Preparation method of quaternized lignocellulose nanofibril and hydrogel drug carrier
By using eutectic solvents and quaternization modification technology on bagasse, quaternized lignocellulose nanofiber filaments and using them to prepare hydrogels, the problems of complex processes and environmental pollution in the prior art are solved, and the problems of process complexity and environmental pollution in the existing technology are realized. Efficient, green lignocellulose nanofiber filament preparation and hydrogel application.
Patent Information
- Application Number
- CN202410910778.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-08
- Publication Date
- 2025-01-03
AI Technical Summary
The prior art has complex processes and severe environmental pollution when preparing lignocellulose nanofiber filaments, making it difficult to achieve efficient preparation methods for green and environmental protection.
The bagasse was pretreated by eutectic solvent synthesized by choline chloride and imidazole, and on the basis of which it was added toluenesulfonyl chloride and betaine hydrochloride for quaternization and modification, and quaternary ammonium was obtained by mechanical microfibrosis. Lignocellulose nanofiber filaments were melted and hydrogels were prepared by inducing radical polymerization with metal ions.
It has achieved low-cost and efficient preparation of quaternized lignocellulose nanofibers, has good biocompatibility and antibacterial properties, can serve as a sustained-release carrier to achieve slow drug release, and has a green and environmentally friendly process, which meets the requirements of sustainable development.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of nanocellulose, and particularly relates to a method for preparing quaternized lignocellulose nanofibrils and a hydrogel drug carrier. Background Art
[0002] Lignocellulose is an abundant renewable resource that is widely found in plant cell walls. By refining and processing lignocellulose into nanofibers, wood resources can be used more efficiently and dependence on limited resources can be reduced. Bagasse is the solid residue left after sugar is extracted from sugarcane. It is a common agricultural by-product, and its main components include cellulose (40-50%), hemicellulose (15-25%), lignin (20-25%), etc.
[0003] So far, people are paying more and more attention to bio-based nanocellulose materials. Lignocellulose nanofibrils (LCNF), as an emerging member of the green nanofiber family, combine the characteristics of lignocellulose and nanocellulose. Its production process is relatively simple, low cost, low energy consumption, and more environmentally friendly. And due to the presence of lignin, LCNF has certain reducibility, high dispersion stability and thermal stability, anti-ultraviolet and antioxidant activity.
[0004] The cell wall of lignocellulose is a compact hierarchical structure, and it is difficult to directly dissociate nanofibrils from lignocellulose. Pretreatment is a key step in achieving the separation and high-value utilization of lignocellulose biomass components. Studies have shown that the introduction of charged functional groups into the fiber structure can cause electrostatic repulsion between fibers, promote the microfibrillation process of the fibers, and the introduced functional groups can also increase the active sites of cellulose. For example, the use of a green alternative to traditional molecular solvents, a deep eutectic solvent (DES), to modify cellulose fibers. This production process is more environmentally friendly and economically feasible than the traditional (cellulose nanofibrils) CNF preparation route, and no longer requires lignin removal and bleaching steps. Announcement No.: CN 114481658B, discloses a method for preparing nanocellulose using bagasse as a raw material through NaOH pretreatment and TEMPO oxidation, and the prepared nanocellulose has the advantages of good dispersibility, controllable morphology, and high yield. Publication number: CN 116463873A, discloses a method for preparing a hydrophobically modified lignocellulose nanofibril by DES pretreatment using bagasse as raw material, wherein the low eutectic solvent is a ternary system composed of a mixture of a hydrogen bond acceptor, a hydrogen bond donor and an acidic auxiliary agent, choline chloride, ethylene glycol and dilute hydrochloric acid, and dilute hydrochloric acid is an additional auxiliary agent for removing lignin. Although this method can successfully dissociate lignocellulose, it requires additional addition of dilute hydrochloric acid to achieve the reaction conditions, which is easy to pollute the environment. In the above preparation process, the prepared nanocellulose has good performance, but the process flow of cellulose extraction is complicated, and the reagents used have great pollution to the environment, which does not meet the requirements of green and sustainable development. Green modified lignocellulose will be an ideal solution for the efficient preparation of LCNF, and the functional groups introduced in LCNF and the retained lignin will give the nanofibers more active sites and reducing properties. This is conducive to the application of lignocellulose nanofibrils in the preparation of hydrogels.
