Preparation method of antibacterial gamma-polyglutamic acid superabsorbent hydrogel

Abstract

The invention relates to a preparation method of antibacterial gamma-polyglutamic acid superabsorbent hydrogel. The preparation method comprises the following steps: (1) preparing a gamma-polyglutamic acid solution; (2) dissolving an antibacterial agent in the gamma-polyglutamic acid solution, and fully stirring and uniformly mixing to obtain a mixed solution 1; adjusting the pH value of the mixed solution 1, heating the mixed solution 1 to 60 DEG C, and continuously reacting for 1-2 hours to obtain a mixed solution 2; cooling the mixed solution 2 to room temperature, adding a cross-linking agent, and uniformly mixing to obtain a mixed solution 3; standing the mixed solution 3 at room temperature for 1-3 hours and then carrying out gradient heating reaction to obtain an antibacterial gelatinous product; and (3) dehydrating the antibacterial gelatinous product, and carrying out vacuum negative pressure drying to obtain a dried hydrogel product, namely the antibacterial gamma-polyglutamic acid super absorbent hydrogel. The antibacterial gamma-polyglutamic acid superabsorbent hydrogel prepared by the invention has good biocompatibility, is safe and non-toxic, also has excellent water absorption performance and antibacterial performance, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polymer hydrogel, and particularly relates to a preparation method of antibacterial gamma-polyglutamic acid superabsorbent hydrogel. BACKGROUND

[0002] The hydrogel is a soft material with a cross-linked polymer network structure in water or other solution as a dispersion medium, has a slightly cross-linked three-dimensional network structure, can absorb water hundreds of times or even thousands of times of its own weight, has good water retention performance, has variability and softness, and shows elastic characteristics, and has become one of the materials widely used in interdisciplinary research fields. It has been applied to the fields of agriculture, forestry, horticulture, medical health, petroleum and chemical industry, daily necessities, environmental protection, building materials, food and the like.

[0003] At present, the acrylic superabsorbent hydrogel has become a dominant product in the market due to its high water absorption rate and simple synthesis process. However, the acrylic superabsorbent resin has two problems in use: (1) difficult to degrade in the environment, which can pollute the ecological environment; (2) mainly based on petroleum resources, and with the gradual depletion of petroleum, the production cost will gradually increase. Therefore, the development of biodegradable low-cost superabsorbent hydrogel has become a hot spot in this field. At present, more than 80% of the total global production of superabsorbent hydrogel is applied to medical care. In the medical care field, the superabsorbent hydrogel is often applied to directly contact the human skin. In order to ensure safety, good antibacterial performance is required. Therefore, the research on the antibacterial superabsorbent hydrogel with very broad application prospect is very meaningful. SUMMARY

[0004] The application provides a preparation method of antibacterial gamma-polyglutamic acid superabsorbent hydrogel, and solves the problems of non-degradability and poor antibacterial performance of the existing superabsorbent hydrogel.

[0005] The application provides a preparation method of antibacterial gamma-polyglutamic acid superabsorbent hydrogel, and solves the problems of non-degradability and poor antibacterial performance of the existing superabsorbent hydrogel.

[0006] (1) dissolving gamma-polyglutamic acid in pure water, fully stirring until completely dissolved to obtain a gamma-polyglutamic acid solution;

[0007] (2) dissolving an antibacterial drug in the gamma-polyglutamic acid solution, fully stirring and mixing uniformly to obtain a mixed solution 1; adjusting the pH of the mixed solution 1, and heating the mixed solution 1 to 60 DEG C for 1-2 h to obtain a mixed solution 2; after the mixed solution 2 is cooled to room temperature, a crosslinking agent is added, and the mixed solution 3 is uniformly mixed to obtain a mixed solution 3; after the mixed solution 3 is placed at room temperature, it is first heated to 60 DEG C for 1-2 h, and then heated to 70 DEG C at a rate of 0.5 DEG C / min for 4-6 h to obtain an antibacterial gel-like product;

[0008] (3) dehydrating the antibacterial gelatinous product, vacuum negative pressure drying to obtain a dried hydrogel product, namely antibacterial gamma-polyglutamic acid superabsorbent hydrogel.

