阅读说明：本技术 一种具有凝胶涂层的缝合线及其制备方法 (Suture line with gel coating and preparation method thereof ) 是由 郑兆柱 王文君 汪涛 方岩 李刚 卢神州 王晓沁 于 2021-09-13 设计创作，主要内容包括：本发明涉及一种具有凝胶涂层的缝合线,将缝合线表面部分溶解形成溶融层,部分分子一端游离,一端仍固定在缝合线上,然后通过这些分子自身交联和/或与其他物质交联在缝合线表面形成水凝胶层,得到本发明的缝合线。本发明制备的缝合线克服了涂层与缝合线结合不强、缝合线表面粗糙的问题,能在缝合过程和之后极大减少与组织间摩擦拉扯,便于负载药物、生物活性制剂等且对所载物质进行有效延缓或控释,促进损伤组织愈合。(The invention relates to a suture with a gel coating, which is obtained by partially dissolving the surface of the suture to form a dissolved layer, leaving one end of partial molecules free and the other end still fixed on the suture, and then forming a hydrogel layer on the surface of the suture through self-crosslinking and/or crosslinking with other substances of the molecules. The suture prepared by the invention overcomes the problems of weak bonding between the coating and the suture and rough surface of the suture, can greatly reduce friction and pulling between the suture and tissues during and after the suture process, is convenient for loading drugs, bioactive preparations and the like, effectively delays or controls the release of the loaded substances, and promotes the healing of damaged tissues.)

1. A suture having a gel coating, characterized by: the surface of the suture is a hydrogel coating, and the hydrogel coating is obtained by partially dissolving the surface of the suture and then forming hydrogel on the surface of the suture through chemical crosslinking.

2. The suture of claim 1, wherein: the hydrogel is formed by crosslinking a part of dissolved suture matrix by itself, and/or by crosslinking the dissolved suture matrix and the suture matrix, and/or by crosslinking the dissolved suture matrix and a natural high molecular material.

3. The suture of claim 2, wherein: the natural polymer material is selected from silk fibroin, hyaluronic acid, chitosan, gelatin, alginate, collagen and one or more of silk fibroin, hyaluronic acid, chitosan, gelatin, alginate or collagen derivatives.

4. The suture of claim 1, wherein: the suture line is a real silk suture line, a collagen suture line or a synthetic suture line.

5. The suture of any one of claims 1-4, wherein: the hydrogel contains one or more of humectant, antibacterial substance, antiinflammatory substance, cell and growth factor.

6. The suture of claim 5, wherein:

the humectant is selected from one or more of ethylene glycol, glycerol, ethylene glycol, propylene glycol, sodium lactate, sodium hyaluronate and sodium acetate;

the antibacterial substance is selected from one or more of natural antibacterial agent, organic antibacterial agent, photocatalytic inorganic antibacterial agent, metal inorganic antibacterial agent and broad-spectrum antibiotic;

the anti-inflammatory substance is selected from one or more of curcumin, artemisinin, dexamethasone, methylprednisolone and diphosphate liposome;

the growth factor is one or more selected from peptide hormone, epidermal growth factor, fibroblast growth factor, platelet-derived proliferation factor, growth hormone release inhibiting factor, cortisol and thyroxine.

7. A method for preparing a suture thread with a gel coating is characterized by comprising the following steps: dissolving the surface part of the suture to form a dissolved layer on the surface, and then loading hydrogel on the surface of the suture through chemical crosslinking to obtain the suture.

8. The method of claim 7, comprising the steps of:

s1: dissolving the surface part of the suture to form a dissolved layer, wherein the dissolved layer contains a dissolved suture matrix;

s2: crosslinking the molten suture matrix itself to form a gel to obtain the suture;

or adding a suture matrix solution, and crosslinking the molten suture matrix and the suture matrix in the suture matrix solution to form gel to obtain the suture;

or adding a natural polymer material solution and a cross-linking agent, and enabling the melted suture line matrix and the natural polymer material to be cross-linked to form gel, so as to obtain the suture line.

9. The method of claim 8, wherein: before the gel coating forms gel, one or more of a humectant, an antibacterial substance, an anti-inflammatory substance, cells and a growth factor are added into the melting layer, the suture matrix solution or the natural polymer material solution.

10. The method of claim 7, wherein: after partial dissolution, the strength of the suture does not vary by more than 60%.

Technical Field

The invention relates to the technical field of biomedical materials, in particular to a suture with a gel coating and a preparation method thereof.

Background

Sutures are a class of special threads based on fibers, in the form of monofilaments or multifilaments, and designed to be degradable or permanently left in the body. A variety of materials have been invented and used as surgical sutures, including plastics (degradable polyvinyl alcohol and polylactic acid or non-degradable nylon and polypropylene), biologically derived proteins (collagen and silk) and metals (stainless steel and nitinol). Sutures have been widely used in many branches of medicine, such as wound closure and anastomosis. However, the suture thread does not satisfy the effect of promoting healing by simply suturing a wound, and the research of a suture product with low injury and high efficiency is further hoped. There are also many studies focusing on different types of medical wound repair articles, such as medical adhesives, metal staples, medical tapes and metal wires as alternatives. However, the development and commercialization of alternative products are not mature, and the stability and flexibility of medical sutures are not yet provided.

However, the performance of existing sutures is limited by their poor biomechanical properties and functionality, which can easily lead to surgical and post-operative complications. This is due to the inherent drawbacks of the suture, which is made of rigid dry material, first, because of the large mechanical loads required to be carried along the shaft to access the tissue, which mechanical mismatch can lead to inflammation and impaired healing results. Second, the rough surface of the suture, particularly the braided suture, can drag and frictionally contact tissue during and after suture placement, and this mechanical irritation can damage delicate tissue and tissue in disease conditions such as aneurysms and ulcers, leading to postoperative complications.

