Preparation method of medical gel dressing with anti-freezing and photo-thermal rewarming performance

Abstract

The invention relates to a preparation method of a medical gel dressing with anti-freezing performance and photo-thermal rewarming performance, belongs to the field of hydrogel composite materials, and is applied to prevention and treatment of frostbite of field operation personnel in high-cold regions under emergency conditions. The preparation method comprises the following steps: preparing hydrogel with a double-network structure from chitosan (CS) and acrylamide (AM), stripping and layering Ti3AlC2 to obtain an MXene nanosheet as a photothermal conversion component for rewarming, betaine as an anti-freezing component, N 'N-methylene bisacrylamide as a cross-linking agent and ammonium persulfate as an initiator, and preparing CS / PAM / MXene / Betaine / AgNPs gel through a one-pot method. According to the invention, the good photo-thermal conversion effect of MXene is utilized, so that the gel dressing for frostbite is endowed with photo-thermal rewarming performance; due to the synergistic interaction of the betaine ammonium sulfate, the good anti-freezing tolerance is also shown; the nano-silver is loaded in the gel matrix, so that the gel can be endowed with remarkable antibacterial activity. The medical anti-freezing and rewarming gel dressing has the advantages that the medical anti-freezing and rewarming gel dressing is expected to be used for emergency prevention and treatment under the condition of frostbite of field operating personnel in high-cold regions.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a medical gel dressing with anti-freezing and photothermal rewarming performance, and belongs to the technical field of medical dressing preparation. BACKGROUND

[0002] China is vast in territory and long in border line. The climate in northeast China, north China and northwest China is cold in winter. National defense officers and soldiers and field operation personnel are exposed to the environment below the freezing point for a long time, and frostbite may occur at any time. Severe frostbite can cause disability and even endanger life. With the deepening of the strategy of strengthening the army, the officers and soldiers of the army participate in various military training and non-war military operations more and more, and the incidence of frostbite in high-cold and high-humidity conditions gradually increases. At present, the key to treating frostbite is to rapidly rewarm and accelerate the blood circulation of the frostbite part. The traditional water gel is difficult to inhibit the growth of ice crystals between the networks below zero temperature, and is usually hardened due to the low-temperature environment, so that the use performance is lost. Therefore, the medical gel dressing with anti-freezing performance, photothermal rewarming and antibacterial performance applied to the prevention and treatment of frostbite in emergency situations in high-cold areas has important social significance, and is also an important supplement to the market functional medical auxiliary products.

[0003] Chinese patent publication number CN104027833B, published on November 18, 2015, titled "A method for preparing a chitosan hydrogel dressing", Chinese patent publication number CN111228564A, published on June 5, 2020, titled "A method for preparing a novel medical antibacterial and healing-promoting hydrogel dressing and its application", Chinese patent publication number CN108671263B, published on May 18, 2021, The invention is titled “A preparation method for a medical antibacterial hydrogel dressing”, China Patent Publication No. CN102698313A, with a publication date of 2021.10.03, the invention is titled “A nanosilver antibacterial hydrogel and its preparation method”, China Patent Publication No. CN113527714A, with a publication date of 2021.10.22, the invention is titled “An antifreeze conductive hydrogel and its preparation method and force-responsive sensing application”, China Patent Publication No. CN11 3736102A, published on December 3, 2021, entitled "Preparation and application of integrated hydrogel suitable for plateau medical diagnosis and treatment", China Patent Publication No. CN114159618A, published on March 11, 2022, entitled "Preparation method and application of photothermal controlled oxygen release MXene nanosheet-injectable hydrogel", China Patent Publication No. CN216365553U, published on April 2, 2022 6. The invention is titled "A nanohydrogel dressing with antibacterial and hemostatic function," with Chinese patent publication number CN114748684A, published on July 15, 2022, and titled "An antibacterial hydrogel wound dressing that effectively promotes wound healing and its preparation method," and Chinese patent publication number CN114949338A, published on August 30, 2022, and titled "A hydrogel with long-lasting resistance to drug-resistant bacteria, its preparation method, and application." The above patents describe the design, functional implementation, and preparation methods of the hydrogel structure, giving the hydrogel a wealth of properties, such as antibacterial properties, healing promotion, high physical and mechanical strength, and good biocompatibility. However, how to achieve the hydrogel dressing's antifreeze properties, photothermal rewarming, and antibacterial properties in low-temperature environments, and how to expand the application range of medical hydrogel dressings to lower temperatures, has not yet been mentioned. Summary of the Invention

[0004] In response to the above problems, the purpose of the present invention is to provide a method for preparing a medical gel dressing that has antifreeze properties, photothermal rewarming, antibacterial properties, etc., and can be effectively used in low-temperature environments, so as to fill the gap in the field of medical gel dressings that can be used at low temperatures.

