A thermosensitive gel and its preparation method

Abstract

The present invention discloses a thermosensitive gel and a preparation method thereof, belonging to the technical field of gels. The thermosensitive gel provided by the present invention is prepared by mixing a temperature-sensitive material N-isopropylacrylamide containing double bonds with a self-made modified cross-linking agent of the present invention, adding a photoinitiator 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, and finally cross-linking and polymerizing under the action of ultraviolet light with a wavelength of 365 nm. Through detection, the thermosensitive gel prepared by the present invention has excellent thermosensitive properties. At the same time, the present invention improves the cross-linking agent to prepare a modified cross-linking agent, and then applies the modified cross-linking agent to the preparation process of the above thermosensitive gel. Finally, the prepared thermosensitive gel has a significantly improved antibacterial property on the basis of retaining excellent thermosensitive properties. The thermosensitive gel prepared by the present invention can be used in the field of wound repair of skin, oral cavity, esophageal mucosa, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of gels, and particularly relates to a temperature-sensitive gel and a preparation method thereof. Background Art

[0002] Intelligent hydrogels, also known as stimulus-sensitive hydrogels or environmentally responsive hydrogels, can undergo corresponding physical and chemical property changes when the external environment changes (temperature, pH, magnetic field, etc.). According to the different stimuli received, intelligent hydrogels can be divided into temperature-sensitive hydrogels, pH-sensitive hydrogels, pressure-sensitive hydrogels, photosensitive hydrogels, etc. Among the numerous stimulus response factors, temperature is the most easily controlled response condition, so temperature-responsive hydrogels have been widely studied.

[0003] Under the stimulation of environmental temperature changes, the volume of temperature-sensitive hydrogels (abbreviation: thermosensitive gels) will undergo drastic shrinkage and swelling. Utilizing the temperature responsiveness of thermosensitive gels, controlled release of drugs can be achieved, so they are widely used in the medical field.

[0004] In the medical field, thermosensitive gels are usually applied in scenarios such as wound dressings and drug delivery carriers. In these applications, the skin or tissues of patients may have been damaged, and the immune system is in a relatively vulnerable state, extremely susceptible to the invasion of pathogens such as bacteria. If the thermosensitive gel does not have good antibacterial properties, bacteria may grow and reproduce on the surface or inside of the gel, further increasing the infection risk of patients. This will not only delay the wound healing process but may also lead to serious complications such as sepsis, posing a great threat to the life and health of patients; secondly, there are a large number of pathogenic microorganisms in the hospital environment. During the use of thermosensitive gels, they will inevitably come into contact with these microorganisms. If the antibacterial properties are insufficient, they are likely to become a "hotbed" for bacteria. Summary of the Invention

[0005] The purpose of the present invention is to provide a temperature-sensitive gel and a preparation method thereof to improve the antibacterial properties of the temperature-sensitive gel.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A preparation method of a temperature-sensitive gel, comprising the following steps:

[0008] S1. Add N-isopropylacrylamide, a modified cross-linking agent, and poloxamer 188 to purified water, and magnetically stir for 20 - 30 min to obtain solution component A;

[0009] S2. Add 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone to dimethyl sulfoxide, and magnetically stir for 20 - 30 min to obtain solution component B;

[0010] S3. Mix solution component A and solution component B, then stir magnetically for 20 - 30 min to obtain a mixed solution. Use a dropper to drip the mixed solution onto a gel mold, and then irradiate it with a 365 nm ultraviolet curing lamp for 1 min to obtain a thermosensitive gel.

[0011] Further, the dosage ratio of the purified water, N - isopropylacrylamide, modified cross - linker, and poloxamer 188 in S1 is 100 g: 9 - 10 g: 0.2 g: 3.2 - 3.5 g.

[0012] Further, the dosage ratio of the dimethyl sulfoxide and 2 - hydroxy - 1 - [4 - (2 - hydroxyethoxy)phenyl] - 2 - methyl - 1 - propanone in S2 is 70 g: 33 - 35 g.

[0013] Further, the solution component A and solution component B in S3 are mixed at a volume ratio of 50:1.

