Absorbable suture containing silk fibroin and method for preparing the same

Abstract

The application discloses a silk protein-containing absorbable suture and a preparation method thereof, and relates to the technical field of absorbable sutures.The silk protein-containing absorbable suture comprises the following raw materials in parts by weight: 35-50 parts of silk protein, 10-20 parts of polylactic acid, 15-25 parts of polyglycolide, 1-3 parts of an antibacterial agent, 2-5 parts of a modified toughening agent, 1-4 parts of a nano-mineral filler, 0.5-2 parts of a crosslinking agent and 2-5 parts of a plasticizer.The application generates an intermediate 1 by reacting protocatechuic acid with ethanolamine; the intermediate 1 is reacted with 5,10,15,20-tetra(4-carboxyphenyl)porphyrin to generate the antibacterial agent.The silk protein-containing absorbable suture prepared by the application has good mechanical properties, self-repairing properties and antibacterial properties.

Description

Technical Field

[0001] This invention relates to the field of absorbable suture technology, specifically to an absorbable suture containing silk fibroin and its preparation method. Background Technology

[0002] Absorbable sutures, as a key material to replace traditional silk sutures in surgical procedures, have core requirements for synergistic optimization of biocompatibility, mechanical stability, degradation rate matching, and antibacterial function. While traditional absorbable sutures (such as polyglycolic acid) are biodegradable, they easily release acidic products (such as lactic acid) during degradation, triggering local inflammatory reactions. Furthermore, they are brittle and difficult to adapt to the suturing requirements of dynamic tissues such as joints and the heart. Silk fibroin, a natural protein extracted from silkworm cocoons, is mainly composed of fibroin protein. Its degradation products are small molecule peptides and amino acids, which can be metabolized and absorbed by the human body without toxic byproducts. It possesses good biocompatibility and mechanical properties, and compared to traditional absorbable sutures, it can significantly reduce the level of inflammatory factors, thus being widely used in various surgical procedures. However, the field of absorbable silk fibroin sutures still faces challenges such as limitations in antibacterial properties, difficulty in balancing flexibility and strength, and deficiencies in self-healing performance.

[0003] Chinese invention patent CN118903522A discloses a method for preparing a sericin absorbable suture. The sericin absorbable suture comprises: 55%-75% sericin, 10%-20% biocompatibility enhancer, 2%-6% anti-inflammatory or anti-allergic agent, 1%-3% cross-linking agent residue remover, 3%-8% nano-mineral filler, and 0.5%-2% bioactive peptides. This invention's sericin absorbable suture exhibits good mechanical strength and stable degradation characteristics, but its antibacterial and self-healing properties are insufficient. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an absorbable suture containing silk fibroin and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] An absorbable suture containing silk protein, comprising the following parts by weight of raw material:

[0007] Silk protein: 35-50 parts;

[0008] Polylactic acid: 10-20 parts;

[0009] Poly(glycolic acid) and lactide: 15-25 parts;

[0010] Antibacterial agent: 1-3 parts;

[0011] Modified toughening agent: 2-5 parts;

[0012] Nano-mineral filler: 1-4 parts;

[0013] Crosslinking agent: 0.5-2 parts;

[0014] Plasticizer: 2-5 parts;

[0015] The antibacterial agent is prepared by the following method:

[0016] S1: Under nitrogen protection, protocatechuic acid was first protected with phenolic hydroxyl groups to obtain acetylated protocatechuic acid. Then, anhydrous toluene, ethanolamine, and p-toluenesulfonic acid were mixed and stirred at 80-90℃. The acetylated protocatechuic acid was added in batches under light protection and the reaction was carried out for 6-9 hours to obtain intermediate 1.

[0017] S2: Under nitrogen protection and in the dark at room temperature, 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide and triethylamine are added sequentially to anhydrous THF, stirred and activated, and then intermediate 1 is added. The reaction is carried out at 25-35℃ for 14-16 hours to obtain the antibacterial agent.

[0018] In step S1, the molar ratio of protocatechuic acid and ethanolamine is 1:(1.2-1.5).

[0019] In step S2, the molar ratio of 5,10,15,20-tetra(4-carboxyphenyl)porphyrin to intermediate 1 is 1:(4.1-4.3).

[0020] The modified toughening agent is prepared by the following method:

[0021] N1: Under nitrogen protection, 2-formyl-furan-2-carboxylic acid, 4-dimethylaminopyridine and N,N'-dicyclohexylcarbodiimide were added sequentially to anhydrous tetrahydrofuran (THF), and the mixture was activated by stirring at room temperature. Then polyethylene glycol was added, and the mixture was reacted at room temperature to obtain intermediate A.

[0022] N2: Mix intermediate A, aminopolyethylene glycol hydroxyl group, anhydrous ethanol and PBS buffer, add triethylamine, and react at 30-40℃ for 8-12h to obtain the modified toughening agent.

[0023] In step N1, the mass ratio of polyethylene glycol to 2-formyl-furan-2-carboxylic acid is 1:(0.29-0.32).