[0005] To achieve the above purpose, the technical solution is as follows:

[0006] 1. A method for preparing a medical gel dressing with antifreeze and photothermal rewarming properties is carried out by the following steps:

[0007] a. Exfoliation of Ti3AlC2

[0008] Concentrated HCl was diluted with ultrapure water to obtain a 7-12 M solution (8-12 mL), 0.5-0.8 g of lithium fluoride (LiF) was added to the solution, and a magnetic stir bar was used to stir for half an hour to fully dissolve the salt. Then 0.1-0.6 g of powder was gradually added to the mixed solution to avoid a violent exothermic reaction. The suspension was kept at 30-50 °C for 24 hours. Then, the mixture was washed about 3-5 times by a repeated procedure of adding ultrapure water or ethanol, centrifugation (6000-9000 rpm x 6-8 minutes for each cycle) until the pH value of the supernatant reached 5.5-8.5;

[0009] b. Exfoliation of Ti3C2T x and preparation of MXene

[0010] Exfoliation was performed by ultrasonication for 4-8 hours under flowing nitrogen and centrifugation at 6000-9000 rpm for 3-6 minutes. Then the supernatant containing Ti3C2T x was collected, i.e. a stable MXene solution. Then it was put into a petri dish, sealed with plastic wrap after punching a hole, and placed in the refrigerator overnight. The next day, the petri dish was placed in a freeze dryer, and the obtained MXene was ready for use.

[0011] c. Preparation of chitosan solution

[0012] 1-4 g of chitosan was dissolved in 95-100 mL of water and 1-4 mL of glacial acetic acid solution, heated and stirred at 93-97 °C for 3-8 h to obtain a clear yellow chitosan solution ready for use.

[0013] d. Preparation of Ag NPs

[0014] Silver nanoparticles (AgNPs) were prepared using silver nitrate (AgNO3) as raw material and polyvinylpyrrolidone (PVP) as protective agent and reducing agent. The preparation method is as follows: 0.10-0.30 g of AgNO3 and 0.20-0.50 g of PVP were weighed and dissolved in 22-27 mL of anhydrous ethanol, respectively. After mixing at room temperature, the obtained solution was continuously stirred and ready for use.

[0015] e. Preparation of CS / PAM / MXene / Betaine / AgNPs gel

[0016] The CS / PAM / MXene / Betaine / Ag NPs gel was prepared by thermal initiation radical polymerization. The whole reaction steps are as follows: first, MXene was dispersed in ultrapure water to form a uniform black MXene dispersion solution for standby. At room temperature, 18.0-22.0 g of chitosan (CS) solution, 4.0-8.0 g of acrylamide (AM), different contents of betaine (Betaine), 0.015-0.030 g of crosslinking agent BIS, 0.070-0.075 g of initiator APS were placed in two round-bottom flasks, and then mechanically stirred until completely dissolved and mixed uniformly. Subsequently, the pre-gel solution was poured into a mold, sealed with plastic wrap and in-situ radical copolymerization at 50-70℃ in an environment, and the prepared gel was soaked in an ethanol dispersion solution containing AgNO3 and PVP to obtain a CS / PAM / MXene / Betaine / AgNPs antifreeze rewarming gel.

[0017] MXene, due to its large surface area, exhibits good optical absorption under a xenon lamp light source system simulating natural sunlight, which can endow the frostbite gel dressing with photothermal rewarming performance. Betaine (Betaine) is a quaternary amine alkaloid (N,N,N-trimethylglycine) widely present in animals and plants, and has excellent biocompatibility. Studies have shown that the cationic and anionic groups of betaine can combine with water molecules through electrostatic induction, which can interfere with the formation of dense hydrogen bond structure of water, and inhibit the freezing process. The derivatives of betaine can also enhance the antifreeze performance of hydrogel, most of which can keep supercooling at zero Celsius. The synergistic interaction between betaine and ammonium sulfate in the gel also shows good antifreeze tolerance. Betaine can endow the frostbite gel dressing with antifreeze performance. The antibacterial effect of pure chitosan is not satisfactory, and nano-silver (AgNPs) has inhibitory and killing effect on Escherichia coli, and will not cause drug resistance. Loading nano-silver in the gel matrix can endow the gel with significant antibacterial activity.