The traditional suture coating uses beeswax as a coating agent, and the beeswax coating has the advantages of smooth surface, uniform and consistent wire diameter and lower coating process cost and is still widely used at present due to good biological performance of the beeswax. Besides beeswax, the polyether amide is used as a coating agent in foreign countries, and the coating agent not only can ensure the performance of the original suture, but also can improve the effectiveness of the suture coating, so that the coated suture is smooth and flexible and has good performance. Davis & Gerk company adopts silicon coating to replace traditional beeswax coating, and the properties of the suture such as hand feeling, knotting strength and the like are further improved. However, the traditional coating can only make the surface of the suture smooth on a certain basis, improve the surface hand feeling of the suture and improve the knotting strength. Chinese patent CN 111529752 a reports that the outer surface of the suture is provided with a hydrogel coating which acts as tissue glue and has antibacterial, anti-inflammatory and healing promoting effects, and the gel-forming natural polymer material comprises chitosan, gelatin, collagen, sodium alginate or silk fibroin. In the patent, Tannic Acid (TA) is used as a hydrogel crosslinking agent, and meanwhile, the TA has a glue effect and has antibacterial and anti-inflammatory effects. On one hand, the tannin cross-linking agent limits the gel property and application, and on the other hand, the hydrogel and the suture line are hard mixed, namely, only weak acting force exists between the hydrogel and the suture line, and more is a package. However, due to the chemical inertness of the suture material and the high mechanical load requirements of the suture application, the physical coating of the suture is generally brittle, easily chipped and delaminated and does not bond sufficiently strongly to the suture, there is no well-defined force-chemical bond between the suture and the gel, and there is no fusion and chemical cross-linking in the molten state. Obviously, the adhesion of the suture coating is crucial and is considered a prerequisite for any reliable functionalization, from which the present invention follows.

Disclosure of Invention

In order to solve the technical problems, the invention provides the suture with the gel coating, the surface of the suture is provided with the melting layer, and then the hydrogel coating is formed through chemical crosslinking, so that the problems of weak bonding between the coating and the suture and rough surface of the suture are solved, the friction and pulling between the coating and tissues can be greatly reduced in the suturing process and later, the strong bonding between the coating and the suture is realized, and the gel stripping phenomenon in the clinical application and the recovery period is avoided.

The first purpose of the invention is to provide a suture with a gel coating, wherein the surface of the suture is provided with the hydrogel coating, and the hydrogel coating is obtained by partially dissolving the surface of the suture and then forming hydrogel on the surface of the suture through chemical crosslinking.

Further, the hydrogel is formed by crosslinking a partially dissolved molten suture matrix with itself, and/or by crosslinking a partially dissolved molten suture matrix with a suture matrix, and/or by crosslinking a molten suture matrix with a natural polymer material.

In the prior art, most of the suture line coatings are formed by soaking, drying, carrying out surface activation by plasma or dopamine, then loading hydrogel or normal saline to soak and activate gel hydrophilic groups to form a suture line coating, the suture line is partially dissolved on the surface to form a dissolved layer, one end of partial molecules is free, and the other end of the partial molecules is still fixed on the suture line, the formed coating and the suture line are fused mutually in a dissolved state and are chemically cross-linked to form gel, the binding force of the formed coating and the suture line is stronger, the surface is smooth, various substances can be loaded on the basis of the gel, the suture line coatings can be applied to specific tissues to promote wound healing, different loaded substances can be replaced to be applicable to functional applications under different scenes, and the suture line coatings are non-toxic and safe and expand downstream applications.

Further, the suture is a silk suture, a collagen suture or a chemical synthetic suture. The silk fibroin hydrogel is preferably a silk suture, the surface of the silk suture is formed by hydrogel, and the hydrogel is obtained by dissolving part of the surface of the silk suture and then forming silk fibroin-based hydrogel through chemical crosslinking.

Preferably, the silk fibroin-based hydrogel is formed by crosslinking a partially dissolved fused silk fibroin by itself, and/or by crosslinking a fused silk fibroin with silk fibroin, and/or by crosslinking a fused silk fibroin with a natural polymer material.

Further, the natural polymer material is silk fibroin, hyaluronic acid, chitosan, gelatin, alginate, collagen and derivatives thereof, etc.

Further, the chemically synthesized suture is chemically synthesized suture such as PGA, PDO, PGLA, PGCL, PPDO, PLLA, PCL, etc.

Further, the hydrogel contains a humectant.

Further, the humectant is selected from one or more of ethylene glycol, glycerin, ethylene glycol, propylene glycol, sodium lactate, sodium hyaluronate and sodium acetate.

The requirement of the storage condition of the gel suture is severer than that of the common suture, the water retention rate is also one of important factors for determining the gel suture, and the use effect of the suture after dehydration is even inferior to that of the suture before coating, so the invention adds the moisture retention component into the hydrogel, avoids the excessive dehydration and the deflation of the hydrogel, ensures the warmth and moistness of the gel coating in the recovery period, reduces the pain of patients and promotes the tissue repair, meanwhile, on the basis of keeping the original mechanical property of the suture, the maintenance of the wetness of the gel suture provides a foundation for loading more medicines, growth factors and cells, and can endow the gel suture with more functions.

Further, the hydrogel contains one or more of an antibacterial substance, an anti-inflammatory substance, cells and a growth factor.