[0005] To prepare quaternized lignocellulose nanofibrils, toluenesulfonyl chloride and betaine hydrochloride are added in the presence of DES, and quaternary ammonium groups are grafted onto the hydroxyl sites of cellulose. Betaine hydrochloride is used as a natural-based cationizing agent, and p-toluenesulfonyl chloride is used as a coupling agent to form an ester bond between cellulose and betaine hydrochloride. Quaternary ammonium salts have low cytotoxicity and antibacterial properties, which are beneficial to the application of lignocellulose nanofibrils in hydrogel carriers. Therefore, it is necessary to develop a method for preparing quaternized lignocellulose nanofibrils with a simple preparation process, mild conditions, and green environmental protection.
[0006] Quaternized lignocellulose nanofibrils have the following advantages: (1) The production strategy of quaternized lignocellulose nanofibers proposed in the present invention has the advantages of low cost and high raw material utilization rate. Compared with conventional fiber raw materials such as cotton and wood, bagasse is an agricultural and industrial waste, and the raw material cost is almost zero; at the same time, it avoids the high-consumption and high-pollution delignification and hemicellulose removal processes, and the retained lignin and hemicellulose can participate in quaternization modification, effectively improving the utilization rate of raw materials, and is suitable for expanding production; (2) The charge on the surface of the original fiber can effectively promote the dissociation of the fiber, which can significantly reduce the energy consumption of high-pressure homogenization; (3) The lignin retained by the lignocellulose nanofibrils can not only act as a reducing agent to increase the free radical polymerization rate of the hydrogel, but also act as a pore-forming agent to increase the porosity of the hydrogel, prolong the release time of the drug, and slow down the drug release rate. Summary of the invention
[0007] In view of the above problems, the present invention provides a method for preparing quaternized lignocellulose nanofibrils and their application, wherein the nanofibrils have a high lignin content and a uniform diameter distribution. The reducing property of lignin in the quaternized lignocellulose nanofibrils is utilized to cause a redox reaction with metal ions to initiate free radical polymerization, thereby obtaining a lignocellulose nanofibril hydrogel. The quaternized lignocellulose nanofibrils and hydrogel of the present invention have good biocompatibility, and the preparation process is green and pollution-free, the reaction conditions are mild, and the energy consumption is low.
[0008] The present invention is achieved through the following technical solutions:
[0009] The invention discloses a quaternized lignocellulose nanofibril. The quaternized lignocellulose nanofibril is prepared by pretreating a bagasse raw material with a low eutectic solvent synthesized from choline chloride and imidazole, then adding toluenesulfonyl chloride and betaine hydrochloride for quaternization modification, and then undergoing mechanical microfibrillation to obtain the quaternized lignocellulose nanofibril.
[0010] As a preferred technical solution, the quaternized lignocellulose nanofibrils have a cation content of 0.9-1.9%, a diameter distribution of 4-10 nm, and a relative crystallinity of 40-50%.
[0011] A method for preparing quaternized lignocellulose nanofibrils as described above comprises the following steps: (1) pretreatment with a low eutectic solvent: crushing, washing and drying bagasse, then adding the treated bagasse to a low eutectic solvent synthesized from choline chloride and imidazole for pretreatment, and mixing evenly to obtain a pretreated bagasse solution;
[0012] (2) quaternization modification: adding toluenesulfonyl chloride and betaine hydrochloride to the bagasse solution pretreated in step (1) for quaternization modification, reacting under mechanical stirring, adding ethanol to terminate the reaction after the reaction, washing the bagasse after the reaction to neutrality by centrifugation, collecting the solid and sealing to balance the moisture, and obtaining the quaternized bagasse;
[0013] (3) Mechanical microfibrillation: The bagasse modified by quaternization in step (2) is dispersed in deionized water to prepare a suspension, and subjected to ultrafine particle grinding treatment to obtain anionized lignocellulose nanofibrils.
