as follows:

[0014] Hydroxybutyl: CH3CH2CHOHCH2-; Carboxymethyl: -CH2COOH; Acetyl:

[0015] The degree of substitution of the hydroxybutyl group is 1.0-4.0; the degree of substitution of the carboxymethyl group is 0.1-2.0.

[0016] The preferred degree of substitution of hydroxybutyl groups is 1.5-3.0; the preferred degree of substitution of carboxymethyl groups is 0.3-1.8.

[0017] Above-mentioned hydroxybutyl / N-carboxymethyl chitosan derivative can form solution with pure water, or with polyol compatibility such as glycerol, mannitol, or even with the osmotic pressure regulating substance compatibility of strongly polar ionic compounds (such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride, potassium nitrate, sodium sulfate, phosphate buffer, etc.), all can obtain the temperature-sensitive solution with good performance. That is, it is a solution that is easy to flow at low temperatures, and it is a non-flowing gel at body temperature. And the solution at low temperatures is homogeneous and transparent, and the gel at body temperature is also uniform, and transparency is very high, and gel strength is relatively large, does not exist the problem of bleaching and scattered, and can have good matching with human physiological environment. This material has good compatibility with cell culture fluid, can be used as cell carrier application, and is a cell carrier with temperature sensitivity that is more excellent in effect.

[0018] Furthermore, the present invention also provides a hydrogel comprising the above-mentioned hydroxybutyl / N-carboxymethyl chitosan derivative, comprising the following components by mass: hydroxybutyl / N-carboxymethyl chitosan derivative: 0.1%-10%; osmotic pressure regulator: 0.1-10%; water: the balance.

[0019] The osmotic pressure regulator is a polyol such as glycerol and mannitol, or a strongly polar ionic compound such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride, potassium nitrate, sodium sulfate, and phosphate buffer.

[0020] Another object of the present invention is to provide a method for preparing the above-mentioned hydroxybutyl / N-carboxymethyl chitosan derivative. The chitosan derivative can be prepared by any of the following methods.

[0021] Method 1: First, chitosan is modified by carboxymethylation to obtain carboxymethyl chitosan, and then modified by hydroxybutylation to obtain hydroxybutyl / N-carboxymethyl chitosan derivatives. The detailed steps are as follows:

[0022] (1) dissolving or dispersing chitosan with a solvent, adding glyoxylic acid, adjusting the pH value of the system with an alkaline solution, reacting at a certain temperature for a certain time, adjusting the pH value and adding a reducing agent, reacting at a certain temperature for a certain time, and performing preliminary purification to obtain carboxymethyl chitosan; (2) dissolving or dispersing carboxymethyl chitosan with a solvent, adding 1,2-butylene oxide and an alkaline solution, reacting at a certain temperature for a certain time; (3) after the reaction is completed, stabilizing the reaction system at room temperature, placing it in a dialysis bag for dialysis for a certain time, taking it out and freeze-drying it to obtain the final chitosan derivative.

[0023] Method 2: First, chitosan is modified by hydroxybutylation to obtain hydroxybutyl-substituted chitosan; then the hydroxybutyl chitosan is modified by carboxymethyl groups to obtain the final hydroxybutyl / N-carboxymethyl chitosan derivative. The detailed steps are as follows:

[0024] (1) chitosan is modified by hydroxybutylation according to the method disclosed in patent application CN 102276756 A to obtain hydroxybutyl chitosan; (2) hydroxybutyl chitosan is dissolved or dispersed with a solvent, glyoxylic acid is added, the pH value of the system is adjusted with an alkaline solution, the reaction is carried out at a certain temperature for a certain time, the pH value is adjusted again and a reducing agent is added, and the reaction is carried out at a certain temperature for a certain time; (3) after the reaction is completed, the reaction system is stabilized at room temperature, placed in a dialysis bag for dialysis for a certain time, and then taken out and freeze-dried to obtain the final chitosan derivative.

[0025] The solvent for dissolving or dispersing chitosan or hydroxybutyl chitosan is a combination of one or more of water, sodium hydroxide solution, potassium hydroxide solution, urea solution, guanidine hydrochloride solution, hydrochloric acid, nitric acid, methanol, formic acid, ethanol, acetic acid, acetonitrile, n-propanol, isopropanol, n-butanol, acetone, dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dioxane.

[0026] The reducing agent is one or more of sodium borohydride, lithium aluminum hydride, lithium borohydride, potassium borohydride, sodium cyanoborohydride, and borane ammonia complex.