Further, the antibacterial substance is a natural antibacterial agent such as extracts of plants including phellodendron, honeysuckle and forsythia, chitosan and derivatives thereof, a low molecular weight organic antibacterial agent such as quaternary ammonium salt, quaternary phosphonium salt, organic metal, halogenated amine and biguanide, a high molecular weight organic antibacterial agent such as quaternary ammonium salt, quaternary phosphonium salt and guanidine, a photocatalytic inorganic antibacterial agent such as zinc oxide, titanium dioxide and zirconium oxide, a metallic inorganic antibacterial agent in which a metal such as silver, copper and zinc or ions thereof are carried on a porous material such as silica gel and zeolite, a broad spectrum antibiotic such as aminoglycosides, quinolones and chloramphenicol, mupirocin antibiotics, vancomycin and the like.

Further, the anti-inflammatory agent is curcumin, artemisinin, dexamethasone, methylprednisolone, diphosphate liposome, etc.

Further, the growth factor is peptide hormone such as insulin, Epidermal Growth Factor (EGF), Fibroblast Growth Factor (FGF), platelet-derived growth factor (PDGF), growth hormone release inhibitory factor (SRIH), and the like, as well as cortisol and thyroxine (T3), and the like.

The suture used clinically at present lacks advanced wound management function, does not have drug delivery or sensing ability and the like. There are also drug eluting or antimicrobial Coated sutures available on the market that are capable of releasing drugs or antimicrobial compounds, such as Coated ViCRYL Plus Antibacterial manufactured by Qiangsheng corporation. However, these methods still suffer from complex manufacturing processes, high costs, limited physical integrity, and biomechanical constraints. Strategies for suture functionalization include bulk modification and surface functionalization. The former involves the bottom-up method of producing sutures, which affects the strength of the suture and is not suitable for use in commercial sutures. To minimize the change in properties, surface functionalization forms suture coatings by dip/dip, layer-by-layer deposition, grafting and dipping, and these physical methods also suffer from weak bonding. The invention loads medicines, growth factors and cells in the gel, can sense, report and respond the wound healing process, effectively reduces the probability of infection of the operation part in a certain range, is nontoxic and safe, has simple and convenient preparation method, and has important significance for clinical application of suture.

The second purpose of the invention is to provide a preparation method of the suture thread, which comprises the following steps: dissolving the surface part of the suture to form a dissolved layer on the surface, and then loading hydrogel on the surface of the suture through chemical crosslinking to obtain the suture.

Further, the preparation method of the suture comprises the following steps:

s1: dissolving the surface part of the suture to form a dissolved layer, wherein the dissolved layer contains a dissolved suture matrix;

s2: crosslinking the melted suture matrix to form gel to obtain the suture;

or adding suture matrix solution to make the suture matrix in the suture matrix solution and the melted suture matrix cross-linked to form gel to obtain suture;

or adding natural polymer material solution and cross-linking agent to make the melted suture matrix and natural polymer material cross-linked to form gel so as to obtain the suture.

Further, before the gel coating forms gel, one or more of a humectant, an antibacterial substance, an anti-inflammatory substance, cells and a growth factor are added into the melting layer, the suture matrix solution or the natural polymer material solution.

Further, the strength of the suture does not change more than 60% after partial dissolution.

Further, in step S1, when the suture thread is a collagen suture thread, the silk dissolving liquid used for partial dissolution is hydrochloric acid.

Further, the concentration of hydrochloric acid is 1-5M when the suture is partially dissolved.

Further, in step S1, when the suture thread is a chemical synthetic suture thread, a solution formed by melting at a high temperature or a solution of benzene, dichloromethane or a mixture thereof is used as a solution for melting.

Further, chitosan and its derivatives use glutaraldehyde as a cross-linking agent, gelatin and its derivatives use glutaraldehyde as a cross-linking agent, alginate and its derivatives use divalent cations as a cross-linking agent, collagen and its derivatives use glutaraldehyde, genipin, carbodiimide, ethylene oxide, diphenylphosphate acyl azide, or quinone compounds as a cross-linking agent.

Further, in step S1, when the suture thread is a silk suture thread, the silk solution used for partial dissolution is a lithium bromide silk solution system, ternary mixed solution (CaCl)₂-EtOH-H₂O) a silk-dissolving system, a formic acid-lithium bromide system, a formic acid-calcium chloride system, a Hexafluoroisopropanol (HFIP) system, and the like have been reported.

Further, the concentration of lithium bromide in partially dissolved sutures is in the range of 1-10M, preferably 2-9.8M.

Further, the silk fibroin is crosslinked by a crosslinking agent, enzyme crosslinking, or photo-crosslinking. The crosslinking agent is diglycidyl ether crosslinking agent (such as BDDE), glutaraldehyde, epoxy compound, carbodiimide, etc. which can crosslink silk fibroin.

Further, in step S2, when crosslinking is performed using a crosslinking agent, the concentration of lithium bromide after the addition of the crosslinking agent is 1 to 10M, preferably 2 to 9.8M.

Further, after the cross-linking agent is added, the concentration of the silk fibroin is 1-300mg/mL, preferably 10-250 mg/mL.

Further, the ratio of the mass of the silk fibroin in the solution to the volume of the cross-linking agent is 1g: 0.5. mu.L-1 mL, preferably 1g: 0.5. mu.L-500. mu.L.

Further, the temperature of the crosslinking reaction is 10 to 100 ℃ and preferably 25 to 80 ℃.

Further, the time of the crosslinking reaction is 3min to 24h, preferably 1 to 6 h.

Further, in step S2, when enzyme crosslinking is employed, horseradish peroxidase, polyphenol oxidase, transglutaminase, neuraminidase, lysyl oxidase, or the like can be used. The HRP ternary system can also catalyze and oxidize the tyrosine residual group in the silk fibroin, so that free radicals are generated on a benzene ring containing phenolic hydroxyl in the tyrosine residual group, self-crosslinking of silk fibroin molecules or graft polymerization of the silk fibroin molecules and exogenous vinyl functional monomers is initiated, and biological functionalization of the silk suture is realized.

