Preparation method and application of antibacterial material

Abstract

The invention relates to the field of high-molecular polymers, relates to an antibacterial product, and in particular relates to a preparation method and application of an antibacterial material. A nano-emulsion with guanidine hydrochloride and a gelatin solid are synthesized respectively, and the double-layer antibacterial material with multiple response stimulation is obtained in a gelatin assembling mode. The double-layer antibacterial material has a pH gating mechanism, the pH sensitivity of the antibacterial material can be improved, the active material is slowly released under the pH condition, and the antibacterial effect is improved through the synthesized novel guanidine hydrochloride. Compared with the prior art, the preparation method has the effects of enhancing interface bonding, reducing dissolution, promoting healing and gated release, and solves the problems of dissolution toxicity and physical property limitation of antibacterial materials in the prior art.

Description

Technical Field

[0001] The present invention application relates to the field of polymer materials, relates to an antibacterial product, and specifically relates to a preparation method and application of an antibacterial material. Background Art

[0002] The safety and mildness of the bactericides widely used in the current market are not sufficient, and most of them have certain toxicity, peculiar smell, corrosiveness or skin irritation, etc., so they are not suitable for the bactericidal application range in direct contact with the human body. For example, hypochlorous acid used for disinfecting human skin and object surfaces has a bad smell, is easy to decompose and is inconvenient to store; alcohol (ethanol) commonly used for disinfecting human skin is flammable, explosive and has strong irritation, and is highly dangerous during storage or transportation. These traditional bactericides all have certain obvious defects and cannot meet the actual needs. Summary of the Invention

[0003] In order to solve the above problems, the present invention application provides a preparation method and application of an antibacterial material. By introducing an imine bond, a pH-responsive chitosan-polyguanidine polymer is prepared, and a bilayer antibacterial material with multiple response stimuli is obtained by assembling gelatin, which can directly act on the disinfection, sterilization and protection of human wounds.

[0004] In order to achieve the above object, the technical solution adopted by the present invention application is as follows:

[0005] In the first aspect, the present invention application provides a preparation method of an antibacterial material. The method includes the following steps: dissolving 2 wt% chitosan in a 1 wt% acid solution at a ratio of 2:1 by weight percentage, fully stirring for 2 h at 25 °C to form a solution, adding an active component to the solution to form an intermediate solution, and centrifuging the intermediate solution to remove air bubbles in the solution; the active component is the guanidine hydrochloride, which is poly-2-methyl-pentamethylene guanidine hydrochloride, and has the following structural formula: , where the degree of polymerization n = 60-100; mixing and stirring the intermediate solution and the nanoemulsion at a weight ratio of (2-1):(1-2) to form a mixed solution, and mixing the mixed solution on a gelatin solid and drying to obtain the antibacterial material; the antibacterial material is a bilayer structure, the first layer is a gelatin solid formed after drying the gelatin solution, and the second layer is an active substance formed by loading the active component and the nanoemulsion on chitosan and drying, and the active substance is wrapped in the gelatin solid.

[0006] In some specific implementation manners, the obtaining of the gelatin solution includes the following steps: adding 2 wt% of gelatin and 1 wt% of glycerol into distilled water, and heating and stirring at 60 °C to obtain an initial gelatin solution, adding 0.5 wt% - 5 wt% of tannic acid into the initial gelatin solution and accelerating stirring and dissolving at 40 °C to obtain the gelatin solution; the gelatin solid is obtained by drying the gelatin solution at 35 °C for 4 h.

[0007] In some specific implementation manners, the nanoemulsion is obtained by mixing and stirring an oil phase with a concentration of 10% and an aqueous phase with a concentration of 90%, and the oil phase is obtained by ultrasonic method based on 5% - 10% of an emulsifier by mass ratio of the oil phase and 90% - 95% of essential oil by mass ratio of the oil phase; the ultrasonic power ratio is 50% - 90%, and the ultrasonic time is 5 min - 25 min.

[0008] In some specific implementation manners, the poly-2-methyl-pentamethyleneguanyl hydrochloride is obtained by synthesizing 2-methyl-1,5-pentanediamine and guanidine hydrochloride.

[0009] In some specific implementation manners, the preparation method of the poly-2-methyl-pentamethyleneguanyl hydrochloride specifically includes: performing a multi-stage temperature-rising reaction on 2-methyl-1,5-pentanediamine and guanidine hydrochloride with a molar ratio of 1:1 under a nitrogen atmosphere to obtain a polymer melt; the multi-stage temperature-rising reaction includes a first temperature-rising reaction stage, a second temperature-rising reaction stage, and a third temperature-rising reaction stage, the target temperature range of the first temperature-rising reaction stage is 75 °C - 85 °C, the target temperature range of the second temperature-rising reaction stage is 115 °C - 125 °C, and the target temperature range of the third temperature-rising reaction stage is 175 °C - 185 °C.

[0010] In some specific implementation manners, the preparation method of the poly-2-methyl-pentamethyleneguanyl hydrochloride further includes: pressing the polymer melt into purified water based on nitrogen pressure and stirring, dissolving, and filtering to collect an aqueous solution containing the crude product of 2-methyl-pentamethyleneguanyl hydrochloride; purifying, concentrating, and drying the aqueous solution containing the crude product of 2-methyl-pentamethyleneguanyl hydrochloride by ion exchange to obtain the poly-2-methyl-pentamethyleneguanyl hydrochloride.

[0011] In some specific implementation manners, stirring is performed for 15 - 30 min after the completion of temperature rising in the first temperature-rising reaction stage to obtain a first-stage product; after the completion of temperature rising in the second temperature-rising reaction stage based on the first-stage product, ammonia gas in the reaction process is excluded and collected to obtain an intermediate product; after the completion of temperature rising in the third temperature-rising reaction stage based on the intermediate product, the reactants are stirred for 2 - 3 h to obtain the polymer melt.

[0012] In some specific embodiments, the purity of the poly-2-methyl-pentamethylene guanidine hydrochloride is greater than or equal to 99%.