[0024] In step N2, the mass ratio of intermediate A to amino polyethylene glycol hydroxyl group is 1:(1.8-1.9).

[0025] The nano-mineral filler is nano-hydroxyapatite.

[0026] The crosslinking agent is genipin.

[0027] The plasticizer is one of acetylglucosyl citrate and tributyl citrate.

[0028] A method for preparing an absorbable suture containing silk fibroin includes the following steps:

[0029] (1) Weigh out the following by weight: 35-50 parts silk protein, 10-20 parts polylactic acid, 15-25 parts polyglycolic acid and lactide, 1-3 parts antibacterial agent, 2-5 parts modified toughening agent, 1-4 parts nano mineral filler, 0.5-2 parts crosslinking agent, and 2-5 parts plasticizer;

[0030] (2) Mix silk fibroin with 9.3M LiBr aqueous solution, stir and mix well, and dialyze to obtain silk fibroin solution; mix polylactic acid and polyglycolic acid with hexafluoroisopropanol, add to silk fibroin solution after ultrasonic rotary evaporation, then add modified toughening agent, nano mineral filler, plasticizer and antibacterial agent, stir, add crosslinking agent, and ultrasonic degassing to obtain spinning solution;

[0031] (3) The spinning solution is used to prepare a fiber membrane by electrospinning technology. After continuous spinning for 4 hours, the fiber membrane is collected and dried under vacuum at 60°C for 12 hours to obtain a dried fiber membrane. The process parameters of the electrospinning technology are set as follows: voltage 20kV, receiving distance 12cm, spinning solution flow rate 2.0ml / h, ambient temperature 25°C, relative humidity 20%, and receiver rotation speed 500rpm.

[0032] (4) Immerse the dried fiber membrane in an ethanol / water mixture containing 0.1% w / v genipin, take it out and dry it after 4 hours. Cut it into strips 0.3-0.4 mm wide and twist them into shape. Heat set at 60℃ for 10 minutes and sterilize with ethylene oxide to obtain absorbable suture containing silk protein.

[0033] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include:

[0034] (1) The antibacterial agent prepared in this invention grafts protocatechuic acid onto porphyrin, achieving a dual antibacterial effect through the synergistic effect of photodynamics and membrane disruption. Porphyrin generates reactive oxygen species under light, which weakens the bacterial membrane, and the phenolic hydroxyl groups of protocatechuic acid can destroy the bacterial cell membrane, inhibit biofilm formation, and improve antibacterial performance.

[0035] (2) The modified toughening agent prepared in this invention introduces flexible segments and dynamic Schiff base structures. The linear long chains of polyethylene glycol and amino polyethylene glycol hydroxyl groups have high degrees of freedom and can absorb external forces through chain segment slippage, thereby reducing the brittleness of the material; the introduced Schiff base bonds can undergo reversible breakage / reorganization, and dissipate energy through bond breakage when under stress, avoiding fracture caused by stress concentration. Attached Figure Description

[0036] Figure 1 The 1H NMR spectrum of intermediate 1 prepared in Example 1.

[0037] Figure 2 The image shows the 1H NMR spectrum of the antibacterial agent prepared in Example 1.

[0038] Figure 3 The high-resolution mass spectrum of intermediate 1 prepared in Example 1.

[0039] Figure 4 The image shows a high-resolution mass spectrum of the antibacterial agent prepared in Example 1. Detailed Implementation

[0040] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments.

[0041] Example 1: Preparation of antibacterial agent:

[0042] S1: Under nitrogen protection and ice bath conditions, 0.1 mol of protocatechuic acid was added to 150 ml of anhydrous pyridine, and 0.35 mol of acetic anhydride was slowly added dropwise (temperature controlled <5℃, added over 20 min). After stirring in the dark at room temperature for 12 h, the reaction solution was poured into 500 ml of ice water and extracted with ethyl acetate (3 × 120 ml). The organic phase was washed with 5 wt% dilute hydrochloric acid until neutral, dried over 20 g of anhydrous MgSO4, and rotary evaporated at 45℃ for 1 h to obtain acetylated protocatechuic acid. Under nitrogen protection, 250 ml of anhydrous toluene, 0.12 mol of ethanolamine, and 0.005 mol of p-toluenesulfonic acid were mixed thoroughly. The temperature was raised to 80℃ and stirred for 30 min. Under the dark, the acetylated protocatechuic acid was divided into 4 equal portions, and one batch was added every 15 min to maintain a temperature of 80℃. The reaction was carried out at 0℃ for 9 h (during which water generated in the reaction was separated using a water separator); after cooling to room temperature, 50 ml of saturated NaHCO3 solution was added and stirred for 15 min; the mixture was extracted with ethyl acetate (3 × 100 ml), the organic phases were combined, washed with 80 ml of 5 wt% NaCl solution, dried over 25 g of anhydrous MgSO4, filtered, and distilled under reduced pressure at 50℃ for 2 h. Then, 200 ml of methanol / water (volume ratio 7:3) mixed solvent and 0.5 mol K2CO3 were added, and the mixture was stirred at 25℃ for 4 h to deacetylate; the mixture was extracted with ethyl acetate (3 × 100 ml), rotary evaporated at 50℃ for 1 h, and then subjected to silica gel column chromatography (v / v petroleum ether:ethyl acetate = 3:1 → 1:1 gradient elution), and dried under vacuum at 50℃ for 3 h to obtain intermediate 1; the reaction equation is shown below:

