A pH-responsive nanocellulose hydrogel and a preparation method and application thereof
By crosslinking aldehyde-modified cellulose nanofibers with carboxymethyl chitosan and tannic acid, the pH responsiveness and antibacterial properties of existing hydrogel materials in wound dressings were solved. Drug release and antibacterial effects were achieved in acidic environments, solving the problem of insufficient pH responsiveness and antibacterial properties of existing hydrogel materials. The prepared hydrogel material has significant swelling and excellent antibacterial properties in acidic environments, promoting wound healing.
Patent Information
- Application Number
- CN202411926901.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-25
- Publication Date
- 2025-11-07
- Estimated Expiration
- 2044-12-25
AI Technical Summary
Existing hydrogel materials lack pH responsiveness and antibacterial properties in wound dressings, making it difficult to meet diverse wound healing needs, especially in terms of insufficient drug release and antibacterial effects in acidic environments.
A pH-responsive cellulose nanofiber was constructed by crosslinking aldehyde-modified cellulose nanofibers with carboxymethyl chitosan, tannic acid, and curcumin-conjugated chitosan. The pH responsiveness of carboxymethyl chitosan and the antibacterial properties of tannic acid and curcumin were utilized to achieve targeted drug release and antibacterial effects.
The prepared hydrogel exhibits significant swelling under acidic conditions, enabling slow drug release. It possesses excellent antibacterial and mechanical properties, promotes wound healing, and reduces scar formation.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of hydrogel materials, and particularly relates to a pH-responsive nanocellulose hydrogel as well as a preparation method and application thereof. BACKGROUND
[0002] Skin is the largest organ of the human body, and is a basic barrier to protect internal tissues, maintain body fluid balance and prevent pathogen invasion. However, the skin is easily damaged by acute trauma, chronic ulcers and diseases, leading to excessive loss of protein and water, bacterial infection and even immune system disorder. When the wound is deep to the dermis or subcutaneous tissue, the spontaneous healing process of the wound is difficult. At the same time, bacterial infection also poses a serious threat to wound healing, which can delay collagen synthesis and prolong wound healing time.
[0003] Hydrogels used as wound dressings can maintain a moist environment for wounds, promote cell growth and reduce inflammation, and are beneficial to wound healing. However, the structure and function of water are still single, which cannot meet the diversified needs in actual application. In recent years, the molecular design and structure engineering of hydrogels have been continuously developed, so that they have multiple purposes and adjustable characteristics. The addition of antibacterial ingredients or drugs in hydrogels can prepare antibacterial hydrogels, but the burst release of drugs should be prevented to avoid short-term drug efficacy or toxicity to normal cells.
[0004] As one of the indicators for judging internal and surgical diseases, many disease symptoms are accompanied by significant changes in the pH of the human microenvironment. According to the difference in the pH of the microenvironment between the diseased tissue and the normal physiological tissue, the hydrogel can be responsive to the tissue microenvironment, and the targeted release of drugs can be achieved.
[0005] Nanocellulose has excellent physical and chemical properties, such as high tensile strength and elastic modulus, high specific surface area, low density, biodegradability and renewability, and is widely used in the field of hydrogels. However, nanocellulose itself does not have antibacterial properties and pH responsiveness. In recent years, pH-sensitive hydrogels have attracted much attention in the field of medical research. Therefore, the preparation of a nanocellulose hydrogel with pH responsiveness and excellent antibacterial properties can achieve its wide application in the field of wound dressings. SUMMARY
[0006] The purpose of the present application is to provide a pH-responsive nanocellulose hydrogel and a preparation method and application thereof. The nanocellulose hydrogel prepared by the method not only has pH responsiveness, but also has excellent antibacterial properties.
[0007] The purpose of the present application can be achieved by the following technical solutions:
[0008] The present application provides a preparation method of a pH-responsive nanocellulose hydrogel, comprising the following steps:
[0009] Step one, mix the aldehyde-based cellulose nanofiber suspension and carboxymethyl chitosan solution, stir at 25-90℃ for 1-12h, the molar ratio of amino group to aldehyde group is 1:5-5:1;
[0010] Step two, add tannic acid and curcumin conjugated chitosan to the mixture of aldehyde-based cellulose nanofiber and carboxymethyl chitosan, the concentration of tannic acid is 1-10mg / mL, the concentration of curcumin conjugated chitosan is 0.5-5mg / mL, mix and stir to carry out crosslinking reaction, and obtain pH-responsive nanocellulose hydrogel.
[0011] Carboxymethyl chitosan (CMCS) is an important amphoteric polyelectrolyte with significant pH responsiveness. Its molecular structure contains carboxyl and amino groups. In acidic environment, the swelling rate of carboxymethyl chitosan increases, while in neutral or alkaline conditions, it shows smaller swelling rate, which can trigger drug release and achieve precise control of drug release.