Further, the step (2) is followed by a step of removing the silk solution, unreacted cross-linking agent or natural polymer material, and free silk fibroin.

By the scheme, the invention at least has the following advantages:

the suture line of the invention is partially dissolved on the surface to form a dissolved layer, one end of partial molecules is free, and the other end is still fixed on the suture line, and then a hydrogel layer is formed on the surface of the suture line through chemical crosslinking, thus overcoming the problems of weak bonding between a coating and the suture line and rough surface of the suture line, greatly reducing friction and pulling between the suture line and tissues during and after the suture process, facilitating loading of medicines, bioactive preparations and the like, effectively delaying or controlling release of the loaded substances, and promoting healing of injured tissues.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following description is made with reference to the preferred embodiments of the present invention and the accompanying detailed drawings.

Drawings

In order that the present disclosure may be more readily and clearly understood, reference will now be made in detail to the present disclosure, examples of which are illustrated in the accompanying drawings.

FIG. 1 is a comparison of the silk suture of example 1 before and after partially dissolving;

FIG. 2 is a diagram of the dip coating of example 2 in a natural polymer solution;

fig. 3 is a suture penetration intravascular test force diagram prepared in example 3.

Detailed Description

The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.

EXAMPLE 1 formation of a molten layer on the surface of a Silk suture

S1, adopting a 16-spindle knitting machine, wherein the knitting parameters are gear ratio 81/44#, the knitting speed is 80rmp, the thread body part of the suture thread is made of two strands of raw silk, 2.2Tex silk is used as a shell thread, and 7.3Tex silk is used as a core thread. According to the requirement of 2-0 in YY0167-2020 standard, a braided medical suture is designed, and the diameter of the suture is 0.300-0.349 mm.

S2, measuring the braided silk suture, dipping the braided silk suture in a mixed solution of a lithium bromide solution and BDDE, and preparing hydrogel on the surface of the braided silk suture after partial dissolution. Orthogonal tests were performed on lithium bromide concentration, reaction temperature and reaction time conditions:

concentration of lithium bromide: 1M, 2M, 3M, 4M, 5M, 6M, 7M, 8M, 9.3M, 9.5M, 9.8M.

Reaction time: 1 minute, 3 minutes, 5 minutes, 7 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes.

Reaction temperature: -20 ℃, 0 ℃, 4 ℃, 25 ℃, 37 ℃, 60 ℃, 80 ℃.

Weighing the mass of the real silk suture before partial dissolution, repeatedly washing the real silk suture with deionized water after partial dissolution according to the test conditions until a molten layer obtained by partial dissolution is completely removed, drying, weighing the mass of the real silk suture after partial dissolution, and calculating to obtain the mass loss rate W of the real silk suture. The mass loss rate formula is as follows, wherein W is the suture mass loss rate%, W₁Is the weight g, W of the suture before partial dissolution₂Is the mass g of the suture after partial dissolution. Mass loss rate

W(％)＝(W₁-W₂)/W₁×100％

And (3) testing the breaking strength: and a simple knot is tied at the middle position of the suture to tighten the knot. The two ends of the suture line are respectively fixed on two fixing clamps of a material testing machine, the knot is positioned between the two fixing clamps, the suture line is tightened, the suture line is broken at a specified speed, and the maximum tension value is recorded and is used as a single value of breaking strength. If the suture breaks within lcm of the clamp, the data is discarded and another suture is taken. And obtaining the breaking strength value of a single suture, and calculating the breaking strength loss rate of the suture. The breaking strength loss rate formula is as follows, wherein F is the breaking strength loss rate% of the suture thread, F₁Is the breaking strength cN, F of the suture before partial dissolution₂Is the breaking strength cN of the suture after partial dissolution. Loss rate of breaking strength

F(％)＝(F₁-F₂)/F₁×100％

S3, result

The front and back pairs of partially dissolved silk suture are shown in fig. 1.

Under the condition of fixing the lithium bromide solution line bath ratio, the reaction temperature and the reaction time of a reaction system, changing the concentration of lithium bromide, putting 1g of the measured suture line into 10mL of lithium bromide solution, reacting for 3 minutes at 25 ℃, repeatedly washing with deionized water, drying and weighing, and calculating the mass loss rate and the fracture strength loss rate of the suture line. The resulting suture quality loss rate and breaking strength loss rate were varied as shown in the following table.

Concentration of lithium bromide (M)	1	2	3	4	5	6	7	8	9.3	9.5	9.8
												Mass loss rate W (%)	0.3	1	2	4	7	11	16	22	30	37	45
Breaking Strength loss Rate (%)	0.8	2	3	7	11	13	15	18	25	34	46

Under the condition of fixing the lithium bromide solution line bath ratio, the lithium bromide concentration and the reaction time of a reaction system, changing the reaction temperature, putting 1g of the measured suture line into 10mL of 7M lithium bromide solution, repeatedly washing the suture line with deionized water after reacting for 3 minutes, drying and weighing the suture line, and calculating the mass loss rate and the breaking strength loss rate of the suture line. The resulting suture quality loss rate and breaking strength loss rate were varied as shown in the following table.

Reaction temperature (. degree.C.)	-20	0	4	25	37	60	80
								Mass loss rate W (%)	0.01	0.03	0.1	12	19	35	47
Breaking Strength loss Rate (%)	0.02	0.5	4	20	45	59	77

Under the condition of fixing the lithium bromide solution line bath ratio, the lithium bromide concentration and the reaction temperature of a reaction system, changing the reaction time, putting 1g of the measured suture line into 10mL of 7M lithium bromide solution, repeatedly washing the suture line with deionized water after the reaction at the temperature of 25 ℃, drying and weighing the suture line, and calculating the mass loss rate and the fracture strength loss rate of the suture line. The resulting suture quality loss rate and breaking strength loss rate were varied as shown in the following table.