[0009] Preferably, the molecular weight of the gamma-polyglutamic acid in the step (1) is 100-200 million; the mass concentration of the gamma-polyglutamic acid solution is 8-12%.

[0010] Preferably, the pure water in the step (1) refers to RO water.

[0011] Preferably, the antibacterial drug in the step (2) is 2,3-epoxy methyl propyl trimethyl ammonium chloride (GTA) or epoxy propyl dodecyl dimethyl quaternary ammonium salt, and the addition amount is 0.5-2% of the mass of the gamma-polyglutamic acid.

[0012] Preferably, the pH of the mixed solution 1 in the step (2) is adjusted by using 1-2 mol / L HCl solution, and the pH range is 4.0-6.0.

[0013] Preferably, the crosslinking agent in the step (2) is at least one of ethylene glycol diglycidyl ether (EGDE), 1,4-butanediol glycidyl ether, 1,6-hexanediol glycidyl ether, and neopentyl glycol glycidyl ether, and the addition amount is 8-14% of the mass of the gamma-polyglutamic acid.

[0014] Preferably, the standing time of the mixed solution 3 in the step (2) at room temperature is 1-3 h.

[0015] Preferably, the antibacterial gelatinous product in the step (3) is dehydrated by using anhydrous ethanol.

[0016] Preferably, the vacuum negative pressure drying temperature in the step (3) is 80-100℃.

[0017] Preferably, the dried hydrogel product in the step (3) is crushed to obtain antibacterial gamma-polyglutamic acid superabsorbent hydrogel powder.

[0018] The application also provides an antibacterial gamma-polyglutamic acid superabsorbent hydrogel prepared by using the preparation method.

[0019] The gamma-polyglutamic acid (gamma-PGA) hydrogel in the application is a kind of biological macromolecular material with a three-dimensional network structure formed by cross-linking of gamma-PGA, wherein the gamma-PGA is a kind of high molecular weight anionic homopolyamino acid formed by connecting glutamic acid monomers through amide bonds formed by gamma-carboxyl and amino groups, the gamma-PGA is a kind of water-soluble biodegradable new green biological material obtained through microbial fermentation, has high water absorption, high mechanical strength and good biocompatibility. The antibacterial drug 2,3-epoxypropyl trimethyl ammonium chloride is a kind of solid active cationic etherifying agent containing active epoxy units, and such a structure makes it have diversity in organic synthesis, especially in the synthesis process of quaternary ammonium salt chemicals containing amino alcohol structures. It can react with various organic matters, and the addition of the antibacterial drug into the gamma-polyglutamic acid hydrogel makes the gamma-polyglutamic acid hydrogel have good antibacterial performance, and better meets the needs of people.

[0020] Advantages

[0021] (1) The antibacterial gamma-polyglutamic acid high water absorption hydrogel prepared in the application has good biodegradability, and can be degraded by microorganisms under natural conditions into harmless substances to the environment, which helps to reduce environmental pollution.

[0022] (2) The antibacterial gamma-polyglutamic acid high water absorption hydrogel prepared in the application has good biocompatibility, is safe and non-toxic, and will not irritate the human body.

[0023] (3) The antibacterial gamma-polyglutamic acid high water absorption hydrogel prepared in the application has excellent water absorption performance and antibacterial performance, has good bacteriostatic properties to staphylococcus aureus and escherichia coli, and meets the daily use needs of people. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a SEM schematic diagram of the antibacterial gamma-polyglutamic acid high water absorption hydrogel, wherein (a) is the EGDE addition amount of 10%, and (b) is the EGDE addition amount of 12%.

[0025] Figure 2 is a degradation performance characterization schematic diagram of the antibacterial gamma-polyglutamic acid high water absorption hydrogel.

[0026] Figure 3 is a liquid absorption performance schematic diagram of the antibacterial gamma-polyglutamic acid high water absorption hydrogel.

[0027] Figure 4 is a pressurized liquid absorption performance schematic diagram of the antibacterial gamma-polyglutamic acid high water absorption hydrogel.

[0028] Figure 5 is a water retention performance schematic diagram of the antibacterial gamma-polyglutamic acid high water absorption hydrogel.

[0029] Figure 6 is a schematic diagram of antibacterial γ-polyglutamic acid high water-absorption hydrogel E. coli inhibition rate.

