A chitosan hydrospunlace biodegradable medical dressing substrate and its preparation method

Abstract

This invention relates to the field of medical materials technology, and discloses a chitosan hydrospun biodegradable medical dressing substrate and its preparation method; the method includes the following steps: chitosan fibers, modified cellulose and viscose fibers are opened and mixed evenly, then carded into a web by a carding machine and cross-laid to obtain a fiber web; the fiber web is hydrospun and reinforced by a flat web hydrospunting machine to obtain a chitosan hydrospun nonwoven fabric; the spinning solution is vacuum degassed and placed in a push pump; the chitosan hydrospun nonwoven fabric is fixed on a collector for electrospinning, dried, then immersed in a zinc acetate ethanol solution and sonicated for 5-10 minutes, cleaned with ethanol, dried, cut and packaged to obtain the chitosan hydrospun biodegradable medical dressing substrate.

Description

Technical Field

[0001] This invention relates to the field of medical materials technology, specifically to a chitosan hydrospunlace biodegradable medical dressing substrate and its preparation method. Background Technology

[0002] Medical dressings are crucial for wound repair and must possess good biocompatibility, antibacterial properties, biodegradability, and structural stability. Traditional dressings suffer from weak antibacterial effects, uncontrollable degradation, and easy breakage after absorbing liquid. Chitosan fibers, containing amino and hydroxyl groups, have good biocompatibility with human tissues, are anti-inflammatory, and absorb liquid, but are brittle. Cellulose can enhance mechanical properties, and viscose fibers facilitate uniform fiber dispersion, but the tightness of fiber entanglement after hydroentangling still needs optimization. In addition, electrospinning technology can prepare nanofiber films, giving dressings good breathability and drug loading capacity, but single-component spinning solutions often fail to balance mechanical properties and bioactivity.

[0003] In the existing technology, the combination of chitosan spunlace nonwoven fabric and electrospun film can optimize the mechanical properties and functional modification of dressings, but traditional methods have problems such as unstable crosslinking and difficult-to-control degradation.

[0004] In summary, the preparation of a chitosan hydrospunlace biodegradable medical dressing substrate is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a chitosan hydrospunlace biodegradable medical dressing substrate and its preparation method, so as to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A chitosan spunlace biodegradable medical dressing substrate, comprising a chitosan spunlace nonwoven fabric and a film layer; the thickness of the film layer is 40-50 µm; the thickness of the chitosan spunlace nonwoven fabric is 1.5-2.5 mm; and the weight per unit area of ​​the chitosan spunlace nonwoven fabric is 30-40 g / m². 2 .

[0008] A method for preparing a chitosan hydrospunlace biodegradable medical dressing substrate includes the following steps:

[0009] Step 1: Chitosan fiber, modified cellulose and viscose fiber are opened and then mixed evenly to obtain mixed fibers; the mixed fibers are carded into a web by a carding machine and laid crosswise to obtain a fiber web; the fiber web is reinforced by hydroentangling using a flat web hydroentangling machine to obtain chitosan hydroentangled nonwoven fabric;

[0010] Step 2: (1) Mix the alkylated chitosan acetic acid aqueous solution and the modified polyvinyl alcohol ethanol aqueous solution evenly to obtain the spinning solution;

[0011] (2) After vacuum degassing the spinning solution, place it in the propulsion pump; fix the chitosan spunlace nonwoven fabric on the collector for electrospinning, dry it in a vacuum drying oven at 30~50℃, then immerse it in zinc acetate ethanol solution and sonicate for 5~10 minutes, clean it with ethanol, dry it, cut it and package it to obtain chitosan spunlace biodegradable medical dressing substrate.

[0012] The preparation method of chitosan fiber is as follows: chitosan and PVA (polyvinyl alcohol) are weighed at a mass ratio of 1:1; added to a 20wt% acetic acid solution, stirred at 90℃ for 6 hours, cooled to room temperature to obtain spinning solution; electrospinning is carried out under the conditions of 13kV voltage and 15cm receiving distance to obtain chitosan fiber.

[0013] In a more optimized configuration, the mass ratio of chitosan fiber, modified cellulose, and viscose fiber is (1~2.5):(3~5):(4~6); the mass ratio of the alkylated chitosan acetic acid aqueous solution to the modified polyvinyl alcohol solution is (3~4):(1~3); in the alkylated chitosan acetic acid aqueous solution, the concentration of alkylated chitosan is 4~7 wt%, and the solvent is a 1~3 wt% acetic acid aqueous solution; in the modified polyvinyl alcohol ethanol aqueous solution, the concentration of modified polyvinyl alcohol is 5~7 wt%, and the solvent is a 40~50 wt% ethanol aqueous solution; and the concentration of the zinc acetate ethanol solution is 3~5 wt%.