[0018] 2. The preparation method of a medical gel dressing with antifreeze and photothermal rewarming performance according to claim 1, wherein the additive for enhancing the photothermal rewarming performance of the hydrogel is (MXene).

[0019] 3. The preparation method of a medical gel dressing with antifreeze and photothermal rewarming performance according to claim 1, wherein the additive for enhancing the antifreeze performance of the hydrogel is betaine (Betaine).

[0020] 4. The preparation method of a medical gel dressing with antifreeze and photothermal rewarming performance according to claim 1, wherein the additive for enhancing the antibacterial performance of the hydrogel is nano-silver (Ag NPs).

[0021] Inventive advantages

[0022] The hydrogel dressing for preventing and treating frostbite of personnel in high-cold area in emergency and its preparation method are provided, and compared with the prior art, have the following advantages:

[0023] 1) The CS / PAM / MXene / Betaine / Ag NPs gel is prepared by one-pot method, so that the preparation method is simple, the equipment is simple, and the cost is low;

[0024] 2) The prepared hydrogel dressing is compounded with three components, which respectively play the roles of photothermal rewarming (MXene), anti-freezing (Betaine) and antibacterial (AgNPs), so that the multifunctionality of the anti-freezing gel dressing is realized, and the ordinary gel dressing is distinguished. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is the anti-freezing behavior of CS / PAM / MXene / Betaine / Ag NPs gel. Wherein (a) and (b) are the mechanical deformation images of the hydrogel of CS / PAM / MXene / Ag NPs at 25℃ and-24℃; (a1) and (b1) are the compression images of the hydrogel of CS / PAM / MXene / Ag NPs at 25℃ and-24℃.

[0026] Figure 2 is the antibacterial performance diagram of the hydrogel. Wherein (a) is the macroscopic antibacterial effect picture of CS / PAM / MXene / Betaine hydrogel on E.coli and S.aureus. DETAILED DESCRIPTION

[0027] The present application will be described in detail below in combination with five specific embodiments.

[0028] Example 1

[0029] A preparation method of a medical gel dressing with anti-freezing performance and photothermal rewarming performance is as follows:

[0030] a. Ti3AlC2 exfoliation

[0031] Concentrated HCl was diluted with ultrapure water to obtain a 7M solution (10mL), 0.5g lithium fluoride (LiF) was added to the solution, and a magnetic stirring rod was used to stir for half an hour to fully dissolve the salt. Then 0.2g of powder was gradually added to the mixed solution to avoid violent exothermic reaction. The suspension was kept at 35℃ for 24 hours. Then, the mixture was washed about 3 times by a repeated procedure of adding ultrapure water or ethanol, centrifugation (6000rpm x 7 minutes for each cycle) until the pH value of the supernatant reached 5.5;

[0032] b. Ti3C2T x Layering of Ti3C2T

[0033] Layering was performed by ultrasonication for 5 hours under flowing nitrogen and centrifugation at 7000 rpm for 5 minutes. The supernatant containing Ti3C2T x , i.e. the stable MXene solution, was then collected and placed in a petri dish, sealed with plastic wrap and pierced, and placed in the refrigerator overnight. The next day, the petri dish was placed in a freeze dryer and the obtained MXene was ready for use.

[0034] c. Preparation of chitosan solution

[0035] 2 g of chitosan was dissolved in 96 mL of water and 3 mL of glacial acetic acid solution, heated and stirred at 95°C for 6 h to obtain a clear yellow chitosan solution ready for use.

[0036] d. Preparation of Ag NPs

[0037] Silver nanoparticles (AgNPs) were prepared using silver nitrate (AgNO3) as raw material and polyvinylpyrrolidone (PVP) as protective agent and reducing agent. The preparation method is as follows: 0.15 g of AgNO3 and 0.25 g of PVP were weighed and dissolved in 23 mL of anhydrous ethanol, respectively. The mixture was continuously stirred at room temperature to obtain a solution ready for use.

