Preparation method of silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid

Abstract

The present application is about a preparation method of silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid, and relates to the field of medical antibacterial textile materials. In the present application, the chitosan oligosaccharide modified with protocatechuic acid is coupled with the degummed silk fiber by laccase promotion, and then the modified silk fiber is formed into a braided wire using a braiding machine, and finally the silver nanoparticles are stably deposited on the silk braided wire by amino-mediated reduction of silver ions, thereby achieving the excellent antibacterial properties of the silk braided wire. In this case, the antibacterial properties of the silk suture are improved by protocatechuic acid and chitosan oligosaccharide, and more silver nanoparticle deposition sites are provided; it is achieved that a suture can be completed on a medical braiding machine, the process adjustment is convenient, the thickness and length of the product are highly adjustable, no toxic chemical reagents are used, personal health is guaranteed, and it can be safely and widely used in medical, health and other fields.

Description

Technical Field

[0001] The present application relates to the technical field of medical antibacterial textile materials, and in particular to a method for preparing a silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid. Background Art

[0002] As the application of textiles in the medical field continues to develop, the functional requirements for medical sutures are constantly increasing. Ideal sutures should have good biocompatibility, mechanical properties, and the ability to promote wound healing. Silk, as a natural protein fiber, is extracted and processed into silk sutures that are widely used. They have excellent biocompatibility, are not prone to causing inflammation and rejection reactions in the body, and have excellent knotting strength. However, after wound suture, bacteria are prone to grow at the suture site, which in turn causes symptoms of bacterial infection. Therefore, the anti-inflammatory properties of sutures need to be paid attention to. Therefore, antibacterial modification of silk sutures is performed to reduce the risk of wound infection.

[0003] Chitosan oligosaccharide (COS) is a depolymerized polysaccharide product obtained by chemical and enzymatic hydrolysis of chitosan. COS is water-soluble, non-toxic, and biocompatible, and exhibits a wide range of biological activities, including antimicrobial, anti-inflammatory, anti-obesity, neuroprotective, anticancer, and antioxidant properties. The hydroxyl and amino groups in chitosan oligosaccharide are highly reactive, and can be enzymatically oxidized by laccase to tyrosine residues in silk, which can then be covalently coupled to chitosan oligosaccharide via Michael addition and Schiff base reactions.

[0004] Protocatechuic acid (PCA), also known as 3,4-dihydroxybenzoic acid, is a phenolic acid naturally present in many vegetables and fruits. It has inhibitory effects on Staphylococcus aureus, Staphylococcus aureus, and Escherichia coli. Because some tyrosine residues in silk are difficult to enzymatically graft directly onto chitosan oligosaccharides, to promote the grafting efficiency of chitosan oligosaccharides onto silk fibers and enhance the antibacterial properties of silk sutures, chitosan oligosaccharides are modified with protocatechuic acid and then enzymatically grafted. This allows amino groups to mediate the reduction of silver ions, resulting in their stable deposition on the silk.

[0005] In the related art, some degradable sutures with a short degradation cycle are disclosed, including polylactic acid sutures, collagen sutures, etc.; in addition, some sutures made of textile fibers such as medical polyester and medical silk that are high in strength but do not have antibacterial functions are also disclosed.

[0006] However, the medical sutures in the related art have the following defects: some degradable sutures cannot reach the strength required to withstand wounds with relatively high tension, which limits the use of the product; in addition, some non-degradable sutures do not have certain biological activity and antibacterial and anti-inflammatory properties, and after use, they are likely to cause redness and swelling at the wound suture site, or even bacterial infection. Summary of the Invention

[0007] The purpose of this application is to provide a method for preparing silk sutures based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid to solve the problems existing in the above-mentioned prior art.