[0014] A more optimized method for preparing the modified cellulose is as follows: (1) β-cyclodextrin, 5-benzimidazole carboxylic acid, EDC·HCl (1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride), and DMAP (4-dimethylaminopyridine) are added to DMSO (dimethyl sulfoxide) and mixed evenly. The mixture is heated to 72~75℃ and stirred for 10~15 hours. After dialyzing and freeze-drying, the modified cyclodextrin is obtained; (2) The modified cyclodextrin is added to deionized water at 60~65℃. Mix evenly, cool to room temperature in an ice water bath, add sodium periodate, stir for 1 to 1.5 hours, add ethylene glycol to terminate the reaction, add calcium chloride and mix evenly, remove the precipitate, dialyze to obtain aldehyde-cyclodextrin; (3) Add aldehyde-cyclodextrin to deionized water, mix evenly at 37 to 40°C, add 0.01 to 0.02M sodium hydroxide aqueous solution, adjust pH to 7.5 to 8, add gelatin and amino cellulose, mix ultrasonically, let stand for 30 to 35 minutes to obtain modified cellulose.

[0015] In a more optimized manner, the molar ratio of β-cyclodextrin to 5-benzimidazole carboxylic acid is 1:(1~1.2); the mass ratio of modified cyclodextrin to sodium periodate is 1:(0.4~0.7); and the raw material of the modified cellulose includes the following components: by mass parts, 1 part aldehyde-cyclodextrin, 1~3 parts gelatin, and 1.2~2 parts aminoated cellulose.

[0016] The preparation method of aminated cellulose is as follows: cellulose is added to 2M APS and mixed evenly. The mixture is then subjected to a microwave hydrothermal reaction at 65℃ for 1.6 hours. The reaction is terminated by adding deionized water. The reaction solution is removed by centrifugation and washing to obtain a suspension. 100mL of the suspension is added to 1.15g of EDC and 0.85g of NHS and stirred for 30 minutes. 1mL of EDTA is added dropwise to adjust the pH to 7.5. The mixture is stirred for 24 hours and then washed with acetone and deionized water in sequence. After dialysis, aminated cellulose is obtained.

[0017] A more optimized method for preparing the modified polyvinyl alcohol solution is as follows: lysine, 5-benzimidazole carboxylic acid, polyvinyl alcohol, EDC·HCl, and DMAP are added to DMSO and mixed evenly. The mixture is heated to 72~75℃ and stirred for 15~18 hours. After dialyzing and freeze-drying, the mixture is added to an ethanol aqueous solution and mixed evenly to obtain the modified polyvinyl alcohol solution.

[0018] In a more optimized manner, the mass ratio of lysine, 5-benzimidazole carboxylic acid, and polyvinyl alcohol is 0.1~0.2:0.07~0.12:1.

[0019] A more optimized method for preparing alkylated chitosan is as follows: carboxymethyl chitosan is added to a 0.1-0.15M phosphate buffer solution and stirred for 6-8 hours. Ethylenediamine is added and mixed evenly. The pH is adjusted to 5-5.5. EDC·HCl is added and stirred at 37-42℃ for 4-5 hours. The mixture is dialyzed and freeze-dried to obtain polyamino chitosan. The polyamino chitosan is added to deionized water and mixed evenly. The temperature is raised to 80-85℃, alkyl epoxy ether is added, and the mixture is stirred for 2-3 hours. The mixture is washed and dried to obtain alkylated chitosan.

[0020] More optimized, the molar ratio of carboxymethyl chitosan to ethylenediamine is 1:(5~6); the mass ratio of polyamino chitosan to alkyl epoxy ether is 1:(0.1~0.2); and the alkyl epoxy ether is one of n-butyl glycidyl ether and 2,3-epoxypropane pentyl ether.

[0021] The optimized process conditions for hydroentangling reinforcement are: hydroentangling pressure of 40~60 bar, number of hydroentangling heads of 3~6; and the process conditions for electrospinning are: voltage of 18~22kV, receiving distance of 10~20cm, spinning solution propulsion rate of 0.8~1.2mL / h, temperature of 20~30℃, and humidity of 40~45%.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] In this invention, chitosan fibers, cellulose and viscose fibers are combed into a web and then cross-laid to form a fiber web, which is then reinforced by hydroentangling to obtain chitosan hydroentangled nonwoven fabric; a spinning solution containing alkylated chitosan and modified polyvinyl alcohol is electrospinned to prepare a thin film layer on the chitosan hydroentangled nonwoven fabric to obtain a chitosan hydroentangled biodegradable medical dressing substrate.