[0013] In some specific embodiments, the acid solution includes glacial acetic acid, and the acid solution includes glacial acetic acid.

[0014] In a second aspect, provided is an application of an antibacterial material prepared by the method described in any one of the above in a medical dressing.

[0015] In the technical solution provided by the embodiments of the present application, a novel antibacterial material matrix for disinfecting human wounds and injuries is provided. By separately synthesizing a nanoemulsion with guanidine hydrochloride and a gelatin solid, and obtaining a bilayer antibacterial material with multiple response stimuli through the assembly of gelatin. This bilayer antibacterial material has a pH gating mechanism, which can improve the pH sensitivity of the antibacterial material, achieve slow release of the active material under pH conditions, and improve the antibacterial effect through the synthesized novel guanidine hydrochloride. Compared with the prior art, the present invention application has the effects of enhancing interfacial binding, reducing dissolution, promoting healing, and gated release, and solves the problems of dissolution toxicity and physical property limitations of antibacterial materials in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention application, the following will briefly introduce the drawings required for use in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 is a flowchart of the method for preparing the antibacterial material provided by the present invention application.

[0018] Figure 2 is a flowchart of the method for synthesizing guanidine hydrochloride provided by the present invention application.

[0019] Figure 3 is a schematic diagram of the experimental results of pH response and controlled release performance provided by the present invention application.

[0020] Figure 4 is a schematic diagram of the experimental results of the inhibition zone method provided by the present invention application.

[0021] Figure 5 is a schematic diagram of the experimental results of the inhibition zone method provided by the prior art. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this invention application clearer, the technical solutions in the embodiments of this invention application will be clearly and completely described below. For those not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are followed. For reagents or instruments not indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase. The embodiments described below are some, rather than all, of the embodiments of this invention application. All other embodiments obtained by those of ordinary skill in the art in combination with the embodiments in this invention application without creative efforts belong to the scope of protection of this invention application.

[0023] In a specific embodiment of this invention application, a method for preparing an antibacterial material is provided for preparing a dual-responsive antibacterial material. Moreover, in another specific embodiment of this invention application, an application of this antibacterial material on a medical dressing is also provided.

[0024] Among them, the antibacterial material provided in this embodiment has a bilayer structure. The first layer is a gelatin solid formed after drying the gelatin solution, and the second layer is an active substance formed after drying the nanoemulsion, which is encapsulated in the gelatin solid and has an active component loaded with chitosan as a negative carrier.

[0025] Specifically, the active component in this embodiment is guanidine hydrochloride. Among them, guanidine hydrochloride is used as the antibacterial main body, chitosan is used as the carrier, and an imine bond is formed through the amino group on chitosan and the nanoemulsion to obtain a pH-sensitive carrier material. Combining this carrier material with guanidine hydrochloride has good antibacterial activity and controlled release performance. Among them, the nanoemulsion is obtained by mixing and stirring an oil phase with a concentration of 10% and an aqueous phase with a concentration of 90%. Among them, the oil phase is obtained by ultrasonic method with an emulsifier accounting for 5% - 10% of the mass of the oil phase and essential oil accounting for 90% - 95% of the mass of the oil phase. Moreover, to further enhance the biological activity of the material, plant essential oil is preferably selected as the essential oil in this embodiment, and tsaoko fruit essential oil is optimally selected. Among them, the emulsifier is selected as a mixed emulsifier, which is obtained by mixing Tween 20 and sucrose fatty acid ester in equal proportions.

[0026] In an implementable manner, to enable this antibacterial material to directly act on the human body and provide an efficient antibacterial effect, guanidine hydrochloride is obtained through a newly synthesized method. Specifically, the guanidine hydrochloride in this embodiment is a poly-2-methyl-pentamethylene guanidine hydrochloride, and its structure is different from that of guanidine hydrochloride in the prior art, as shown below: , where the degree of polymerization n = 60 - 100.

[0027] It can be seen from the above structural formula that the guanidine hydrochloride in this embodiment adopts a novel structure. The methyl side chain of 2-methylpentanediamine in its structure can disrupt the linear symmetry of hexamethylenediamine, increase the spatial distribution density of the guanidine group, enhance the positive charge density, improve the adsorption capacity for bacterial cell membranes, thereby increasing the bactericidal efficiency, making its inactivation rate for Escherichia coli and Staphylococcus aureus more efficient than that of guanidine hydrochloride in the prior art. Moreover, its branched-chain structure can reduce the crystallinity of the polymer, making the final product more likely to form a loose film layer, making it easier and more sufficient to combine with the nanoemulsion, and promoting the penetration of antibacterial components to the outside, thereby enhancing the control of deep positions. Compared with the existing guanidine hydrochloride, such as polyhexamethylene biguanide hydrochloride commonly used for broad-spectrum antibacterial use, the guanidine hydrochloride provided in this embodiment is more suitable for antibacterial use on the human skin surface.

[0028] It should be noted that for some pathogenic bacteria such as Staphylococcus aureus and Escherichia coli, acidic metabolites (such as lactic acid and acetic acid) will be produced during the growth process, resulting in a decrease in the environmental pH value. Based on this characteristic, the applicant designs the antibacterial material in this embodiment to be sensitive to acid. Specifically, in this embodiment, an acid-sensitive imine bond is formed by chitosan and tsaoko essential oil to construct an acid-sensitive antibacterial material; the antibacterial material based on the imine bond has the advantages of fast in-situ formation, self-repair, no cytotoxicity, on-demand release of antibacterial agent active components, and excellent antibacterial activity.

[0029] Compared with traditional release-type materials, the acid-sensitive antibacterial material proposed in this embodiment can intelligently sense the external environmental changes, generate a response to release active substances only when there is a stimulation signal, and the active substance in this embodiment uses newly synthesized guanidine hydrochloride, which can directly act on the human surface and has a high antibacterial effect. Through this assembly method, the use efficiency and antibacterial effect of antibacterial molecules can be directly improved.