[0008] To achieve the above objectives, the technical solutions adopted in this application are:

[0009] In a first aspect, the present application provides a method for preparing a silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid, the method comprising:

[0010] S1. Modifying chitosan oligosaccharide with protocatechuic acid to obtain protocatechuic acid-modified chitosan oligosaccharide powder;

[0011] S2, preparing a solution of the protocatechuic acid-modified chitosan oligosaccharide powder and laccase, and then performing an enzymatic reaction with the degummed silk fibroin fibers to obtain enzymatically grafted silk fibroin fibers;

[0012] S3. In response to weaving the enzymatically grafted silk fibroin fibers into a silk braided thread, in-situ deposition of silver nanoparticles is performed using a silver nitrate solution to obtain a silk suture thread based on enzymatically grafted chitosan oligosaccharide-protocatechuic acid.

[0013] In a possible implementation, step S1 includes:

[0014] In response to protocatechuic acid being dissolved in ethanol, chitosan oligosaccharide being dissolved in buffer, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide being dissolved in buffer, the three solutions are mixed, dialyzed and freeze-dried to obtain protocatechuic acid-modified chitosan oligosaccharide powder.

[0015] In a possible implementation, the buffer is a PBS buffer prepared by dissolving potassium dihydrogen phosphate and disodium hydrogen phosphate dodecahydrate in deionized water, and the pH of the PBS buffer is 5.5.

[0016] In a possible implementation, the molar ratio of the potassium dihydrogen phosphate to the disodium hydrogen phosphate dodecahydrate is 25.54:1.

[0017] In a possible implementation, the molar ratio of the protocatechuic acid to the ethanol is 1:8.2.

[0018] In a possible implementation, the chitosan oligosaccharide and the buffer solution are prepared at a mass ratio of 2:25.

[0019] In a possible implementation, the molar ratio of the 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride to the N-hydroxysuccinimide is 1:2.

[0020] In a possible implementation, the mass ratio of the 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, the N-hydroxysuccinimide, and the buffer solution is 199:239:1000.

[0021] In a possible implementation, step S1 includes:

[0022] In response to protocatechuic acid being dissolved in ethanol, chitosan oligosaccharide being dissolved in buffer, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide being dissolved in buffer, the three solutions are mixed at a volume ratio of 4:1:2 to obtain a first mixed solution;

[0023] The first mixed solution was stirred at room temperature for 12 hours, dialyzed using a dialysis membrane for three days, and then freeze-dried to obtain protocatechuic acid-modified chitosan oligosaccharide powder.

[0024] In a possible implementation, in the dialysate used for the dialysis, the volume ratio of deionized water to the first mixed solution is 100:1.

[0025] In a possible implementation, the molecular weight of the chitosan oligosaccharide is less than 2000.

[0026] In one possible implementation, the molecular structure of the protocatechuic acid is:

[0027]

[0028] In a possible implementation, step S2 includes:

[0029] The protocatechuic acid-modified chitosan oligosaccharide powder and laccase are prepared into a second mixed solution with concentrations of 1.5-2.0 g / L and 0.1-0.15 U / ml, respectively, using a buffer solution. The degummed silk fiber and the second mixed solution are sealed at a liquid ratio of 20:1 to 30:1 and placed in a 50°C constant temperature water bath for reaction for 12-16 hours. The fiber is then washed with deionized water for 3-5 times and finally dried thoroughly at 40-50°C to obtain enzymatically grafted silk fiber.

[0030] In a possible implementation, the buffer is a PBS buffer prepared by dissolving potassium dihydrogen phosphate and disodium hydrogen phosphate dodecahydrate in deionized water, and the pH of the PBS buffer is 5.5.

[0031] In a possible implementation manner, the activity of the laccase is 0.5 U / mg.

[0032] In a possible implementation, the fineness of the degummed silk fiber is 75D.

[0033] In a possible implementation, step S3 includes:

[0034] Weaving the enzymatically grafted silk fibroin fibers into silk braided yarns on a braiding machine with 8 strands and an intercept length of 2 mm;

[0035] The braided silk braided thread is placed in a prepared 0.8% silver nitrate solution, reacted in a sealed water bath at 70°C for 20 minutes, then washed with deionized water 3-5 times, and finally dried at a constant temperature of 50°C to obtain a silk suture thread based on enzymatic grafted chitosan oligosaccharide-protocatechuic acid.