[0038] e. Preparation of CS / PAM / MXene / Betaine / AgNPs gel

[0039] CS / PAM / MXene / Betaine / AgNPs gel was prepared by thermal initiation of free radical polymerization. The whole reaction steps are as follows: first, MXene was dispersed in ultrapure water to form a uniform black MXene dispersion solution ready for use. At room temperature, 20.0 g of chitosan (CS) solution, 6.0 g of acrylamide (AM), and different amounts of betaine (Betaine) were placed in two round-bottom flasks, 0.015 g of crosslinking agent BIS was added, and mechanical stirring was uniform, then 0.072 g of initiator APS was added, and mechanical stirring was continued to make it completely dissolved and mixed uniformly. Subsequently, the pre-gel solution was poured into a mold, sealed with plastic wrap and pierced, and in-situ free radical copolymerization was carried out at 55°C, and the prepared gel was soaked in an ethanol dispersion solution containing AgNO3 and PVP to obtain a CS / PAM / MXene / Betaine / AgNPs antifreeze and rewarming gel.

[0040] Example 2

[0041] A method for preparing a medical gel dressing with antifreeze and photothermal rewarming properties is as follows:

[0042] a. Exfoliation of Ti3AlC2

[0043] Concentrated HC1 was diluted with ultrapure water to obtain an 8M solution (9 mL), to the solution was added 0.7 g of lithium fluoride (LiF) and stirred with a magnetic stir bar for half an hour to fully dissolve the salt. Then 0.3 g of powder was gradually added to the mixed solution to avoid a violent exothermic reaction. The suspension was kept at 40 °C for 24 hours. Then, the mixture was washed about 4 times by the repeated procedure of adding ultrapure water or ethanol, centrifugation (7000 rpm x 6 minutes for each cycle) until the pH value of the supernatant reached 6;

[0044] b. Ti3C2T x exfoliation and preparation of MXene

[0045] Exfoliation was performed by ultrasonication for 4 hours under flowing nitrogen and centrifugation at 6000 rpm for 4 minutes. Then the supernatant containing Ti3C2T x was collected, i.e. the stable MXene solution, which was then put into a petri dish, sealed with plastic wrap after punching a hole, and placed in the refrigerator overnight. The next day, the petri dish was placed in a freeze dryer, and the obtained MXene was ready for use.

[0046] c. Preparation of chitosan solution

[0047] 4 g of chitosan was dissolved in 98 mL of water and 2 mL of glacial acetic acid solution, heated and stirred at 94 °C for 7 h to obtain a clear yellow chitosan solution ready for use.

[0048] d. Preparation of Ag NPs

[0049] Silver nanoparticles (AgNPs) were prepared using silver nitrate (AgN03) as raw material and polyvinylpyrrolidone (PVP) as protective agent and reducing agent. The preparation method is as follows: 0.10 g of AgN03 and 0.30 g of PVP were weighed and dissolved in 22 mL of anhydrous ethanol, respectively. After mixing the two at room temperature, the obtained solution was continuously stirred and ready for use.

[0050] e. Preparation of CS / PAM / MXene / Betaine / AgNPs gel

[0051] The CS / PAM / MXene / Betaine / Ag NPs gel was prepared by thermal initiated radical polymerization. The whole reaction steps are as follows: first, MXene was dispersed in ultrapure water to form a uniform black MXene dispersion solution for standby. At room temperature, 18.0 g of chitosan (CS) solution, 5.0 g of acrylamide (AM), different contents of betaine (Betaine) were placed in two round-bottom flasks, 0.020 g of crosslinking agent BIS was added, and mechanical stirring was uniform, then 0.073 g of initiator APS was added, and mechanical stirring was continued to make it completely dissolved and mixed uniformly. Subsequently, the pre-gel solution was poured into a mold, sealed with plastic wrap and in situ radical copolymerization at 60°C in an environment, and the prepared gel was soaked in an ethanol dispersion solution containing AgNO3 and PVP to obtain a CS / PAM / MXene / Betaine / AgNPs antifreeze rewarming gel.