[0030] Moreover, gelatin can be directly in contact with external objects as the underlying structure. In order to endow the underlying structure with antibacterial properties and improve the performance of gelatin, tannic acid is configured in the gelatin solid in this embodiment. Tannic acid is an ester formed by the combination of gallic acid or phenolic carboxylic acids and polyols with a biogenetic relationship with gallic acid. Its relative molecular weight is relatively small, 500 - 3000 Da, with strong hydrolyzability, soluble in water, and easily hydrolyzed by acids, alkalis, and enzymes. The polyphenolic hydroxyl structure of tannic acid has a series of unique chemical properties and physiological activities, such as having a high affinity for proteins, and can also combine with alkaloids and polysaccharides to undergo physical and chemical reactions to change properties, can form complexation and electrostatic interactions with a variety of metal ions, and has reducibility and the activity of capturing free radicals.

[0031] Regarding tannic acid as a plant polyphenol, it can directly interact with gelatin through non-covalent bonds. First, it oxidizes to produce quinone compounds, and then the quinone compounds react with the amino acid residues of gelatin to obtain a chemically cross-linked membrane with good compatibility, which can be directly used as a natural cross-linking agent for gelatin to enhance the mechanical and thermal stability of gelatin. Moreover, tannic acid itself has antioxidant, hemostatic, and antibacterial activities, and can directly adhere to the wound surface on the human body surface, thereby improving the applicability of the antibacterial material to adhere to the human body. Furthermore, for the branched chain of the guanidine hydrochloride provided in this embodiment, it endows the film with high elasticity. The combination of the two makes the skin fit and breathability better than traditional dressings, thereby reducing the risk of skin maceration. And the branched-chain structure of guanidine hydrochloride can enhance the interfacial binding force with the substrate, thereby preventing the dressing from peeling off during movement and being more suitable for use in joint parts.

[0032] In summary, for the antibacterial material provided in this embodiment, by synthesizing a new type of guanidine hydrochloride as an active material and combining the gated release mechanism of the nanoemulsion and the strengthening effect of gelatin, it has a better effect in antibacterial on the human body surface compared with existing antibacterial materials. It can significantly enhance antibacterial activity, has higher biocompatibility, and in the application on the skin surface, by enhancing interfacial binding, reducing dissolution, promoting healing, and gated release, it solves the problems of dissolution toxicity and physical property limitations of antibacterial materials in the prior art.

[0033] For the preparation method of the antibacterial material provided in this embodiment, please refer to Figure 1 the process shown below, which includes the following steps:

[0034] Step S11. Dissolve 22 wt% chitosan in a 1 wt% acid solution at a weight ratio of 2:1, stir well for 2 h at 25 °C to form a solution, add an active component to the solution to form an intermediate solution, and centrifuge the intermediate solution to remove the bubbles in the solution.

[0035] In this embodiment, the acid solution includes glacial acetic acid.

[0036] The active component is guanidine hydrochloride, specifically poly-2-methyl-pentamethylene guanidine hydrochloride, which has the following structural formula: , where the degree of polymerization n = 60 - 100.

[0037] Specifically, poly-2-methyl-pentamethylene guanidine hydrochloride is a new type of polymer synthesized from 2-methyl-1,5-pentanediamine and guanidine hydrochloride. The synthesis method of this polymer is described in detail. For the detailed synthesis process, please refer to Figure 2 , which includes the following steps:

[0038] Step S21. 2-methyl-1,5-pentanediamine and guanidine hydrochloride with a molar ratio of 1:1 are subjected to multi-stage temperature-rising reaction under a nitrogen atmosphere to obtain a polymer melt.

[0039] Among them, the multi-stage temperature-rising reaction in this embodiment includes a three-stage temperature-rising process. The target temperatures, i.e., the temperature-rising cut-off temperatures, of the three-stage temperature-rising process are 75°C - 85°C, 115°C - 125°C, and 175°C - 185°C respectively. In the first temperature-rising stage, after the temperature-rising is completed, the reactants are stirred for 15 - 30 min to obtain the first-stage product. This process is the initial reaction stage, which is used to disperse the substrate to make the subsequent reaction more sufficient. The second temperature-rising stage is based on the first-stage product. When the second temperature-rising reaction is completed, reaction by-products will start to be generated. The main reaction by-product in this stage is ammonia gas. During this process, the ammonia gas needs to be discharged. And when entering the third temperature-rising stage, in order to control the rate of ammonia gas generation, the temperature-rising rate in this temperature-rising stage should be a uniform temperature rise until the target temperature of the third temperature-rising stage is reached and the temperature-rising stops. After the temperature-rising in the third temperature-rising stage is completed, the reaction product is stirred and reacted for 2 - 3 h to obtain the polymer melt.

[0040] Step S22. Based on the nitrogen pressure, the polymer melt is pressed into purified water, and then stirred, dissolved, filtered, and an aqueous solution containing crude 2-methyl-pentamethylguanidine hydrochloride is collected.

[0041] In this process, the polymer melt obtained in step S21 is transferred from the reaction kettle to a separation tank filled with purified water based on the nitrogen pressure, and the impurities are filtered by sufficient stirring and dissolution, and the filtrate is collected. The obtained filtrate is the aqueous solution of crude poly-2-methyl-pentamethylguanidine hydrochloride.

[0042] Step S23. The aqueous solution containing crude 2-methyl-pentamethylguanidine hydrochloride is purified, concentrated, and dried by ion exchange to obtain the poly-2-methyl-pentamethylguanidine hydrochloride.

[0043] In this process, the aqueous solution of crude poly-2-methyl-pentamethylguanidine hydrochloride is purified twice through an ion exchange membrane, and then the purified solution is concentrated and dried to obtain poly-2-methyl-pentamethylguanidine hydrochloride solid with a purity greater than or equal to 99%.