[0014] Further, the modified cross - linker in S1 is prepared by the following steps:

[0015] Add N,N - methylenebisacrylamide to absolute ethanol, stir for 1 - 2 h, then add a 6 mol / L sodium nitrite aqueous solution thereto, charge nitrogen for protection, stir for another 1 - 2 h, then dropwise add a 6 mol / L hydrochloric acid aqueous solution thereto while stirring. After the addition is complete, stir for 5 - 6 h. After stirring is completed, centrifuge to collect the precipitate, wash the precipitate three times with deionized water and an ethanol aqueous solution with a volume fraction of 50% in sequence, and then place it in a vacuum drying in the dark for 24 h to obtain the modified cross - linker. The preparation process of the modified cross - linker is shown as follows:

[0016]

[0017] Further, the dosage ratio of the absolute ethanol, N,N - methylenebisacrylamide, sodium nitrite aqueous solution, and hydrochloric acid aqueous solution is 200 mL: 15.5 - 16.0 g: 200 mL: 200 mL.

[0018] Further, the thermosensitive gel is prepared by the above - mentioned preparation method.

[0019] Advantages of the present invention:

[0020] The present invention provides a thermosensitive gel and a preparation method thereof. Specifically, the thermosensitive gel provided by the present invention is formed by mixing a temperature-sensitive material N-isopropylacrylamide containing double bonds with a self-made modified crosslinking agent of the present invention, adding a photoinitiator 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, and finally crosslinking and polymerizing under the action of ultraviolet light with a wavelength of 365 nm. After testing, the thermosensitive gel prepared by the present invention has excellent thermosensitive properties. Specifically, the present invention verifies its thermosensitive properties by measuring the equilibrium swelling ratio of the prepared gel at different temperatures, and the difference in the equilibrium swelling ratio of the gel at different temperatures can reflect the response of the gel to temperature.

[0021] Meanwhile, the present invention improves the crosslinking agent to prepare a modified crosslinking agent, and then applies the modified crosslinking agent to the preparation process of the above thermosensitive gel. Finally, the prepared thermosensitive gel has significantly improved antibacterial properties while retaining excellent thermosensitive properties. Specifically, the modified crosslinking agent of the present invention is formed by nitrosation of the secondary amino group of N,N-methylenebisacrylamide under acidic conditions. Nitrosation forms a nitroso group (-NO), and the nitroso group is prone to breakage with the N-N bond on the main chain under the action of light and heat, thereby releasing NO gas. NO has broad-spectrum antibacterial properties, promotes wound healing and has an anti-inflammatory effect. The present invention combines NO gas with the gel to prepare a thermosensitive gel with excellent antibacterial properties. When the prepared thermosensitive gel is coated on the skin surface, under the heating of the human skin, the thermosensitive gel can slowly discharge moisture and release NO gas, releasing antibacterial NO gas while keeping the skin surface moist, thereby inhibiting the growth of bacteria. At the same time, NO also has anti-inflammatory and wound healing promotion effects. Detailed implementation manners

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] Example 1

[0024] Preparation of the modified crosslinking agent:

[0025] Add 15.5 g of N,N - methylenebisacrylamide (CP; 98.0%; purchased from Sinopharm Chemical Reagent Co., Ltd.) to 200 mL of absolute ethanol (AR; 99.7%; purchased from Sinopharm Chemical Reagent Co., Ltd.), stir for 1 h, then add 200 mL of 6 mol / L sodium nitrite aqueous solution (prepared in the laboratory), purge with nitrogen for protection, stir for another 1 h, then add 200 mL of 6 mol / L hydrochloric acid aqueous solution (prepared in the laboratory) dropwise while stirring. After the addition is complete, stir for 5 h. After stirring, centrifuge to collect the precipitate, wash the precipitate three times with deionized water and 50% (by volume) ethanol aqueous solution (prepared in the laboratory) in sequence, and then place it in the dark for vacuum drying for 24 h to obtain the modified cross - linker.