[0024] In this approach, chitosan fiber, cellulose, and viscose fiber are easily decomposed into oligosaccharides or monosaccharides by microorganisms in the environment, and eventually metabolized into carbon dioxide and water. Among them, chitosan fiber contains a large number of amino and hydroxyl groups, which have good compatibility with human tissues and can reduce wound inflammation. The polar groups in its molecules give it good liquid absorption capacity and can absorb wound exudate.

[0025] Cellulose can improve the mechanical properties of the substrate and prevent damage during processing or use; viscose fiber is regenerated cellulose, which has high compatibility with chitosan fiber and natural cellulose. It is easy to disperse evenly when carded into a web and cross-laid, reducing fiber agglomeration, ensuring the entanglement effect during hydroentanglement reinforcement, and making the substrate structure more uniform.

[0026] To address the issue of loose fiber entanglement after hydroentanglement reinforcement, the proposed solution involves introducing amino groups into cellulose, which are then combined with gelatin and aldehyde-cyclodextrin to create modified cellulose. The aldehyde-cyclodextrin, gelatin, and aminoated cellulose form a cross-linked network through a Schiff base reaction (the aldehyde group combines with the amino group), enhancing the mechanical strength and swelling resistance of the cellulose fibers, compensating for the brittleness of chitosan fibers, and ensuring that the hydroentangled nonwoven fabric maintains structural stability after liquid absorption, reducing breakage. The introduction of gelatin regulates the hydrophilicity of cellulose, preventing excessive water absorption and swelling collapse, while retaining adequate liquid absorption capacity.

[0027] Modified cellulose provides structural strength and long-lasting antibacterial function to the substrate, while modified polyvinyl alcohol imparts rapid antibacterial and repair-promoting capabilities to the film layer, forming a composite system of structural support and surface function.

[0028] Among them, 5-benzimidazole carboxylic acid (containing benzimidazole group) has antibacterial and anti-inflammatory activities, which synergize with the antibacterial effect of chitosan to enhance the anti-infection effect of dressings; however, the content of 5-benzimidazole carboxylic acid should not be too high, otherwise it will affect the degradation effect; the hollow structure of β-cyclodextrin can encapsulate inflammatory factors or odor molecules in wound exudate, achieving slow release, thereby providing long-lasting antibacterial effect.

[0029] In this scheme, alkylated chitosan acetic acid aqueous solution and modified polyvinyl alcohol ethanol aqueous solution are used to make spinning solution; then, a nanofiber interwoven film is formed by electrospinning, which can act as a physical barrier to effectively block external bacteria, dust and other pollutants from entering the wound. Compared with simple spunlace nonwoven fabric (large pores and loose structure), the film layer can reduce the rapid penetration of liquid, balance the contradiction between "breathability" and "leakage prevention", allowing the exchange of oxygen and water vapor required by the wound, while delaying the leakage of a large amount of exudate.

[0030] Chitosan, due to its high molecular weight and cationic properties, typically has high viscosity and high conductivity, which can easily lead to jet instability. Chitosan (CS) can be significantly reduced in solution viscosity through alkylation modification, but the carbon chain length cannot be too long, otherwise it will affect its dispersibility in the spinning solution and thus its strength.

[0031] In this scheme, chitosan's poor hydrophilicity affects spinning performance; the limited number of amino groups on carboxymethyl chitosan hinders amination. The scheme introduces amino groups through the amidation reaction of ethylenediamine and carboxyl groups, followed by alkylation for regulation, thereby improving the tensile strength and toughness of the fiber membrane. The moderately hydrophobic alkyl chains can reduce the swelling rate of the material in wound exudate (avoiding excessively rapid dissolution and failure), while retaining some hydrophilicity, balancing stability and water absorption. The incompletely substituted amino groups from alkylation can combine with Zn in zinc acetate. 2+ (Antibacterial ions) enable stable loading and sustained release of antibacterial components.

[0032] The introduction of lysine and 5-benzimidazole carboxylic acid improves the solution flowability and spinning stability of PVA, forming a continuous and uniform nanofiber membrane, avoiding bead-like defects, and enhancing the barrier function of the film; the amino and carboxylic acid groups in the modified PVA can bind Zn through coordination. 2+ This enables the controlled release of zinc ions; Zn 2+ It has a dual function of antibacterial and promoting fibroblast proliferation; the polar group of lysine enhances the hydrophilicity of the membrane, enabling it to quickly absorb wound exudate and maintain a moist environment;

[0033] In this method, chitosan spunlace nonwoven fabric containing a thin film layer is impregnated in a zinc acetate ethanol solution and ultrasonically treated. This effectively improves the bonding between the thin film layer and the chitosan spunlace nonwoven fabric, and the Zn... 2+It can coordinate with active groups such as benzimidazole to enhance intermolecular forces and antibacterial properties; reduce the hydrophilicity and swelling capacity of polymer chains, thereby reducing the degree of swelling, and maintain the stability of the fiber network structure, avoiding fiber adhesion or collapse caused by excessive swelling, and reducing pore blockage. Detailed Implementation

[0034] In the following detailed embodiments, each part refers to a mass fraction. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] In this embodiment, it should be noted that there are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: lysine with CAS number 56-87-1; 5-benzimidazole carboxylic acid with CAS number 15788-16-6; carboxymethyl chitosan with CAS number 83512-85-0; polyvinyl alcohol with product number S30196; β-cyclodextrin with CAS number 7585-39-9; gelatin with product number SS8959, pharmaceutical grade; and n-butyl glycidyl ether with CAS number 2426-08-6.