[0030] Figure 7 is a schematic diagram of antibacterial γ-polyglutamic acid high water-absorption hydrogel S. aureus inhibition rate.

[0031] Figure 8 is a schematic diagram of antibacterial γ-polyglutamic acid high water-absorption hydrogel E. coli inhibition zone; wherein (a) is GTA addition amount 0.5%, (b) is GTA addition amount 1%, (c) is GTA addition amount 1.5%, and (d) is GTA addition amount 2%.

[0032] Figure 9 is a schematic diagram of antibacterial γ-polyglutamic acid high water-absorption hydrogel S. aureus inhibition zone; wherein (a) is GTA addition amount 0.5%, (b) is GTA addition amount 1%, (c) is GTA addition amount 1.5%, and (d) is GTA addition amount 2%. Figure 10 is a schematic diagram of antibacterial γ-polyglutamic acid high water-absorption hydrogel E. coli live and dead staining; wherein (a) is a control group without adding antibacterial hydrogel, and (b) is an experimental group adding GTA addition amount 1.5% antibacterial hydrogel.

[0033] Figure 11 is a schematic diagram of antibacterial γ-polyglutamic acid high water-absorption hydrogel S. aureus live and dead staining; wherein (a) is a control group without adding antibacterial hydrogel, and (b) is an experimental group adding GTA addition amount 1.5% antibacterial hydrogel. DETAILED DESCRIPTION

[0034] The application will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the application and not used to limit the scope of the application. Furthermore, it should be understood that after reading the content of the present application, those skilled in the art can make various modifications or changes to the present application, and these equivalent forms also fall within the scope of the appended claims of the present application.

[0035] Example 1

[0036] (1) 1.0 g of 1.5 million molecular weight γ-polyglutamic acid was dissolved in 9 mL of RO water, and fully stirred until completely dissolved to obtain a γ-polyglutamic acid solution;

[0037] (2) 0.015 g of 2,3-epoxy methyl propyl trimethyl ammonium chloride GTA was dissolved in the γ-polyglutamic acid solution, and mixed uniformly by stirring to obtain a mixed solution 1; the pH of the mixed solution 1 was adjusted to 5.0, and the mixed solution 1 was warmed to 60°C for 1 h to obtain a mixed solution 2; 0.1 g of ethylene glycol diglycidyl ether EGDE was added to the mixed solution 2 after being cooled to room temperature, and mixed uniformly at room temperature for 2 h, and then warmed to 60°C for 2 h, and then warmed to 70°C at a rate of 0.5°C / min for 4 h to obtain an antibacterial gel-like product;

[0038] (3) The antibacterial gel-like product was dehydrated and dried at 90°C under vacuum negative pressure to obtain a dried hydrogel product 1, denoted as EGDE-10%.

[0039] Example 2

[0040] (1) 1.0 g of 150 million molecular weight γ-polyglutamic acid was dissolved in 9 mL of RO water, and stirred until completely dissolved to obtain a γ-polyglutamic acid solution;

[0041] (2) 0.015 g of 2,3-epoxy methyl propyl trimethyl ammonium chloride GTA was dissolved in the γ-polyglutamic acid solution, and mixed uniformly by stirring to obtain a mixed solution 1; the pH of the mixed solution 1 was adjusted to 5.0, and the mixed solution 1 was warmed to 60°C for 1 h to obtain a mixed solution 2; 0.1 g of 1,4-butanediol diglycidyl ether was added to the mixed solution 2 after being cooled to room temperature, and mixed uniformly at room temperature for 2 h, and then warmed to 60°C for 2 h, and then warmed to 70°C at a rate of 0.5°C / min for 4 h to obtain an antibacterial gel-like product;

[0042] (3) The antibacterial gel-like product was dehydrated and dried at 90°C under vacuum negative pressure to obtain a dried hydrogel product 2.