[0027] The pH value of the carboxymethylation reaction ranges from 3 to 7.

[0028] The pH value of the reduction reaction ranges from 8 to 14.

[0029] The alkali is sodium hydroxide or potassium hydroxide.

[0030] The molar concentration of the alkaline solution in the hydroxybutylation reaction is 0.01-15 mol / L.

[0031] The reaction temperature is 0°C-70°C.

[0032] The reaction time is 0.5h-120h.

[0033] The advantages of the present invention are:

[0034] 1. The hydroxybutyl / N-carboxymethyl chitosan derivative of the present invention can form a solution with pure water, or be compatible with polyols such as glycerol and mannitol, or even be compatible with an osmotic pressure regulator of a strongly polar ionic compound (such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride, potassium nitrate, sodium sulfate, etc.), and a temperature-sensitive solution with good performance can be obtained: that is, it is an easy-flowing solution at low temperature and a non-flowing gel at body temperature; and the solution at low temperature is uniform and transparent, and the gel at body temperature is also uniform, with high transparency, high gel strength, no whitening and fragmentation problems, and can be well matched with the physiological environment of the human body.

[0035] 2. The hydroxybutyl / N-carboxymethyl chitosan derivative of the present invention can also have good compatibility with cell culture medium, and is a cell carrier and tissue engineering scaffold material with better effect and temperature sensitivity.

[0036] 3. The hydroxybutyl / N-carboxymethyl chitosan derivative of the present invention can be mixed with drugs in various dosage forms, including liquid preparations, powder preparations, etc., and after mixing, it is still a gel under physiological conditions, there is no precipitation problem, and the effect of slow release can be achieved.

[0037] 4. The hydroxybutyl / N-carboxymethyl chitosan derivative of the present invention can meet the requirements of further filtration sterilization or wet heat sterilization after the solution is prepared, and will not cause the material to precipitate due to temperature fluctuations, resulting in the inability to filter or agglomeration after wet heat sterilization.

[0038] 5. The hydroxybutyl / N-carboxymethyl chitosan derivative of the present invention can be used for superficial body surface, deep body surface tissue or implanted in the body. It can be used for chronic wound care, packing and hemostasis of deep wounds, tissue adhesion prevention and hemostasis after implantation or placement in the body. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the infrared spectrum of the sample of Example 2 of the present invention.

[0040] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the sample in Example 1 of the present invention.

[0041] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of the sample in Example 2 of the present invention.

[0042] Figure 4 This is the H NMR spectrum of hydroxybutyl chitosan.

[0043] Figure 5 This is the hydrogen nuclear magnetic resonance spectrum of the sample of comparative example 1 of the present invention.

[0044] Figure 6 This is the acid-base titration curve of the sample in Example 1 of the present invention.

[0045] Figure 7 This is a photo of the state of the sample of Example 1 of the present invention after being dissolved in 0.85% sodium chloride solution at low temperature to prepare a 3% concentration solution and then heated to 37°C

[0046] Figure 8 This is a photo of the state of the sample of comparative example 1 of the present invention after being dissolved in 0.85% sodium chloride solution at low temperature to prepare a 3% concentration solution and then heated to 37°C

[0047] Fig. 9 This is a test chart of the gel temperature of the sample of Example 1 of the present invention, which is prepared into a 5% solution using 0.85% sodium chloride solution.

[0048] Fig.10 The present invention is a gel temperature test graph of the sample of Example 3 prepared into a 3% solution using 0.7% sodium chloride solution and 0.2M phosphate buffer. DETAILED DESCRIPTION

[0049] The present invention will be further described in detail below with reference to the accompanying drawings and through specific embodiments.

[0050] Embodiment 1:

[0051] (1) 30 g of chitosan was dispersed in 120 mL of purified water, and then 120 mL of isopropanol was added. The mixture was stirred for 2 h to make it uniformly dispersed. 120 mL of isopropanol solution containing 30 g of glyoxylic acid and 120 mL of purified water were added, and the pH value was adjusted to 4-5. The mixture was reacted at 30° C. for 2 h. The pH value of the reacted material was adjusted to 8-9 with sodium hydroxide solution, and then 20 mL of an aqueous solution containing 12 g of sodium borohydride was added. The mixture was reacted for 2 h. After dialysis and freeze-drying, 35.2 g of N-carboxymethyl chitosan was obtained.