[0044] Furthermore, the reaction in step S21 is carried out in a reaction kettle, and the reactions in steps S22 - S23 are carried out in a separation tank. Among them, in the reactions of steps S21 - S23, only two reaction main bodies, 2-methyl-1,5-pentanediamine and guanidine hydrochloride, are introduced, and no other reaction aids are introduced. Compared with the prior art, the reaction process of guanidine hydrochloride is simpler, more efficient, and cleaner, avoiding the purity influence caused by the introduction of initiators and terminators.

[0045] Specifically, a novel guanidine hydrochloride can be obtained by using steps S21 - S23 in this embodiment, and the yield of poly-2-methyl-pentamethylene guanidine hydrochloride obtained by the reaction is 96 - 99%, and the purity is greater than or equal to 99%.

[0046] Step S12. Mix and stir the intermediate solution and the nanoemulsion in a weight ratio of (2 - 1):(1 - 2) to form a mixed solution, and mix the mixed solution on the gelatin solid and dry it to obtain the antibacterial material.

[0047] In this embodiment, the nanoemulsion is obtained by mixing and stirring an oil phase with a concentration of 10% and an aqueous phase with a concentration of 90%. The oil phase is obtained by ultrasonic method with an emulsifier accounting for 5% - 10% of the mass of the oil phase and essential oil accounting for 90% - 95% of the mass of the oil phase.

[0048] Specifically, the essential oil is tsaoko fruit essential oil in this embodiment, and the emulsifier is a mixed emulsifier obtained by mixing tween 20 and sucrose fatty acid ester in equal proportions. The ultrasonic power ratio is 50% - 90%, and the ultrasonic time is 5 min - 25 min.

[0049] In this embodiment, to obtain the gelatin solution, first add 2 wt% of gelatin and 1 wt% of glycerol to distilled water, and heat and stir at 60°C to obtain the initial gelatin solution. Then add 0.5 wt% - 5 wt% of tannic acid to the initial gelatin solution and accelerate stirring and dissolving at 40°C to obtain the gelatin solution.

[0050] Among them, the gelatin solid is obtained by drying the gelatin solution at 35°C for 4 h.

[0051] The preparation method of the antibacterial material described in this invention application will be further illustrated by specific examples below.

[0052] Example 1

[0053] This application example provides a preparation method of an antibacterial material, including the following steps:

[0054] Synthesis of active components:

[0055] Step S11. With stirring started, sequentially add 116.2 kg of 2-methyl-1,5-pentanediamine and 95.53 kg of guanidine hydrochloride to the reaction kettle, close the reaction kettle and introduce nitrogen for reaction protection under a nitrogen atmosphere, raise the temperature, and continuously stir. Raise the temperature to 75°C and stir for 15 - 30 minutes to make it evenly stirred to obtain the first-stage product.

[0056] Step S12. Continue to heat up to 115°C, discharge the generated ammonia gas through a pipeline for collection, and obtain an intermediate product.

[0057] Step S13. Uniformly control the heating rate and heat up to 175°C, and stir and react for 2 h to obtain a polymer melt.

[0058] Step S14. Based on the nitrogen pressure, transfer the obtained polymer melt in a molten state from the reaction kettle to a separation tank filled with purified water, fully stir and dissolve, filter, and collect the filtrate to obtain an aqueous solution of crude poly-2-methyl-pentamethylene guanidine hydrochloride.

[0059] Step S15. Re-purify the aqueous solution of poly-2-methyl-pentamethylene guanidine hydrochloride through an ion exchange membrane, then concentrate and dry the purified solution to obtain a solid, that is, 204 kg of poly-2-methyl-pentamethylene guanidine hydrochloride with a purity of more than 99%.

[0060] Synthesis of nanoemulsion:

[0061] Step S21. Mix Tween 20 and sucrose fatty acid ester in equal proportions to obtain an emulsifier.

[0062] Step S22. Add 9 mass times of tsaoko fruit essential oil to the compounded emulsifier, and obtain an oil phase through ultrasonic treatment with an ultrasonic power ratio of 50% and an ultrasonic time of 25 min.

[0063] Step S23. Mix the oil phase and distilled water at a concentration ratio of 1:9 and stir for 15 min to obtain a nanoemulsion.

[0064] Synthesis of gelatin solid:

[0065] Step S31. Add 400 kg of 2 wt% gelatin and 200 kg of 1 wt% glycerol to 600 kg of distilled water, and heat and stir at 60°C to obtain an initial gelatin solution.

[0066] Step S32. Add 0.5 wt% of tannic acid to the initial gelatin solution and accelerate stirring and dissolving at 40°C to obtain a gelatin solution.

[0067] Step S33. Dry the gelatin solution at 35°C for 4 h to obtain a gelatin solid.

[0068] Preparation of antibacterial material:

[0069] Step S1. Dissolve 100 kg of 2 wt% chitosan in 50 kg of 1 wt% glacial acetic acid, stir thoroughly for 2 h at 25° C. to form a solution, add 25 kg of poly-2-methyl-pentamethyleneguanidine hydrochloride solid to the stirred solution to form an intermediate solution, and centrifuge the intermediate solution to remove bubbles in the solution.

[0070] Step S2. The intermediate solution and the nanoemulsion are mixed and stirred at a weight ratio of 2:1 to form a mixed solution, and the mixed solution is mixed on a gelatin solid and dried to obtain an antibacterial material.

[0071] Example 2

[0072] The present invention provides a method for preparing an antibacterial material, comprising the following steps:

[0073] Synthesis of active ingredients:

[0074] Step S11. With stirring turned on, 116.2 kg of 2-methyl-1,5-pentanediamine and 95.53 kg of guanidine hydrochloride were added to the reactor in sequence, the reactor was sealed and nitrogen was introduced to protect the reaction with a nitrogen atmosphere, the temperature was raised and stirring was continued until the temperature reached 80°C, and the mixture was stirred for 15 to 30 minutes to allow the mixture to be evenly stirred, to obtain the first-stage product.

[0075] Step S12: Continue to raise the temperature to 120° C., discharge the generated ammonia through a pipeline and collect it, and obtain an intermediate product.