[0043] Example 3

[0044] (1) 1.0 g of 150 million molecular weight γ-polyglutamic acid was dissolved in 9 mL of RO water, and stirred until completely dissolved to obtain a γ-polyglutamic acid solution;

[0045] (2) 0.015 g of 2,3-epoxy methyl propyl trimethyl ammonium chloride GTA was dissolved in the γ-polyglutamic acid solution, and mixed uniformly by stirring to obtain a mixed solution 1; the pH of the mixed solution 1 was adjusted to 5.0, and the mixed solution 1 was warmed to 60°C for 1 h to obtain a mixed solution 2; 0.1 g of 1,6-hexanediol diglycidyl ether was added to the mixed solution 2 after being cooled to room temperature, and mixed uniformly at room temperature for 2 h, and then warmed to 60°C for 2 h, and then warmed to 70°C at a rate of 0.5°C / min for 4 h to obtain an antibacterial gel-like product;

[0046] (3) The antibacterial gelatinous product is dehydrated and dried under vacuum negative pressure at 90°C to obtain a dried hydrogel product 3.

[0047] Example 4

[0048] (1) 1.0 g of 1.5 million molecular weight γ-polyglutamic acid is dissolved in 9 mL of RO water, and fully stirred until completely dissolved to obtain a γ-polyglutamic acid solution;

[0049] (2) 0.015 g of 2,3-epoxy methyl propyl trimethyl ammonium chloride GTA is dissolved in the γ-polyglutamic acid solution, and fully stirred and mixed uniformly to obtain a mixed solution 1; the pH of the mixed solution 1 is adjusted to 5.0, and the mixed solution 1 is warmed to 60°C for 1 h to obtain a mixed solution 2; after the mixed solution 2 is cooled to room temperature, 0.1 g of neopentyl glycol glycidyl ether is added, and mixed uniformly at room temperature for 2 h, then warmed to 60°C for 2 h, and then warmed to 70°C at a rate of 0.5°C / min for 4 h to obtain an antibacterial gelatinous product;

[0050] (3) The antibacterial gelatinous product is dehydrated and dried under vacuum negative pressure at 90°C to obtain a dried hydrogel product 4.

[0051] Example 5

[0052] (1) 1.0 g of 1.5 million molecular weight γ-polyglutamic acid is dissolved in 9 mL of RO water, and fully stirred until completely dissolved to obtain a γ-polyglutamic acid solution;

[0053] (2) 0.015 g of 2,3-epoxy methyl propyl trimethyl ammonium chloride GTA is dissolved in the γ-polyglutamic acid solution, and fully stirred and mixed uniformly to obtain a mixed solution 1; the pH of the mixed solution 1 is adjusted to 5.0, and the mixed solution 1 is warmed to 60°C for 1 h to obtain a mixed solution 2; after the mixed solution 2 is cooled to room temperature, 0.08 g of ethylene glycol diglycidyl ether is added, and mixed uniformly at room temperature for 2 h, then warmed to 60°C for 2 h, and then warmed to 70°C at a rate of 0.5°C / min for 4 h to obtain an antibacterial gelatinous product;

[0054] (3) The antibacterial gelatinous product is dehydrated and dried under vacuum negative pressure at 90°C to obtain a dried hydrogel product 5, denoted as EGDE-8%.

[0055] Example 6

[0056] (1) 1.0 g of 1.5 million molecular weight γ-polyglutamic acid is dissolved in 9 mL of RO water, and fully stirred until completely dissolved to obtain a γ-polyglutamic acid solution;

[0057] (2) 0.015 g of 2,3-epoxymethylpropyltrimethylammonium chloride GTA was dissolved in the γ-polyglutamic acid solution, and mixed uniformly by stirring to obtain a mixed solution 1; the pH of the mixed solution 1 was adjusted to 5.0, and the mixed solution 1 was warmed to 60°C for 1 h to obtain a mixed solution 2; 0.12 g of ethylene glycol diglycidyl ether was added to the mixed solution 2 after being cooled to room temperature, and mixed uniformly at room temperature for 2 h, and then warmed to 60°C for 2 h, and then warmed to 70°C at a rate of 0.5°C / min for 4 h to obtain an antibacterial gel-like product;

[0058] (3) The antibacterial gel-like product was dehydrated and dried at 90°C under vacuum negative pressure to obtain a dried hydrogel product 6, denoted as EGDE-12%.