[0014] In step (2) of the present invention, the reaction formula of the reaction between the pretreated bagasse and betaine hydrochloride is:
[0015] As a preferred technical solution, in step (1), the mass ratio of bagasse to low eutectic solvent is 1:20-30; the molar ratio of choline chloride to imidazole is 3:7, the reaction temperature is 80-160°C, and the reaction is carried out for 4-12 hours under mechanical stirring.
[0016] As a preferred technical solution, in step (2), the molar ratio of toluenesulfonyl chloride to betaine hydrochloride is 2-3:3, and the molar ratio of toluenesulfonyl chloride to cellulose is 3:1.
[0017] As a preferred technical solution, in step (2), the reaction is carried out at a temperature of 80° C. and a rotation speed of 200 to 400 rpm under mechanical stirring for 4 to 6 hours.
[0018] As a preferred technical solution, in step (3), the grinding disc gap of the ultrafine particle grinding is 50 to 200 nm, and the number of cycles is 20 to 30 times.
[0019] As a preferred technical solution, in step (3), the concentration of the suspension is 0.5 to 2 wt%.
[0020] The quaternized lignocellulose nanofibrils as described above are used as a reducing agent and reinforcing agent to prepare a lignocellulose hydrogel and achieve the release of levofloxacin. The preparation method of the hydrogel material is characterized in that the quaternized lignocellulose nanofibrils are cross-linked and polymerized with stannous chloride, dimethylaminoethyl methacrylate (DMAEMA) and acrylic acid (AA) to prepare the quaternized lignocellulose nanofibril hydrogel, and the specific steps are as follows:
[0021] (1) Add 1.5 mL of quaternized lignocellulose nanofibrils (10 mg / mL), 0.06 g of stannous chloride, and 5.3 mL of water and stir for 10 min;
[0022] (2) Add 2 mL DMAEMA and 1.2 mL AA to the solution in step (1) and stir for 5 min;
[0023] (3) adding 3 mg of N,N′-methylenebisacrylamide (MBA) to the mixed solution in step (2) and stirring for 5 min;
[0024] (4) adding 20 mg of ammonium persulfate (APS) to the mixed solution in step (3), stirring for 5 min, and then standing to form a hydrogel;
[0025] The preparation of the drug-loaded hydrogel is as follows: after step (3), 0.1 g of levofloxacin (Lev) is added and stirred evenly, and then ammonium persulfate is added and stirred evenly and allowed to stand to obtain the drug-loaded hydrogel.
[0026] Reaction principle of the present invention:
[0027] The present invention first pre-treats bagasse, synthesizes a low eutectic solvent from choline chloride and imidazole, and choline chloride and imidazole play a synergistic role to degrade the molecular chain of cellulose and weaken the hydrogen bond of cellulose. After being treated with the low eutectic solvent, the cleavage of ether bonds and ester bonds in lignocellulose is catalyzed. In addition, the low eutectic solvent has a good swelling ability, can open the cellulose structure, increase the reaction surface area, and is conducive to exposing more reaction sites.