[0036] In a second aspect, the present application provides a silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid, wherein the silk suture is prepared by any of the above methods for preparing a silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid.

[0037] The beneficial effects of the technical solution provided by this application include at least:

[0038] 1. Based on the excellent biocompatibility of silk fibroin and the natural antibacterial, anti-inflammatory and antioxidant properties of protocatechuic acid and chitosan oligosaccharides, this application has excellent antibacterial properties and applicability;

[0039] 2. Under the promotion of laccase, the grafting rate of silk fibroin and chitosan oligosaccharide-protocatechuic acid was improved;

[0040] 3. Through the eight-strand braiding structure, the mechanical properties of the antibacterial silk suture meet the requirements of suture;

[0041] 4. A single suture can be completed on a single medical braiding machine, making process adjustment easy and the thickness and length of the product highly adjustable.

[0042] 5. No toxic chemical reagents are used, which ensures human health and can be safely and widely used in medical, health and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings:

[0044] Figure 1 A flow chart of a method for preparing a silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid provided by an exemplary embodiment of the present application is shown;

[0045] Figure 2 The figure shows the Fourier near-infrared spectrum test graph of the protocatechuic acid-modified chitosan oligosaccharide powder and chitosan oligosaccharide provided in the first embodiment of the present application;

[0046] Figure 3 The graph showing the surface Zeta potential test of the degummed silk fibroin fiber before and after grafting provided in the first embodiment of the present application is shown;

[0047] Figure 4 The schematic diagram of the enzymatic grafting mechanism provided in the first embodiment of the present application is shown;

[0048] Figure 5 The surface SEM image of the silk braided yarn provided in the first embodiment of the present application is shown;

[0049] Figure 6 Shown are the EDS graph (a) of Ag particle-deposited silk braided wire and the silver element content graph (b) provided in the first specific embodiment of the present application. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0051] Among them, the same parts are represented by the same figure marks. It should be noted that the words "front", "rear", "left", "right", "up" and "down" used in the following description refer to the directions in the drawings of the present application specification, and the words "bottom" and "top", "inside" and "outside" refer to directions toward or away from specific parts, respectively. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application specification, the meaning of "multiple" is two or more.

[0052] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0053] Figure 1 A flow chart of a method for preparing a silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid provided by an exemplary embodiment of the present application is shown, and the method comprises the following steps:

[0054] Step S1: Modifying chitosan oligosaccharide with protocatechuic acid to obtain protocatechuic acid-modified chitosan oligosaccharide powder.

[0055] Specifically, step S1 includes: in response to protocatechuic acid being dissolved in ethanol, chitosan oligosaccharides being dissolved in buffer, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide being dissolved in buffer, mixing the above three solutions, dialysis and freeze drying, and obtaining protocatechuic acid modified chitosan oligosaccharide powder. Wherein, the buffer is: PBS buffer prepared by dissolving potassium dihydrogen phosphate and disodium hydrogen phosphate dodecahydrate in deionized water, the pH of the PBS buffer is 5.5, and the molar ratio of potassium dihydrogen phosphate to disodium hydrogen phosphate dodecahydrate is 25.54:1

[0056] Furthermore, the molar ratio of the above-mentioned protocatechuic acid to ethanol is 1:8.2, and the solution is prepared by chitosan oligosaccharide and buffer at a mass ratio of 2:25; the molar ratio of the above-mentioned 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride to N-hydroxysuccinimide is 1:2; and the mass ratio of the above-mentioned 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride, N-hydroxysuccinimide, and buffer is 199:239:1000.