[0059] Example 7

[0060] (1) 1.0 g of 150 million molecular weight γ-polyglutamic acid was dissolved in 9 mL of RO water, and stirred until completely dissolved to obtain a γ-polyglutamic acid solution;

[0061] (2) 0.015 g of 2,3-epoxymethylpropyltrimethylammonium chloride GTA was dissolved in the γ-polyglutamic acid solution, and mixed uniformly by stirring to obtain a mixed solution 1; the pH of the mixed solution 1 was adjusted to 5.0, and the mixed solution 1 was warmed to 60°C for 1 h to obtain a mixed solution 2; 0.12 g of ethylene glycol diglycidyl ether was added to the mixed solution 2 after being cooled to room temperature, and mixed uniformly at room temperature for 2 h, and then warmed to 60°C for 2 h, and then warmed to 70°C at a rate of 0.5°C / min for 4 h to obtain an antibacterial gel-like product;

[0062] (3) The antibacterial gel-like product was dehydrated and dried at 90°C under vacuum negative pressure to obtain a dried hydrogel product 7, denoted as EGDE-14%.

[0063] Example 8

[0064] (1) 1.0 g of 150 million molecular weight γ-polyglutamic acid was dissolved in 9 mL of RO water, and stirred until completely dissolved to obtain a γ-polyglutamic acid solution;

[0065] (2) 0.005 g of 2,3-epoxymethylpropyltrimethylammonium chloride GTA was dissolved in the γ-polyglutamic acid solution, and mixed uniformly by stirring to obtain a mixed solution 1; the pH of the mixed solution 1 was adjusted to 5.0, and the mixed solution 1 was warmed to 60°C for 1 h to obtain a mixed solution 2; 0.12 g of ethylene glycol diglycidyl ether was added to the mixed solution 2 after being cooled to room temperature, and mixed uniformly at room temperature for 2 h, and then warmed to 60°C for 2 h, and then warmed to 70°C at a rate of 0.5°C / min for 4 h to obtain an antibacterial gel-like product;

[0066] (3) The antibacterial gel-like product was dehydrated and dried at 90°C under vacuum negative pressure to obtain a dried hydrogel product 8, denoted as GTA-0.5%.

[0067] Example 9

[0068] (1) 1.0 g of 1.5 million molecular weight γ-polyglutamic acid was dissolved in 9 mL of RO water, and fully stirred until completely dissolved to obtain a γ-polyglutamic acid solution;

[0069] (2) 0.01 g of 2,3-epoxy methyl propyl trimethyl ammonium chloride GTA was dissolved in the γ-polyglutamic acid solution, and fully stirred to mix uniformly to obtain a mixture 1; the pH of the mixture 1 was adjusted to 5.0, and the mixture 1 was warmed to 60°C for 1 h to obtain a mixture 2; after the mixture 2 was cooled to room temperature, 0.12 g of ethylene glycol diglycidyl ether was added, and mixed uniformly at room temperature for 2 h, and then warmed to 60°C for 2 h, and then warmed to 70°C at a rate of 0.5°C / min for 4 h to obtain an antibacterial gel-like product;

[0070] (3) The antibacterial gel-like product was dehydrated and dried at 90°C under vacuum negative pressure to obtain a dried hydrogel product 9, denoted as GTA-1%.

[0071] Example 10

[0072] (1) 1.0 g of 1.5 million molecular weight γ-polyglutamic acid was dissolved in 9 mL of RO water, and fully stirred until completely dissolved to obtain a γ-polyglutamic acid solution;

[0073] (2) 0.015 g of 2,3-epoxy methyl propyl trimethyl ammonium chloride GTA was dissolved in the γ-polyglutamic acid solution, and fully stirred to mix uniformly to obtain a mixture 1; the pH of the mixture 1 was adjusted to 5.0, and the mixture 1 was warmed to 60°C for 1 h to obtain a mixture 2; after the mixture 2 was cooled to room temperature, 0.12 g of ethylene glycol diglycidyl ether was added, and mixed uniformly at room temperature for 2 h, and then warmed to 60°C for 2 h, and then warmed to 70°C at a rate of 0.5°C / min for 4 h to obtain an antibacterial gel-like product;

[0074] (3) The antibacterial gel-like product was dehydrated and dried at 90°C under vacuum negative pressure to obtain a dried hydrogel product 10, denoted as GTA-1.5%.