[0043]

[0044] Its proton nuclear magnetic resonance spectrum is as follows: Figure 1 As shown, the proton NMR data are as follows: 1 H NMR (300 MHz, Chloroform- d δ 7.68 (dd, J = 7.5, 2.0 Hz, 1H), 7.30 (d, J = 2.0 Hz, 1H), 6.86 (d, J = 7.5 Hz, 1H), 4.58 (s, 1H), 4.35 (s, 1H), 4.27 (s, 2H), 3.23 (d, J = 0.6 Hz, 2H), 2.42 (dt, J = 36.8, 0.6 Hz, 2H); its high-resolution mass spectrum is shown below. Figure 3 The high-resolution mass spectrometry data are as follows: HRMS (m / z): 198.0678 [M+H] + .

[0045] S2: Under nitrogen protection and in the dark at room temperature, 0.1 mol of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, 0.5 mol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.5 mol of N-hydroxysuccinimide, and 0.65 mol of triethylamine were sequentially added to 800 mL of anhydrous THF and stirred for 45 min. Then, 0.41 mol of intermediate 1 was added, and the reaction was carried out at 25 °C in the dark for 16 h. After the reaction was completed, the reaction solution was poured into 1000 mL of ice water to precipitate the precipitate. The precipitate was filtered, and the filter cake was washed sequentially with 500 mL of anhydrous ethanol and 500 mL of anhydrous diethyl ether. The precipitate was then subjected to silica gel column chromatography (eluent: methanol / water). V / V The mixture of 6:4 (ratio of 1:4) was purified and rotary evaporated at 55°C for 4 hours to obtain the antibacterial agent; the reaction equation is shown below:

[0046]

[0047] Its proton nuclear magnetic resonance spectrum is as follows: Figure 2 As shown, the proton NMR data are as follows: 1 H NMR (300 MHz, Chloroform- d δ 9.83 (d, J = 17.3 Hz, 2H), 8.10 (t, J = 0.5 Hz, 4H), 7.98-7.87 (m, 8H), 7.68 (dd, J = 7.5, 2.0 Hz, 4H), 7.59-7.46 (m, 10H), 7.40 (s, 2H), 7.30 (d, J = 2.0 Hz, 4H), 7.13 (s, 2H), 6.90-6.76 (m, 6H), 4.58 (s, 4H), 4.41 (s, 8H), 4.35 (s, 4H), 3.65 (d, J = 0.5 Hz, 8H); its high-resolution mass spectrum is shown below. Figure 4 The high-resolution mass spectrometry data are shown below: HRMS (m / z): 1507.4327 [M+H] + .

[0048] Example 2: Preparation of antibacterial agent:

[0049] S1: Under nitrogen protection and ice bath conditions, 0.1 mol of protocatechuic acid was added to 150 ml of anhydrous pyridine, and 0.35 mol of acetic anhydride was slowly added dropwise (temperature controlled <5℃, added over 20 min). After stirring for 12 h in the dark at room temperature, the reaction solution was poured into 500 ml of ice water and extracted with ethyl acetate (3 × 120 ml). The organic phase was washed with 5 wt% dilute hydrochloric acid until neutral, dried over 20 g of anhydrous MgSO4, and rotary evaporated at 45℃ for 1 h to obtain acetylated protocatechuic acid. Under nitrogen protection, 250 ml of anhydrous toluene, 0.13 mol of ethanolamine, and 0.005 mol of p-toluenesulfonic acid were mixed thoroughly. The temperature was raised to 85℃ and stirred for 30 min. Under the dark, the acetylated protocatechuic acid was divided into 4 equal portions, and one portion was added every 15 min. The reaction was carried out at 85℃ for 7 hours (during which the water generated in the reaction was separated by a water separator); the mixture was cooled to room temperature, and 50 ml of saturated NaHCO3 solution was added and stirred for 15 min; the mixture was extracted with ethyl acetate (3 × 100 ml), the organic phases were combined, washed with 100 ml of 5 wt% NaCl solution, dried with 25 g of anhydrous MgSO4, filtered, and distilled under reduced pressure at 50℃ for 2 h. Then, 200 ml of methanol / water (volume ratio 7:3) mixed solvent and 0.5 mol K2CO3 were added, and the mixture was stirred at 25℃ for 4 h to deacetylate; the mixture was extracted with ethyl acetate (3 × 100 ml), rotary evaporated at 50℃ for 1 h, and then subjected to silica gel column chromatography (v / v petroleum ether: ethyl acetate = 3:1 → 1:1 gradient elution), and dried under vacuum at 50℃ for 3 h to obtain intermediate 1;