[0052] Example 3

[0053] A method for preparing a medical gel dressing with antifreeze and photothermal rewarming properties is as follows:

[0054] a. Exfoliation of Ti3AlC2

[0055] Concentrated HC1 was diluted with ultrapure water to obtain a 10M solution (11 mL), 0.6 g of lithium fluoride (LiF) was added to the solution, and a magnetic stirring rod was used to stir for half an hour to fully dissolve the salt. Then 0.5 g of powder was gradually added to the mixed solution to avoid violent exothermic reaction. The suspension was kept at 30°C for 24 hours. Then, the mixture was washed about 5 times by repeated procedures of adding ultrapure water or ethanol, centrifugation (8000 rpm x 6 minutes for each cycle) until the pH value of the supernatant reached 7;

[0056] b. Preparation of Ti3C2T x and MXene

[0057] Exfoliation was carried out by ultrasonic treatment for 6 hours under flowing nitrogen and centrifugation at 8000 rpm for 5 minutes. Then the supernatant containing Ti3C2T x , i.e. the stable MXene solution, was collected, then it was put into a petri dish, sealed with plastic wrap and pierced, placed in the refrigerator overnight, and the next day the petri dish was placed in a freeze dryer to obtain MXene for standby.

[0058] c. Preparation of chitosan solution

[0059] 1 g of chitosan was dissolved in 95 mL of water and 4 mL of glacial acetic acid solution, heated and stirred at 97°C for 4 h to obtain a clear yellow chitosan solution for standby.

[0060] d. Preparation of Ag NPs

[0061] Silver nanoparticles (AgNPs) were prepared using silver nitrate (AgNO3) as raw material and polyvinylpyrrolidone (PVP) as protective agent and reducing agent. The preparation method is as follows: 0.25 g of AgNO3 and 0.40 g of PVP were weighed and dissolved in 25 mL of absolute ethanol, respectively. After mixing at room temperature, the solution was continuously stirred and prepared for use.

[0062] e. Preparation of CS / PAM / MXene / Betaine / AgNPs gel

[0063] The CS / PAM / MXene / Betaine / AgNPs gel was prepared by thermal initiation radical polymerization. The whole reaction steps are as follows: first, MXene was dispersed in ultrapure water to form a uniform black MXene dispersion solution for standby. At room temperature, 19.0 g of chitosan (CS) solution, 7.0 g of acrylamide (AM), and different amounts of betaine (Betaine) were placed in two round-bottom flasks, 0.022 g of crosslinking agent BIS was added, and mechanical stirring was uniform, then 0.074 g of initiator APS was added, and mechanical stirring was continued to make it completely dissolved and mixed uniformly. Subsequently, the pre-gel solution was poured into a mold, sealed with plastic wrap and in-situ radical copolymerization at 50°C, and the prepared gel was soaked in an ethanol dispersion solution containing AgNO3 and PVP to obtain a CS / PAM / MXene / Betaine / AgNPs antifreeze and rewarming gel.

[0064] Example 4

[0065] A method for preparing a medical gel dressing with antifreeze and photothermal rewarming properties is as follows:

[0066] a. Exfoliation of Ti3AlC2

[0067] Concentrated HCl was diluted with ultrapure water to obtain a 9M solution (11 mL), 0.8 g of lithium fluoride (LiF) was added to the solution, and a magnetic stirring rod was used to stir for half an hour to fully dissolve the salt. Then 0.4 g of powder was gradually added to the mixed solution to avoid violent exothermic reaction. The suspension was kept at 45°C for 24 hours. Then, the mixture was washed about 4 times by repeated procedures of adding ultrapure water or ethanol, centrifugation (9000 rpm x 8 minutes for each cycle) until the pH value of the supernatant reached 7.5;

[0068] b. Layering of Ti3C2T x and preparation of MXene

[0069] Layering was carried out by ultrasonic treatment under flowing nitrogen for 8 hours and centrifugation at 9000 rpm for 3 minutes. Then the Ti3C2T xThe supernatant, i.e. the stable MXene solution, was then placed in a petri dish, sealed with plastic wrap and pierced, and placed in the refrigerator overnight. The next day, the petri dish was placed in a freeze dryer to obtain the MXene, which was stored for later use.

[0070] c. Preparation of chitosan solution

[0071] 3 g of chitosan was dissolved in 99 mL of water and 1 mL of glacial acetic acid solution, heated and stirred at 97°C for 3 h to obtain a clear yellow chitosan solution for later use.