[0075] Example 11

[0076] (1) 1.0 g of 1.5 million molecular weight γ-polyglutamic acid was dissolved in 9 mL of RO water, and fully stirred until completely dissolved to obtain a γ-polyglutamic acid solution;

[0077] (2) 0.02 g of 2,3-epoxymethylpropyl trimethyl ammonium chloride GTA was dissolved in the γ-polyglutamic acid solution, and stirred to mix uniformly to obtain a mixed solution 1; the pH of the mixed solution 1 was adjusted to 5.0, and the mixed solution 1 was warmed to 60°C for 1 h to obtain a mixed solution 2; 0.12 g of ethylene glycol diglycidyl ether was added to the mixed solution 2 after cooling to room temperature, and mixed uniformly at room temperature for 2 h, then warmed to 60°C for 2 h, and then warmed to 70°C at a rate of 0.5°C / min for 4 h to obtain an antibacterial gel product;

[0078] (3) The antibacterial gel product was dehydrated and dried at 90°C under vacuum negative pressure to obtain a dried hydrogel product 10, denoted as GTA-2%.

[0079] Retention amount of test example 1

[0080] A certain mass (m0, unit: g) of the hydrogel sample powder prepared in example 1 was oven-dried to constant weight, and was buried in a flowerpot containing fresh soil, with a burial depth of 2 cm from the soil surface. The flowerpot was cultured at room temperature, and the soil and hydrogel mixture in one of the flowerpots was taken out regularly. The mixture was immersed in a 75% ethanol solution for gentle rinsing to remove impurities such as mud, and then washed once with deionized water. After drying to constant weight again, the mass (m1, unit: g) was recorded. The sample retention rate was calculated according to the following formula:

[0081] Retention rate (%) = m1 / m0 x 100%

[0082] m0 - sample mass (unit: g);

[0083] m1 - constant weight after drying (unit: g).

[0084] Absorption amount of test example 2

[0085] The initial mass W0 of the dried hydrogel products 1, 2, 3, and 4 was weighed, respectively, and then the hydrogel samples were soaked in 0.9% physiological saline. The wet weight W of the hydrogel after 5 s, 10 s, 15 s, …, 100 s (weighed every 5 s) was recorded, respectively. The surface water of the hydrogel was absorbed with filter paper before weighing. t The absorption amount of the hydrogel was calculated according to the following formula:

[0086] Absorption amount: S = (Wt-W0) / W0

[0087] S - absorption amount (unit: g / g);

[0088] W t - wet weight of the sample (unit: g);

[0089] W0 - initial mass of the dried sample (unit: g).

[0090] Test Example 3: Pressure Absorption

[0091] Add physiological saline to a shallow pan (85mm inner diameter, with two 2mm diameter metal wires inside) until the liquid level exceeds the metal wires. Weigh 0.900g of the sample and place it into a plastic cylindrical container (60.0mm inner diameter, 50.0mm height, with 36μm nylon mesh attached to the bottom). Evenly install the piston (60mm outer diameter, applying 2068Pa pressure) and weigh it (mass m1). Absorb physiological saline under pressure for 60 minutes. Remove the weights and weigh the sample after water absorption (mass m2).

[0092] Calculation formula:

[0093] P=(m2-m1) / m

[0094] P – Pressure absorption capacity (unit: g / g);

[0095] m — Sample mass (unit: g);

[0096] m1 — Mass of the cylinder before liquid absorption (unit: g);

[0097] m2 — The mass of the cylinder after absorbing the liquid (unit: g).

[0098] Experimental Example 4 Water retention

[0099] Weigh 0.200g of the sample and place it into a tea bag (60mm×85mm, air permeability 230±50L / (min·100cm). 2 Record the sample as m, and soak it in physiological saline for 30 minutes. After hanging the droplet for 10 minutes, dehydrate it for 3 minutes under a centrifugal force of 250g (1500r / min) and weigh it (mass m1). Blank test: Repeat the steps with a tea bag without the sample, and finally dehydrate it and weigh it (mass m2). Calculation formula:

[0100] R = (m1 - m2 - m) / m

[0101] R – Water retention capacity (unit: g / g);

[0102] m — Sample mass (unit: g);

[0103] m1——The mass of the tea bag containing the sample after dehydration (unit: g);

[0104] m2 — Mass of the tea bag after dehydration in the blank test (unit: g).