[0028] As shown in the above reaction formula, the reaction mechanism of the modification of lignocellulose is as follows: first, alkaline imidazole acts as a catalyst to deprotonate the carboxylic acid group of betaine; then the deprotonated betaine reacts with toluenesulfonyl chloride to form a mixed anhydride, and imidazole acts as an acid scavenger by neutralizing the hydrogen chloride formed as a byproduct at this stage; the hydroxyl oxygen atom of lignocellulose reacts with the mixed anhydride on the carbonyl carbon to form an intermediate. The intermediate is then deprotonated by imidazole to form a product cellulose betaine ester, i.e., quaternized lignocellulose. This pretreatment can not only reduce the fiber particle size and hydrolyze part of the amorphous region, but also graft quaternary ammonium groups on the fiber surface, which is beneficial to prevent cellulose from being hydrolyzed and dissolved during the pretreatment process of the low eutectic solvent. The unhydrolyzed cellulose solid residue is mechanically ground to obtain nanocellulose, which can reduce energy consumption. In addition, the introduction of charged functional groups into the fiber structure can produce electrostatic repulsion between fibers and promote the microfibrillation process of the fibers. Quaternized lignocellulose nanofibrils can be efficiently prepared by hydrolysis, swelling and esterification of bagasse using a low eutectic solvent combined with betaine and toluenesulfonyl chloride treatment.
[0029] Compared with the prior art, the advantages and beneficial effects of the present invention are:
[0030] 1. The present invention pre-treats bagasse with a green low eutectic solvent and introduces charged groups on the fiber through quaternization modification. This process effectively promotes the dissociation of the fiber, generates electrostatic forces between the fibers, promotes the microfibrillation process of the fiber, and reduces the energy consumption of mechanical grinding. The modified bagasse can be easily ground into a gel by ultrafine particles, and the quaternized lignocellulose nanofibrils obtained have a narrow diameter distribution range and uniform size. The preparation process is green and environmentally friendly, and meets the requirements of green chemical production.
[0031] 2. The quaternized lignocellulose nanofibrils of the present invention retain lignin, which is rich in phenolic hydroxyl, alcoholic hydroxyl, phenyl and other active groups, so that it has good thermal stability and reducibility. At the same time, lignin located between cellulose chains can also reduce fiber agglomeration.
[0032] 3. The quaternized lignocellulose nanofibrils of the present invention can be used to prepare hydrogels by redox-initiated free radical polymerization with metal ions. The process can be carried out efficiently and quickly at room temperature without the need for additional initiators. The preparation process of the present invention is simple and environmentally friendly, and provides a new idea for the green extraction of lignocellulose from bagasse and the simple and effective preparation of lignocellulose hydrogels.
[0033] 4. The lignocellulose nanofibril hydrogel of the present invention has good mechanical properties, biocompatibility and antibacterial properties, and can be used as a sustained-release carrier to achieve a slow and sustained release of levofloxacin.
[0034] 5. The present invention uses abundant bagasse as raw material to prepare quaternized lignocellulose nanofibrils, which opens up a channel for the utilization of bagasse and promotes the sustainable development of the economy in sugarcane-growing areas. The lignocellulose nanofibril hydrogel prepared by the present invention has great practical application prospects in the field of medical biology. BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Figure 1 Flow chart of the preparation of quaternized lignocellulose nanofibrils.
[0036] Figure 2 The infrared spectra of the quaternized lignocellulose and bagasse prepared in Examples 1 and 2 are shown.
[0037] Figure 3 TEM images and diameter distribution diagrams of Examples 1(a) and 2(b) are shown.
[0038] Figure 4 Field emission scanning electron microscopy images of Examples 1(a) and 2(b).
[0039] Figure 5 The thermal stability curves of Examples 1 and 2 are shown in FIG.
[0040] Figure 6 The hydrogel prepared in Application Example 1.
[0041] Figure 7 This is the hydrogel prepared in Application Example 2.
[0042] Figure 8 This is the hydrogel prepared in Comparative Example 3.
[0043] Fig. 9Field emission scanning electron microscopy images of the hydrogels of Examples 3(a), 4(b) and Comparative Example 1(c) are shown.
[0044] Fig.10 Hydrogel tensile strain-stress curves (a) and fracture energy (b) of quaternized lignocellulose nanofibril hydrogel.