[0052] (2) Disperse 20 g of the obtained carboxymethyl chitosan in 100 mL of 50% sodium hydroxide solution, stir for 2 h to make the dispersion uniform, then add 120 mL of isopropanol and 200 mL of 1,2-butylene oxide, and react at 40° C. for 50 h.

[0053] (3) The pH value of the reacted material was adjusted to neutral with hydrochloric acid at room temperature, and 27.9 g of hydroxybutyl / N-carboxymethyl chitosan was obtained through dialysis and freeze-drying.

[0054] Embodiment 2:

[0055] (1) Hydroxybutyl chitosan was prepared according to the method disclosed in patent application CN 102276756 A.

[0056] (2) Take 50 g of hydroxybutyl chitosan and dissolve it in 200 mL of purified water and 50 mL of acetic acid. After uniform dissolution, add 100 mL of isopropanol solution containing 75 g of glyoxylic acid and react at 50° C. for 1 h. After the reaction, adjust the pH value of the material to 9-10 with sodium hydroxide solution, then add 40 mL of aqueous solution containing 20 g of potassium borohydride and react for 1 h.

[0057] (3) The reacted material was dialyzed and freeze-dried to obtain 58.2 g of hydroxybutyl / N-carboxymethyl chitosan.

[0058] Embodiment 3:

[0059] (1) Hydroxybutyl chitosan was prepared according to the method disclosed in patent application CN 102276756 A.

[0060] (2) Take 100 g of hydroxybutyl chitosan and disperse it in 300 mL of purified water and 200 mL of dimethyl sulfoxide. After uniform dispersion, add 100 mL of acetone solution containing 300 g of glyoxylic acid, adjust the pH to 5-6, and react at 40°C for 2 h. After the reaction, adjust the pH value of the material to 10-11 with sodium hydroxide solution, and then add 200 mL of aqueous solution containing 100 g of borane ammonia and react for 5 h.

[0061] (3) The material after the reaction was dialyzed and freeze-dried to obtain 55.6 g of hydroxybutyl / N-carboxymethyl chitosan.

[0062] Embodiment 4:

[0063] (1) Disperse 100 g of chitosan in 1000 mL of an aqueous solution containing 11% potassium hydroxide and 8% urea, stir to make the dispersion uniform, freeze overnight and then take out and thaw at low temperature to obtain a uniform solution, add 1000 mL of 1,2-butylene oxide, react at 30°C for 48 h, adjust the pH value of the reacted material to neutral with hydrochloric acid, dialyze and freeze-dry to obtain 122.6 g of hydroxybutyl chitosan.

[0064] (2) Take 100 g of hydroxybutyl chitosan and disperse it in 300 mL of N,N-dimethylformamide. After uniform dispersion, add 100 mL of an aqueous solution containing 300 g of glyoxylic acid, adjust the pH to 6-7, and react at 25°C for 6 h. After the reaction, adjust the pH value of the material to 11-12 with sodium hydroxide solution, then add 200 mL of an aqueous solution containing 100 g of sodium cyanoborohydride, and react for 5 h.

[0065] (3) The reacted material was dialyzed and freeze-dried to obtain 117.8 g of hydroxybutyl / N-carboxymethyl chitosan.

[0066] Comparative Example 1:

[0067] (1) Hydroxybutyl chitosan was prepared according to the method disclosed in patent application CN 102276756 A.

[0068] (2) Take 50g of hydroxybutyl chitosan and dissolve it in 200mL of purified water and 50mL of acetic acid. After uniform dissolution, add 100mL of isopropanol solution containing 75g of glyoxylic acid and react at 50°C for 1h. The pH value of the reacted material is adjusted to 9-10 with sodium hydroxide solution. Compared with Example 2, no reducing agent such as potassium borohydride is added and the reaction is continued for 1h.

[0069] (3) The material after the reaction was dialyzed and freeze-dried to obtain 51.2 g of sample.

[0070] Example 5: Material structure test

[0071] The samples in Example 2 were subjected to infrared spectroscopy test. Figure 1 The peak position is as follows: 1589cm -1 Left and right 1397cm -1 The absorption peaks on the left and right are the asymmetric and symmetric stretching vibration absorption peaks of carboxyl, indicating the presence of carboxyl; 2963cm -1 Around, 2929cm -1 Around, 2875cm -1 The three peaks on the left and right and 1460cm -1 The absorption peaks on the left and right are the stretching vibration and bending vibration absorption peaks of the C-H bond, indicating the presence of hydroxybutyl; 3377cm -1 The strong and broad absorption peaks on the left and right are the stretching vibration absorption peaks of O—H and N—H.