[0036] The modified polyvinyl alcohol solution is prepared as follows: lysine, 5-benzimidazole carboxylic acid, and polyvinyl alcohol are weighed in a mass ratio of 0.1:0.07:1; lysine, 5-benzimidazole carboxylic acid, polyvinyl alcohol, 1.2 parts of EDC·HCl, and 0.08 parts of DMAP are added to DMSO and mixed evenly. The mixture is heated to 75℃ and stirred for 15 hours, dialyzed, freeze-dried, and then added to an ethanol aqueous solution (65wt%) and mixed evenly to obtain the modified polyvinyl alcohol solution.

[0037] The preparation method of alkylated chitosan is as follows: Carboxymethyl chitosan and ethylenediamine are weighed at a molar ratio of 1:5; carboxymethyl chitosan is added to 0.1M phosphate buffer solution and stirred for 6 hours, ethylenediamine is added and mixed evenly, the pH is adjusted to 5.2, EDC·HCl (the molar ratio of EDC·HCl to carboxymethyl chitosan is 2:1) is added, and the mixture is stirred at 38℃ for 4.2 hours, dialyzed, and freeze-dried to obtain polyamino chitosan; polyamino chitosan and n-butyl glycidyl ether are weighed at a mass ratio of 1:0.2; polyamino chitosan is added to deionized water and mixed evenly, the temperature is raised to 80℃, n-butyl glycidyl ether is added, and the mixture is stirred for 2-3 hours, washed, and dried to obtain alkylated chitosan.

[0038] Example 1: A method for preparing a chitosan hydrospunlace biodegradable medical dressing substrate, comprising the following steps;

[0039] Step 1: Weigh chitosan fiber, modified cellulose and viscose fiber in a mass ratio of 2:3:5, open them separately and mix them evenly to obtain mixed fibers; card the mixed fibers into a web using a carding machine and lay them crosswise to obtain a fiber web; use a flat web hydroentangling machine to hydroentangle and reinforce the fiber web (hydroentangling pressure of 60 bar, number of hydroentangling heads of 6) to obtain a 2mm chitosan hydroentangled nonwoven fabric;

[0040] Step 2: (1) Mix the alkylated chitosan acetic acid aqueous solution (the concentration of alkylated chitosan is 4wt%) and the modified polyvinyl alcohol solution (the concentration of modified polyvinyl alcohol is 5wt%) in a mass ratio of 3:1 to obtain the spinning solution;

[0041] (2) After vacuum degassing the spinning solution, place it in a push pump; fix the chitosan spunlace nonwoven fabric on the collector for electrospinning (voltage is 20kV, receiving distance is 15cm, spinning solution push rate is 1.2mL / h, temperature is 25℃, humidity is 40%), place it in a vacuum drying oven at 40℃ to dry, form a 40μm thin film layer, then immerse it in a zinc acetate ethanol solution (zinc acetate concentration is 3wt%) and sonicate for 10 minutes, clean with ethanol, dry, cut and package to obtain chitosan spunlace biodegradable medical dressing substrate;

[0042] The modified cellulose is prepared by: (1) weighing β-cyclodextrin and 5-benzimidazole carboxylic acid in a molar ratio of 1:1; adding β-cyclodextrin, 5-benzimidazole carboxylic acid, EDC·HCl, and DMAP to DMSO and mixing evenly, heating to 75℃ and stirring for 15 hours, dialyzing, and freeze-drying to obtain modified cyclodextrin; (2) weighing modified cyclodextrin and sodium periodate in a mass ratio of 1:0.6; adding modified cyclodextrin to deionized water at 65℃. Mix evenly, cool to room temperature in an ice water bath, add sodium periodate, stir for 1.5 hours, add ethylene glycol to terminate the reaction, add calcium chloride and mix evenly, remove the precipitate, dialyze to obtain aldehyde-cyclodextrin; (3) Add 1 part of aldehyde-cyclodextrin to deionized water, mix evenly at 40°C, add 0.01M sodium hydroxide aqueous solution, adjust pH to 7.8, add 3 parts of gelatin and 1.7 parts of amino cellulose, mix ultrasonically, let stand for 35 minutes to obtain modified cellulose.