[0012] The aldehyde group on the aldehyde-based cellulose nanofiber is crosslinked with the amino group on the carboxymethyl chitosan through Schiff base bond to construct an injectable hydrogel.
[0013] Tannic acid can improve the mechanical properties of the hydrogel through non-covalent interaction with cellulose and carboxymethyl chitosan. Moreover, tannic acid contains a large number of phenolic hydroxyl functional groups, which can provide multiple interaction binding sites. Tannic acid has antibacterial and antioxidant properties, which can remove free radicals in the wound and promote wound healing.
[0014] Curcumin is a natural polyphenolic compound with good anti-inflammatory and antioxidant effects. Studies have shown that curcumin can inhibit the production of various pro-inflammatory cytokines and inhibit a variety of microorganisms including drug-resistant bacteria. Curcumin and chitosan undergo Schiff base reaction to form curcumin conjugated chitosan, which improves the water solubility of curcumin and enhances its bioavailability. The prepared hydrogel can continuously release curcumin, improving the anti-inflammatory and antioxidant properties.
[0015] Further, the preparation steps of the aldehyde-based cellulose nanofiber are as follows:
[0016] Step 1, disperse nanocellulose in water, and pretreat the nanocellulose by TEMPO oxidation method to obtain carboxylated nanocellulose with a surface carboxyl content of 0.8-1.8mmol / g;
[0017] Step 2, the carboxylated nanocellulose is dispersed in water at 0.5-1.5 wt%, the pH is adjusted to 3.0-6.0, NaIO4 is added at a molar ratio of 1:1-3:1 of NaIO4 to glucose units in the carboxylated nanocellulose, and the reaction is carried out at room temperature for 6-48 h in the dark, after the reaction is completed, centrifugal washing is carried out until neutral, and after freeze-drying, aldehyde-modified cellulose nanofibers are obtained.
[0018] Further, the nanocellulose is prepared by using cotton pulp through sulfuric acid hydrolysis and mechanical ball milling.
[0019] Further, the aldehyde-modified cellulose nanofiber suspension is obtained by diluting aldehyde-modified cellulose nanofibers with water at a mass concentration of 1-2%.
[0020] Further, the carboxymethyl chitosan solution is obtained by stirring and mixing carboxymethyl chitosan with water at a mass concentration of 0.5-3%.
[0021] Further, the preparation steps of the curcumin conjugated chitosan are as follows:
[0022] Curcumin is dissolved in ethanol at a concentration of 0.1-0.2 mol / mL, chitosan is dissolved in acetic acid solution at 1-2 wt%, and the two are mixed at a molar ratio of curcumin to chitosan of 1-1.1:2, stirred uniformly, and then microwave-heated at 60-80℃ for 10-20 min, after the reaction is completed, the mixture is cooled, filtered, and freeze-dried to obtain curcumin conjugated chitosan.
[0023] Further, the temperature of the crosslinking reaction is 30-40℃, and the reaction time is 3-5 min.
[0024] The application also provides a pH-responsive nanocellulose hydrogel prepared by the preparation method described above.
[0025] The application also provides an application of the pH-responsive nanocellulose hydrogel described above, and the pH-responsive nanocellulose hydrogel can be used for preparing a wound dressing.
[0026] The application has the following beneficial effects:
[0027] The application takes natural products with good biocompatibility such as cellulose, chitosan, curcumin and tannic acid as raw materials to construct a hydrogel with injectability, self-healing and antibacterial properties. Under acidic conditions, the amino groups are protonated, the Schiff base bonds between the raw materials are broken, the intermolecular space of the hydrogel is large, the slow release of drugs can be realized, and the pH responsiveness is remarkable. By using the hydrogen bonding between tannic acid, curcumin and nanocellulose, the mechanical properties of the hydrogel are improved. The prepared hydrogel can provide physical isolation and a moist environment for the wound, better fill irregular wounds, and the synergistic effect of tannic acid and curcumin can play a role in antibacterial, promoting wound healing and reducing scar. DETAILED DESCRIPTION
[0028] The technical solutions in the embodiments of the application will be clearly and completely described below in combination with the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.
[0029] Embodiment 1
[0030] Preparation of pH-responsive nanocellulose hydrogel:
[0031] Step one, nanocellulose was prepared by mechanical ball milling of cotton linter pulp, and the nanocellulose was dispersed in water. TEMPO oxidation method was used to pretreat the nanocellulose to obtain carboxylated nanocellulose with a surface carboxyl content of 0.8 mmol / g.