[0057] Furthermore, the above step S1 includes: in response to protocatechuic acid being dissolved in ethanol, chitosan oligosaccharide being dissolved in buffer, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide being dissolved in buffer, the above three solutions are mixed in a volume ratio of 4:1:2 to obtain a first mixed solution; the first mixed solution is stirred at room temperature for 12 hours, dialyzed using a dialysis membrane for three days, and then freeze-dried to obtain protocatechuic acid-modified chitosan oligosaccharide powder. Wherein, in the dialysate used for dialysis, the volume ratio of deionized water to the first mixed solution is 100:1.

[0058] It should be noted that the molecular weight of chitosan oligosaccharide is less than 2000, and the molecular structure of protocatechuic acid is:

[0059]

[0060] Step S2: preparing a solution of protocatechuic acid-modified chitosan oligosaccharide powder and laccase, and then subjecting the solution to an enzymatic reaction with the degummed silk fibroin fibers to obtain enzymatically grafted silk fibroin fibers.

[0061] Specifically, step S2 includes: preparing a second mixed solution of protocatechuic acid-modified chitosan oligosaccharide powder and laccase with a buffer solution to prepare concentrations of 1.5-2.0 g / L and 0.1-0.15 U / ml, respectively; then, sealing the degummed silk fibroin fibers and the second mixed solution at a liquid ratio of 20:1 to 30:1 and placing them in a 50°C constant temperature water bath for reaction for 12-16 hours; then, washing them 3-5 times with deionized water; and finally, thoroughly drying them at 40-50°C to obtain enzymatically grafted silk fibroin fibers. The buffer solution is a PBS buffer solution prepared by dissolving potassium dihydrogen phosphate and disodium hydrogen phosphate dodecahydrate in deionized water; the pH of the PBS buffer solution is 5.5.

[0062] Furthermore, the activity of laccase was 0.5 U / mg, and the fineness of the degummed silk fiber was 75D.

[0063] Step S3: After the enzymatically grafted silk fibroin fibers are woven into a silk braided thread, silver nanoparticles are in situ deposited using a silver nitrate solution to obtain a silk suture thread based on enzymatically grafted chitosan oligosaccharide-protocatechuic acid.

[0064] Specifically, step S3 includes: weaving the enzymatically grafted silk fibroin fibers into 8 strands with an intercept of 2 mm on a weaving machine into a silk braided thread; placing the braided silk braided thread in a configured 0.8% silver nitrate solution, reacting it in a sealed water bath at 70°C for 20 minutes, then washing it with deionized water 3-5 times, and finally drying it at a constant temperature of 50°C to obtain a silk suture thread based on enzymatically grafted chitosan oligosaccharide-protocatechuic acid.

[0065] It is understandable that a silk suture prepared by the above-mentioned method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid also falls within the scope of protection of this application.

[0066] In order to better understand the present application, the present application is further described below in conjunction with the accompanying drawings and two specific embodiments. It should be noted that the embodiments described in the specific embodiments are only part of the embodiments of the present application and do not limit the scope of protection of the present application. Specific embodiment one:

[0068] A method for preparing a silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid, wherein the buffer used in the following method is the above-mentioned PBS buffer with a pH of 5.5, and the method comprises the following steps:

[0069] (1) Preparation and characterization of protocatechuic acid modified chitosan oligosaccharides:

[0070] 3.2 g of protocatechuic acid solid was placed in 10 ml of ethanol and slowly stirred with a glass rod to dissolve to prepare solution A1;

[0071] Solution A2 was prepared by dissolving 3.2 g of chitosan oligosaccharide in 40 ml of PBS buffer;

[0072] Solution A3 was prepared by dissolving 3.98 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 4.78 g of N-hydroxysuccinimide in 20 ml of PBS buffer.

[0073] Solutions A1, A2, and A3 were mixed and stirred at room temperature for 12 h, then dialyzed and freeze-dried to obtain protocatechuic acid-modified chitosan oligosaccharide powder;

[0074] In this embodiment, the prepared protocatechuic acid modified chitosan oligosaccharide powder and chitosan oligosaccharide were tested by Fourier near infrared spectroscopy, and the results were as follows: Figure 2 As shown, due to the addition of benzene ring groups after the modification of chitosan oligosaccharide with protocatechuic acid, the absorption peak of the characteristic functional group of protocatechuic acid appeared in the test curve of the protocatechuic acid-modified chitosan oligosaccharide powder, indicating that the modification reaction of the two was completed.