[0043] Example 2: A method for preparing a chitosan hydrospunlace biodegradable medical dressing substrate, comprising the following steps;

[0044] Step 1: Weigh chitosan fiber, modified cellulose and viscose fiber in a mass ratio of 2:3:5, open them separately and mix them evenly to obtain mixed fibers; card the mixed fibers into a web using a carding machine and lay them crosswise to obtain a fiber web; use a flat web hydroentangling machine to hydroentangle and reinforce the fiber web (hydroentangling pressure of 60 bar, number of hydroentangling heads of 6) to obtain a 1.5 mm chitosan hydroentangled nonwoven fabric;

[0045] Step 2: (1) Mix the alkylated chitosan acetic acid aqueous solution (the concentration of alkylated chitosan is 4wt%) and the modified polyvinyl alcohol solution (the concentration of modified polyvinyl alcohol is 5wt%) in a mass ratio of 3:1 to obtain the spinning solution;

[0046] (2) After vacuum degassing the spinning solution, place it in a push pump; fix the chitosan spunlace nonwoven fabric on the collector for electrospinning (voltage is 20kV, receiving distance is 15cm, spinning solution push rate is 1.2mL / h, temperature is 25℃, humidity is 40%), place it in a vacuum drying oven at 40℃ to dry, form a 40μm thin film layer, then immerse it in a zinc acetate ethanol solution (zinc acetate concentration is 3wt%) and sonicate for 10 minutes, clean with ethanol, dry, cut and package to obtain chitosan spunlace biodegradable medical dressing substrate;

[0047] The modified cellulose is prepared by: (1) weighing β-cyclodextrin and 5-benzimidazole carboxylic acid in a molar ratio of 1:1; adding β-cyclodextrin, 5-benzimidazole carboxylic acid, EDC·HCl, and DMAP to DMSO and mixing evenly, heating to 75℃ and stirring for 15 hours, dialyzing, and freeze-drying to obtain modified cyclodextrin; (2) weighing modified cyclodextrin and sodium periodate in a mass ratio of 1:0.6; adding modified cyclodextrin to deionized water at 65℃. Mix evenly, cool to room temperature in an ice water bath, add sodium periodate, stir for 1.5 hours, add ethylene glycol to terminate the reaction, add calcium chloride and mix evenly, remove the precipitate, dialyze to obtain aldehyde-cyclodextrin; (3) Add 1 part of aldehyde-cyclodextrin to deionized water, mix evenly at 40°C, add 0.01M sodium hydroxide aqueous solution, adjust pH to 7.8, add 3 parts of gelatin and 1.7 parts of amino cellulose, mix ultrasonically, let stand for 35 minutes to obtain modified cellulose.

[0048] Example 3: A method for preparing a chitosan hydrospunlace biodegradable medical dressing substrate, comprising the following steps;

[0049] Step 1: Weigh chitosan fiber, modified cellulose and viscose fiber in a mass ratio of 2:3:5, open them separately and mix them evenly to obtain mixed fibers; card the mixed fibers into a web using a carding machine and lay them crosswise to obtain a fiber web; use a flat web hydroentangling machine to hydroentangle and reinforce the fiber web (hydroentangling pressure of 60 bar, number of hydroentangling heads of 6) to obtain a 1.5 mm chitosan hydroentangled nonwoven fabric;

[0050] Step 2: (1) Mix the alkylated chitosan acetic acid aqueous solution (the concentration of alkylated chitosan is 4wt%) and the modified polyvinyl alcohol solution (the concentration of modified polyvinyl alcohol is 5wt%) in a mass ratio of 3:1 to obtain the spinning solution;

[0051] (2) After vacuum degassing the spinning solution, place it in a push pump; fix the chitosan spunlace nonwoven fabric on the collector for electrospinning (voltage is 20kV, receiving distance is 15cm, spinning solution push rate is 1.2mL / h, temperature is 25℃, humidity is 40%), place it in a vacuum drying oven at 40℃ to dry, form a 40μm thin film layer, then immerse it in a zinc acetate ethanol solution (zinc acetate concentration is 3wt%) and sonicate for 10 minutes, clean with ethanol, dry, cut and package to obtain chitosan spunlace biodegradable medical dressing substrate;