[0026] Example 2

[0027] Preparation of modified cross - linker:

[0028] Add 15.8 g of N,N - methylenebisacrylamide (CP; 98.0%; purchased from Sinopharm Chemical Reagent Co., Ltd.) to 200 mL of absolute ethanol (AR; 99.7%; purchased from Sinopharm Chemical Reagent Co., Ltd.), stir for 2 h, then add 200 mL of 6 mol / L sodium nitrite aqueous solution (prepared in the laboratory), purge with nitrogen for protection, stir for another 2 h, then add 200 mL of 6 mol / L hydrochloric acid aqueous solution (prepared in the laboratory) dropwise while stirring. After the addition is complete, stir for 6 h. After stirring, centrifuge to collect the precipitate, wash the precipitate three times with deionized water and 50% (by volume) ethanol aqueous solution (prepared in the laboratory) in sequence, and then place it in the dark for vacuum drying for 24 h to obtain the modified cross - linker.

[0029] Example 3

[0030] Preparation of modified cross - linker:

[0031] Add 16.0 g of N,N - methylenebisacrylamide (CP; 98.0%; purchased from Sinopharm Chemical Reagent Co., Ltd.) to 200 mL of absolute ethanol (AR; 99.7%; purchased from Sinopharm Chemical Reagent Co., Ltd.), stir for 2 h, then add 200 mL of 6 mol / L sodium nitrite aqueous solution (prepared in the laboratory), purge with nitrogen for protection, stir for another 2 h, then add 200 mL of 6 mol / L hydrochloric acid aqueous solution (prepared in the laboratory) dropwise while stirring. After the addition is complete, stir for 6 h. After stirring, centrifuge to collect the precipitate, wash the precipitate three times with deionized water and 50% (by volume) ethanol aqueous solution (prepared in the laboratory) in sequence, and then place it in the dark for vacuum drying for 24 h to obtain the modified cross - linker.

[0032] Example 4

[0033] A preparation method of a temperature-sensitive gel, comprising the following steps:

[0034] S1. Add the temperature-sensitive material N-isopropylacrylamide (98%; purchased from Shanghai Macklin Biochemical Co., Ltd.), the modified cross-linking agent prepared in Example 1, and poloxamer 188 (Shanghai Macklin Biochemical Co., Ltd.) to purified water (sterile purified water, purchased from Shanghai Yuanye Bio-Technology Co., Ltd.), and stir magnetically for 20 min to obtain solution component A. Among them, the dosage ratio of purified water, N-isopropylacrylamide, the modified cross-linking agent prepared in Example 1, and poloxamer 188 is 100 g: 9 g: 0.2 g: 3.2 g;

[0035] S2. Add the photoinitiator 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone (98.0%; purchased from Sinopharm Chemical Reagent Co., Ltd.) to dimethyl sulfoxide (99.7%; purchased from Sinopharm Chemical Reagent Co., Ltd.), and stir magnetically for 30 min to obtain solution component B. Among them, the dosage ratio of dimethyl sulfoxide and 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone is 70 g: 33 g;

[0036] S3. Mix solution component A and solution component B in a volume ratio of 50:1, and then stir magnetically for 20 min to obtain a mixed solution. Use a dropper to drop the mixed solution onto a gel mold, and then irradiate it with a 365-nm ultraviolet curing lamp for 1 min to obtain the temperature-sensitive gel.

[0037] Example 5

[0038] A preparation method of a temperature-sensitive gel, comprising the following steps:

[0039] S1. Add the temperature-sensitive material N-isopropylacrylamide (98%; purchased from Shanghai Macklin Biochemical Co., Ltd.), the modified cross-linking agent prepared in Example 2, and poloxamer 188 (Shanghai Macklin Biochemical Co., Ltd.) to purified water (sterile purified water, purchased from Shanghai Yuanye Bio-Technology Co., Ltd.), and stir magnetically for 30 min to obtain solution component A. Among them, the dosage ratio of purified water, N-isopropylacrylamide, the modified cross-linking agent prepared in Example 2, and poloxamer 188 is 500 g: 50 g: 1 g: 17 g;

[0040] S2. Add photoinitiator 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone (98.0%; purchased from Sinopharm Chemical Reagent Co., Ltd.) to dimethyl sulfoxide (99.7%; purchased from Sinopharm Chemical Reagent Co., Ltd.), and stir magnetically for 30 min to obtain solution component B. The dosage ratio of dimethyl sulfoxide to 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone is 35 g:17 g;

[0041] S3. Mix solution component A and solution component B in a volume ratio of 50:1, then stir magnetically for 30 min to obtain a mixed solution. Use a dropper to drip the mixed solution onto a gel mold, and then irradiate it with a 365-nm ultraviolet curing lamp for 1 min to obtain a thermosensitive gel.