[0076] Step S13: uniformly control the heating rate and raise the temperature to 180° C., stir and react for 2.2 h to obtain a polymer melt.

[0077] Step S14. The polymer melt in a molten state is transferred from the reactor to a separation tank filled with purified water based on nitrogen pressure, and the polymer melt is fully stirred to dissolve, filtered and the filtrate is collected to obtain an aqueous solution of a crude product of poly-2-methyl-pentamethyleneguanidine hydrochloride.

[0078] Step S15. The aqueous solution of poly-2-methyl-pentamethyleneguanidine hydrochloride is purified again through an ion exchange membrane, and the purified liquid is concentrated and dried to obtain a solid, i.e., 204.7 kg of poly-2-methyl-pentamethyleneguanidine hydrochloride with a purity of more than 99%.

[0079] Synthesis of Nanoemulsion:

[0080] Step S21. Mix Tween 20 and sucrose fatty acid ester in equal proportions to obtain an emulsifier.

[0081] Step S22. Add 12 times the mass of tsaoko essential oil to the compounded emulsifier, and obtain the oil phase by ultrasonic treatment with an ultrasonic power ratio of 75% and an ultrasonic time of 15 min.

[0082] Step S23. Mix the oil phase and distilled water at a concentration ratio of 1:9 and stir for 15 min to obtain a nanoemulsion.

[0083] Synthesis of gelatin solid:

[0084] Step S31. Add 400 kg of 2 wt% gelatin and 200 kg of 1 wt% glycerol to 600 kg of distilled water, and heat and stir at 60 °C to obtain an initial gelatin solution.

[0085] Step S32. Add 1.5 wt% tannic acid to the initial gelatin solution and accelerate stirring and dissolution at 40 °C to obtain a gelatin solution.

[0086] Step S33. Dry the gelatin solution at 35 °C for 4 h to obtain gelatin solid.

[0087] Preparation of antibacterial material:

[0088] Step S1. Dissolve 100 kg of 2 wt% chitosan in 50 kg of 1 wt% glacial acetic acid, fully stir for 2 h at 25 °C to prepare a solution, add 25 kg of poly-2-methyl-pentamethylguanidine hydrochloride solid to the stirred solution to form an intermediate solution, and centrifuge the intermediate solution to remove air bubbles in the solution.

[0089] Step S2. Mix and stir the intermediate solution and the nanoemulsion at a weight ratio of 2:2 to form a mixed solution, and mix the mixed solution on the gelatin solid and dry it to obtain an antibacterial material.

[0090] Example 3

[0091] The embodiment of the present application provides a method for preparing an antibacterial material, including the following steps:

[0092] Synthesis of active components:

[0093] Step S11. With stirring started, sequentially add 116.2 kg of 2-methyl-1,5-pentanediamine and 95.53 kg of guanidine hydrochloride to the reaction kettle, close the reaction kettle and introduce nitrogen for reaction protection under a nitrogen atmosphere, raise the temperature, continuously stir, raise the temperature to 85 °C, and stir for 25 minutes to make it evenly stirred to obtain a first-stage product.

[0094] Step S12. Continue to raise the temperature to 125 °C, discharge the generated ammonia through a pipeline and collect it, and obtain an intermediate product.

[0095] Step S13. Uniformly control the heating rate and raise the temperature to 185 °C, stir and react for 3 h to obtain a polymer melt.

[0096] Step S14. Transfer the obtained polymer melt in a molten state from the reaction kettle to a separation tank filled with purified water based on the nitrogen pressure, stir and dissolve it thoroughly, filter, and collect the filtrate to obtain an aqueous solution of crude poly-2-methyl-pentamethyleneguanidine hydrochloride.

[0097] Step S15. Re-purify the aqueous solution of poly-2-methyl-pentamethyleneguanidine hydrochloride through an ion exchange membrane, then concentrate and dry the purified solution to obtain a solid, namely 205.1 kg of poly-2-methyl-pentamethyleneguanidine hydrochloride with a purity of more than 99%.

[0098] Synthesis of nanoemulsion:

[0099] Step S21. Mix Tween 20 and sucrose fatty acid ester in equal proportions to obtain an emulsifier.

[0100] Step S22. Add 15 times the mass of tsaoko essential oil to the compounded emulsifier, and obtain an oil phase through ultrasonic treatment with an ultrasonic power ratio of 80% and an ultrasonic time of 10 min.

[0101] Step S23. Mix the oil phase and distilled water at a concentration ratio of 1:9 and stir for 15 min to obtain a nanoemulsion.

[0102] Synthesis of gelatin solid:

[0103] Step S31. Add 400 kg of 2 wt% gelatin and 200 kg of 1 wt% glycerol to 600 kg of distilled water, and heat and stir at 60 °C to obtain an initial gelatin solution.

[0104] Step S32. Add 3 wt% of tannic acid to the initial gelatin solution and accelerate stirring and dissolving at 40 °C to obtain a gelatin solution.

[0105] Step S33. Dry the gelatin solution at 35 °C for 4 h to obtain a gelatin solid.

[0106] Preparation of antibacterial material:

[0107] Step S1. Dissolve 100 kg of 2 wt% chitosan in 50 kg of 1 wt% glacial acetic acid, stir thoroughly for 2 h at 25 °C to prepare a solution, and add 25 kg of poly-2-methyl-pentamethyleneguanidine hydrochloride solid to the stirred solution to form an intermediate solution. Centrifuge the intermediate solution to remove air bubbles in the solution.

[0108] Step S2. Mix and stir the intermediate solution and the nanoemulsion at a weight ratio of 1:2 to form a mixed solution, and mix the mixed solution on the gelatin solid and dry it to obtain an antibacterial material.

[0109] Example 4

[0110] An antibacterial material preparation method provided by an embodiment of the present application includes the following steps:

[0111] Synthesis of active components:

[0112] Step S11. While stirring, sequentially add 116.2 kg of 2-methyl-1,5-pentanediamine and 95.53 kg of guanidine hydrochloride to the reaction kettle, close the reaction kettle and introduce nitrogen for reaction protection under a nitrogen atmosphere, raise the temperature, and continue stirring. Raise the temperature to 75 °C and stir for 30 minutes to make it evenly stirred to obtain a first-stage product.

