Aminated lignin and preparation method and application thereof
阅读说明：本技术 一种氨基化木质素及其制备方法和应用 (Aminated lignin and preparation method and application thereof ) 是由 陈凯 陈凤凤 王丹 袁胜荣 于 2020-12-23 设计创作，主要内容包括：本发明涉及生物质基多功能抗菌剂技术领域,提供了一种兼具抗菌、抗紫外氧化和乳化性能的氨基化木质素及其制备方法和应用。所述氨基化木质素由酶解木质素,赖氨酸和乙二醛反应得到,通过Manich反应,在木质素多酚聚合物中引入氨基,增加静电相互作用,提高抗菌活性,实现木质素在生物医药中的高值化利用,具有重要的社会、环境和经济意义。利用氨基化木质素协同小分子助剂,稳定高内相乳液,用于负载天然抗菌试剂,提高天然抗菌试剂的化学稳定性、抑菌活性和生物利用度,为构建新型抗菌材料提供新策略。(The invention relates to the technical field of biomass-based multifunctional antibacterial agents, and provides aminated lignin with antibacterial, ultraviolet oxidation resistant and emulsifying properties, and a preparation method and application thereof. The aminated lignin is obtained by reacting enzymolysis lignin, lysine and glyoxal, amino is introduced into a lignin polyphenol polymer through a Manich reaction, so that the electrostatic interaction is increased, the antibacterial activity is improved, the high-value utilization of the lignin in biomedicine is realized, and the method has important social, environmental and economic significance. The aminated lignin is utilized to cooperate with the micromolecule auxiliary agent to stabilize the high internal phase emulsion, and the high internal phase emulsion is used for loading a natural antibacterial agent, so that the chemical stability, the bacteriostatic activity and the bioavailability of the natural antibacterial agent are improved, and a new strategy is provided for constructing a novel antibacterial material.)
1. An aminated lignin, characterized by being obtained by reacting: enzymatic hydrolysis of lignin, lysine and glyoxal.
2. The preparation method of the aminated lignin is characterized by comprising the following steps:
s1, dissolving the enzymatic hydrolysis lignin in an alkali solution to obtain an enzymatic hydrolysis lignin solution, adding lysine and glyoxal, stirring, heating and reacting for a certain time;
s2, after the reaction is finished, adding an acid solution to adjust the pH of the reaction solution to be neutral, and dialyzing for 2-6 days by using a dialysis bag;
and S3, drying the obtained dialysate to obtain the aminated lignin.
3. The method for preparing aminated lignin according to claim 2, further comprising at least one of the following additional technical features:
the concentration of the enzymatic hydrolysis lignin solution is 5-20 wt%;
the mass ratio of the enzymatic hydrolysis lignin to the lysine to the glyoxal is 1: 0.5-3: 0.5 to 3;
the molecular weight of the dialysis bag is 2500-4000 Da;
the drying is freeze drying.
4. The method for preparing aminated lignin according to claim 2, characterized in that the conditions of stirring and heating reaction are as follows: the reaction temperature is 30-60 ℃, and the reaction time is 2-10 h.
5. The aminated lignin according to any one of claims 1 to 4, wherein said aminated lignin is used for inhibiting Escherichia coli and Staphylococcus aureus.
6. The aminated lignin according to any one of claims 1 to 4, characterized by the use thereof for the preparation of stable high internal phase emulsions.
7. A method of preparing a stable high internal phase emulsion comprising the steps of:
1) dissolving a certain amount of natural antibacterial agent in the oil phase, filling into a brown bottle, and placing in a refrigerator for later use;
2) mixing a certain amount of aminated lignin, small molecular auxiliary agent and ultrapure water with a certain volume of the oil phase, and carrying out high-speed shearing emulsification.
8. The method of claim 7, wherein in step 1) the oil phase is one of palm oil, soybean oil, liquid paraffin, turpentine, toluene, and n-hexane; and/or
In the step 2), the small molecular auxiliary agent is one or more of sodium dodecyl sulfate and alkyl glucoside.