[0075] (2) Laccase-induced grafting of chitosan oligosaccharide-protocatechuic acid onto silk fibers:

[0076] The above-mentioned protocatechuic acid-modified chitosan oligosaccharide powder and laccase with an activity of 0.5U / mg were prepared into a mixed solution with concentrations of 2.0g / L and 0.15U / ml respectively using PBS buffer. The degummed silk fiber with a fineness of 75D and the mixed solution were sealed at a liquid ratio of 30:1 and placed in a 50℃ constant temperature water bath for reaction for 14h. The fiber was then washed with deionized water 4 times and finally dried thoroughly at 45℃ to obtain enzymatically grafted silk fiber.

[0077] In this example, untreated degummed silk fiber B1, degummed silk fiber directly mixed with protocatechuic acid-modified chitosan oligosaccharide powder B2, and degummed silk fiber grafted with protocatechuic acid-modified chitosan oligosaccharide powder under enzymatic conditions B3 were placed in the same amount of deionized water and sealed for 5 hours. The supernatant was taken for each group and the Zeta potential test was performed three times. The test results are shown in Figure 2. Figure 3 As shown in the figure, due to the ionization of carboxyl groups in the degummed silk fibers, the untreated degummed silk fibers will be negatively charged above the isoelectric point. Since chitosan oligosaccharide is the only positively charged cationic alkaline amino oligosaccharide in nature, the higher Zeta potential of B3 indicates that under the action of laccase, more protocatechuic acid-modified chitosan oligosaccharide powder is grafted onto the surface of the degummed silk fibers. Figure 4 The figure shows a schematic diagram of the enzymatic grafting mechanism. Laccase hydroformylates the surface groups of the degummed silk fibers to increase the reaction activity.

[0078] (3) Preparation of silk sutures and deposition of silver nanoparticles:

[0079] The above-mentioned enzymatically grafted silk fibers are woven into silk braided thread on a braiding machine with 8 strands and an intercept of 2 mm; the braided silk braided thread is placed in a prepared 0.8% silver nitrate solution, reacted in a sealed water bath at 70°C for 20 minutes, then washed with deionized water 4 times, and finally dried at a constant temperature of 50°C to obtain a silk suture thread based on enzymatically grafted chitosan oligosaccharide-protocatechuic acid.

[0080] In this embodiment, the silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid was subjected to surface electron microscopy analysis and surface element EDS test, such as Figure 5 As shown in FIG, after degumming, the silk fibers are woven to form a tight braided wire structure. Figure 6 As shown, the C, N, O, and Ag elements on the surface of the silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid were tested. The surface Ag element was evenly distributed on the surface of the silk thread, and the content reached 2.8%, which has excellent antibacterial properties. Specific embodiment two:

[0082] A method for preparing a silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid, wherein the buffer used in the following method is the above-mentioned PBS buffer with a pH of 5.5, and the method comprises the following steps:

[0083] (1) Preparation and characterization of protocatechuic acid modified chitosan oligosaccharides:

[0084] Place 1.6 g of protocatechuic acid solid in 5 ml of ethanol and slowly stir with a glass rod to dissolve to prepare solution C1;

[0085] Solution C2 was prepared by dissolving 1.6 g of chitosan oligosaccharide in 20 ml of PBS buffer;

[0086] Solution C3 was prepared by dissolving 1.99 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 2.39 g of N-hydroxysuccinimide in 10 ml of PBS buffer.