[0113] Step S12. Continue to raise the temperature to 120 °C, discharge the generated ammonia through a pipeline for collection, and obtain an intermediate product.

[0114] Step S13. Uniformly control the heating rate and raise the temperature to 180 °C, and stir and react for 2.5 h to obtain a polymer melt.

[0115] Step S14. Based on the nitrogen pressure, transfer the obtained polymer melt in a molten state from the reaction kettle to a separation tank filled with purified water, fully stir and dissolve, filter and collect the filtrate to obtain an aqueous solution of crude poly-2-methyl-pentamethylguanidine hydrochloride.

[0116] Step S15. Re-purify the aqueous solution of poly-2-methyl-pentamethylguanidine hydrochloride through an ion exchange membrane, and then concentrate and dry the purified solution to obtain a solid, that is, 205.8 kg of poly-2-methyl-pentamethylguanidine hydrochloride with a purity of more than 99%.

[0117] Synthesis of nanoemulsion:

[0118] Step S21. Mix Tween 20 and sucrose fatty acid ester in equal proportions to obtain an emulsifier.

[0119] Step S22. Add 19 mass times of tsaoko essential oil to the compounded emulsifier, and obtain an oil phase through ultrasonic treatment with an ultrasonic power ratio of 90% and an ultrasonic time of 5 min.

[0120] Step S23. Mix the oil phase and distilled water at a concentration ratio of 1:9 and stir for 15 min to obtain a nanoemulsion.

[0121] Synthesis of gelatin solid matter:

[0122] Step S31. Add 400 kg of 2 wt% gelatin and 200 kg of 1 wt% glycerol to 600 kg of distilled water, and heat and stir at 60 °C to obtain an initial gelatin solution.

[0123] Step S32. Add 4 wt% tannic acid to the initial gelatin solution and stir vigorously for dissolution at 40 °C to obtain a gelatin solution.

[0124] Step S33. Dry the gelatin solution at 35 °C for 4 h to obtain a gelatin solid.

[0125] Preparation of antibacterial material:

[0126] Step S1. Dissolve 100 kg of 2 wt% chitosan in 50 kg of 1 wt% glacial acetic acid, stir well for 2 h at 25 °C to prepare a solution, add 25 kg of poly-2-methyl-pentamethylene guanidine hydrochloride solid to the stirred solution to form an intermediate solution, and centrifuge the intermediate solution to remove air bubbles in the solution.

[0127] Step S2. Mix and stir the intermediate solution and the nanoemulsion at a weight ratio of 2:1 to form a mixed solution, and mix the mixed solution on the gelatin solid and dry it to obtain an antibacterial material.

[0128] Example 5

[0129] The embodiment of the present application provides a method for preparing an antibacterial material, including the following steps:

[0130] Synthesis of active components:

[0131] Step S11. With stirring, sequentially add 116.2 kg of 2-methyl-1,5-pentanediamine and 95.53 kg of guanidine hydrochloride to the reaction kettle, close the reaction kettle and introduce nitrogen for reaction protection under a nitrogen atmosphere, heat up and continue stirring, heat up to 85 °C, and stir for 30 minutes to make it evenly stirred to obtain a first-stage product.

[0132] Step S12. Continue to heat up to 125 °C, discharge the generated ammonia gas through a pipeline and collect it, and obtain an intermediate product.

[0133] Step S13. Uniformly control the heating rate and heat up to 185 °C, stir and react for 2 h to obtain a polymer melt.

[0134] Step S14. Based on the nitrogen pressure, transfer the obtained polymer melt in a molten state from the reaction kettle to a separation tank filled with purified water, stir well for dissolution, filter and collect the filtrate to obtain an aqueous solution of crude poly-2-methyl-pentamethylene guanidine hydrochloride.

[0135] Step S15. Re-purify the aqueous solution of poly-2-methyl-pentamethylene guanidine hydrochloride through an ion exchange membrane, and then concentrate and dry the purified solution to obtain a solid, that is, 206.5 kg of poly-2-methyl-pentamethylene guanidine hydrochloride with a purity of more than 99%.

[0136] Synthesis of nanoemulsion:

[0137] Step S21. Mix Tween 20 and sucrose fatty acid ester in equal proportion to obtain an emulsifier.

[0138] Step S22. Add 9 - 19 times the mass of tsaoko fruit essential oil to the compounded emulsifier, and obtain the oil phase through ultrasonic treatment with an ultrasonic power ratio of 50% and an ultrasonic time of 25 min.

[0139] Step S23. Mix the oil phase and distilled water at a concentration ratio of 1:9 and stir for 15 min to obtain the nanoemulsion.

[0140] Synthesis of gelatin solid:

[0141] Step S31. Add 400 kg of 2 wt% gelatin and 200 kg of 1 wt% glycerol to 600 kg of distilled water, and heat and stir at 60 °C to obtain the initial gelatin solution.

[0142] Step S32. Add 0.5 wt% tannic acid to the initial gelatin solution and accelerate stirring and dissolution at 40 °C to obtain the gelatin solution.

[0143] Step S33. Dry the gelatin solution at 35 °C for 4 h to obtain the gelatin solid.

[0144] Preparation of antibacterial material:

[0145] Step S1. Dissolve 100 kg of 2 wt% chitosan in 50 kg of 1 wt% glacial acetic acid, stir well for 2 h at 25 °C to prepare a solution, add 25 kg of poly - 2 - methyl - pentamethylene guanidine hydrochloride solid to the stirred solution to form an intermediate solution, and centrifuge the intermediate solution to remove the bubbles in the solution.

[0146] Step S2. Mix the intermediate solution and the nanoemulsion at a weight ratio of 1:1 and stir to form a mixed solution, and mix the mixed solution on the gelatin solid and dry it to obtain the antibacterial material.