9. The method of claim 7, further comprising at least one of the following additional features in step 2):
the volume ratio of the ultrapure water to the oil phase is 1: 8-3: 7;
the grafting ratio of the aminated lignin is 0.1-1.0 mmol/g;
the concentration of the aminated lignin is 0.5-10.0 wt% based on the mass of ultrapure water;
the concentration of the small molecular auxiliary agent is 0.5-5.0 wt% based on the mass of the ultrapure water;
the high-speed shearing and emulsifying speed is 10000-13000 rpm.
10. The stable high internal phase emulsion prepared by the preparation method according to any one of claims 7 to 9, which is characterized by application in the preparation of an antibacterial drug delivery system.
Technical Field
The invention relates to the technical field of biomass-based multifunctional antibacterial agents, in particular to aminated lignin with antibacterial, ultraviolet oxidation resistant and emulsifying properties, and a preparation method and application thereof.
EHL refers to enzymatically hydrolyzed lignin, Lys refers to lysine, and HIPEs refers to high internal phase emulsions.
Background
Serious infectious diseases caused by different pathogenic bacteria, such as suppurative wound infection, respiratory inflammation, dermatitis and the like, still remain one of the biggest threats to the life and health of people. More seriously, the resistance of pathogenic bacteria is increasing due to the abuse of traditional antibiotics, which poses a great threat to the existing bacterial infection treatment systems. Therefore, new, effective antimicrobial strategies and drugs are urgently needed to reduce the dependence on antibiotic therapy.
Since ancient times, herbal medicines and phytochemicals have been widely used for the treatment of various infectious diseases. Curcumin is a natural polyphenol compound extracted from turmeric rhizome, and has been shown to have highly effective inhibitory activity against a number of pathogenic bacteria including helicobacter pylori, escherichia coli against candida albicans and multidrug resistant bacteria. However, curcumin is sensitive to temperature, oxygen and light, leading to easy degradation and inactivation, and poor water solubility leading to low bioavailability, which is severely limited in clinical application.
Lignin is the second most abundant polyphenolic polymer in plants. Industrial lignin yields also exceed 5000 million tons per year, but most are only used for low-yield applications such as fuel-fired heating and energy generation for industrial processes. The process not only wastes a large amount of biological resources, but also seriously harms the living environment of human beings. In fact, protection of plants from bacterial and fungal attack is one of the key functions of lignin. Yang et al found that industrial lignin has a wide inhibitory activity against plant pathogens and can be used as an antimicrobial agent against plant pathogens or food packaging. The Wang et al research shows that the industrial lignin also has certain inhibitory activity on common nosocomial pathogenic bacteria including Escherichia coli and Staphylococcus aureus. However, the poor water solubility and low antimicrobial activity of industrial lignin limit its clinical use. The literature reports that the antibacterial activity of the industrial lignin can be improved by chemical modification such as acetylation, epoxidation, hydroxymethylation, ammonification and the like. In addition, lignin molecules contain a plurality of aromatic ring structures, so that the lignin molecules have excellent ultraviolet blocking performance, and can be widely applied to protective agents of photothermal unstable drugs such as curcumin and beta-carotene. In conclusion, the synthesis of the multifunctional lignin-based antibacterial agent and the synergy of the multifunctional lignin-based antibacterial agent and the natural polyphenol compound are an ideal strategy for constructing a novel antibacterial material.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and construct a novel antibacterial material and application thereof.
The invention aims to provide an aminated lignin which has high antibacterial activity and water solubility and is obtained by reacting the following components: enzymatic hydrolysis of lignin, lysine and glyoxal.