[0032] Step two, the carboxylated nanocellulose was dispersed in water at 0.5wt%, the pH was adjusted to 3.0, NaIO4 was added according to the molar ratio of NaIO4 to glucose units in carboxylated nanocellulose of 1:1, and the reaction was carried out at room temperature for 6h in the dark. After the reaction was completed, centrifugal washing was carried out until it was neutral, and then freeze-drying was carried out to obtain aldehyde cellulose nanofiber.
[0033] Step three, curcumin was dissolved in ethanol at a concentration of 0.1 mol / mL, chitosan was dissolved in acetic acid solution at a concentration of 1wt%, and the two were mixed according to the molar ratio of curcumin to chitosan of 1:2, stirred uniformly, then microwave heated at 60℃ for 20min, cooled after the reaction was completed, filtered and freeze-dried to obtain curcumin conjugated chitosan.
[0034] Step four, aldehyde cellulose nanofiber suspension was obtained by diluting aldehyde cellulose nanofiber with water according to a mass concentration of 1%, and carboxymethyl chitosan solution was obtained by stirring and mixing carboxymethyl chitosan with water according to a mass concentration of 0.5%.
[0035] Step five, the aldehyde group of the cellulose nanofiber suspension and the carboxymethyl chitosan solution were mixed at a molar ratio of amino group to aldehyde group of 1:5, and stirred at 25°C for 12h.
[0036] Step six, tannic acid and curcumin conjugated chitosan were added to the mixed solution of aldehyde group of the cellulose nanofiber and carboxymethyl chitosan, the concentration of tannic acid was 1mg / mL, the concentration of curcumin conjugated chitosan was 0.5mg / mL, mixed and stirred, and crosslinking reaction was carried out at 40°C for 3min, to obtain a pH responsive nanocellulose hydrogel.
[0037] Example 2
[0038] The difference from example 1 is that the molar ratio of amino group to aldehyde group in step five is adjusted to 3:1, and the other steps and conditions are the same as example 1.
[0039] Example 3
[0040] The difference from example 1 is that the molar ratio of amino group to aldehyde group in step five is adjusted to 5:1, and the other steps and conditions are the same as example 1.
[0041] Example 4
[0042] The difference from example 2 is that the concentration of tannic acid in step six is 6mg / mL, and the other steps and conditions are the same as example 2.
[0043] Example 5
[0044] The difference from example 2 is that the concentration of tannic acid in step six is 10mg / mL, and the other steps and conditions are the same as example 2.
[0045] Example 6
[0046] The difference from example 4 is that the concentration of curcumin conjugated chitosan in step six is 3mg / mL, and the other steps and conditions are the same as example 4.
[0047] Example 7
[0048] The difference from example 4 is that the concentration of curcumin conjugated chitosan in step six is 5mg / mL, and the other steps and conditions are the same as example 4.
[0049] Comparative example 1
[0050] The difference from example 1 is only that no tannic acid is added to the hydrogel, and the other steps and conditions are the same as example 1.
[0051] Comparative example 2
[0052] The difference from example 1 is only that no curcumin conjugated chitosan is added to the hydrogel, and step three is omitted, and the other steps and conditions are the same as example 1.
[0053] Comparative Example 3
[0054] The difference from Example 1 is only that no tannic acid and curcumin conjugated chitosan is added in the hydrogel, step three is omitted, and other steps and conditions are the same as Example 1.
[0055] 0.5 g of the hydrogel prepared in Example 1 after lyophilization was weighed and immersed in 500 mL of PBS solution with pH = 3.2, pH = 7.2 and pH = 8.2 respectively. After swelling equilibrium, the hydrogel sample was taken out, the surface moisture was wiped with filter paper, the wet weight was measured, and the equilibrium swelling degree was calculated. The equilibrium swelling degree at pH = 3.2 is 41.50 g / g, the equilibrium swelling degree at pH = 7.2 is 30.13 g / g, and the equilibrium swelling degree at pH = 8.2 is 13.27 g / g. The swelling degree of the hydrogel under different pH conditions is different, and the swelling degree under acidic conditions is significantly greater than that under weak alkaline conditions, which proves that the hydrogel has pH sensitivity and can be used as a targeted pH-responsive drug carrier to continuously and stably deliver drugs. The hydrogel as a wound dressing can accelerate the release of drugs under acidic conditions (such as infected wounds) to inhibit bacterial growth and promote wound healing.
[0056] The hydrogels prepared in Examples 1-7 and Comparative Examples 1-3 were tested for performance, and the results are shown in Table 1:
[0057] Gel formation time determination: The gel time of the hydrogel material was detected using the inverted method at 37°C.