[0105] Test Example 5 Antibacterial Performance

[0106] E. coli and S. aureus were selected as test strains, and high-temperature and high-pressure sterilization was performed to ensure the sterility of the experimental instruments and prepared solutions. Subsequently, the hydrogel was cultured with bacteria, and the antibacterial performance was evaluated by means of live / dead fluorescent staining.

[0107] Results and discussion:

[0108] (1) From the results of the retention rate of Test Example 1, it can be seen that the hydrogel has biodegradable performance, and the optimized structure of gradient heating can accelerate the initial degradation, and can be completely degraded in about 60 days, which is environmentally friendly and non-polluting. Figure 1 It can be seen that the gradient heating promotes uniform pre-crosslinking, forming a more regular hydrogel porous network, and as the EGDE content increases, the hydrogel pore size increases, the pore size is 200 μm-400 μm, and the hydrogel porous structure is beneficial to increase the liquid absorption capacity.

[0109] (2) Figure 2 (2) From the results of the absorption capacity of Test Example 2, it can be seen that as the EGDE content increases, the water absorption performance of the hydrogel is enhanced, which is related to the uniformity and increase of the pore size of the hydrogel gradient heating shown in the SEM image, especially when the EGDE content is 12%, the water absorption reaches the maximum of 199.9 g / g. But with the further increase of EGDE content, the water absorption performance of the hydrogel decreases slightly, which may be due to the large crosslinking density, resulting in dense hydrogel structure and decreased water absorption performance. Figure 2 (3) From the results of the absorption capacity of Test Example 2, it can be seen that as the EGDE content increases, the water absorption performance of the hydrogel is enhanced, which is related to the uniformity and increase of the pore size of the hydrogel gradient heating shown in the SEM image, especially when the EGDE content is 12%, the water absorption reaches the maximum of 199.9 g / g. But with the further increase of EGDE content, the water absorption performance of the hydrogel decreases slightly, which may be due to the large crosslinking density, resulting in dense hydrogel structure and decreased water absorption performance.

[0110] Figure 3 (3) From the results of the absorption capacity of Test Example 2, it can be seen that as the EGDE content increases, the water absorption performance of the hydrogel is enhanced, which is related to the uniformity and increase of the pore size of the hydrogel gradient heating shown in the SEM image, especially when the EGDE content is 12%, the water absorption reaches the maximum of 199.9 g / g. But with the further increase of EGDE content, the water absorption performance of the hydrogel decreases slightly, which may be due to the large crosslinking density, resulting in dense hydrogel structure and decreased water absorption performance.

[0111] (4) From the results of the pressurized absorption capacity of Test Example 3, it can be seen that as the EGDE content increases, the pressurized water absorption performance of the hydrogel is also enhanced, and when the EGDE content is 12%, the pressurized water absorption also reaches the maximum of 26.85 g / g. Good pressurized water absorption performance makes the hydrogel still have good water absorption under certain pressure, and the uniformity of the pore size of the gradient heating also makes it more stable, which meets the use requirements in specific scenarios. Figure 4 (5) From the results of the water retention of Test Example 4, it can be seen that compared with ordinary hydrogel, the gradient heating reduces internal defects, making it have better water retention, and as the EGDE content increases, the water retention performance of the hydrogel is also enhanced, and good water retention performance can effectively prevent liquid from seeping back, which can better meet people's needs.

[0112] Figure 5 (6) From the results of the water retention of Test Example 4, it can be seen that compared with ordinary hydrogel, the gradient heating reduces internal defects, making it have better water retention, and as the EGDE content increases, the water retention performance of the hydrogel is also enhanced, and good water retention performance can effectively prevent liquid from seeping back, which can better meet people's needs.

[0113] (6) From the results of the water retention of Test Example 4, it can be seen that compared with ordinary hydrogel, the gradient heating reduces internal defects, making it have better water retention, and as the EGDE content increases, the water retention performance of the hydrogel is also enhanced, and good water retention performance can effectively prevent liquid from seeping back, which can better meet people's needs. Figure 6 ​​It can be seen that the hydrogel has good antibacterial performance, and the gradient heating also makes the GTA uniformly distributed. With the increase of GTA content, the antibacterial performance of the hydrogel also increases, especially when the GTA content reaches 1.5%, the antibacterial rate of E. coli reaches 99.24%.