The second aspect of the invention is a preparation method of aminated lignin, which improves the antibacterial activity and water solubility of lignin. The method is realized by the following scheme:
the invention provides a preparation method of aminated lignin, which comprises the following steps:
s1, dissolving the enzymatic hydrolysis lignin in an alkali solution to obtain an enzymatic hydrolysis lignin solution, adding lysine and glyoxal, stirring, heating and reacting for a certain time;
s2, after the reaction is finished, adding an acid solution to adjust the pH of the reaction solution to be neutral, and dialyzing for 2-6 days by using a dialysis bag;
and S3, drying the obtained dialysate to obtain the aminated lignin.
Preferably, the preparation method of the aminated lignin further comprises at least one of the following additional technical features:
the concentration of the enzymatic hydrolysis lignin solution is 5-20 wt%;
the mass ratio of the enzymatic hydrolysis lignin to the lysine to the glyoxal is 1: 0.5-3: 0.5 to 3;
the molecular weight of the dialysis bag is 2500-4000 Da;
the drying is freeze drying.
Preferably, the conditions of the stirring heating reaction are as follows: the reaction temperature is 30-60 ℃, and the reaction time is 2-10 h.
The third aspect of the invention aims at providing the application of the aminated lignin in inhibiting escherichia coli and staphylococcus aureus.
The fourth aspect of the invention is to provide the application of the aminated lignin in preparing stable high internal phase emulsion. The method is realized by the following scheme:
the invention provides a preparation method of a stable high internal phase emulsion, which comprises the following steps:
1) dissolving a certain amount of natural antibacterial agent in the oil phase, filling into a brown bottle, and placing in a refrigerator for later use;
2) mixing a certain amount of aminated lignin, small molecular auxiliary agent and ultrapure water with a certain volume of the oil phase, and carrying out high-speed shearing emulsification.
Preferably, the oil phase in the step 1) is one of palm oil, soybean oil, liquid paraffin, turpentine, toluene and n-hexane; and/or
In the step 2), the small molecular auxiliary agent is one or more of sodium dodecyl sulfate and alkyl glucoside.
Preferably, the method for preparing a stable high internal phase emulsion according to the present invention, step 2), further comprises at least one of the following additional technical features:
the volume ratio of the ultrapure water to the oil phase is 1: 8-3: 7;
the concentration of the aminated lignin is 0.5-10.0 wt% based on the mass of ultrapure water;
the grafting ratio of the aminated lignin is 0.1-1.0 mmol/g; wherein, the product grafting ratio is the carboxylic acid content in the aminated lignin-the carboxylic acid content in the lignin;
the concentration of the small molecular auxiliary agent is 0.5-5.0 wt% based on the mass of the ultrapure water;
the high-speed shearing and emulsifying speed is 10000-13000 rpm.
The fourth aspect of the invention is to provide the application of the high internal phase emulsion based on the aminated lignin for stabilizing the natural antibacterial agent delivery system.
The mechanism of the invention is as follows:
through Manich reaction, amino is introduced to the ortho-position of phenolic hydroxyl, so that the lignin is endowed with electropositivity, the electrostatic interaction with bacteria is increased, and the antibacterial activity is improved. And secondly, the original phenolic hydroxyl and benzene ring structures of the lignin are not damaged, so that the lignin still has excellent ultraviolet absorption, oxidation resistance and antibacterial effects. Therefore, the natural antibacterial agent can be endowed with good ultraviolet, heat and oxygen protective performance, and the antibacterial activity and bioavailability of the natural antibacterial agent are improved.
Compared with the prior art, the invention can obtain the following beneficial effects:
1. through Manich reaction, amino is introduced into the lignin polyphenol polymer, so that electrostatic interaction is increased, antibacterial activity is improved, high-value utilization of lignin in biomedicine is realized, and the method has important social, environmental and economic significance.
2. The amino group is introduced at the ortho position of the phenolic hydroxyl group of the lignin, the original phenolic hydroxyl group and benzene ring structures of the lignin are not damaged, the intrinsic characteristics of the lignin such as antibiosis, ultraviolet resistance, oxidation resistance and the like are well kept, and the lignin has more excellent antibiosis, ultraviolet resistance and oxidation resistance.