[0072] d. Preparation of Ag NPs

[0073] Silver nanoparticles (AgNPs) were prepared using silver nitrate (AgNO3) as raw material and polyvinylpyrrolidone (PVP) as protective agent and reducing agent. The preparation method is as follows: 0.30 g of AgNO3 and 0.35 g of PVP were weighed and dissolved in 27 mL of anhydrous ethanol, respectively. The mixture was continuously stirred at room temperature to obtain a solution for later use.

[0074] e. Preparation of CS / PAM / MXene / Betaine / AgNPs gel

[0075] The CS / PAM / MXene / Betaine / AgNPs gel was prepared by thermal initiation of free radical polymerization. The whole reaction steps are as follows: first, MXene was dispersed in ultrapure water to form a uniform black MXene dispersion solution for later use. At room temperature, 22.0 g of chitosan (CS) solution, 8.0 g of acrylamide (AM), and different amounts of betaine (Betaine) were placed in two round-bottom flasks, 0.022 g of crosslinking agent BIS was added, and mechanical stirring was performed until uniform, then 0.070 g of initiator APS was added, and mechanical stirring was continued until complete dissolution and uniform mixing. Subsequently, the pre-gel solution was poured into a mold, sealed with plastic wrap and placed in a 65°C environment for in-situ free radical copolymerization. The prepared gel was soaked in an ethanol dispersion solution containing AgNO3 and PVP to obtain a CS / PAM / MXene / Betaine / AgNPs antifreeze and rewarming gel.

[0076] Example 5

[0077] A method for preparing a medical gel dressing with antifreeze and photothermal rewarming properties is as follows:

[0078] a. Exfoliation of Ti3AlC2

[0079] Concentrated HC1 was diluted with ultrapure water to obtain a 12 M solution (8 mL), to the solution was added 0.6 g of lithium fluoride (LiF) using a magnetic stir bar to stir for half an hour to fully dissolve the salt. Then 0.3 g of powder was gradually added to the mixed solution to avoid a violent exothermic reaction. The suspension was kept at 50 °C for 24 hours. Then, the mixture was washed about 5 times by the repeated procedure of adding ultrapure water or ethanol, centrifugation (8000 rpm x 6 minutes for each cycle) until the pH value of the supernatant reached 6.5;

[0080] b. Ti3C2T x Layering of Ti3C2T

[0081] Layering was performed by ultrasonication for 7 hours under flowing nitrogen and centrifugation at 8000 rpm for 6 minutes. Then the supernatant containing Ti3C2T x , i.e. the stable MXene solution, was collected and then put into a petri dish, sealed with plastic wrap after punching a hole, and placed in the refrigerator overnight. The next day, the petri dish was placed in a freeze dryer, and the obtained MXene was ready for use.

[0082] c. Preparation of chitosan solution

[0083] 4 g of chitosan was dissolved in 97 mL of water and 3 mL of glacial acetic acid solution, heated and stirred at 93 °C for 5 h to obtain a clear yellow chitosan solution ready for use.

[0084] d. Preparation of Ag NPs

[0085] Silver nanoparticles (AgNPs) were prepared using silver nitrate (AgN03) as raw material and polyvinylpyrrolidone (PVP) as protective agent and reducing agent. The preparation method is as follows: 0.20 g of AgN03 and 0.45 g of PVP were weighed and dissolved in 24 mL of anhydrous ethanol, respectively. After mixing the two at room temperature, the obtained solution was continuously stirred and ready for use.

[0086] e. Preparation of CS / PAM / MXene / Betaine / AgNPs gel

[0087] The CS / PAM / MXene / Betaine / Ag NPs gel is prepared by thermal initiation free radical polymerization. The whole reaction steps are as follows: firstly, MXene is dispersed in ultrapure water to form a uniform black MXene dispersion solution for standby. At room temperature, 21.0g of chitosan (CS) solution, 4.5g of acrylamide (AM), different contents of betaine (Betaine) are placed in two round-bottom flasks, 0.025g of crosslinking agent BIS is added, and mechanical stirring is uniform, then 0.075g of initiator APS is added, and mechanical stirring is continued to make it completely dissolved and mixed uniformly. Subsequently, the pre-gel solution is poured into a mold, sealed with plastic wrap and in-situ free radical copolymerization at 70℃ environment, and the prepared gel is soaked in an ethanol dispersion solution containing AgNO3 and PVP to obtain a CS / PAM / MXene / Betaine / AgNPs anti-freezing rewarming gel.

