Neural suture line and preparation method thereof

Abstract

The invention discloses a nerve suture line and a preparation method thereof. The preparation method comprises the following steps: step 1, mixing type I collagen powder, glycerol and glutaraldehyde according to a weight ratio of 95: (4-10): (1-5); 2, preheating and melting the mixture, then carrying out melt spinning, and carrying out cooling, stretching and surface treatment on spun tows to obtain a primary suture line product; step 3, mixing the PLGA solution and the dexamethasone solution according to a volume ratio of 9: (1-6), and carrying out high-speed shearing emulsification on the mixed solution; 4, coating, drying and curing, surface treatment and sterilization treatment are conducted on the primary suture line product through an impregnation method, and the nerve suture line is obtained. The suture line prepared by adopting the preparation method of the nerve suture line can realize sustained release of dexamethasone, and is beneficial to reducing inflammatory response at the early stage of nerve injury and promoting nerve repair; in addition, dexamethasone also has the effect of reducing foreign body reaction, rejection reaction of an organism after the suture line is implanted can be reduced, and the biocompatibility of the suture line is improved.

Description

Technical Field

[0001] The invention relates to the technical field of medical materials, and in particular to a nerve suture and a preparation method thereof. Background Art

[0002] Peripheral nerve injury is one of the most common types of trauma in clinical practice, accounting for about 2-3% of all trauma. This type of injury not only causes the patient to lose motor and sensory functions, but may also cause chronic pain, seriously affecting the patient's quality of life. When a peripheral nerve is ruptured, end-to-end suture of the epineurium is usually required to restore the continuity of the nerve and create conditions for subsequent nerve regeneration.

[0003] At present, the commonly used nerve sutures in clinical practice are mainly 6-0, 8-0 or 10-0 absorbable sutures, such as sutures made of polylactic-co-glycolic acid (PLGA) or polydioxanone (PDS). Although these sutures can achieve mechanical fixation of the nerve stump, they can only play a passive supporting role and do not have the function of promoting nerve repair or regulating the local microenvironment.

[0004] However, a strong inflammatory response will occur early after peripheral nerve injury. This inflammatory response is the body's normal response to injury, but excessive inflammatory response will produce a series of adverse consequences: 1) Hindering the regeneration of nerve axons: Excessive inflammatory response will produce a large number of inflammatory factors and free radicals, which may inhibit the expression of nerve growth factor and hinder the extension of axons. 2) Leading to abnormal activation of fibroblasts: In an inflammatory environment, fibroblasts will be overactivated and produce a large amount of extracellular matrix proteins. 3) Causing scar formation and nerve adhesion: Excessive proliferation of extracellular matrix will form scar tissue, causing nerves to adhere to surrounding tissues, affecting the normal sliding and signal conduction of nerves.

[0005] In addition, surgical sutures, as foreign bodies implanted in the body, may also cause the body's rejection reaction. This rejection reaction will not only aggravate local inflammation, but may also lead to fibrosis of the tissue around the sutures, further affecting nerve repair. Summary of the invention

[0006] The purpose of the present invention is to provide a nerve suture and a preparation method thereof in view of the deficiencies in the prior art.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] The first aspect is to provide a method for preparing a nerve suture, comprising the following steps:

[0009] Step 1, mixing type I collagen powder, glycerol and glutaraldehyde in a weight ratio of 95:(4-10):(1-5);

[0010] Step 2, preheating and melting the mixture, and then performing melt spinning, cooling, stretching and surface treatment on the spun filament bundle to obtain a preliminary suture product;

[0011] Step 3, mixing the PLGA solution and the dexamethasone solution in a volume ratio of 9:(1-6), and subjecting the mixed solution to high-speed shear emulsification;

[0012] Step 4: coating the primary suture by dipping method, drying and solidifying, surface treatment and sterilization to obtain the nerve suture.

[0013] Furthermore, in the step 2, the melt spinning process includes: conveying the molten mixture to the spinneret through a metering pump, the spinneret temperature is controlled at 160-180° C., the spinneret hole diameter is 50-100 μm, and the spinning speed is 100-120 m / min.

[0014] Furthermore, in step 2, nitrogen at 25° C. is used as a cooling medium during the cooling process.

[0015] Furthermore, in the step 2, the stretching process is carried out at 40°C.

[0016] Furthermore, in step three, the PLGA solution is a 10-15% w / v PLGA (lactic acid: glycolic acid=75:25) dichloromethane solution; and the dexamethasone solution is a 2-5% w / v dexamethasone methanol solution.

[0017] Furthermore, in step three, the emulsification treatment is carried out in a 40-45° C. water bath, and high-speed shear emulsification is performed at a speed of 10000-12000 rpm for 10-15 minutes, and then 1-1.5% w / v Tween 80 is added as an emulsifier, and emulsification is continued for 5-10 minutes.