3. The aminated lignin is utilized to cooperate with the micromolecule auxiliary agent to stabilize the high internal phase emulsion, and the high internal phase emulsion is used for loading a natural antibacterial agent, so that the chemical stability, the bacteriostatic activity and the bioavailability of the natural antibacterial agent are improved, and a new strategy is provided for constructing a novel antibacterial material.
4. The aminated lignin is biocompatible, safe, nontoxic, green and environment-friendly, and can be widely popularized in biological medicines.
Drawings
FIG. 1 is a scheme showing the synthesis scheme of aminated lignin according to a preferred embodiment of the present invention;
FIG. 2 is a graph of the bacteriostatic activity of aminated lignin against Staphylococcus aureus in accordance with a preferred embodiment of the present invention;
FIG. 3 is a graph of the bacteriostatic activity of aminated lignin against E.coli in accordance with a preferred embodiment of the present invention;
FIG. 4 is a graph of the hemolysis rate of aminated lignin according to a preferred embodiment of the present invention;
FIG. 5 is a macro and micro topography of a stable high internal phase emulsion according to a preferred embodiment of the present invention;
fig. 6 is a graph of retention of curcumin in a drug-loaded emulsion of a preferred embodiment of the present invention;
fig. 7 is a bacterial topography after treatment with a medicated emulsion according to a preferred embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1:
and (3) synthesizing a series of aminated lignin.
Firstly, dissolving 4.0g of enzymatic lignin in 40mL of 0.5mol/L sodium hydroxide aqueous solution, adding lysine and glyoxal (enzymatic lignin: lysine: glyoxal is 1: 0.5: 0.5, 1: 1.0: 1.0, 1: 1.5: 1.5 and 1: 2.0: 2.0) in different mass ratios, stirring and reacting at 40 ℃ for 6 hours, adjusting the pH of the reaction solution to be neutral by using hydrochloric acid, dialyzing for 3 days by using a dialysis bag (Mw is 3000Da), and freeze-drying to obtain a final sample. The synthetic route of the aminated lignin is shown in figure 1.
The calculation method of the grafting rate of the aminated lignin comprises the following steps: the product grafting yield is the carboxylic acid (carboxylate) content in the aminated lignin-the carboxylic acid content in the lignin. The grafting ratio is respectively: 0.15mmol/g, 0.27mmol/g, 0.38mmol/g, 0.64mmol/g, 0.50 mmol/g.
Example 2
The aminated lignin prepared in example 1 was subjected to an antibacterial activity test.
The antimicrobial activity of aminated lignin derivatives against the gram-positive bacteria staphylococcus aureus and the gram-negative bacteria escherichia coli was evaluated according to the national clinical laboratory standardization Committee (CLSI) standards. The test procedure was as follows:
first, the sample was dissolved in sterile water and serially diluted with Muller-Hinton broth in 96-well plates to final concentrations of 1mg/mL, 2mg/mL, 4mg/mL, 6mg/mL, 8mg/mL, 10mg/mL, 12mg/mL, 14mg/mL, 16mg/mL, 18mg/mL, 20mg/mL, respectively.
Then, a certain amount of bacterial suspension was added, the tested concentration of which was 5X 105CFU/mL, and two microtiter plates with sample only and bacteria suspension only as growth (no copolymer) and sterility (no bacteria) controls. All microtiter plates were incubated at 37 ℃ for 18 h.
The optical density of the suspension was measured at 600nm with a microplate reader. All experiments were repeated three times. The aminated lignin bacteriostatic activity is shown in figure 2. As is clear from FIGS. 2 and 3, the sterilizing rates of the aminated lignin against Staphylococcus aureus and Escherichia coli at 20mg/mL were 93% and 50%, respectively.