[0088] The medical gel dressing obtained by the method has excellent anti-freezing and photothermal rewarming properties, has good biocompatibility, can promote wound healing in a low temperature environment, and is applied to the prevention and treatment of frostbite in emergency situations of personnel working in high-cold areas. The preparation method is simple and easy to operate, and can be widely applied to the treatment of frostbite, burn and other wounds. In addition, the preparation method is low in cost, simple in operation, easy to realize industrialized production, has wide market prospect and application value.

[0089] The above disclosure is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto.

Claims

1. A method for preparing a medical gel dressing with antifreeze and photothermal rewarming properties, characterized in that: It is prepared from the following raw materials: chitosan (CS), acrylamide (AM), Ti3AlC2, betaine (Betaine), N'N-methylenebisacrylamide, and ammonium persulfate (APS).

2. The method for preparing a medical gel dressing having antifreeze properties and photothermal rewarming properties according to claim 1, characterized in that: The steps include: a. Peeling of Ti3AlC2 Concentrated HCl is diluted with ultrapure water to obtain a 7-12M solution (8-12 mL). 0.5-0.8 g of lithium fluoride (LiF) is added to the solution and stirred with a magnetic stirring bar for half an hour to fully dissolve the salt. 0.1-0.6 g of powder is then gradually added to the mixed solution to avoid a violent exothermic reaction. The suspension is kept at 30-50°C for 24 hours. The mixture is then washed 3-5 times by repeating the procedure of adding ultrapure water or ethanol and centrifuging (6000-9000 rpm × 6-8 minutes per cycle) until the pH value of the supernatant reaches 5.5-8.5; b.Ti3C2T x Delamination and preparation of MXene The layers were separated by ultrasonic treatment under flowing nitrogen for 4-8 hours and centrifugation at 6000-9000 rpm for 3-6 minutes. x The supernatant, i.e. the stable MXene solution, is placed in a culture dish, sealed with plastic wrap and pierced with holes, and placed in a refrigerator overnight. The next day, the culture dish is placed in a freeze-drying environment, and the obtained MXene is ready for use. c. Preparation of chitosan solution Dissolve 1-4 g of chitosan in 95-100 mL of water and 1-4 mL of glacial acetic acid solution, heat and stir at 93-97° C. for 3-8 h to obtain a clear yellow chitosan solution for use. d. Preparation of Ag NPs Silver nanoparticles (AgNPs) were prepared using silver nitrate (AgNO3) as raw material and polyvinylpyrrolidone (PVP) as protective agent and reducing agent. The preparation method is as follows: weigh 0.10-0.30 g of AgNO3 and 0.20-0.50 g of PVP, dissolve them in 22-27 mL of anhydrous ethanol respectively, mix the two at room temperature and stir continuously, and the obtained solution is used for standby use. e. Preparation of CS / PAM / MXene / Betaine / AgNPs gel CS / PAM / MXene / Betaine / Ag NPs gels were prepared by thermally initiated free radical polymerization. The reaction steps are as follows: First, MXene was dispersed in ultrapure water to form a uniform black MXene dispersion for later use. At room temperature, 18.0-22.0g of chitosan (CS) solution, 4.0-8.0g of acrylamide (AM), and varying amounts of betaine (Betaine) were placed in a two-necked round-bottom flask. 0.015-0.030g of the crosslinker BIS was added and mechanically stirred until uniformly dissolved. Then, 0.070-0.075g of the initiator APS was added and mechanically stirred until completely dissolved and mixed. Subsequently, the pregel solution was poured into a mold, sealed with plastic wrap, and subjected to in-situ free radical copolymerization at 50-70°C. The prepared gel was then immersed in an ethanol dispersion containing AgNO3 and PVP to obtain a CS / PAM / MXene / Betaine / Ag NPs freeze-resistant and rewarming gel.

3. The method for preparing a medical gel dressing having antifreeze properties and photothermal rewarming properties according to claim 1, characterized in that: The additive used to enhance the photothermal rewarming performance of the hydrogel is MXene.

4. The method for preparing a medical gel dressing having antifreeze properties and photothermal rewarming properties according to claim 1, characterized in that: The additive used to enhance the antifreeze performance of the hydrogel is betaine.

5. The method for preparing a medical gel dressing having antifreeze properties and photothermal rewarming properties according to claim 1, characterized in that: The additive used to enhance the antibacterial properties of the hydrogel is silver nanoparticles (Ag NPs).

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