[0114] (7) by Figure 7 It can be seen that the hydrogel has good antibacterial performance, and the gradient heating also makes the GTA uniformly distributed. With the increase of GTA content, the antibacterial performance of the hydrogel also increases, especially when the GTA content reaches 1.5%, the antibacterial rate of E. coli reaches 99.24%.

[0115] (8) by Figure 8 It can be seen that the hydrogel has good antibacterial performance, and the gradient heating also makes the GTA uniformly distributed. With the increase of GTA content, the antibacterial performance of the hydrogel also increases, especially when the GTA content reaches 1.5%, the antibacterial rate of E. coli reaches 99.24%.

[0116] (9) by Figure 9 It can be seen that the hydrogel has good antibacterial performance, and the gradient heating also makes the GTA uniformly distributed. With the increase of GTA content, the antibacterial performance of the hydrogel also increases, especially when the GTA content reaches 1.5%, the antibacterial rate of E. coli reaches 99.24%.

[0117] (10) by Figure 10 It can be seen that compared with the control sample without adding hydrogel, after adding the antibacterial hydrogel, the green fluorescence of live and dead staining is weakened, the red fluorescence is enhanced, and the number of dead cells of E. coli is increased, which proves that the hydrogel has good antibacterial performance on E. coli. Figure 11 It can be seen that compared with the control sample without adding hydrogel, after adding the antibacterial hydrogel, the green fluorescence of live and dead staining is weakened, the red fluorescence is enhanced, and the number of dead cells of E. coli is increased, which proves that the hydrogel has good antibacterial performance on E. coli.

Claims

1. A method for preparing an antibacterial γ-polyglutamic acid superabsorbent hydrogel, comprising the following steps: (1) Dissolve γ-polyglutamic acid in pure water and stir thoroughly until completely dissolved to obtain a γ-polyglutamic acid solution; (2) Dissolve the antibacterial drug in the γ-polyglutamic acid solution and stir thoroughly to obtain mixture 1; adjust the pH of mixture 1 and heat mixture 1 to 60°C and continue to react for 1 to 2 hours to obtain mixture 2; cool mixture 2 to room temperature and add crosslinking agent, mix thoroughly to obtain mixture 3; let mixture 3 stand at room temperature and then heat it to 60°C for 1 to 2 hours, and then heat it to 70°C at a rate of 0.5°C / min for 4 to 6 hours to obtain antibacterial gel product; (3) The antibacterial gel product is dehydrated and dried under vacuum negative pressure to obtain a dried hydrogel product, namely antibacterial γ-polyglutamic acid superabsorbent hydrogel.

2. The preparation method according to claim 1, characterized in that: The molecular weight of γ-polyglutamic acid in step (1) is 100,000 to 2,000,000; the mass concentration of the γ-polyglutamic acid solution is 8% to 12%.

3. The preparation method according to claim 1, characterized in that: The antibacterial drug in step (2) is 2,3-epoxymethylpropyltrimethylammonium chloride or epioxypropyldodecyl dimethyl quaternary ammonium salt, and the amount added is 0.5% to 2% of the mass of γ-polyglutamic acid.

4. The preparation method according to claim 1, characterized in that: In step (2), the pH of the mixture 1 is adjusted using a 1-2 mol / L HCl solution, with a pH range of 4.0-6.

0.

5. The preparation method according to claim 1, characterized in that: The crosslinking agent in step (2) is at least one of ethylene glycol diglycidyl ether, 1,4-butanediol glycidyl ether, 1,6-hexanediol glycidyl ether, and neopentyl glycol glycidyl ether, and the amount added is 8% to 14% of the mass of γ-polyglutamic acid.

6. The preparation method according to claim 1, characterized in that: The mixture 3 in step (2) is left to stand at room temperature for 1 to 3 hours.

7. The preparation method according to claim 1, characterized in that: The antibacterial gel product in step (3) is dehydrated with anhydrous ethanol.

8. The preparation method according to claim 1, characterized in that: The vacuum negative pressure drying temperature in step (3) is 80-100℃.

9. An antibacterial γ-polyglutamic acid superabsorbent hydrogel prepared by the preparation method according to any one of claims 1-8.

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