[0050] S2: Under nitrogen protection and in the dark at room temperature, 0.1 mol of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, 0.5 mol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.5 mol of N-hydroxysuccinimide, and 0.65 mol of triethylamine were sequentially added to 800 mL of anhydrous THF and stirred for 45 min to activate. Then, 0.42 mol of intermediate 1 was added, and the reaction was carried out at 30 °C in the dark for 15 h. After the reaction was completed, the reaction solution was poured into 1000 mL of ice water to precipitate the precipitate. The precipitate was filtered, and the filter cake was washed sequentially with 500 mL of anhydrous ethanol and 500 mL of anhydrous diethyl ether. The precipitate was then subjected to silica gel column chromatography (eluent: methanol / water). V / V Purify the mixture (6:4 ratio), then rotary evaporate at 55°C for 4 hours to obtain the antibacterial agent.

[0051] Example 3: Preparation of antibacterial agent:

[0052] S1: Under nitrogen protection and ice bath conditions, 0.1 mol of protocatechuic acid was added to 150 ml of anhydrous pyridine, and 0.35 mol of acetic anhydride was slowly added dropwise (temperature controlled <5℃, addition over 20 min). After stirring at room temperature in the dark for 12 h, the reaction solution was poured into 500 ml of ice water and extracted with ethyl acetate (3 × 120 ml). The organic phase was washed with 5 wt% dilute hydrochloric acid until neutral, dried over 20 g of anhydrous MgSO4, and rotary evaporated at 45℃ for 1 h to obtain acetylated protocatechuic acid; under nitrogen protection, 2 Mix 0.00 ml anhydrous toluene, 0.15 mol ethanolamine, and 0.005 mol p-toluenesulfonic acid; heat to 90 °C and stir for 30 min; under light protection, divide acetylated protocatechuic acid into 4 equal portions, adding one batch every 15 min, and maintain the reaction at 90 °C for 6 h (during which water generated in the reaction is separated by a water separator); cool to room temperature, add 50 ml saturated NaHCO3 solution and stir for 15 min; extract with ethyl acetate (3 × 100 ml), combine the organic phases, wash with 100 ml 5 wt% NaCl solution, dry with 25 g anhydrous MgSO4, filter, distill under reduced pressure at 50 °C for 2 h, add 200 ml methanol / water (volume ratio 7:3) mixed solvent and 0.5 mol K2CO3, stir at 25 °C to deacetylate for 4 h; extract with ethyl acetate (3 × 100 ml), rotary evaporate at 50 °C for 1 h, then perform silica gel column chromatography (v / v petroleum ether: ethyl acetate = 3:1 → 1:1 gradient elution), dry under vacuum at 50 °C for 3 h to obtain intermediate 1;

[0053] S2: Under nitrogen protection and in the dark at room temperature, 0.1 mol of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, 0.5 mol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.5 mol of N-hydroxysuccinimide, and 0.65 mol of triethylamine were sequentially added to 800 mL of anhydrous THF and stirred for 45 min to activate the reaction. Then, 0.43 mol of intermediate 1 was added, and the reaction was carried out at 35 °C in the dark for 14 h. After the reaction was completed, the reaction solution was poured into 1000 mL of ice water to precipitate the precipitate. The precipitate was filtered, and the filter cake was washed sequentially with 500 mL of anhydrous ethanol and 500 mL of anhydrous diethyl ether. The precipitate was then subjected to silica gel column chromatography (eluent: methanol / water). V / V Purify the mixture (6:4 ratio), then rotary evaporate at 55°C for 4 hours to obtain the antibacterial agent.

[0054] Example 4: Preparation of modified toughening agent:

[0055] N1: Under nitrogen protection, 5.8 g of 2-formyl-furan-2-carboxylic acid, 2 g of 4-dimethylaminopyridine, and 10 g of N,N'-dicyclohexylcarbodiimide were sequentially added to 200 ml of anhydrous THF and stirred at room temperature for 40 min. Then, 20 g of polyethylene glycol (PEG1000) was added, and the mixture was stirred until homogeneous. The reaction was carried out at room temperature for 20 h. After filtration, the filtrate was precipitated with 300 ml of cold diethyl ether. The precipitate was dissolved in 200 ml of anhydrous THF, precipitated with 300 ml of cold diethyl ether, filtered, and dried under vacuum at 40 °C for 8 h to obtain intermediate A. The reaction equation is shown below:

[0056]

[0057] N2: Mix 30g of intermediate A, 54g of amino-polyethylene glycol hydroxyl group, 350ml of anhydrous ethanol, and 150ml of PBS buffer (PBS buffer concentration: 0.1M, pH: 7.2). Stir in the dark for 20min, add 10g of triethylamine, and react at 30℃ for 12h. Cool to room temperature, transfer the reaction solution to a dialysis bag (molecular weight cutoff: 1500Da), and dialyze for 24h (changing the solution every 6 hours, 2000ml each time; the first two dialyzes were with 0.1M, pH 7.2 PBS buffer, and the last two dialyzes were with deionized water). Freeze-dry at -50℃ for 24h to obtain the modified toughening agent; the reaction equation is shown below:

[0058]

[0059] Example 5: Preparation of the modified toughening agent:

[0060] N1: Under nitrogen protection, 6.2 g of 2-formyl-furan-2-carboxylic acid, 2 g of 4-dimethylaminopyridine and 10 g of N,N'-dicyclohexylcarbodiimide were added sequentially to 200 ml of anhydrous THF and stirred at room temperature for 40 min. Then, 20 g of PEG1000 was added and stirred until homogeneous. The mixture was reacted at room temperature for 18 h, filtered, and the filtrate was precipitated with 300 ml of cold diethyl ether. The precipitate was dissolved again in 200 ml of anhydrous THF and precipitated with 300 ml of cold diethyl ether. After filtration, the mixture was dried under vacuum at 40 °C for 8 h to obtain intermediate A.

[0061] N2: Mix 30g of intermediate A, 55.5g of aminopolyethylene glycol hydroxyl group, 350ml of anhydrous ethanol and 150ml of PBS buffer (PBS buffer concentration is 0.1M, pH is 7.2) and stir in the dark for 20min. Add 10g of triethylamine and react at 35℃ for 10h. Cool to room temperature, transfer the reaction solution to a dialysis bag (molecular weight cutoff 1500Da), dialyze for 24h (change the solution every 6 hours, 2000ml each time, the first two dialyzes are with 0.1M, pH 7.2 PBS buffer, the last two dialyzes are with deionized water), freeze dry at -50℃ for 24h to obtain the modified toughening agent.

[0062] Example 6 Preparation of modified toughening agent:

[0063] N1: Under nitrogen protection, 6.4 g of 2-formyl-furan-2-carboxylic acid, 2 g of 4-dimethylaminopyridine and 10 g of N,N'-dicyclohexylcarbodiimide were added sequentially to 200 ml of anhydrous THF and stirred at room temperature for 40 min. Then, 20 g of PEG1000 was added and stirred until homogeneous. The mixture was reacted at room temperature for 18 h, filtered, and the filtrate was precipitated with 300 ml of cold diethyl ether. The precipitate was dissolved again in 200 ml of anhydrous THF and precipitated with 300 ml of cold diethyl ether. After filtration, the mixture was dried under vacuum at 40 °C for 8 h to obtain intermediate A.

[0064] N2: Mix 30g intermediate A, 57g aminopolyethylene glycol hydroxyl group, 350ml anhydrous ethanol and 150ml PBS buffer (PBS buffer concentration is 0.1M, pH is 7.2) and stir in the dark for 20min. Add 10g triethylamine and react at 40℃ for 8h. Cool to room temperature, transfer the reaction solution to a dialysis bag (molecular weight cutoff 1500Da), dialyze for 24h (change the solution every 6 hours, 2000ml each time, the first two dialyzes are with 0.1M, pH 7.2 PBS buffer, the last two dialyzes are with deionized water), freeze dry at -50℃ for 24h to obtain the modified toughening agent.

[0065] Example 7: Preparation of absorbable sutures containing silk fibroin:

[0066] (1) Weigh the following by weight: 350g silk protein, 100g polylactic acid, 150g polyglycolic acid and lactide, 10g antibacterial agent (prepared in Example 1), 20g modified toughening agent (prepared in Example 4), 10g nano mineral filler (nano hydroxyapatite), 5g crosslinking agent (genipin), and 20g plasticizer (triethyl acetylacetic acid).

[0067] (2) Mix silk fibroin with 3500ml of 9.3M LiBr aqueous solution, stir at 60℃ for 2h, dialyze (molecular weight cutoff 8000Da) for 48h to remove salt to obtain silk fibroin solution; mix polylactic acid, polyglycolic acid and lactide with 2500ml of hexafluoroisopropanol, sonicate at 40kHz for 20min, rotary evaporate at 40℃ for 2h and then add to silk fibroin solution, then add modified toughening agent, nano mineral filler, plasticizer and antibacterial agent to silk fibroin solution, stir at 40℃ for 2h, add crosslinking agent, sonicate at 40kHz for 20min to degas to obtain spinning solution;

[0068] (3) The spinning solution is used to prepare a fiber membrane by electrospinning technology. After continuous spinning for 4 hours, the fiber membrane is collected and dried under vacuum at 60°C for 12 hours to obtain a dried fiber membrane. The process parameters of the electrospinning technology are set as follows: voltage 20kV, receiving distance 12cm, spinning solution flow rate 8.0ml / h, ambient temperature 25°C, relative humidity 20%, and receiver rotation speed 500rpm.

[0069] (4) The dried fiber membrane was immersed in a mixed solution of ethanol / water (volume ratio 75:25) containing 0.1% w / v genipin, crosslinked at 25℃ for 4h, dried at 60℃ for 2h, cut into strips 0.4mm wide and twisted (twist: 30 twists / 10cm), heat-set at 60℃ for 10min, and sterilized with ethylene oxide (sterilization conditions: temperature 55℃, relative humidity 60%, concentration 800mg / l, time 6h) to obtain absorbable suture containing silk protein.