[0045] Fig.11 Sustained release of levofloxacin from quaternized lignocellulose nanofibril hydrogel.
[0046] Fig.12 Antibacterial properties of quaternized lignocellulose nanofibril hydrogels.
[0047] Fig.13 Cytocompatibility of quaternized lignocellulose nanofibril hydrogels. DETAILED DESCRIPTION
[0048] The present invention is further described in detail below by way of examples. These examples are only used to illustrate the present invention and do not limit the protection scope of the present invention.
[0049] Example 1
[0050] Preparation of quaternized lignocellulose nanofibrils:
[0051] (1) Pretreatment with low eutectic solvent: crush bagasse to 200 μm using a pulverizer, wash repeatedly with deionized water and ethanol until the solution is clear, and then dry in an oven at 60°C. Then add 25 g of the treated bagasse to 625 g of low eutectic solvent for pretreatment, mix well, and react at 80°C for 19 h to obtain a pretreated bagasse solution. The low eutectic solvent is obtained by reacting choline chloride and imidazole at a molar ratio of 3:7 at 80°C for 1 h.
[0052] (2) Quaternization modification: 35.53 g of betaine hydrochloride and 44.10 g of p-toluenesulfonyl chloride were added to the bagasse solution pretreated in step (1) for quaternization modification. The mixture was reacted for 4 h under mechanical stirring conditions at a temperature of 80° C. and a rotation speed of 300 rpm. After the reaction was completed, ethanol was added to terminate the reaction. The bagasse suspension after the reaction was separated by vacuum filtration. The solid residue was collected and repeatedly washed with ethanol until the filtrate was colorless. Deionized water was then added and the mixture was centrifuged at a rotation speed of 4000 rpm for 20 min. The washing solution was washed until it was neutral. The solid was collected and sealed to balance the moisture content to obtain quaternized bagasse, i.e., quaternized lignocellulose.
[0053] (3) The quaternary ammonium lignocellulose is dispersed in deionized water to prepare a suspension with a concentration of 2 wt %, and after being stirred evenly, an ultrafine grinding treatment is performed with a grinding disc gap of 100 nm and a total of 30 cycles to obtain quaternary ammonium lignocellulose nanofibrils.
[0054] Example 2
[0055] Preparation of quaternized lignocellulose:
[0056] (1) Pretreatment with low eutectic solvent: crush bagasse to 200 μm using a pulverizer, wash repeatedly with deionized water and ethanol until the solution is clear, and then dry in an oven at 60°C. Then add 25 g of the treated bagasse to 625 g of low eutectic solvent for pretreatment, mix well, and react at 140°C for 19 h to obtain a pretreated bagasse solution. The low eutectic solvent is obtained by reacting choline chloride and imidazole at a molar ratio of 3:7 at 80°C for 1 h.
[0057] (2) Quaternization modification: 35.53 g of betaine hydrochloride and 44.10 g of p-toluenesulfonyl chloride were added to the bagasse solution pretreated in step (1) for quaternization modification. The mixture was reacted for 4 h under mechanical stirring conditions at a temperature of 140° C. and a rotation speed of 300 rpm. After the reaction was completed, ethanol was added to terminate the reaction. The bagasse suspension after the reaction was separated by vacuum filtration. The solid residue was collected and repeatedly washed with ethanol until the filtrate was colorless. Deionized water was then added and the mixture was centrifuged at a rotation speed of 4000 rpm for 20 min. The washing solution was washed until it was neutral. The solid was collected and sealed to balance the moisture to obtain quaternized bagasse, i.e., quaternized lignocellulose.
[0058] (3) The quaternary ammonium lignocellulose is dispersed in deionized water to prepare a suspension with a concentration of 2 wt %, and after being stirred evenly, an ultrafine grinding treatment is performed with a grinding disc gap of 100 nm and a total of 30 cycles to obtain quaternary ammonium lignocellulose nanofibrils.