[0087] Solutions C1, C2, and C3 were mixed and stirred at room temperature for 12 h, then dialyzed and freeze-dried to obtain protocatechuic acid-modified chitosan oligosaccharide powder;

[0088] (2) Laccase-induced grafting of chitosan oligosaccharide-protocatechuic acid onto silk fibers:

[0089] The above-mentioned protocatechuic acid-modified chitosan oligosaccharide powder and laccase with an activity of 0.5U / mg were prepared into a mixed solution with concentrations of 1.5g / L and 0.1U / ml respectively using PBS buffer. The degummed silk fiber with a fineness of 75D and the mixed solution were sealed at a liquid ratio of 20:1 and placed in a 50℃ constant temperature water bath for reaction for 15h. The fiber was then washed with deionized water 5 times and finally dried thoroughly at 45℃ to obtain enzymatically grafted silk fiber.

[0090] (3) Preparation of silk sutures and deposition of silver nanoparticles:

[0091] The above-mentioned enzymatically grafted silk fibers are woven into silk braided thread on a braiding machine with 8 strands and an intercept of 2 mm; the braided silk braided thread is placed in a prepared 0.8% silver nitrate solution, reacted in a sealed water bath at 70°C for 20 minutes, then washed with deionized water 4 times, and finally dried at a constant temperature of 50°C to obtain a silk suture thread based on enzymatically grafted chitosan oligosaccharide-protocatechuic acid.

[0092] Antibacterial performance characterization:

[0093] The antibacterial test test method was based on GB / T 20944.1-2007 "Evaluation of Antibacterial Properties of Textiles Part 1: Agar Plate Diffusion Method". The antibacterial properties of the modified silk braided yarns prepared in the above-mentioned Specific Example 1 and Specific Example 2 were analyzed by the disk diffusion method. The bacterial species were Staphylococcus aureus and Escherichia coli. The antibacterial efficiency of the silk sutures enzymatically grafted with chitosan oligosaccharide-protocatechuic acid and nanosilver deposited was determined in accordance with GB / T 20944.3-2008. The antibacterial efficiency was calculated according to the formula: Antibacterial Efficiency = [(N1-N2) / N1] × 100%, where N1 is the bacterial colony count of the degummed silk fibroin fiber braided yarn that has not been antibacterial modified; N2 is the bacterial colony count of the braided yarn that has been degummed, grafted with modified silk fibroin fibers, and deposited with nanosilver (i.e., the silk braided yarns prepared in Specific Example 1 and Specific Example 2). The antibacterial rates of N1 and N2 were calculated after they were tested without washing. Then, the antibacterial rates were calculated again after N1 and N2 were washed 10 times according to the GB / T 20944.1-2007 washing standard.

[0094] The antibacterial test results of the silk braided yarn prepared in Example 1 are shown in Table 1 below:

[0095] Table 1:

[0096] Washing conditions Escherichia coli inhibition rate Staphylococcus aureus inhibition rate Unwashed 98.6％ 99.3％ Wash 10 times 80.4％ 84.7％

[0097] The antibacterial test results of the silk braided yarn prepared in Example 2 are shown in Table 2 below:

[0098] Table 2:

[0099] Washing conditions Escherichia coli inhibition rate Staphylococcus aureus inhibition rate Unwashed 98.1％ 98.9％ Wash 10 times 81.6％ 83.8％

[0100] It can be seen from Table 1 and Table 2 that the braided wire prepared in specific Example 1 and Example 2 has an antibacterial property of more than 98% against both bacteria when the number of washings is 0, and after 10 washings, the antibacterial rate against Escherichia coli and Staphylococcus aureus is still maintained at more than 80%. It can be concluded that the silk braided wire prepared in this application has strong antibacterial properties.