Reaction time (min)	1	3	5	7	10	20	30	40
									Mass loss rate W (%)	5	10	16	22	29	37	41	63
Breaking Strength loss Rate (%)	9	13	18	21	25	36	55	89

Example 2 direct formation of hydrogel coating on Silk suture Using the melt layer

S1, adopting a 16-spindle knitting machine, wherein the knitting parameters are gear ratio 81/44#, the knitting speed is 80rmp, the thread body part of the suture thread is made of two strands of raw silk, 2.2Tex silk is used as a shell thread, and 7.3Tex silk is used as a core thread. According to the requirement of 2-0 in YY0167-2020 standard, a braided medical suture is designed, and the diameter of the suture is 0.300-0.349 mm.

S2, measuring the braided silk suture, dipping the braided silk suture in a mixed solution of a lithium bromide solution and BDDE, and preparing hydrogel on the surface of the braided silk suture after partial dissolution. Orthogonal tests were performed on lithium bromide concentration, lithium bromide to suture ratio, BDDE addition in lithium bromide, reaction temperature and reaction time conditions:

concentration of lithium bromide: 1M, 2M, 3M, 4M, 5M, 6M, 7M, 8M, 9.3M, 9.5M, 9.8M.

Ratio of suture to lithium bromide: 0.5 mg: 1g, 5 mg: 1g, 50 mg: 1g, 100 mg: 1g, 50 mg: 1g, 1g: 1g, 2 g: 1g, 5: 1g, 10 g: 1g, 50 g: 1g, 100 g: 1g, 200 g: 1g, 500 g: 1g of the total weight of the composition.

Lithium bromide to BDDE ratio: 1g: 0.2. mu.L, 1g: 0.5. mu.L, 1g: 0.75. mu.L, 1g: 1 μ L, 1g: 2 μ L, 1g: 5 μ L, 1g: 10 μ L, 1g: 20 μ L, 1g: 50 μ L, 1g: 100. mu.L, 1g: 120 μ L, 1g: 150 μ L, 1g: 300. mu.L, 1g: 500. mu.L, 1g: 750 μ L, 1g: 1000. mu.L.

Reaction temperature: -20 ℃, 0 ℃, 4 ℃, 25 ℃, 37 ℃, 60 ℃, 80 ℃.

Reaction time: 1 minute, 3 minutes, 5 minutes, 7 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 1 hour, 1.5 hours, 3 hours, 6 hours, 12 hours, 18 hours, 24 hours, 36 hours, 48 hours.

S3, result

According to the experimental scheme, the concentration of lithium bromide in a reaction system, the volume ratio of suture quality to a cross-linking agent, the reaction temperature and the reaction time are researched, and the silk fibroin hydrogel suture can be prepared when the concentration of lithium bromide in the reaction system is more than or equal to 1M, the reaction temperature is 25-80 ℃, and the reaction time is 3 minutes-48 hours. The higher the concentration of lithium bromide, the higher the temperature and the longer the time, the higher the dissolution proportion of the real silk suture, the larger the formation amount of the molten layer and the larger the mechanical loss of the suture. The invention can regulate and control the amount of the melting layer and protect the mechanical property of the suture line through the concentration, temperature and time of the lithium bromide.

Example 3 formation of composite hydrogel coating on Silk suture thread surface Using the molten layer

S1 preparation of a molten layer according to example 1, with the following specific conditions:

lithium bromide concentration at the time of formation of molten layer: 7M;

ratio of suture to lithium bromide: 1g: 10 mL;

lithium bromide ratio BDDE: 1g: 200 mu L;

time: 3 minutes;

temperature: at 25 ℃.

S2, dipping and coating in natural polymer solution:

concentration of silk fibroin solution: 0.5mg/mL, 1mg/mL, 4mg/mL, 7mg/mL, 10mg/mL, 15mg/mL, 20mg/mL, 25mg/mL, 50mg/mL, 75mg/mL, 100mg/mL, 120mg/mL, 125mg/mL, 150mg/mL, 175mg/mL, 200mg/mL, 250mg/mL, 300 mg/mL. Silk fibroin ratio BDDE: 1g: 200 μ L. See fig. 2.

Hyaluronic acid solution concentration: 0.5mg/mL, 1mg/mL, 4mg/mL, 7mg/mL, 10mg/mL, 15mg/mL, 20mg/mL, 25mg/mL, 50mg/mL, 75mg/mL, 100mg/mL, 120mg/mL, 125mg/mL, 150mg/mL, 175mg/mL, 200mg/mL, 250mg/mL, 300 mg/mL. Hyaluronic acid ratio BDDE: 1g: 200 μ L.

Silk fibroin/hyaluronic acid solution: 100 mg/mL. The total mass ratio of silk fibroin/hyaluronic acid BDDE: 1g: 200 μ L. The mass ratio of silk fibroin to hyaluronic acid is as follows: 10: 0. 9: 1. 8: 2. 7: 3. 6: 4. 5: 5. 4: 6. 3: 7. 2: 8. 1: 9. 0: 10.

s3: reaction temperature: 25 ℃, 37 ℃ and 60 ℃.

Reaction time: 1 minute, 3 minutes, 5 minutes, 7 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 1 hour, 1.5 hours, 3 hours, 6 hours, 12 hours, 18 hours, 24 hours, 36 hours, 48 hours.

S4, embedding the suture with the surface partially dissolved into a hydrogel cuboid, adhering two opposite sides of the hydrogel cuboid to two acrylic plates as rigid constraints, and pulling out with an Instron machine while testing the tensile force F data for the pulled suture. The suture without partial dissolution was tested for peel tension in the same manner as a control.