[0018] Furthermore, in step 4, the coating process includes: immersing the primary suture thread in the emulsified coating solution for 30-40 seconds, air-drying in a 40-45° C. incubator for 5-8 minutes, and repeating the process 3 times.

[0019] Furthermore, in the step 4, drying and curing is carried out in a vacuum drying oven at 37-40° C. for 24-36 hours.

[0020] Furthermore, in step 4, the sterilization treatment uses ethylene oxide gas sterilization at 37-40° C. for 4-6 hours.

[0021] The second aspect is to provide a nerve suture prepared by the above-mentioned preparation method.

[0022] The present invention adopts the above technical solution, and has the following technical effects compared with the prior art:

[0023] The present invention uses type I collagen with good biocompatibility as a substrate and prepares a suture with excellent mechanical properties by a melt spinning method; uses PLGA as a drug carrier and forms a uniform and stable dexamethasone coating on the surface of the suture by an emulsification-impregnation method; and by controlling the reaction temperature and emulsification technology, effectively avoids agglomeration and local deposition of dexamethasone during the coating process, thereby achieving uniform distribution of the drug.

[0024] By adopting the nerve suture preparation method of the present invention, three specifications of sutures of 6-0, 8-0 and 10-0 can be prepared to meet the needs of different nerve repair surgeries; the prepared sutures can achieve the sustained release of dexamethasone, which is beneficial to reduce the early inflammatory response of nerve damage and promote nerve repair; dexamethasone also has the effect of reducing foreign body reaction, which can reduce the body's rejection reaction after the suture is implanted and improve the biocompatibility of the suture. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with specific embodiments, but is not intended to be limiting of the present invention. It should be noted that the embodiments and features in the embodiments of the present invention may be combined with each other without conflict.

[0026] Example 1

[0027] This embodiment provides a method for preparing a nerve suture, comprising the following steps:

[0028] Step 1: Mix type I collagen powder (medical grade), glycerol (medical grade) and glutaraldehyde (medical grade) in a weight ratio of 95:4:1, and stir thoroughly for 30 minutes under vacuum conditions to ensure uniform mixing;

[0029] Step 2, melt spinning:

[0030] 1) Preheating: Place the mixture in a vacuum drying oven and preheat at 65°C for 2 hours to remove moisture;

[0031] 2) Melting: The preheated mixture is transferred to the hopper of the melt spinning machine, heated to 165°C, and maintained for 30 minutes to fully melt the collagen;

[0032] 3) Spinning: The molten collagen is delivered to the spinneret by a metering pump, the spinneret temperature is controlled at 160-180°C (preferably 160°C), the spinneret hole diameter is 50-100 μm (preferably 80 μm), and the spinning speed is 100-120 m / min (preferably 100 m / min);

[0033] 4) Cooling: The spun tow immediately enters the cooling zone, using 25°C nitrogen as the cooling medium;

[0034] 5) Stretching: The cooled filament bundle is subjected to hot stretching, and the stretching process is carried out at 40°C;

[0035] The stretching ratio is 3:1 to 5:1, preferably 4:1, and the wire diameter is controlled to three specifications: 0.07-0.099 mm (6-0 suture), 0.04-0.049 mm (8-0 suture), and 0.02-0.029 mm (10-0 suture);

[0036] 6) Surface treatment: The stretched tow was immersed in a 2% w / v glutaraldehyde aqueous solution for 30 seconds, and then rinsed with deionized water three times, each for 1 minute;

[0037] 7) Drying: Dry in a vacuum drying oven at 40°C for 4 hours.

[0038] Step 3, the PLGA solution and the dexamethasone solution are mixed in a volume ratio of 9:1-6, stirred at room temperature for 30 minutes, and the mixed solution is high-speed shear emulsified at a speed of 10000-12000 rpm (preferably 10000 rpm) in a 40-45° C. (preferably 40° C.) water bath for 10-15 minutes (preferably 10 minutes), and then 1-1.5% w / v (preferably 1% w / v) of Tween 80 is added as an emulsifier, and emulsification is continued for 5-10 minutes (preferably 5 minutes);

[0039] The PLGA solution is a 10-15% w / v (preferably 10% w / v) PLGA (lactic acid: glycolic acid = 75:25) dichloromethane solution; the dexamethasone solution is a 2-5% w / v (preferably 2% w / v) dexamethasone methanol solution.

[0040] Step 4: Coating by dipping method:

[0041] 1) immersing the suture prepared in step 2 into the emulsified coating solution for 30-40 seconds (preferably 30 seconds), air-drying in a thermostat at 40-45° C. (preferably 40° C.) for 5 minutes, repeating the immersion-air-drying process 3 times to form a multilayer coating;

[0042] 2) placing the coated suture in a vacuum drying oven at 37-40°C (preferably 37°C) for 24 hours to ensure that the solvent is completely evaporated;

[0043] 3) Gently rinse the surface of the suture with PBS buffer (pH = 7.4) to remove the drug that is not firmly adhered, and let it air dry naturally under sterile conditions;

[0044] 4) Sterilize with ethylene oxide gas at a temperature of 37-40°C (preferably 37°C) for 4 hours;

[0045] 5) Place the prepared suture in a sterile sealed package and store at 4°C in the dark for future use.