[0070] Example 8: Preparation of absorbable sutures containing silk fibroin:

[0071] (1) Weigh the following by weight: 450g silk protein, 150g polylactic acid, 200g polyglycolic acid and lactide, 20g antibacterial agent (prepared in Example 2), 35g modified toughening agent (prepared in Example 5), 25g nano mineral filler (nano hydroxyapatite), 15g crosslinking agent (genipin), and 35g plasticizer (tributyl citrate);

[0072] (2) Mix silk fibroin with 4500ml of 9.3M LiBr aqueous solution, stir at 60℃ for 2h, dialyze (molecular weight cutoff 8000Da) for 48h to remove salt to obtain silk fibroin solution; mix polylactic acid, polyglycolic acid and lactide with 3500ml of hexafluoroisopropanol, sonicate at 40kHz for 20min, rotary evaporate at 40℃ for 2h and then add to silk fibroin solution, then add modified toughening agent, nano mineral filler, plasticizer and antibacterial agent to silk fibroin solution, stir at 40℃ for 2h, add crosslinking agent, sonicate at 40kHz for 20min to degas to obtain spinning solution;

[0073] (3) The spinning solution is used to prepare a fiber membrane by electrospinning technology. After continuous spinning for 4 hours, the fiber membrane is collected and dried under vacuum at 60°C for 12 hours to obtain a dried fiber membrane. The process parameters of the electrospinning technology are set as follows: voltage 20kV, receiving distance 12cm, spinning solution flow rate 8.0ml / h, ambient temperature 25°C, relative humidity 20%, and receiver rotation speed 500rpm.

[0074] (4) The dried fiber membrane was immersed in a mixed solution of ethanol / water (volume ratio 75:25) containing 0.1% w / v genipin, crosslinked at 25℃ for 4h, dried at 60℃ for 2h, cut into strips 0.4mm wide and twisted (twist: 25 twists / 10cm), heat-set at 60℃ for 10min, and sterilized with ethylene oxide (sterilization conditions: temperature 55℃, relative humidity 60%, concentration 800mg / l, time 6h) to obtain absorbable suture containing silk protein.

[0075] Example 9: Preparation of absorbable sutures containing silk fibroin:

[0076] (1) Weigh the following by weight: 500g silk protein, 200g polylactic acid, 250g polyglycolic acid and lactide, 30g antibacterial agent (prepared in Example 3), 50g modified toughening agent (prepared in Example 6), 40g nano mineral filler (nano hydroxyapatite), 20g crosslinking agent (genipin), and 50g plasticizer (triethyl acetylacetic acid).

[0077] (2) Mix silk fibroin with 5000ml of 9.3M LiBr aqueous solution, stir at 60℃ for 2h, dialyze (molecular weight cutoff 8000Da) for 48h to remove salt to obtain silk fibroin solution; mix polylactic acid, polyglycolic acid and lactide with 4500ml of hexafluoroisopropanol, sonicate at 40kHz for 20min, rotary evaporate at 40℃ for 2h and then add to silk fibroin solution, then add modified toughening agent, nano mineral filler, plasticizer and antibacterial agent to silk fibroin solution, stir at 40℃ for 2h, add crosslinking agent, sonicate at 40kHz for 20min to degas to obtain spinning solution;

[0078] (3) The spinning solution is used to prepare a fiber membrane by electrospinning technology. After continuous spinning for 4 hours, the fiber membrane is collected and dried under vacuum at 60°C for 12 hours to obtain a dried fiber membrane. The process parameters of the electrospinning technology are set as follows: voltage 20kV, receiving distance 12cm, spinning solution flow rate 8.0ml / h, ambient temperature 25°C, relative humidity 20%, and receiver rotation speed 500rpm.

[0079] (4) The dried fiber membrane was immersed in a mixed solution of ethanol / water (volume ratio 75:25) containing 0.1% w / v genipin, crosslinked at 25℃ for 4h, dried at 60℃ for 2h, cut into strips 0.3mm wide and twisted (twist: 20 twists / 10cm), heat-set at 60℃ for 10min, and sterilized with ethylene oxide (sterilization conditions: temperature 55℃, relative humidity 60%, concentration 800mg / l, time 6h) to obtain absorbable suture containing silk protein.

[0080] Comparative Example 1

[0081] The raw material composition and process of the absorbable suture containing silk protein are basically the same as those in Example 8, except that no modified toughening agent is added to the components.

[0082] Comparative Example 2

[0083] The raw material composition and process of the absorbable suture containing silk fibroin are basically the same as in Example 8, except that the antibacterial agent is replaced with an equal weight of an antibacterial agent prepared by the following method:

[0084] The preparation method of the antibacterial agent is basically the same as that in Example 2, except that 5,10,15,20-tetra(4-aminophenyl)porphyrin in step S2 is replaced with an equimolar amount of perylene-2,5,8,11-tetracarboxylic acid.