[0147] Example 6

[0148] The embodiment of the present application provides a method for preparing an antibacterial material, including the following steps:

[0149] Synthesis of active component:

[0150] Step S11. With stirring started, sequentially add 116.2 kg of 2 - methyl - 1,5 - pentanediamine and 95.53 kg of guanidine hydrochloride to the reaction kettle, close the reaction kettle and introduce nitrogen for reaction protection under a nitrogen atmosphere, heat up and continue stirring, heat up to 75 °C, and stir for 30 minutes to make it evenly stirred to obtain the first - stage product.

[0151] Step S12. Continue to raise the temperature to 115°C, discharge the generated ammonia through a pipeline and collect it, and obtain an intermediate product.

[0152] Step S13. Uniformly control the heating rate and raise the temperature to 175°C, and stir and react for 3 h to obtain a polymer melt.

[0153] Step S14. Based on the nitrogen pressure, transfer the obtained polymer melt in a molten state from the reaction kettle to a separation tank filled with purified water, fully stir and dissolve, filter and collect the filtrate to obtain an aqueous solution of crude poly-2-methyl-pentamethylene guanidine hydrochloride.

[0154] Step S15. Re-purify the aqueous solution of poly-2-methyl-pentamethylene guanidine hydrochloride through an ion exchange membrane, and then concentrate and dry the purified solution to obtain a solid, namely 204.4 kg of poly-2-methyl-pentamethylene guanidine hydrochloride with a purity of more than 99%.

[0155] Synthesis of nanoemulsion:

[0156] Step S21. Mix Tween 20 and sucrose fatty acid ester in equal proportions to obtain an emulsifier.

[0157] Step S22. Add 15 times the mass of tsaoko essential oil to the compounded emulsifier, and obtain an oil phase through ultrasonic treatment with an ultrasonic power ratio of 75% and an ultrasonic time of 10 min.

[0158] Step S23. Mix the oil phase and distilled water at a concentration ratio of 1:9 and stir for 15 min to obtain a nanoemulsion.

[0159] Synthesis of gelatin solid:

[0160] Step S31. Add 400 kg of 2 wt% gelatin and 200 kg of 1 wt% glycerol to 600 kg of distilled water, and heat and stir at 60°C to obtain an initial gelatin solution.

[0161] Step S32. Add 4.5 wt% of tannic acid to the initial gelatin solution and accelerate stirring and dissolving at 40°C to obtain a gelatin solution.

[0162] Step S33. Dry the gelatin solution at 35°C for 4 h to obtain a gelatin solid.

[0163] Preparation of antibacterial material:

[0164] Step S1. Dissolve 100 kg of chitosan at 2 wt% in 50 kg of glacial acetic acid at 1 wt%, stir well for 2 h based on the condition of 25 °C to form a solution, and add 25 kg of poly-2-methyl-pentamethylene guanidine hydrochloride solid to the stirred solution to form an intermediate solution. Centrifuge the intermediate solution to remove the air bubbles in the solution.

[0165] Step S2. Mix and stir the intermediate solution and the nanoemulsion at a weight ratio of 1:2 to form a mixed solution, and mix the mixed solution on the gelatin solid and dry it to obtain the antibacterial material.

[0166] Experimental Example 1

[0167] Select the antibacterial materials corresponding to Examples 1 - 6 to achieve pH response and controlled release performance. Immerse the antibacterial materials corresponding to Examples 1 - 6 in ethanol aqueous solutions with pH values of 6.0 and 7.0 respectively for release tests. For the release results, refer to Figure 3 as shown.

[0168] For Figure 3-1 in the A - C drawings, they are the release curves of Examples 1 - 3 under the condition of pH 6.0 respectively, Figure 3-2 in the G - I drawings, they are the release curves of Examples 4 - 6 under the condition of pH 6.0 respectively; for Figure 3-1 in the D - F drawings, they are the release curves of Examples 1 - 3 under the condition of pH 7.0 respectively, Figure 3-2 in the J - L drawings, they are the release curves of Examples 4 - 6 under the condition of pH 7.0 respectively. It can be seen from the above drawings that in the acidic environment, the release rate of the antibacterial material is relatively high in the initial release stage, and the release rate increases with the increase of the nanoemulsion content in the antibacterial material. After about 4 h, the release rates of each antibacterial material gradually slow down and finally reach equilibrium. And, the time required to reach equilibrium is positively correlated with the nanoemulsion content, which indicates that the increase of nanoemulsion can promote the crosslinking of the matrix, increase the slow - release performance and thus obtain longer antibacterial activity. And, through the results in Figures D - F, it can be known that in the central environment, the antibacterial material hardly releases nanoemulsion.

[0169] Experimental Example 2

[0170] Refer to Figure 4 which is the experimental result of the antibacterial performance of the antibacterial materials obtained by the preparation methods disclosed in Examples 1 - 6 determined by the inhibition zone method. The disc diffusion method is used to measure the antibacterial activities of Examples 1 - 6 against two kinds of bacteria, namely Escherichia coli and Staphylococcus aureus for bacteria respectively.

[0171] Take 200 μL of the concentration of 1×10 6The bacterial suspension of CFU / mL was evenly spread on the LB nutrient agar plate with a sterile spreader. Three drug sensitivity test papers were placed on each petri dish, and the antibacterial materials corresponding to Examples 1 - 6 were taken and placed on the drug sensitivity test papers. The petri dishes were placed in an incubator at 37°C for incubation, and the antibacterial materials were taken out to measure the diameter of the inhibition zone.

[0172] Among them, for Figures a - f are the experimental results of the antibacterial materials obtained by the preparation methods corresponding to Examples 1 - 6 for the Escherichia coli inhibition zone method, and for Figures j - l are the experimental results of the antibacterial materials obtained by the preparation methods corresponding to Examples 1 - 6 for the Staphylococcus aureus inhibition zone method.