S5, result

According to the concentration of the added natural polymer, a layer of melting layer can be formed on the surface of the suture line within the reaction time of 3 minutes to 48 hours.

As shown in fig. 3, when the partially dissolved suture thread is threaded into the capillary, and the mother solution before forming the gel is injected into the capillary, and the gel is formed in the capillary according to the above reaction conditions, the whole gel suture thread can be completely pulled out of the capillary, which shows that the bonding force between the gel and the suture thread is much larger than the friction between the gel and the capillary, and the conclusion that the gel is strongly bonded with the partially dissolved suture thread is confirmed.

Under the same condition, compared with the suture line which is not partially dissolved, the pulling force required for pulling the silk fibroin gel suture line formed after the silk suture line is partially dissolved is about 3 times higher, and in the subsequent suture application, only 1 of 10 gel suture lines with the dissolved layer on the surface has the stripping phenomenon, which is far less than 3 gel suture lines without the dissolved layer. All of the above approaches can verify that there is a strong bond between the partially dissolved suture and the gel.

Through the test of the peeling force of the gel and the suture line, the hyaluronic acid gel suture line subjected to partial dissolution treatment is improved by more than one time compared with the peeling pulling force of a control group, and the conclusion that the suture line subjected to partial dissolution to form a dissolution layer has stronger bonding force with the gel is verified. In vivo, the hydrogel significantly enhances the healing efficiency of diabetic full-thickness skin wounds, and is characterized by increased wound closure rate, rapid angiogenesis, re-epithelialization and collagen deposition within the wound site. In vitro, the hydrogel remarkably promotes the proliferation, migration and tube forming capability of human umbilical vein endothelial cells.

The research finds that the crosslinking degree of the silk fibroin mixed hyaluronic acid and BDDE crosslinking on the suture is similar to that under the condition of independent crosslinking. The mechanical property of the suture coated by the hydrogel is obviously improved, and compared with a control group, the stripping tension is obviously improved. Chronic wound healing evaluation in vivo in diabetic rats showed that the dressing resulted in faster wound healing and also showed excellent re-epithelialization, dense collagen deposition and angiogenic properties.

Similar results and conclusions can be obtained from other natural high molecular polymers such as chitosan, gelatin, alginate, collagen or one or more of the derivatives thereof. Except that chitosan and its derivatives use glutaraldehyde as a cross-linking agent, gelatin and its derivatives use glutaraldehyde as a cross-linking agent, alginate and its derivatives use divalent cations as a cross-linking agent, collagen and its derivatives use glutaraldehyde, genipin, carbodiimide, ethylene oxide, diphenylphosphate acyl azide, or quinone compounds as a cross-linking agent.

Example 4 HRP-crosslinked silk fibroin gel suture with composite hydrogel coating formed on the surface of silk suture by using the melting layer

S1, preparing a molten layer according to the step S1 in example 3;

s2, dipping the coating in silk fibroin solution:

and taking 20mL of 6 wt% regenerated silk fibroin solution, and then adding 400 mu L of horseradish peroxidase, 1000U/mL of horseradish peroxidase and 200 mu L of 0.1 wt% hydrogen peroxide to obtain a mixed solution. The suture thread treated in step 1 of example 3 was dipped in the mixed solution.

S3, standing in an incubator at 37 ℃ for 30min for crosslinking to obtain the HRP crosslinked silk fibroin gel suture. The same gluing operation was also performed on the suture surface that was not treated in step S1 of example 3, as a control.

S4, two sets of sutures were embedded in a hydrogel cuboid, two opposite sides of the hydrogel cuboid were glued to two acrylic plates as rigid constraints, and then pulled out with an Instron machine while testing the tensile force F data for the pulled out sutures.

S5, result

Research shows that the HRP cross-linked silk fibroin gel suture line can be prepared by dipping 20mL of 6 wt% regenerated silk fibroin solution, adding 400 mu L of suture line of 1000U/mL horseradish peroxidase and 200 mu L of 0.1 wt% hydrogen peroxide mixed solution, and standing in an incubator at 37 ℃ for 30 min. And the pulling force required for extracting the suture from the gel block by the HRP silk fibroin gel suture obtained by partial dissolution is improved by more than 2 times compared with the suture which is not subjected to partial dissolution, and the strong combination between the suture and the gel after partial dissolution is proved.

HRP crosslinked gel sutures outside of the above conditions can also achieve the same numerical results as the above results. In addition, enzyme crosslinking such as transglutaminase (TGase), Tyrosinase (Tyrosinase), lysine Oxidase (Lysyl Oxidase) and the like mostly occurs in a neutral water environment at body temperature, the reaction conditions are mild, the crosslinking time is short, and the prepared hydrogel material has a stable structure and high mechanical strength, which is similar to the above results.

Example 5 photo-crosslinked silk fibroin gel suture with composite hydrogel coating formed on silk suture surface by using melting layer

S1, preparing a molten layer according to the step S1 in example 3;

s2, dipping the coating in silk fibroin solution:

A. ultraviolet crosslinking silk fibroin:

the photoinitiator Irgacure 2959 was added to a 6 wt% SFMA hydrogel prepolymer solution to a final concentration of 1 wt%. The SFMA prepolymer solution was stirred vigorously at room temperature for 10 minutes and the uniform solution was dipped into the suture treated with S1 in example 3. And then exposed to uv light for 2 minutes to allow free radical polymerization of the SFMA chains by photocrosslinking. SFMA is crosslinked under the conditions of ultraviolet light and the existence of a photoinitiator Irgacure 2959 to form a chemically crosslinked photocrosslinking network. The same treatment was carried out on the suture thread which was not subjected to the step S1 in example 3 as a control.