[0052] The modified cellulose is prepared by: (1) weighing β-cyclodextrin and 5-benzimidazole carboxylic acid in a molar ratio of 1:1; adding β-cyclodextrin, 5-benzimidazole carboxylic acid, EDC·HCl, and DMAP to DMSO and mixing evenly, heating to 75℃ and stirring for 15 hours, dialyzing, and freeze-drying to obtain modified cyclodextrin; (2) weighing modified cyclodextrin and sodium periodate in a mass ratio of 1:0.6; adding modified cyclodextrin to deionized water at 65℃. Mix evenly, cool to room temperature in an ice water bath, add sodium periodate, stir for 1.5 hours, add ethylene glycol to terminate the reaction, add calcium chloride and mix evenly, remove the precipitate, dialyze to obtain aldehyde-cyclodextrin; (3) Add 1 part of aldehyde-cyclodextrin to deionized water, mix evenly at 40°C, add 0.01M sodium hydroxide aqueous solution, adjust pH to 7.8, add 2 parts of gelatin and 1.7 parts of amino cellulose, mix ultrasonically, let stand for 35 minutes to obtain modified cellulose.

[0053] Comparative Example 1 is based on Example 1, but without the introduction of 5-benzimidazole carboxylic acid; the remaining steps are the same.

[0054] The modified cellulose is prepared by: (1) weighing β-cyclodextrin and sodium periodate at a mass ratio of 1:0.6; adding the modified cyclodextrin to deionized water at 65°C and mixing evenly, cooling to room temperature under an ice-water bath, adding sodium periodate, stirring for 1.5 hours, adding ethylene glycol to terminate the reaction, adding calcium chloride and mixing evenly, removing the precipitate, dialysis, and obtaining aldehyde-cyclodextrin; (2) adding 1 part of aldehyde-cyclodextrin to deionized water, mixing evenly at 40°C, adding 0.01M sodium hydroxide aqueous solution, adjusting the pH to 7.8, adding 3 parts of gelatin and 1.7 parts of amino cellulose, ultrasonically mixing, and standing for 35 minutes to obtain modified cellulose;

[0055] The modified polyvinyl alcohol solution is prepared as follows: lysine and polyvinyl alcohol are weighed at a mass ratio of 0.1:1; lysine, 5-benzimidazole carboxylic acid, polyvinyl alcohol, 1.2 parts of EDC·HCl, and 0.08 parts of DMAP are added to DMSO and mixed evenly. The mixture is heated to 75℃ and stirred for 15 hours, dialyzed, freeze-dried, and then added to an ethanol aqueous solution (65wt%) and mixed evenly to obtain the modified polyvinyl alcohol solution.

[0056] Comparative Example 2 is based on Example 1, but without modification of polyvinyl alcohol; the remaining steps are the same.

[0057] Step 1: Weigh chitosan fiber, modified cellulose and viscose fiber in a mass ratio of 2:3:5, open them separately and mix them evenly to obtain mixed fibers; card the mixed fibers into a web using a carding machine and lay them crosswise to obtain a fiber web; use a flat web hydroentangling machine to hydroentangle and reinforce the fiber web (hydroentangling pressure of 60 bar, number of hydroentangling heads of 6) to obtain a 1.5 mm chitosan hydroentangled nonwoven fabric;

[0058] Step 2: (1) Mix the alkylated chitosan acetic acid aqueous solution (alkylated chitosan concentration is 4wt%) and the polyvinyl alcohol solution (polyvinyl alcohol concentration is 5wt%) in a mass ratio of 3:1 to obtain the spinning solution;

[0059] (2) After vacuum degassing the spinning solution, place it in a propulsion pump; fix the chitosan spunlace nonwoven fabric on the collector for electrospinning (voltage is 20kV, receiving distance is 15cm, spinning solution propulsion rate is 1.2mL / h, temperature is 25℃, humidity is 40%), place it in a vacuum drying oven at 40℃ to dry, form a 40μm thin film layer, then immerse it in a zinc acetate ethanol solution (zinc acetate concentration is 3wt%) and sonicate for 10 minutes, clean with ethanol, dry, cut and package to obtain chitosan spunlace biodegradable medical dressing substrate.

[0060] Comparative Example 3 was based on Example 1, but was not immersed in zinc acetate ethanol solution; the other steps were the same.

[0061] Step 1: Weigh chitosan fiber, modified cellulose and viscose fiber in a mass ratio of 2:3:5, open them separately and mix them evenly to obtain mixed fibers; card the mixed fibers into a web using a carding machine and lay them crosswise to obtain a fiber web; use a flat web hydroentangling machine to hydroentangle and reinforce the fiber web (hydroentangling pressure of 60 bar, number of hydroentangling heads of 6) to obtain a 1.5 mm chitosan hydroentangled nonwoven fabric;

[0062] Step 2: (1) Mix the alkylated chitosan acetic acid aqueous solution (the concentration of alkylated chitosan is 4wt%) and the modified polyvinyl alcohol solution (the concentration of modified polyvinyl alcohol is 5wt%) in a mass ratio of 3:1 to obtain the spinning solution;

[0063] (2) After vacuum degassing the spinning solution, place it in a propulsion pump; fix the chitosan spunlace nonwoven fabric on the collector for electrospinning (voltage 20kV, receiving distance 15cm, spinning solution propulsion rate 1.2mL / h, temperature 25℃, humidity 40%), place it in a vacuum drying oven at 40℃ to dry, form a 40μm thin film layer, cut and package it to obtain chitosan spunlace biodegradable medical dressing substrate.