[0085] Comparative Example 3

[0086] The raw material composition and process of the absorbable suture containing silk fibroin are basically the same as in Example 8, except that the antibacterial agent is replaced with an equal weight of an antibacterial agent prepared by the following method:

[0087] The preparation method of the antibacterial agent is basically the same as that in Example 2, except that protocatechuic acid in step S1 is replaced with an equimolar amount of p-hydroxybenzoic acid.

[0088] Comparative Example 4

[0089] The raw material composition and process of the absorbable suture containing silk fibroin are basically the same as in Example 8, except that the modified toughening agent is replaced with an equal weight of a modified toughening agent prepared by the following method:

[0090] The preparation method of the modified toughening agent is basically the same as that in Example 5, except that PEG1000 in step N1 is replaced with an equal weight of PEG400.

[0091] Comparative Example 5

[0092] The raw material composition and process of the absorbable suture containing silk protein are basically the same as those in Example 8, except that the modified toughening agent is replaced with an equal weight of intermediate A.

[0093] The silk fibroin used in the embodiments and comparative examples of this application has a fineness of 100 mesh, an effective ingredient content of 98%, and is produced by Fufeng Sinote Biotechnology Co., Ltd.; the polylactic acid is grade 6201D and is produced by Nature Works, USA; the polyglycolic acid is grade PLGA75-06 and is produced by Chengdu Dicon Pharmaceutical Co., Ltd.; the nano-hydroxyapatite is grade HAP03-20 and is produced by Nanjing Junzhuo Biotechnology Co., Ltd. The amino-polyethylene glycol has a number-average molecular weight of 1000 Da.

[0094] The elongation at break of absorbable sutures was tested using a universal tensile testing machine according to ASTM D3822 standard. A knot was first tied in the center of the suture and tightened. A 130mm section of the suture with the knot was selected and fixed on the testing machine. The tensile speed was 300mm / min, and the tensile test was performed until the suture broke at the knot. The elongation at break was recorded at this point.

[0095] Self-healing performance test: The absorbable sutures of Examples 7-9 and the comparative example were tested for initial breaking strength and breaking strength after damage repair according to the YY 1116-2020 standard. The gauge length was 130 mm and the speed was 300 mm / min. The breaking strength of the undamaged suture (initial breaking strength) and the breaking strength of the suture after damage repair (breaking strength after repair) were recorded. The test results are shown in Table 1.

[0096] Repair test: A standard incision (0.2 mm depth, 0.15 mm width, and 1 mm length) was made in the middle of the suture using a scalpel. The damaged suture was then immersed in 20 ml of PBS buffer at 37°C, 0.1 M, and pH 7.4, with 1 ml of 0.1 wt% triethylamine added. After soaking for 2 hours, the repaired suture was obtained.

[0097] Antibacterial performance test: The antibacterial performance of absorbable sutures was tested according to GB / T 20944.3-2008 standard. Staphylococcus aureus was selected as the bacterial strain, and the sample mass was 0.75g, without washing. The sample was thoroughly contacted with the cultured bacterial solution and placed on a constant temperature shaker at 24℃ and 250r / min for 1min. The bacterial solution was then removed, diluted with 9ml of PBS buffer, and quantitatively inoculated into a culture dish containing sterile agar medium (AGAR). After incubation at 37℃ for 48h, bacterial counts were performed, and the inhibition rate was calculated. The control sample was absorbable suture without added antibacterial agent (the raw material composition and process of absorbable suture containing silk fibroin were basically the same as in Example 8, except that no antibacterial agent was added to the components). The test results are shown in Table 1.

[0098] Table 1 Performance Indicators of Absorbable Sutures

[0099]

[0100] As can be seen from Table 1, the absorbable sutures containing silk fibroin prepared in Examples 7-9 of this application have excellent mechanical properties, self-healing properties, and antibacterial properties.

[0101] The absorbable sutures prepared in Comparative Examples 1 and 4 showed poorer elongation at break compared to the examples. This was mainly because the flexible segments introduced in the modified toughening agent improved the flexibility of the absorbable sutures. The polyethylene glycol long-chain structure with a number-average molecular weight of 400 used in Comparative Example 4 was shorter than that in the examples, resulting in reduced flexibility. Furthermore, the absorbable sutures prepared in Comparative Example 1 exhibited poorer self-healing properties compared to the examples, primarily because no modified toughening agent was added. The dynamic Schiff base structure introduced by the modified toughening agent allows for reversible fracture and recombination, endowing the absorbable sutures with excellent self-healing properties.

[0102] The absorbable sutures prepared in Comparative Examples 2 and 3 exhibited inferior antibacterial properties compared to the examples. This was primarily because the antibacterial agents prepared in the examples grafted protocatechuic acid onto porphyrins, achieving a dual antibacterial effect through a synergistic effect of photodynamic therapy and membrane disruption. The perylene-2,5,8,11-tetracarboxylic acid used in Comparative Example 2 lacked a porphyrin structure and could not generate reactive oxygen species under light, resulting in poor photodynamic antibacterial performance. The p-hydroxybenzoic acid used in Comparative Example 3 lacked one phenolic hydroxyl group, resulting in a weaker ability to disrupt bacterial membranes, thus leading to a decrease in the antibacterial properties of the absorbable sutures.