Two sets of sutures were embedded in a cuboid of hydrogel with two opposing sides of the cuboid of hydrogel adhered to two acrylic plates as rigid constraints and then pulled out with an Instron machine while tensile force F data was tested for comparison as the sutures were pulled out.

The research shows that after the suture is irradiated by ultraviolet light, a layer of SFMA hydrogel is formed on the surface of the suture. Furthermore, the partially dissolved suture showed about 1.5 times higher pulling force than the suture without partial dissolution treatment as a result of the test pulling force for withdrawing the suture from the gel block, confirming that the bond between the gel and the suture was stronger with the partially dissolved suture.

In addition, the silk fibroin-based hydrogel suture of the present invention can be prepared by the following methods (but not limited to the following methods):

the PVA modified by isocyano ethyl methacrylate and SF (silk fibroin) are blended and polymerized by ultraviolet light initiation, and then semi-interpenetrating network hydrogel is formed on a melting layer, wherein the PVA capable of being crosslinked under the ultraviolet light forms a single network, and the SF has no crosslinking capability and is distributed among the networks formed by the PVA.

Modifying ethylene groups on SF nano/micron particles, blending the modified particles and chitosan modified with the ethylene groups, and carrying out copolymerization under ultraviolet light to realize the preparation of the photo-crosslinking SF hydrogel, successfully modifying the ethylene groups on SF molecules, so that the single SF can be crosslinked on a melting layer under the ultraviolet light to form a hydrogel network.

Adding riboflavin and horseradish peroxidase into an SF aqueous solution, continuously introducing oxygen into a reaction system, exciting the riboflavin to generate active oxygen free radicals under ultraviolet irradiation, enabling the active oxygen free radicals to react with amino groups, phenol groups and the like on SF molecules, and finally initiating SF to crosslink on a melting layer to form hydrogel. The hydrogel has good elasticity and transparency, and shows excellent cell compatibility in cell culture.

B. Visible light cross-linked silk fibroin:

ruthenium is used as a catalyst, ammonium persulfate is used as an electron acceptor, and tyrosine on SF molecules is oxidized and reacts with each other to form di-tyrosine cross-linking through an intermediate formed under visible light. The hydrogel prepared by the method shows a storage modulus of about 78MPa under the condition of complete water absorption, and shows good biocompatibility and cell proliferation effect on the mouse chondroprotein cell culture. In addition, the method only needs 2min to realize the conversion of SF gelation, and overcomes the defect of long time consumption of genipin and enzyme crosslinking.

Under visible light, the riboflavin absorbs light energy and then captures electrons of tyrosine on SF molecules to form free tyrosine radicals, and the free tyrosine radicals react to generate two tyrosine bonds. The SF hydrogel formed on the melting layer by the method also shows good elasticity and optical transparency, which are probably common characteristics of the SF hydrogel formed by crosslinking two tyrosine bonds.

Other photoinitiators the silk fibroin-based hydrogel formed on the melt layer can yield experimental results similar to those described above.

Example 6 formation of humectant-containing composite gel coating suture on Silk suture by Using melting layer

S1, preparing a molten layer according to the step S1 in example 3;

s2, dipping the coating in silk fibroin solution:

adding various humectants (glycerol, ethylene glycol, propylene glycol, sodium lactate, sodium hyaluronate and sodium acetate) into the mixed solution before forming gel in the examples 1-5 respectively to prepare a mixed solution containing 1-50 wt% of glycerol, 30 wt% of ethylene glycol, 30 wt% of propylene glycol, 30 wt% of sodium lactate, 30 wt% of sodium hyaluronate and 30 wt% of sodium acetate, gelling according to the steps, and testing the water content W of the silk suture. The water content formula is as follows, wherein W is the water content of the hydrogel, and W is₁And W₂The weight of the hydrogel and the weight of the xerogel are kg, respectively.

W＝(W₁-W₂)/W₁

Taking 30 wt% of glycerin mixed solution, ethylene glycol mixed solution, propylene glycol mixed solution, sodium lactate mixed solution, sodium hyaluronate mixed solution and sodium acetate mixed solution as examples, the water content test results are shown in the following table, wherein the moisturizing effect of glycerin is taken as a reference, and the moisturizing effect is shown to be obviously improved compared with glycerin by ℃.

Moisture-retaining agent

Glycerol

Ethylene glycol

Propylene glycol

Sodium lactate

Hyaluronic acid sodium salt

Sodium acetate

Effect

-

↑

↓

↓

↓

↑

Example 7 formation of composite gel-coated suture containing antibacterial substance, anti-inflammatory substance, cell or growth factor on Silk suture by Using the fused layer

S1, preparing a molten layer according to the step S1 in example 3;

s2, dipping the coating in silk fibroin solution:

(1) weighing berberine powder, dissolving in deionized water, adding into the mixed solution before forming gel in example 3, mixing the 4mg/mL berberine solution and silk fibroin solution uniformly, wherein the mass ratio of silk fibroin to berberine is 10:1, and forming gel according to the steps.

(2) The prepared silk fibroin/berberine gel has good antibacterial property, especially has outstanding antibacterial effect on staphylococcus aureus and escherichia coli, has a large antibacterial bandwidth, and has antibacterial persistence of 4 days. The prepared silk fibroin/berberine gel has good slow release performance, the release rate of the berberine on the silk fibroin is high in the first 48 hours, the stable state is achieved in 96 hours, and the sustained release time of the berberine on the silk fibroin can be more than 7 days.

Similar results can be obtained by replacing the berberine with other antibacterial substances, anti-inflammatory substances, cells or growth factors.