[0059] Table 1 Chemical components of quaternized lignocellulose nanofibrils
[0060] It can be found from the data in Table 1 that after DES pretreatment, the lignin content is reduced and the cellulose content is increased compared with the lignin content of bagasse. In Example 1, the reaction temperature is 80°C, and a quaternized ammonium lignocellulose with a high lignin content (QAHLCNF) is obtained; in Example 2, the reaction temperature is 140°C, and the lignin content is 8.5%, which is a quaternized ammonium lignocellulose with a medium lignin content (QAMLCNF). This is because as the temperature increases, the solubility of lignin in DES increases, resulting in different lignin contents in lignocellulose. The crystallinity of quaternized lignocellulose nanofibrils decreases after mechanical grinding, because mechanical grinding can cause the destruction of the cellulose crystalline region and the depolymerization of cellulose. At the same time, the crystallinity increases with the increase of the pretreatment temperature. This is because when the temperature increases, the removal rate of lignin is higher (as shown in Table 1), which helps to improve the crystallinity of the undissolved solid material.
[0061] Figure 2 This is the infrared spectrum of quaternized lignocellulose. Due to the stretching vibration of the methyl group in the quaternary ammonium group, QALCNF is at 2926 cm -1 The characteristic peak intensity of the CH bond at 1739 cm -1 The appearance of a new peak (C=O stretching) at 40°C confirmed the formation of ester bonds with the cellulose backbone, indicating that betaine was grafted onto cellulose via ester bonds. In addition, the intensity of the carbonyl peak increased, indicating the successful formation of betaine esters of lignocellulose.
[0062] Figure 3 The transmission electron microscope images of Examples 1 and 2 show that the quaternized lignocellulose nanofibril aggregates are composed of many fine nanocelluloses, which are highly ordered and oriented along the length of the aggregates, and their diameter distribution is concentrated at 4 nm.
[0063] Figure 4 The field emission scanning electron microscope images of Examples 1 and 2 show that the quaternized lignocellulose nanofibrils have a well-layered fibril network structure as shown in TEM.
[0064] Figure 5 The thermal stability curves of Examples 1 and 2 show that the decomposition temperature of QAHLCNF (238°C) is higher than that of QAMLCNF (192°C), which may be due to the high content of lignin, which gives it higher thermal stability.
[0065] Example 3
[0066] Preparation of quaternized lignocellulose nanofibril hydrogel:
[0067] 1.5 mL QAHLCNF (10 mg / mL) of Example 1 and 0.06 g SnCl2 Add to 5.3 mL of deionized water to prepare a uniform suspension and stir for 10 min. Then, at room temperature, add 2 mL of DMAEMA, 1.2 mL of AA, stir for 5 min, add 3 mg of N, N′-methylenebisacrylamide (MBA), stir for 5 min, add 20 mg of ammonium persulfate (APS) to the mixed solution, stir for 5 min, and let stand to form a hydrogel.
[0068] Example 4
[0069] Preparation of quaternized lignocellulose nanofibril hydrogel:
[0070] 1.5 mL QAMLCNF (10 mg / mL) and 0.06 g SnCl 2 Add to 5.3 mL of deionized water to prepare a uniform suspension and stir for 10 min. Then, add 2 mL of DMAEMA, 1.2 mL of AA, stir for 5 min, add 3 mg of N, N'-methylenebisacrylamide (MBA) and stir for 5 min. Add 20 mg of ammonium persulfate (APS) to the mixed solution and stir for 5 min, then let it stand to form a hydrogel.