Example 3
The aminated lignin prepared in example 1 was subjected to a biocompatibility test according to the following procedure:
first, a sample is dissolved in a buffer,serial dilutions were made with buffer to the concentrations tested (1mg/mL, 2mg/mL, 4mg/mL, 6mg/mL, 8mg/mL, 10mg/mL, 12mg/mL, 14mg/mL, 16mg/mL, 18mg/mL, 20 mg/mL). Then, the red blood cell suspension (6.45X 10) was added12RBCs/L), gently shaken at 37 ℃ for 30 minutes, centrifuged to remove cells, and the supernatant was tested for optical density at 540 nm. In addition, pure buffer and 2% TRITON-X were used as negative and positive controls, respectively. In addition, the pure sample solution served as a blank sample. All experiments were repeated three times. The hemolysis rate of aminated lignin is shown in FIG. 4. As can be seen from FIG. 4, at 20mg/mL, the hemolysis rate of the aminated lignin is still lower than 50%, indicating that the aminated lignin of the present invention has good biocompatibility.
Example 4
The study on the antibacterial mechanism of the aminated lignin prepared in example 1 includes the following steps:
the amount of adsorption of the sample on the bacteria was measured with a quartz crystal microbalance (QCM-D). First, pure water was injected into the QCM-D flow module. After the baseline stabilized, the bacterial suspension was injected and a new balance at the baseline was waited for again. The sample aqueous solution was then injected into the QCM-D flow module and the third overtone frequency shift (. DELTA.F) was recorded3). Wherein the flow rate of pure water is 0.15mL/min, and the concentration of bacterial suspension is 2.6 × 107CFU/mL, sample solution concentration of 1.0 mg/mL.
The adhesion between the bacteria and the sample was measured by Atomic Force Microscopy (AFM). Firstly, a sample is modified on silicon dioxide standard particles by a hot melt method and is fixed on a silicon nitride probe. Secondly, the bacteria are coated on glass by adopting an electrostatic self-assembly technology, and free planktonic bacteria are washed by potassium phosphate buffer solution to prepare cell slices for later use. Wherein the diameter of the silicon dioxide standard particle is 23.33 μm, the nominal cantilever spring constant of the silicon nitride probe is 0.12n/m, and AFM force measurement parameters are a limiting force of 20.0nN, a set value of 5.0nN and a moment of 1.0 μm. Each measurement was repeated 150 times to ensure the reliability of the data.
Experimental results show that the aminated lignin represents a membrane damage mechanism, and the antibacterial activity is increased along with the increase of the positive charge of the aminated lignin.
Example 5
The aminated lignin prepared in example 1 was used to prepare a stable high internal phase emulsion by the following method:
3.0g curcumin was dissolved in 100mL palm oil and filled into a brown bottle and placed in a refrigerator for future use. The aminated lignin (0.1g) having a graft ratio of 0.15mmol/g, alkylglycoside (0.06g) and 2mL of ultrapure water were mixed uniformly. Then, 8mL of the above oil phase was added and high-speed shearing was carried out at 11000rpm for 1 minute to prepare a high internal phase emulsion. In the same manner, 5 groups of high internal phase emulsions were prepared as shown in table 1.
TABLE 1
Wherein, the macro and micro appearance of the aminated lignin high internal phase emulsion obtained by the experimental group of the number 3 is shown in figure 5, and the macro and micro appearance obtained by the rest numbers is similar to that of figure 5. The result shows that the aminated lignin provided by the invention has excellent emulsifying property.
Example 6
The aminated lignin stable high internal phase emulsion prepared in example 5 was used for barrier performance testing including light stability testing, thermal stability testing and storage stability testing.
1. And (3) light stability test: 10g of the drug-loaded emulsion was poured into a glass petri dish (diameter 6cm, height 4cm), irradiated under ultraviolet light (25 watts) for 72h, and the level of original drug retention was measured at 254nm with an ultraviolet-visible spectrophotometer. The retention rates of curcumin in the drug-loaded emulsion prepared by the medicines in the numbers 1-5 are 71%, 65%, 67%, 68% and 71% respectively; the retention of curcumin in the drug-loaded emulsion of No. 3 is shown in fig. 6.