[0064] Comparative Example 4 is based on Example 1, with chitosan modified with dodecyl aldehyde, and the remaining steps are the same;

[0065] The preparation method of alkylated chitosan is as follows: chitosan is dissolved in a 1 wt% acetic acid solution and stirred until completely dissolved. The pH is adjusted to 12 with 1M sodium hydroxide. After the chitosan precipitates, it is filtered. The filter cake is placed in N,N-dimethylformamide and mixed evenly. Laural is added, and the pH is adjusted to 6.5 with acetic acid. The mixture is stirred for 6 hours. Sodium triacetoxyborohydride with an equal mass to laural is added and nitrogen protection is applied. The mixture is stirred for another 12 hours. The mixture is filtered, and the filter cake is washed and dried to obtain alkylated chitosan. The molar ratio of chitosan to laural is 5:1.

[0066] Tests: (1) Test the liquid absorption, water vapor transmission rate and tensile strength of Examples 1-3 and Comparative Example 4;

[0067] (2) Place Example 1 and Comparative Examples 1-4 in phosphate buffer (PBS, pH=7.4) for 72 hours, take them out, dry them, weigh them before and after, and calculate the mass loss rate (%).

[0068] (3) The blank control group, Example 1, and Comparative Examples 1-3 were prepared according to GB / T20944, using Staphylococcus aureus as the bacterial strain, with a bacterial concentration of 2.4 × 10⁻⁶. 5CFU / mL; The chitosan hydrospunlace biodegradable medical dressing substrates prepared in Example 1 and Comparative Examples 1-3 were placed in bacterial solutions and cultured in a shaker at 37°C for 18 hours. 100 μL was taken and diluted twice with PBS buffer (pH=7.4), then spread on a solid culture medium and placed in a bacterial incubator at 37°C for 18 hours. The inhibition rate was calculated.

[0069]

[0070]

[0071] Conclusions: In Table 1, alkyl epoxy ether modification improved the compatibility between chitosan and polyvinyl alcohol, forming a more uniform and continuous film layer; the cross-linking between modified polyvinyl alcohol and chitosan was tighter, the interfacial bonding was stronger, and the delamination phenomenon was avoided; while the long-chain alkyl in Comparative Example 4 was too hydrophobic, resulting in phase separation and structural defects, and the tensile strength was significantly reduced.

[0072] In Table 2, Comparative Example 1 is based on Example 1 but without the introduction of 5-benzimidazole carboxylic acid. Because 5-benzimidazole carboxylic acid has a certain degree of hydrophobicity, the mass loss of Comparative Example 1 is increased, but the antibacterial properties are reduced. Comparative Example 2 is based on Example 1 but without modification of polyvinyl alcohol. This results in a low crosslinking density, making it easier for water molecules to penetrate and more easily decomposed in the physiological environment. Comparative Example 3 is based on Example 1 but without immersion in zinc acetate ethanol solution. This results in a decrease in the structural stability of the chitosan hydrospunlace degradable medical dressing substrate, thus increasing the mass loss, but reducing the antibacterial properties.