[0046] Verification Example 1

[0047] In order to verify that the nerve suture prepared by the present invention has the effect of sustained release of dexamethasone, the following in vitro experiments were conducted:

[0048] 1) Cut the nerve suture sample (6-0 suture prepared in Example 1) into small pieces of 5 cm in length and weigh them accurately;

[0049] 2) Immerse the suture sample in a centrifuge tube containing 10 mL PBS (pH = 7.4) and place it in a 37°C constant temperature water bath;

[0050] 3) At the predetermined time point, 1 mL of supernatant was removed and supplemented with 1 mL of fresh PBS;

[0051] 4) Determine the concentration of dexamethasone in the supernatant using HPLC method;

[0052] The chromatographic conditions are:

[0053] Chromatographic column: C18 reverse phase column (250mm×4.6mm, 5μm)

[0054] Mobile phase: acetonitrile-water (40:60, v / v)

[0055] Flow rate: 1.0mL / min

[0056] Detection wavelength: 240nm

[0057] Column temperature: 30°C

[0058] Injection volume: 20 μL 5) Calculate the cumulative release percentage of dexamethasone. The results are shown in Table 1:

[0059] Cumulative release percentage = (cumulative release amount / total amount of dexamethasone in suture) × 100%

[0060] Table 1

[0061] Time (day) Cumulative release percentage (%) 0.5 15.2±3.1 1 25.3±4.2 2 35.1±5.3 4 45.4±6.1 7 55.2±5.9 14 70.3±5.2 21 80.1±4.3 28 85.4±3.2 35 90.2±2.1 42 93.3±1.8 49 95.1±1.2 56 97.2±0.9

[0062] It can be seen that: 1) The release is faster in the initial stage (0-2 days), reaching about 35%, so as to quickly reach the therapeutic concentration.

[0063] 2) In the medium term (3-14 days), the release is stable, about 15-20% is released every week.

[0064] 3) In the later period (after 14 days), the release rate gradually slows down, showing the characteristics of a typical sustained-release curve.

[0065] 4) At 56 days (8 weeks), the cumulative release reached 97%, basically completing the drug release.

[0066] The above description is only a preferred embodiment of the present invention, and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the specification of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a nerve suture, characterized in that: The steps include: Step 1, mixing type I collagen powder, glycerol and glutaraldehyde in a weight ratio of 95:(4-10):(1-5); Step 2, preheating and melting the mixture, and then performing melt spinning, cooling, stretching and surface treatment on the spun filament bundle to obtain a preliminary suture product; Step 3, mixing the PLGA solution and the dexamethasone solution in a volume ratio of 9:(1-6), and subjecting the mixed solution to high-speed shear emulsification; Step 4: coating the primary suture by dipping method, drying and solidifying, surface treatment and sterilization to obtain the nerve suture.

2. The method for preparing a nerve suture according to claim 1, characterized in that: In the step 2, the melt spinning process includes: conveying the molten mixture to the spinneret through a metering pump, the spinneret temperature is controlled at 160-180° C., the spinneret hole diameter is 50-100 μm, and the spinning speed is 100-120 m / min.

3. The method for preparing a nerve suture according to claim 1, characterized in that: In the step 2, nitrogen at 25° C. is used as the cooling medium during the cooling process.

4. The method for preparing a nerve suture according to claim 1, characterized in that: In the step 2, the stretching process is carried out at 40°C.

5. The method for preparing a nerve suture according to claim 1, characterized in that: In the step 3, the PLGA solution is a 10-15% w / v PLGA (lactic acid: glycolic acid=75:25) dichloromethane solution; and the dexamethasone solution is a 2-5% w / v dexamethasone methanol solution.

6. The method for preparing a nerve suture according to claim 1, characterized in that: In the step 3, the emulsification treatment is carried out in a 40-45° C. water bath, and high-speed shearing emulsification is performed at a speed of 10000-12000 rpm for 10-15 minutes, and then 1-1.5% w / v Tween 80 is added as an emulsifier, and the emulsification is continued for 5-10 minutes.

7. The method for preparing a nerve suture according to claim 1, characterized in that: In step 4, the coating process includes: immersing the primary suture thread in the emulsified coating solution for 30-40 seconds, air-drying in a 40-45° C. incubator for 5-8 minutes, and repeating the process 3 times.

8. The method for preparing a nerve suture according to claim 1, characterized in that: In the step 4, drying and curing is carried out in a vacuum drying oven at 37-40° C. for 24-36 hours.

9. The method for preparing a nerve suture according to claim 1, characterized in that: In step 4, the sterilization treatment is performed by using ethylene oxide gas sterilization at 37-40° C. for 4-6 hours.

10. A nerve suture prepared by the preparation method according to any one of claims 1 to 9.