[0071] Comparative Example 1
[0072] Preparation of quaternized nanocellulose hydrogel:
[0073] 1.5 mL of QACNF (10 mg / mL) and 0.06 g of SnCl2 of Example 1 were added to 5.3 mL of deionized water to prepare a uniform suspension and stirred for 10 min. Then, 2 mL of DMAEMA and 1.2 mL of AA were stirred for 5 min at room temperature, 3 mg of N, N'-methylenebisacrylamide (MBA) was added and stirred for 5 min, and 20 mg of ammonium persulfate (APS) was added to the mixed solution and stirred for 5 min, and then allowed to stand to form a hydrogel.
[0074] Figure 7 The hydrogel prepared in Example 3 can be quickly obtained at room temperature. This is because the lignin content of the lignocellulose nanofibrils in Example 3 is high, and SnCl 2 The redox rate was faster, so the hydrogel was formed in 20 min.
[0075] Figure 7 The hydrogel prepared in Example 4 can be obtained at room temperature for 30 min. This is because the lignin content of the lignocellulose nanofibrils in Example 4 is less than that in Example 3. 2 The rate of redox slowed down and gel could be formed after 30 minutes.
[0076] Figure 8The hydrogel prepared in Comparative Example 1 takes 24 hours to form a gel at room temperature. This is because nanocellulose does not contain lignin, and metal ions cannot initiate free radical polymerization by redox, and the polymerization of the gel is mainly self-polymerization of acrylic acid and methacrylic acid monomers.
[0077] Fig. 9 Field emission scanning electron micrographs of the hydrogels prepared in Examples 3 and 4 and Comparative Example 1 show that the presence of lignin in the quaternized lignocellulose nanofibrils can be used as a porogen to produce different pore structures during the formation of the hydrogel. Due to the presence of lignin, the hydrogel formed by QAHLCNF (Example 3) has a rich pore structure, which is beneficial to prolonging the release of the drug in the hydrogel carrier and slowing down the release rate of the drug.
[0078] Fig.10 The tensile stress-strain curves (a) and fracture energies (b) of the hydrogels prepared in Examples 3, 4 and Comparative Example 1. The elongation at break of the hydrogel formed by QAHLCNF (Example 3) can reach 587%, and the fracture energy is as high as 3790 J / m 2 .
[0079] Example 5
[0080] Study on sustained release of levofloxacin from quaternized lignocellulose nanofibril hydrogel:
[0081] First, the drug-loaded hydrogel was prepared. The main steps were to mix 1.5 mL QAMLCNF (10 mg / mL) and 0.06 g SnCl 2 Add to 5.3 mL of deionized water to prepare a uniform suspension and stir for 10 min. Then, at room temperature, add 2 mL of DMAEMA, 1.2 mL of AA, stir for 5 min, add 3 mg of N, N′-methylenebisacrylamide (MBA), stir for 5 min, add 0.1 g of levofloxacin (Lev) to the mixed solution, then add 20 mg of ammonium persulfate (APS), stir for 5 min, and let stand to form a drug-loaded hydrogel.
[0082] 0.1 g of drug-loaded hydrogel was placed in 10 mL of PBS (pH = 5.0, 7.4), the solution was taken out regularly, and the release of Lev was monitored by UV spectrophotometer. Fig.11 As shown in the figure, the release of levofloxacin from the hydrogel can last for 5 days, and the release efficiency is even higher at pH 5.0, reaching 95.3% after 24 hours. Fig.12 It is the antibacterial effect of quaternized lignocellulose rice fiber hydrogel, the inhibition zone is 40mm, and it has good antibacterial performance. Fig.13It is the cell-degradable property of quaternized lignocellulose rice fibril hydrogel, and its cell activity is greater than 90%. It is green and natural, and is expected to be used as a wound dressing to promote wound healing. a is quaternized lignocellulose rice fibril hydrogel, and b is drug-loaded hydrogel.
Claims
1. A method for preparing quaternized lignocellulose nanofibrils, characterized in that: Bagasse is pretreated with a low eutectic solvent synthesized by imidazole and choline chloride, and then cationic agents toluenesulfonyl chloride and betaine hydrochloride are added for cation modification. After mechanical grinding, quaternary ammonium lignocellulose nanofibrils with different lignin contents can be prepared by utilizing the difference in reaction temperature.