[0073] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A process for the preparation of a chitosan hydro-entangled degradable medical dressing substrate, characterized by: The method comprises the following steps: Step 1: the chitosan fiber, modified cellulose and viscose fiber are respectively subjected to opening treatment and then uniformly mixed to obtain mixed fibers; the mixed fibers are laid on a cross-laying basis through a carding machine to obtain a fiber web; and the fiber web is subjected to water jet reinforcement through a flat screen water jet machine to obtain a chitosan water jet non-woven fabric; Step 2: (1) uniformly mixing an alkylated chitosan acetic acid aqueous solution and a modified polyvinyl alcohol ethanol aqueous solution to obtain a spinning solution; (2) vacuum deaerating the spinning solution and then placing the spinning solution in a propelling pump; electrospinning the chitosan water jet non-woven fabric fixed on a collector to obtain a chitosan water jet degradable medical dressing base material after drying in a vacuum drying box at 30-50 DEG C, then immersing in a zinc acetate ethanol solution for ultrasonic treatment for 5-10 minutes, ethanol cleaning, drying, cutting and packaging; The preparation method of the modified cellulose is as follows: (1) uniformly mixing beta-cyclodextrin, 5-benzimidazole carboxylic acid, EDC.HCl and DMAP in DMSO, stirring at 72-75 DEG C for 10-15 hours, dialysis, freeze drying to obtain modified cyclodextrin; (2) uniformly mixing the modified cyclodextrin in deionized water at 60-65 DEG C, cooling to room temperature in an ice water bath, adding sodium periodate, stirring for 1-1.5 hours, adding ethylene glycol to terminate the reaction, uniformly mixing calcium chloride, removing the precipitate, dialysis to obtain aldehyde-cyclodextrin; (3) uniformly mixing the aldehyde-cyclodextrin in deionized water at 37-40 DEG C, adding 0.01-0.02M sodium hydroxide aqueous solution, adjusting pH to 7.5-8, adding gelatin and aminated cellulose, ultrasonic mixing, standing for 30-35 minutes to obtain modified cellulose; The preparation method of the modified polyvinyl alcohol ethanol aqueous solution is as follows: uniformly mixing lysine, 5-benzimidazole carboxylic acid, polyvinyl alcohol, EDC.HCl and DMAP in DMSO, stirring at 72-75 DEG C for 10-15 hours, dialysis, freeze drying, uniformly mixing in an ethanol aqueous solution to obtain a modified polyvinyl alcohol ethanol aqueous solution; The preparation method of the alkylated chitosan is as follows: stirring carboxymethyl chitosan in 0.1-0.15M phosphate buffer solution for 6-8 hours, uniformly mixing with ethylenediamine, adjusting pH to 5-5.5, adding EDC.HCl, stirring at 37-42 DEG C for 4-5 hours, dialysis, freeze drying to obtain polyamino chitosan; uniformly mixing the polyamino chitosan in deionized water, heating to 80-85 DEG C, adding alkyl epoxy ether, stirring for 2-3 hours, washing, drying to obtain alkylated chitosan.

2. The method for preparing a chitosan hydrospunlace biodegradable medical dressing substrate according to claim 1, characterized in that: The mass ratio of the chitosan fiber, modified cellulose and viscose fiber is (1-2.5):(3-5):(4-6); the mass ratio of the alkylated chitosan acetic acid aqueous solution and modified polyvinyl alcohol ethanol aqueous solution is (3-4):(1-3); in the alkylated chitosan acetic acid aqueous solution, the concentration of alkylated chitosan is 4-7wt%, and the solvent is 1-3wt% acetic acid aqueous solution; in the modified polyvinyl alcohol ethanol aqueous solution, the concentration of modified polyvinyl alcohol is 5-7wt%, and the solvent is 40-50wt% ethanol aqueous solution; the concentration of the zinc acetate ethanol solution is 3-5wt%.

3. The method for preparing a chitosan hydrospunlace biodegradable medical dressing substrate according to claim 1, characterized in that: The molar ratio of the beta-cyclodextrin and 5-benzimidazole carboxylic acid is 1:(1-1.2); the mass ratio of the modified cyclodextrin and sodium periodate is 1:(0.4-0.7); the raw material of the modified cellulose comprises the following components: 1 part of aldehyde-cyclodextrin, 1-3 parts of gelatin, and 1.2-2 parts of aminated cellulose.

4. The method for preparing a chitosan hydrospunlace biodegradable medical dressing substrate according to claim 1, characterized in that: The mass ratio of the lysine, 5-benzimidazole carboxylic acid and polyvinyl alcohol is 0.1-0.2:0.07-0.12:

1.

5. The method for preparing a chitosan hydrospunlace biodegradable medical dressing substrate according to claim 1, characterized in that: The process conditions of the water jet reinforcement are as follows: the water jet pressure is 40-60bar, and the number of water jet heads is 3-6; the process conditions of the electrospinning are as follows: the voltage is 18-22kV, the receiving distance is 10-20cm, the spinning liquid propelling rate is 0.8-1.2mL / h, the temperature is 20-30℃, and the humidity is 40-45%.

6. The process for the preparation of a chitosan hydro-entangled degradable medical dressing substrate as claimed in claim 1, wherein: The molar ratio of the carboxymethyl chitosan and ethylenediamine is 1:(5-6); the mass ratio of the polyamino chitosan and alkyl epoxy ether is 1:(0.1-0.2); the alkyl epoxy ether is one of n-butyl glycidyl ether and 2,3-epoxypropane pentyl ether.

7. A chitosan hydroentangled degradable medical dressing substrate prepared by the method of any one of claims 1 to 6, characterized in that: The medical dressing substrate comprises a chitosan spunlace non-woven fabric, a film layer; the thickness of the film layer is 40-50 µm; the thickness of the chitosan spunlace non-woven fabric is 1.5-2.5 mm; the unit area weight of the chitosan spunlace non-woven fabric is 30-40 g / m 2 .

Images