[0173] Through Figure 4 the inhibition zone radius in the multiple figures shown, it can be seen that for the inhibition zone radius in the results, it is first greater than the diagonal of the antibacterial material, indicating that the antibacterial material can produce an antibacterial effect on Escherichia coli and Staphylococcus aureus within the area. And, from the inhibition zone radius corresponding to the above figures, it can be seen that the higher the content of the nanoemulsion, the larger the corresponding inhibition radius, indicating that the higher the concentration of the active ingredient, the stronger the destructive effect on bacteria.

[0174] Comparative example

[0175] Refer to Figure 5 , which shows the antibacterial effect obtained by the inhibition zone method using two commercially available antibacterial materials in the prior art. Through Figure 5 it can be known that the antibacterial effects of the two commercially available antibacterial materials on Escherichia coli and Staphylococcus aureus are lower than those of the antibacterial materials prepared in any one of Examples 1 - 6.

[0176] Regarding the preparation method and application of an antibacterial material provided in Examples 1 - 6 of this embodiment, a novel antibacterial material for disinfecting human wounds and injuries is provided. By separately synthesizing a novel guanidine hydrochloride, a nanoemulsion, and a gelatin solid, a bilayer antibacterial material with multiple response stimuli is obtained based on the assembly of gelatin. This bilayer antibacterial material has a pH gating mechanism, can improve the pH sensitivity of the antibacterial material, slowly release the active material under pH conditions, and improve the antibacterial effect through the synthesized novel guanidine hydrochloride, and has higher antibacterial properties and human applicability compared with the prior art.

[0177] The above are only the preferred embodiments of the present invention application, and are not intended to limit the present invention application. Any modifications, equivalent replacements, and improvements made within the principles of the present invention application shall be included within the protection scope of the present invention application.

Claims

1. A method for preparing an antibacterial material, characterized in that, The method includes the following steps: Dissolve 2 wt% chitosan in a 1 wt% acid solution at a weight ratio of 2:1, stir well for 2 h at 25 °C to prepare a solution, and add an active component to the solution to form an intermediate solution. Centrifuge the intermediate solution to remove the bubbles in the solution; the active component is poly-2-methyl-pentamethylene guanidine hydrochloride, which has the following structural formula: , where the degree of polymerization n = 60 - 100; Mix and stir the intermediate solution and the nanoemulsion at a weight ratio of (2~1):(1~2) to form a mixed solution, and mix the mixed solution on the gelatin solid and dry it to obtain the antibacterial material; the antibacterial material has a bilayer structure, the first layer is the gelatin solid formed after drying the gelatin solution, and the second layer is the active substance formed by loading the active component and the nanoemulsion on a chitosan carrier and drying, and the active substance is wrapped in the gelatin solid.

2. The method for preparing an antibacterial material according to claim 1, wherein The obtaining of the gelatin solution includes the following steps: Add 2wt% gelatin and 1wt% glycerol to distilled water, and heat and stir at 60°C to obtain an initial gelatin solution. Add 0.5wt%~5wt% tannic acid to the initial gelatin solution and accelerate stirring and dissolving at 40°C to obtain the gelatin solution; the gelatin solid is obtained by drying the gelatin solution at 35°C for 4h.

3. The preparation method of the antibacterial material according to claim 1, wherein, The nanoemulsion is obtained by mixing and stirring an oil phase with a concentration of 10% and an aqueous phase with a concentration of 90%. The oil phase is obtained by ultrasonic method based on an emulsifier accounting for 5%~10% of the mass of the oil phase and essential oil accounting for 90%~95% of the mass of the oil phase; the ultrasonic power ratio is 50%~90%, and the ultrasonic time is 5min~25min.

4. The preparation method of the antibacterial material according to claim 1, wherein, The poly-2-methyl-pentamethyleneguanyl hydrochloride is obtained by synthesizing 2-methyl-1,5-pentanediamine and guanidine hydrochloride.

5. The preparation method of the antibacterial material according to claim 4, wherein, The preparation method of the poly-2-methyl-pentamethyleneguanyl hydrochloride specifically includes: Carry out multi-stage temperature-raising reaction on 2-methyl-1,5-pentanediamine and guanidine hydrochloride with a molar ratio of 1:1 under a nitrogen atmosphere to obtain a polymer melt; the multi-stage temperature-raising reaction includes a first temperature-raising reaction stage, a second temperature-raising reaction stage and a third temperature-raising reaction stage. The target temperature range of the first temperature-raising reaction stage is 75°C~85°C, the target temperature range of the second temperature-raising reaction stage is 115°C~125°C, and the target temperature range of the third temperature-raising reaction stage is 175°C~185°C.

6. The method for preparing an antibacterial material according to claim 5, wherein, The preparation method of the poly-2-methyl-pentamethyleneguanyl hydrochloride further includes: Press the polymer melt into purified water based on nitrogen pressure and stir, dissolve and filter to collect the aqueous solution containing the crude product of 2-methyl-pentamethyleneguanyl hydrochloride; Purify, concentrate and dry the aqueous solution containing the crude product of 2-methyl-pentamethyleneguanyl hydrochloride by ion exchange to obtain the poly-2-methyl-pentamethyleneguanyl hydrochloride.

7. The method for preparing the antibacterial material according to claim 5, wherein After the temperature rise in the first temperature-raising reaction stage is completed, stir for 15~30min to obtain a first-stage product; After the temperature rise in the second temperature-raising reaction stage is completed based on the first-stage product, exclude and collect the ammonia gas during the reaction to obtain an intermediate product; After the temperature rise in the third temperature-raising reaction stage is completed based on the intermediate product, stir the reactants for 2~3h to obtain the polymer melt.

8. The method for preparing an antibacterial material according to claim 5, wherein The purity of the poly-2-methyl-pentamethyleneguanyl hydrochloride is greater than or equal to 99%.

9. The method for preparing the antibacterial material according to claim 1, wherein The acid solution includes glacial acetic acid.

10. Use of an antibacterial material prepared by the method according to any one of claims 1 to 9 in a medical dressing.

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