[0042] Example 6

[0043] A method for preparing a thermosensitive gel, comprising the following steps:

[0044] S1. Add temperature-sensitive material N-isopropylacrylamide (98%; purchased from Shanghai Macklin Biochemical Co., Ltd.), the modified crosslinking agent prepared in Example 3, and poloxamer 188 (Shanghai Macklin Biochemical Co., Ltd.) to purified water (sterile purified water, purchased from Shanghai Yuanye Bio-Technology Co., Ltd.), and stir magnetically for 30 min to obtain solution component A. The dosage ratio of purified water, N-isopropylacrylamide, the modified crosslinking agent prepared in Example 3, and poloxamer 188 is 100 g:9.5 g:0.2 g:3.5 g;

[0045] S2. Add photoinitiator 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone (98.0%; purchased from Sinopharm Chemical Reagent Co., Ltd.) to dimethyl sulfoxide (99.7%; purchased from Sinopharm Chemical Reagent Co., Ltd.), and stir magnetically for 30 min to obtain solution component B. The dosage ratio of dimethyl sulfoxide to 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone is 2 g:1 g;

[0046] S3. Mix solution component A and solution component B in a volume ratio of 50:1, then stir magnetically for 30 min to obtain a mixed solution. Use a dropper to drip the mixed solution onto a gel mold, and then irradiate it with a 365-nm ultraviolet curing lamp for 1 min to obtain a thermosensitive gel.

[0047] Comparative Example 1

[0048] Comparative Example 1 was the control group of Example 5. The modified crosslinking agent prepared in Example 2 of Example 5 was replaced with N,N-methylenebisacrylamide (CP; 98.0%; purchased from Sinopharm Chemical Reagent Co., Ltd.), and the remaining raw materials, raw material dosages, and preparation steps remained unchanged. Finally, a thermosensitive gel was obtained.

[0049] Test Example 1

[0050] Performance tests were carried out on the thermosensitive gels prepared in Examples 4 to 6 and Comparative Example 1. The performance test process was as follows, and the test results are shown in Table 1:

[0051] (1) Equilibrium swelling ratio test: The equilibrium swelling ratios of the thermosensitive gels prepared in Examples 4 to 6 and Comparative Example 1 at different temperatures were measured by the weighing method. The specific steps of the weighing method were as follows: Take the thermosensitive gels prepared in Examples 4 to 6 and Comparative Example 1. Each group of examples / comparative examples was divided into several groups. The thermosensitive gels in the same group of examples / comparative examples were placed in a vacuum drying oven at 30°C and dried to a constant weight. After taking out, the dry thermosensitive gels were obtained and weighed. Then, the dry thermosensitive gels were evenly divided into six groups and placed in pure water at 10°C, 20°C, 25°C, 30°C, 40°C, and 50°C for 12 h respectively. After completion, take out, wipe off the surface moisture with absorbent paper and weigh, and calculate the equilibrium swelling ratio. The calculation formula of the equilibrium swelling ratio is as follows, and the calculation results are recorded in Table 1 below:

[0052] Equilibrium swelling ratio = [(W b - W a ) / W a × 100%;

[0053] Among them, W a is the initial mass of the dry thermosensitive gel;

[0054] Among them, W b is the mass of the thermosensitive gel after swelling equilibrium at different temperatures.