2. The quaternized lignocellulose nanofibrils according to claim 1, characterized in that The quaternized wood cellulose nanofibrils have a cation content of 0.9 to 1.9 mmol / g, a diameter distribution of 4 to 10 nm, and a relative crystallinity of 40 to 50%.
3. A method for preparing quaternized lignocellulose nanofibrils according to claim 1 or 2, characterized in that: The following steps are involved: (1) Pretreatment with a low eutectic solvent: crushing, washing and drying the bagasse, then adding choline chloride and imidazole to the treated bagasse for pretreatment in a synthetic low eutectic solvent, and mixing them evenly to obtain a pretreated bagasse solution; (2) quaternization modification: adding toluenesulfonyl chloride and betaine hydrochloride to the bagasse solution pretreated in step (1) for quaternization modification, reacting under mechanical stirring, adding ethanol to terminate the reaction after the reaction, washing the bagasse after the reaction to neutrality by centrifugation, collecting the solid and sealing to balance the moisture, and obtaining the quaternized bagasse; (3) Mechanical microfibrillation: The quaternized bagasse in step (2) is dispersed in deionized water to prepare a suspension, and subjected to ultrafine grinding treatment to obtain quaternized lignocellulose nanofibrils.
4. The method for preparing quaternized lignocellulose nanofibrils according to claim 3, characterized in that: In step (1), the mass ratio of bagasse to low eutectic solvent is 1:20; the molar ratio of choline chloride to imidazole is 3:7, and the reaction temperature is 80-160°C.
5. The method for preparing quaternized lignocellulose nanofibrils according to claim 3, characterized in that: In step (2), the molar ratio of toluenesulfonyl chloride to betaine hydrochloric acid is 2-3:
3.
6. The method for preparing quaternized lignocellulose nanofibrils according to claim 3, characterized in that: In step (2), the reaction is carried out at a temperature of 80° C. and a rotation speed of 200 to 400 rpm under mechanical stirring for 4 to 12 hours.
7. The method for preparing quaternized lignocellulose nanofibrils according to claim 3, characterized in that: In step (3), the grinding disc gap of the ultrafine particle grinding is 50 to 300 nm, and the number of cycles is 20 to 30 times.
8. The method for preparing quaternized lignocellulose nanofibrils according to claim 3, characterized in that: In step (3), the concentration of the suspension is 0.5-2 wt %.
9. The quaternized lignocellulose nanofibrils as claimed in claims 4 to 8 are used as a reducing agent and reinforcing agent to prepare lignocellulose hydrogel and achieve the release of levofloxacin. The method for preparing a hydrogel material is characterized by: The quaternized lignocellulose nanofibril prepared according to claims 4-8 is cross-linked and polymerized with stannous chloride, dimethylaminoethyl methacrylate (DMAEMA) and acrylic acid (AA) to prepare the quaternized lignocellulose nanofibril hydrogel, and the specific steps are as follows: (1) Add 1.5 mL of quaternized lignocellulose nanofibrils (10 mg / mL), 0.06 g of stannous chloride, and 5.3 mL of water and stir for 10 min; (2) Add 2 mL DMAEMA and 1.2 mL AA to the solution in step (1) and stir for 5 min; (3) adding 3 mg of N,N′-methylenebisacrylamide (MBA) to the mixed solution in step (2) and stirring for 5 min; (4) adding 20 mg of ammonium persulfate (APS) to the mixed solution in step (3), stirring for 5 min, and then standing to form a hydrogel; The preparation of the drug-loaded hydrogel is as follows: after step (3), 0.1 g of levofloxacin (Lev) is added and stirred evenly, and then ammonium persulfate is added and stirred evenly and allowed to stand to obtain the drug-loaded hydrogel.