Example 8 preparation of hydrogel coating on surface of collagen suture Using the melted layer

S1, measuring the collagen suture line, dipping the collagen suture line in a mixed solution of hydrochloric acid solution and glutaraldehyde, and preparing hydrogel on the surface of the collagen suture line after partial dissolution. Orthogonal tests were performed on the conditions of salt acidity, hydrochloric acid to suture ratio, glutaraldehyde addition in hydrochloric acid, reaction temperature and reaction time:

hydrochloric acid concentration: 1M, 2M, 3M, 4M, 5M.

Suture to glutaraldehyde ratio: 0.5 mg: 1g, 5 mg: 1g, 50 mg: 1g, 100 mg: 1g, 50 mg: 1g, 1g: 1g, 2 g: 1g, 5: 1g, 10 g: 1g, 50 g: 1g, 100 g: 1g, 200 g: 1g, 500 g: 1g of the total weight of the composition.

Hydrochloric acid to glutaraldehyde ratio: 1g: 0.2. mu.L, 1g: 0.5. mu.L, 1g: 0.75. mu.L, 1g: 1 μ L, 1g: 2 μ L, 1g: 5 μ L, 1g: 10 μ L, 1g: 20 μ L, 1g: 50 μ L, 1g: 100. mu.L, 1g: 120 μ L, 1g: 150 μ L, 1g: 300. mu.L, 1g: 500. mu.L, 1g: 750 μ L, 1g: 1000. mu.L.

S2: dipping coating in natural polymer solution:

concentration of silk fibroin solution: 100 mg/mL. Silk fibroin ratio BDDE: 1g: 200 μ L.

Hyaluronic acid solution concentration: 100 mg/mL. Hyaluronic acid ratio BDDE: 1g: 200 μ L.

Silk fibroin/hyaluronic acid solution: 100 mg/mL. The total mass ratio of silk fibroin/hyaluronic acid BDDE: 1g: 200 μ L. The mass ratio of silk fibroin to hyaluronic acid is as follows: 1:1.

S3, reaction temperature: 25 ℃, 37 ℃, 60 ℃ and 80 ℃.

Reaction time: 1 minute, 3 minutes, 5 minutes, 7 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 1 hour, 1.5 hours, 3 hours, 6 hours, 12 hours, 18 hours, 24 hours, 36 hours, 48 hours.

S4, result

The higher the hydrochloric acid concentration, the higher the temperature and the longer the time, the higher the ratio of the collagen suture to be dissolved, the larger the amount of the molten layer formed, and the larger the mechanical loss of the suture. The invention can regulate and control the amount of the melting layer and the mechanical property of the protective suture line through the concentration, the temperature and the time of the hydrochloric acid.

According to different reaction temperatures, within the range of 3 minutes to 48 hours, the ideal hydrogel collagen suture can be obtained.

Example 9 preparation of hydrogel coating on PGLA, PGA, PLA, PDO suture thread surface Using the melt layer

S1, measuring the chemically synthesized suture, and dipping the chemically synthesized suture in a solution of benzene or dichloromethane or a mixed solution of the benzene and the dichloromethane.

S2, dipping and coating in natural polymer solution:

concentration of silk fibroin solution: 100 mg/mL. Silk fibroin ratio BDDE: 1g: 200 μ L.

Hyaluronic acid solution concentration: 100 mg/mL. Hyaluronic acid ratio BDDE: 1g: 200 μ L.

Silk fibroin/hyaluronic acid solution: 100 mg/mL. The total mass ratio of silk fibroin/hyaluronic acid BDDE: 1g: 200 μ L. The mass ratio of silk fibroin to hyaluronic acid is as follows: 1:1.

S3, reaction temperature: 25 ℃, 37 ℃ and 60 ℃.

Reaction time: 1 minute, 3 minutes, 5 minutes, 7 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 1 hour, 1.5 hours, 3 hours, 6 hours, 12 hours, 18 hours, 24 hours, 36 hours, 48 hours.

S4, result

The suture line made of PGLA, PGA, PLA, PDO and other materials can form a layer of melting layer on the surface of the suture line, so that the gel coating suture line with strong bonding force is obtained.

Example 10 gel coated suture in vivo experiments

The biological safety of the suture is verified for testing the immune inflammatory response level of the sample in an animal body, the influence on the neovascularization, the tissue healing condition and the like, the service performance of the suture is actually detected in an animal suture model, and the biocompatibility of the suture is characterized.

In animal experiments, 24 SD (Sprague-Dawley) male rats were first selected, the body weight was 310g at 200-. The first group is untreated braided filaments; the second group is a silk suture thread wrapped by silk fibroin gel; the third group was a commercial non-absorbable silk suture; the fourth group was the collagen suture with gel coating prepared in example 8; the fifth group was the gel coated chemically synthesized suture prepared in example 9.

SD rats were acclimatized before and one week later. The rats were anesthetized with pentobarbital (0.2mL/100g) prior to surgery and depilated at the operative field, and the operative site was sterilized. An incision of about 3cm is cut at the center of the abdomen of the rat, a suture sample is implanted into the subcutaneous part, then the suture is disinfected and sutured, and after the disinfection, the rat is put back into a cage to be raised and marked for observation. The rat wound temperature, infection, survival and daily physiological activities were observed and recorded daily at the site of material implantation and suture sites. The corresponding tissues and the wrapped material were taken out at 3, 7 and 14 days, respectively, fixed with 4% paraformaldehyde and stored.

The experimental result proves that the suture material prepared by the invention can cause slight inflammation in a short time when being implanted into an animal body as a foreign body, but the inflammatory reaction is weaker than that of an uncoated suture and a commercial suture, and the duration of the inflammation is shorter, thereby proving that the suture material has good biocompatibility. And the sutures of the second group, the fourth group and the fifth group have more fibroblasts, fibroblasts and new capillaries, so that the coated sutures are more beneficial to tissue recovery and have better accelerated repair capability on wounds.

Other gel sutures may achieve similar results as described above.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.