[0101] The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for preparing a silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid, characterized in that: The method comprises: S1. Modifying chitosan oligosaccharide with protocatechuic acid to obtain protocatechuic acid-modified chitosan oligosaccharide powder; S2, preparing a solution of the protocatechuic acid-modified chitosan oligosaccharide powder and laccase, and then performing an enzymatic reaction with the degummed silk fibroin fibers to obtain enzymatically grafted silk fibroin fibers; S3, in response to weaving the enzymatically grafted silk fibroin fibers into a silk braided thread, performing in situ deposition of silver nanoparticles using a silver nitrate solution to obtain a silk suture thread based on enzymatically grafted chitosan oligosaccharide-protocatechuic acid; The step S1 comprises: In response to protocatechuic acid being dissolved in ethanol, chitosan oligosaccharide being dissolved in buffer, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide being dissolved in buffer, the three solutions are mixed, dialyzed and freeze-dried to obtain protocatechuic acid-modified chitosan oligosaccharide powder.

2. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 1, characterized in that: The buffer solution is a PBS buffer solution prepared by dissolving potassium dihydrogen phosphate and disodium hydrogen phosphate dodecahydrate in deionized water, and the pH value of the PBS buffer solution is 5.

5.

3. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 2, characterized in that: The molar ratio of the potassium dihydrogen phosphate to the disodium hydrogen phosphate dodecahydrate is 25.54:

1.

4. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 1, characterized in that: The molar ratio of the protocatechuic acid to the ethanol is 1:8.

2.

5. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 1, characterized in that: The chitosan oligosaccharide and the buffer solution are prepared at a mass ratio of 2:

25.

6. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 1, characterized in that: The molar ratio of the 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride to the N-hydroxysuccinimide is 1:

2.

7. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 1, characterized in that: The mass ratio of the 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, the N-hydroxysuccinimide, and the buffer solution is 199:239:1000.

8. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 1, characterized in that: The step S1 comprises: In response to protocatechuic acid being dissolved in ethanol, chitosan oligosaccharide being dissolved in buffer, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide being dissolved in buffer, the three solutions are mixed at a volume ratio of 4:1:2 to obtain a first mixed solution; The first mixed solution was stirred at room temperature for 12 hours, dialyzed using a dialysis membrane for three days, and then freeze-dried to obtain protocatechuic acid-modified chitosan oligosaccharide powder.

9. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 8, characterized in that: In the dialysate used for the dialysis, the volume ratio of deionized water to the first mixed solution is 100:

1.

10. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 1, characterized in that: The molecular weight of the chitosan oligosaccharide is less than 2000.

11. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 1, characterized in that: The molecular structure of the protocatechuic acid is: 。 12. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 1, characterized in that: The step S2 comprises: The protocatechuic acid-modified chitosan oligosaccharide powder and laccase are prepared into a second mixed solution with concentrations of 1.5-2.0 g / L and 0.1-0.15 U / ml, respectively, using a buffer solution. The degummed silk fiber and the second mixed solution are sealed at a liquid ratio of 20:1 to 30:1 and placed in a 50°C constant temperature water bath for reaction for 12-16 hours. The fiber is then washed with deionized water for 3-5 times and finally dried thoroughly at 40-50°C to obtain enzymatically grafted silk fiber.

13. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 12, characterized in that: The buffer solution is a PBS buffer solution prepared by dissolving potassium dihydrogen phosphate and disodium hydrogen phosphate dodecahydrate in deionized water, and the pH value of the PBS buffer solution is 5.

5.

14. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 12, characterized in that: The activity of the laccase is 0.5 U / mg.

15. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 12, characterized in that: The fineness of the degummed silk fiber is 75D.

16. The method for preparing silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to claim 1, characterized in that: The step S3 comprises: Weaving the enzymatically grafted silk fibroin fibers into silk braided yarns on a braiding machine with 8 strands and an intercept length of 2 mm; The woven silk braided thread is placed in a prepared 0.8% silver nitrate solution, reacted in a sealed water bath at 70°C for 20 minutes, then washed with deionized water 3-5 times, and finally dried at a constant temperature of 50°C to obtain a silk suture thread based on enzymatic grafted chitosan oligosaccharide-protocatechuic acid.

17. A silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid, characterized in that: The silk suture is prepared by the preparation method of the silk suture based on enzymatic grafting of chitosan oligosaccharide-protocatechuic acid according to any one of claims 1 to 16.

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