[0072] The samples in Example 1 and Example 2 were subjected to liquid nuclear magnetic resonance hydrogen spectrum test. For comparison, hydroxybutyl chitosan and the sample of Comparative Example 1 were also subjected to liquid nuclear magnetic resonance hydrogen spectrum test. The test was carried out by dissolving each sample in a D2O solution containing 20% ​​DCl. The spectra are shown in FIG. Figures 2 to 5. Due to the acidic solvent used, the chemical shift of each spectrum peak will be offset. The relative position and peak type of the sample peaks in Example 1 and Example 2 are basically the same. Taking the liquid nuclear magnetic hydrogen spectrum of the sample in Example 2 as an example, -0.62ppm is the absorption peak of the methyl hydrogen atom on the hydroxybutyl group, and -0.02ppm is the absorption peak of the methylene hydrogen atom on the hydroxybutyl group. The presence of the two indicates that the sample has a hydroxybutyl group. The multiple superimposed absorption peaks between 1.5ppm-3ppm are the absorption peaks of the hydrogen atoms on the carbons at positions 2, 3, 4, 5, and 6 on the chitosan sugar ring and the two carbon atoms connected to the 6 hydroxyl groups on the hydroxybutyl group. 3.12ppm is the absorption peak of the hydrogen atom on the methylene on the carboxymethyl group connected to the amino group, and 2.24ppm is the absorption peak that rises after superposition with other peaks. It is speculated that after the carboxymethyl group is replaced on the amino group, the absorption peak of the hydrogen atom on the 2 carbon atom on the chitosan sugar ring. 3.77ppm is the absorption peak of the hydrogen atom connected to the carbon at position 1 on the chitosan sugar ring. Figure 3 and Figure 2 The carboxymethyl substitution degree of the sample increased, and the two peaks at 2.24ppm and 3.12ppm increased accordingly. The peak types and relative positions of the spectra of the sample in comparative example 1 and hydroxybutyl chitosan were basically the same, indicating that no obvious carboxymethyl substitution reaction occurred when no reducing agent was used.

[0073] Example 6: Material acid-base titration test

[0074] The hydroxybutyl / N-carboxymethyl chitosan material prepared in Example 2 was dissolved in excess hydrochloric acid and titrated with a standard sodium hydroxide solution using a fully automatic potentiometric titrator. The titration curve was as follows: Figure 6 As shown. The solid line is the relationship curve between pH value and the volume consumed by the standard sodium hydroxide solution, and the dotted line is the relationship curve between pH value and volume derivative and the volume consumed by the standard sodium hydroxide solution. It can be seen from the figure that there are three obvious jump points in the curve: the carboxyl titration end point and the different amino titration end points. Combined with the hydrochloric acid titration end point at pH 2.2, the carboxymethyl substitution degree can be calculated to be 0.95.

[0075] Example 7: Solution property test

[0076] The materials in Example 1 were dissolved in purified water and 0.85% sodium chloride solution at a concentration of 3%, respectively, as samples ① and ②. The samples prepared in Comparative Example 1 were dissolved in purified water and 0.85% sodium chloride solution at a concentration of 3%, respectively, as samples ③ and ④. Hydroxybutyl chitosan prepared according to the method disclosed in patent application CN 102276756 A was dissolved in purified water and 0.85% sodium chloride solution at a concentration of 3%, as samples ⑤ and ⑥.

[0077] Table 1 The status of each sample under different conditions

[0078]

[0079] The above data show that the sample in the embodiment of the present invention can form a uniform solution with a nearly isotonic sodium chloride solution after liquid preparation, and transform into a non-flowing gel state after heating to 37°C. The gel is still uniform and transparent and not easy to break, meeting clinical needs.