[0058] Antibacterial property: Gram-negative E. coli and Gram-positive S. aureus were selected to test the antibacterial property of the sample. 100 μL of bacterial solution with a concentration of 10 6 CFU / mL was coated on the LB plate, then a 5 mm diameter and 1 mm thick hydrogel disc was attached to the LB plate, and after 72 h of culture in a 37°C incubator, the antibacterial rate was calculated according to the size of the inhibition zone.
[0059] Mechanical property detection: The hydrogel was prepared into a strip (10 cm long x 1 cm wide x 0.2 cm thick) after gel formation, and the breaking strength was tested using a universal testing machine at 25°C.
[0060] Table 1
[0061]
[0062] As can be seen from Table 1, the gel formation time in Example 2 is the shortest among Examples 1-3, the amino and aldehyde groups in Example 2 have a molar ratio of 3:1, and the addition of tannic acid and curcumin conjugated chitosan can enhance the antibacterial performance of the hydrogel, and the antibacterial performance of the hydrogel of Examples 4-7 against E. coli and S. aureus gradually increases with the increase of the proportion of tannic acid and curcumin conjugated chitosan. It can be known from Examples 1 and Comparative Examples 1-3 that the antibacterial performance of the hydrogel of Example 1 is significantly higher than that of Comparative Examples due to the synergistic effect of tannic acid and curcumin conjugated chitosan. Based on the hydrogen bonding between tannic acid and curcumin conjugated chitosan and nanocellulose, the mechanical properties of the hydrogel of Examples are better than those of Comparative Examples.
[0063] It should be noted that, in this document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.
[0064] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, alternatives, and variations can be made in the embodiments without departing from the principles and spirit of the application, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a pH-responsive nanocellulose hydrogel, characterized by, The method comprises the following steps: Step 1: mixing aldehyde-modified cellulose nanofiber suspension and carboxymethyl chitosan solution, stirring at 25-90℃ for 1-12h, and the molar ratio of amino group to aldehyde group is 1:5-5:1; Step 2: adding tannic acid and curcumin conjugated chitosan into the mixed solution of aldehyde-modified cellulose nanofiber and carboxymethyl chitosan, the concentration of tannic acid is 1-10mg / mL, and the concentration of curcumin conjugated chitosan is 0.5-5mg / mL, and then mixing and stirring to perform cross-linking reaction, thereby obtaining pH-responsive nanocellulose hydrogel; The preparation steps of the curcumin conjugated chitosan are as follows: The curcumin is dissolved in ethanol at a concentration of 0.1-0.2mol / mL, the chitosan is dissolved in acetic acid solution at 1-2wt%, and then the two are mixed at a molar ratio of curcumin to chitosan of 1-1.1:2, and after uniform stirring, microwave heating is performed at 60-80℃ for 10-20min, and after the reaction is completed, cooling, filtration and freeze-drying are performed to obtain curcumin conjugated chitosan.
2. The method for preparing a pH-responsive nanocellulose hydrogel according to claim 1, characterized in that, The preparation steps of the aldehyde-modified cellulose nanofiber are as follows: Step 1: dispersing nanocellulose in water, and performing pretreatment on the nanocellulose by using TEMPO oxidation method to obtain carboxylated nanocellulose with a carboxyl content of 0.8-1.8mmol / g; Step 2: dispersing the carboxylated nanocellulose in water at 0.5-1.5wt%, adjusting the pH to 3.0-6.0, adding NaIO4 at a molar ratio of NaIO4 to glucose units in the carboxylated nanocellulose of 1:1-3:1, and performing reaction under dark room temperature conditions for 6-48h, and after the reaction is completed, centrifugal washing is performed until neutral, and freeze-drying is performed to obtain aldehyde-modified cellulose nanofiber.
3. The method for preparing a pH-responsive nanocellulose hydrogel according to claim 2, characterized in that, The nanocellulose is prepared by using cotton linter pulp through sulfuric acid hydrolysis and mechanical ball milling.
4. The method for preparing a pH-responsive nanocellulose hydrogel according to claim 1, characterized in that, The aldehyde-modified cellulose nanofiber suspension is obtained by diluting aldehyde-modified cellulose nanofiber with water at a mass concentration of 1-2%.
5. The method of claim 1, wherein the pH-responsive nanocellulose hydrogel is prepared by the steps of: The carboxymethyl chitosan solution is obtained by stirring and mixing carboxymethyl chitosan with water at a mass concentration of 0.5-3%.
6. The method of claim 1, wherein the pH-responsive nanocellulose hydrogel is prepared by the steps of: The temperature of the cross-linking reaction is 30-40℃, and the reaction time is 3-5min.
7. A pH-responsive nanocellulose hydrogel, characterized in that, The preparation method is prepared by using any one of claims 1-6.
8. Use of the pH-responsive nanocellulose hydrogel according to claim 7, characterized in that, The pH-responsive nanocellulose hydrogel can be used for preparing wound dressings.