[0103] The self-healing performance of the absorbable suture prepared in Comparative Example 5 was worse than that of the Example 5, mainly because intermediate A lacked a dynamic Schiff base structure with reversible breakage and recombination functions, which led to a significant reduction in self-healing performance.

[0104] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. An absorbable suture containing silk fibroin, characterized in that, The ingredients include the following parts by weight: Silk protein: 35-50 parts; Polylactic acid: 10-20 parts; Poly(glycolic acid) and lactide: 15-25 parts; Antibacterial agent: 1-3 parts; Modified toughening agent: 2-5 parts; Nano-mineral filler: 1-4 parts; Crosslinking agent: 0.5-2 parts; Plasticizer: 2-5 parts; The antibacterial agent is prepared by the following method: S1: Under nitrogen protection, protocatechuic acid was first protected with phenolic hydroxyl groups to obtain acetylated protocatechuic acid. Then, anhydrous toluene, ethanolamine, and p-toluenesulfonic acid were mixed and stirred at 80-90℃. The acetylated protocatechuic acid was added in batches under light protection and the reaction was carried out for 6-9 hours to obtain intermediate 1. S2: Under nitrogen protection and in the dark at room temperature, 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide and triethylamine are added sequentially to anhydrous THF, stirred and activated, and then intermediate 1 is added. The reaction is carried out at 25-35℃ for 14-16 hours to obtain the antibacterial agent.

2. The absorbable suture containing silk fibroin according to claim 1, characterized in that, In step S1, the molar ratio of protocatechuic acid and ethanolamine is 1:(1.2-1.5).

3. The absorbable suture containing silk fibroin according to claim 1, characterized in that, In step S2, the molar ratio of 5,10,15,20-tetra(4-carboxyphenyl)porphyrin to intermediate 1 is 1:(4.1-4.3).

4. The absorbable suture containing silk fibroin according to claim 1, characterized in that, The modified toughening agent is prepared by the following method: N1: Under nitrogen protection, 2-formyl-furan-2-carboxylic acid, 4-dimethylaminopyridine and N,N'-dicyclohexylcarbodiimide were added sequentially to anhydrous THF, stirred and activated at room temperature, and then polyethylene glycol was added and reacted at room temperature to obtain intermediate A; N2: Mix intermediate A, aminopolyethylene glycol hydroxyl group, anhydrous ethanol and PBS buffer, add triethylamine, and react at 30-40℃ for 8-12h to obtain the modified toughening agent.

5. The absorbable suture containing silk fibroin according to claim 4, characterized in that, In step N1, the mass ratio of polyethylene glycol to 2-formyl-furan-2-carboxylic acid is 1:(0.29-0.32).

6. The absorbable suture containing silk fibroin according to claim 4, characterized in that, In step N2, the mass ratio of intermediate A to amino polyethylene glycol hydroxyl group is 1:(1.8-1.9).

7. The absorbable suture containing silk fibroin according to claim 1, characterized in that, The nano-mineral filler is nano-hydroxyapatite.

8. The absorbable suture containing silk fibroin according to claim 1, characterized in that, The crosslinking agent is genipin.

9. The absorbable suture containing silk fibroin according to claim 1, characterized in that, The plasticizer is one of acetylglucosyl citrate and tributyl citrate.

10. A method for preparing an absorbable suture containing silk fibroin according to any one of claims 1-9, characterized in that, Includes the following steps: (1) Weigh out the following by weight: 35-50 parts silk protein, 10-20 parts polylactic acid, 15-25 parts polyglycolic acid and lactide, 1-3 parts antibacterial agent, 2-5 parts modified toughening agent, 1-4 parts nano mineral filler, 0.5-2 parts crosslinking agent, and 2-5 parts plasticizer; (2) Mix silk fibroin with 9.3M LiBr aqueous solution, stir and mix well, and dialyze to obtain silk fibroin solution; mix polylactic acid, polyglycolic acid, and hexafluoroisopropanol, add to silk fibroin solution after ultrasonic rotary evaporation, then add modified toughening agent, nano mineral filler, plasticizer, and antibacterial agent, stir, add crosslinking agent, and ultrasonic degassing to obtain spinning solution; (3) The spinning solution is used to prepare a fiber membrane by electrospinning technology. After continuous spinning for 4 hours, the fiber membrane is collected and dried under vacuum at 60°C for 12 hours to obtain a dried fiber membrane. The process parameters of the electrospinning technology are set as follows: voltage 20kV, receiving distance 12cm, spinning solution flow rate 8.0ml / h, ambient temperature 25°C, relative humidity 20%, and receiver rotation speed 500rpm. (4) Immerse the dried fiber membrane in an ethanol / water mixture containing 0.1% w / v genipin, take it out and dry it after 4 hours. Cut it into strips 0.3-0.4 mm wide and twist them into shape. Heat set at 60℃ for 10 minutes and sterilize with ethylene oxide to obtain absorbable suture containing silk protein.

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