[0080] Example 8: Preparation and performance testing of hydrogel

[0081] The sample of Example 1 was prepared into a 5% solution with 0.85% sodium chloride solution. The osmotic pressure was 301mOsmol / kg when tested by an osmometer. The gel temperature was 16.4°C when tested by a rheometer. The intersection of the storage modulus (G') and the loss modulus (G") is the gel temperature. Fig. 9 The sample of Example 3 was prepared into a 3% solution with 0.7% sodium chloride solution and 0.2M phosphate buffer. The osmotic pressure was 312mOsmol / kg when tested by an osmometer. The gel temperature was 37.2°C when tested by a rheometer. Fig.10 As shown. As can be seen from the figure, the gel temperature of the hydrogel prepared in the sample of Example 1 above is 16.4°C, which is suitable for dressings, fillings or scaffold materials for use in vivo and on the surface of the body, and can be used as a drug or cell carrier to load relevant therapeutic drugs or therapeutic cells to further enhance the therapeutic effect. The gel temperature of the hydrogel prepared in the sample of Example 3 is 37.2°C, which is higher than normal body temperature. It is a flowing liquid at body temperature and can be used as a wound site on the surface or in the body where flowing liquid is required, such as intra-articular injection, liquid dressing application on the surface of the body, etc.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Ordinary technicians in the relevant field can still modify or replace the specific implementation methods of the present invention with equivalents by referring to the above embodiments. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention.

Claims

1. A hydroxybutyl / N-carboxymethyl chitosan derivative, characterized in that: It has the following structure: Wherein, R1, R2, R3, and R4 are one of the following groups: H, hydroxybutyl, carboxymethyl, acetyl.

2. The chitosan derivative according to claim 1, characterized in that: The R1 is hydroxybutyl, R2 is H or hydroxybutyl; the R3 is H, acetyl or hydroxybutyl, and R4 is H or carboxymethyl.

3. The chitosan derivative according to claim 1, characterized in that: The degree of substitution of the hydroxybutyl group is 1.0-4.0; the degree of substitution of the carboxymethyl group is 0.1-2.

0.

4. A hydrogel comprising the hydroxybutyl / N-carboxymethyl chitosan derivative according to claim 1, characterized in that: The invention comprises the following components by mass: 0.1%-10% of hydroxybutyl / N-carboxymethyl chitosan derivative; 0.1%-10% of osmotic pressure regulator; and water as the balance. The osmotic pressure regulator is glycerol, mannitol or sodium chloride, potassium chloride, calcium chloride, magnesium chloride, potassium nitrate, sodium sulfate, or phosphate buffer.

5. The method for preparing the hydroxybutyl / N-carboxymethyl chitosan derivative according to claim 1, characterized in that: The following steps are involved: (1) dissolving or dispersing chitosan with a solvent, adding glyoxylic acid, adjusting the pH value of the system with an alkaline solution, reacting at a certain temperature for a certain time, adjusting the pH value and adding a reducing agent, reacting at a certain temperature for a certain time, and performing preliminary purification to obtain carboxymethyl chitosan; (2) dissolving or dispersing carboxymethyl chitosan with a solvent, adding 1,2-butylene oxide and an alkaline solution, reacting at a certain temperature for a certain time; (3) after the reaction is completed, stabilizing the reaction system at room temperature, placing it in a dialysis bag for dialysis for a certain time, taking it out and freeze-drying it to obtain the final chitosan derivative.

6. The method for preparing the hydroxybutyl / N-carboxymethyl chitosan derivative according to claim 1, characterized in that: The following steps are involved: (1) chitosan is modified by hydroxybutylation according to the method disclosed in patent application CN 102276756 to obtain hydroxybutyl chitosan; (2) hydroxybutyl chitosan is dissolved or dispersed with a solvent, glyoxylic acid is added, the pH value of the system is adjusted with an alkaline solution, the reaction is carried out at a certain temperature for a certain time, the pH value is adjusted again and a reducing agent is added, and the reaction is carried out at a certain temperature for a certain time; (3) after the reaction is completed, the reaction system is stabilized at room temperature, placed in a dialysis bag for dialysis for a certain time, and then taken out and freeze-dried to obtain the final chitosan derivative.

7. The method for preparing the hydroxybutyl / N-carboxymethyl chitosan derivative according to any one of claims 5 to 6, characterized in that: The solvent for dissolving or dispersing chitosan or hydroxybutyl chitosan is a combination of one or more of water, sodium hydroxide solution, potassium hydroxide solution, urea solution, guanidine hydrochloride solution, hydrochloric acid, nitric acid, methanol, formic acid, ethanol, acetic acid, acetonitrile, n-propanol, isopropanol, n-butanol, acetone, dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dioxane.

8. The method for preparing the hydroxybutyl / N-carboxymethyl chitosan derivative according to any one of claims 5 to 6, characterized in that: The alkali is sodium hydroxide or potassium hydroxide; the molar concentration of the alkali solution is 0.01-15 mol / L.

9. The method for preparing the hydroxybutyl / N-carboxymethyl chitosan derivative according to any one of claims 5 to 6, characterized in that: The reaction temperature is 0°C-100°C; the reaction time is 0.5h-120h.

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