[0055] (2) Antibacterial performance test: Respectively take 0.1 g of the thermosensitive gels prepared in Examples 4 to 6 and Comparative Example 1 and mix them with 10 mL of 1×10 7 CFU / mL of Escherichia coli suspension / Staphylococcus aureus suspension and put them into a test tube, and place them on a constant temperature shaking incubator at 37°C and cultivate at a rotation speed of 120 r / min for 4 h. This is used as the experimental group, and the group without mixing the thermosensitive gel is used as the blank group. Take out the bacterial suspensions of the experimental group and the blank group and dilute them to 1×10 5 CFU / mL respectively. Take 100 μL of each bacterial suspension and spread it on the surface of the agar plate, and place it in a shaking incubator at 37°C and incubate for 24 h. Calculate the antibacterial rate by the plate colony counting method. The antibacterial rate calculation formula is as follows, and the calculation results are recorded in Table 1 below:

[0056] Antibacterial rate = [(N a - N b ) / N a × 100%;

[0057] wherein, N a is the number of colonies in the blank group; N b is the number of colonies in the experimental group.

[0058] Table 1 Test Results

[0059]

[0060] It can be seen from Table 1 that the thermosensitive gels prepared in Examples 4 to 6 have excellent thermosensitive properties. From the antibacterial performance data of Comparative Example 1 and Example 5, it can be obtained that the present invention significantly improves the antibacterial (Escherichia coli and Staphylococcus aureus) performance of the thermosensitive gel by improving the crosslinking agent.

[0061] At the same time, further extended, the equilibrium swelling rate of the thermosensitive gels prepared in Examples 4 to 6 has a large change rate at 30°C to 40°C. Applying the prepared thermosensitive gel to the human body conforms to the human body temperature, that is, it has excellent thermosensitive properties within the range of human body temperature. Furthermore, the thermosensitive gels prepared in Examples 4 to 6 can be used in the field of wound repair of skin, oral cavity and esophageal mucosa, etc.

[0062] It should be noted that in this article, terms such as "including, containing" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0063] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a thermosensitive gel, characterized in that: The following steps are involved: S1. Add N-isopropylacrylamide, modified crosslinking agent and poloxamer 188 to purified water and stir magnetically for 20 to 30 minutes to obtain solution component A. S2. Add 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone to dimethyl sulfoxide and stir magnetically for 20 to 30 minutes to obtain solution component B; S3, mixing solution component A and solution component B, and then magnetically stirring for 20 to 30 minutes to obtain a mixed solution, adding the mixed solution dropwise onto the gel mold using a dropper, and then irradiating with a 365nm ultraviolet curing lamp for 1 minute to obtain a thermosensitive gel; The modified cross-linking agent described in S1 is prepared by the following steps: Add N,N-methylenebisacrylamide to anhydrous ethanol, stir for 1 to 2 hours, then add 6 mol / L sodium nitrite aqueous solution, fill with nitrogen protection, stir for 1 to 2 hours, then add 6 mol / L hydrochloric acid aqueous solution dropwise, stirring while dropping, after the addition is completed, stir for 5 to 6 hours, after the stirring is completed, collect the precipitate by centrifugation, wash the precipitate with deionized water and 50% ethanol aqueous solution by volume three times in sequence, and then place it in a light-proof condition and vacuum dry it for 24 hours to obtain a modified cross-linking agent.

2. The method for preparing a thermosensitive gel according to claim 1, characterized in that: The usage ratio of purified water, N-isopropylacrylamide, modified crosslinking agent and poloxamer 188 in S1 is 100g: 9-10g: 0.2g: 3.2-3.5g.

3. The method for preparing a thermosensitive gel according to claim 1, characterized in that: The usage ratio of dimethyl sulfoxide and 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone in S2 is 70g:33-35g.

4. The method for preparing a thermosensitive gel according to claim 1, characterized in that: S3: The solution component A and the solution component B are mixed in a volume ratio of 50:

1.

5. The method for preparing a thermosensitive gel according to claim 1, characterized in that: The usage ratio of the anhydrous ethanol, N,N-methylenebisacrylamide, sodium nitrite aqueous solution and hydrochloric acid aqueous solution is 200mL:15.5-16.0g:200mL:200mL.

6. A thermosensitive gel, characterized in that: The method is prepared by the preparation method described in any one of claims 1 to 5.

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