2. Thermal stability test: the 10g drug-loaded emulsion was poured into a glass bottle (20mL) and placed in an oven for 7 days at 60 ℃ to test the retention of the original drug in the emulsion. The retention rates of curcumin in the drug-loaded emulsion prepared by the medicines in the numbers 1-5 are respectively 70%, 75%, 73%, 73% and 71%; the retention of curcumin in the drug-loaded emulsion of No. 3 is shown in fig. 6.
3. Storage stability test: the 10g of drug-loaded emulsion is poured into a glass bottle (20mL), placed in a room temperature environment for 30 days, and the retention rate of the original drug in the emulsion is tested. The retention rates of curcumin in the drug-loaded emulsion prepared by the medicines in the numbers 1-5 are respectively 92%, 95%, 92%, 93% and 94%; the retention of curcumin in the drug-loaded emulsion of No. 3 is shown in fig. 6.
After ultraviolet, heat radiation and storage treatment, the maximum residual quantity of curcumin in the HIPEs is 60 times, 3 times and 5 times of that of the pure oil phase respectively.
Example 7
The aminated lignin stable high internal phase emulsion prepared in example 5 was used for the synergistic antibacterial performance test of aminated lignin and curcumin. The test procedure was as follows:
first, the drug-loaded emulsion was dispersed in sterile water and serially diluted with Muller-Hinton broth in 96-well plates to the concentrations tested (0.1mg/mL, 0.2mg/mL, 0.4mg/mL, 0.8mg/mL, 1.6mg/mL, 3.2mg/mL, 6.25mg/mL, 12.5mg/mL, 25mg/mL, 50 mg/mL).
Then, a certain amount of bacterial suspension (5X 10) was added5CFU/mL) and two microtiter plates with sample only and bacteria suspension only as growth (no copolymer) and sterility (no bacteria) controls. All microtiter plates were incubated at 37 ℃ for 18 h.
The optical density of the suspension was measured at 600nm with a microplate reader. When the visible growth of the bacteria is inhibited, the Minimum Inhibitory Concentration (MIC) value is taken as the minimum inhibitory concentration. All experiments were repeated three times. Wherein, the appearance of the bacteria treated by the drug-loaded emulsion with the number 3 is shown in figure 7. The figure shows that the bacterial cell membrane changed from smooth to wrinkled, indicating that the cells were killed.
Comparative example 1:
the enzymatic hydrolysis lignin is tested for antibacterial activity against staphylococcus aureus and escherichia coli without introducing amino groups, the test method is the same as that of example 2, and the results are respectively shown in fig. 2 and fig. 3. The result shows that the sterilization rate of the lignin to staphylococcus aureus is about 67 percent and the sterilization rate to escherichia coli is about 10 percent at 20mg/mL, which is far lower than the sterilization rate of the invention, and the antibacterial activity of the lignin can be improved by introducing amino into the lignin.
Comparative example 2:
and (3) testing the original medicine protective performance of the enzymatic hydrolysis lignin: without the introduction of amino groups, the preparation of stable high internal phase emulsions under neutral conditions directly with enzymatic lignin is not possible, since enzymatic lignin needs to be dissolved at pH 12 and above. Therefore, the protective performance to the original medicine is 0.
Comparative example 3:
the preparation of the stable high internal phase emulsion was carried out with the aminated lignin prepared in example 1 without the addition of the small molecule auxiliary agent, and as a result, the stable high internal phase emulsion could not be prepared, indicating that the stable high internal phase emulsion could be prepared only with the aminated lignin in cooperation with the small molecule auxiliary agent.
The invention adopts Manich reaction to synthesize a series of aminated lignin derivatives with biocompatibility, which not only increases the water solubility of lignin, but also increases the bacteriostatic activity of lignin. And then, the curcumin is combined with a small molecular auxiliary agent to stabilize a high internal phase emulsion, is used for loading a natural antibacterial agent curcumin, endows the curcumin with good ultraviolet, heat and oxygen protective properties, and improves the antibacterial activity and bioavailability of the curcumin.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.