Preparation method of biodegradable medical suture with gradient mechanical property

Abstract

The invention relates to a preparation method of a biodegradable medical suture with gradient mechanical properties, and belongs to the field of medical materials. Adding the polylactic acid suture line into absolute ethyl alcohol for ultrasonic treatment; putting the pretreated polylactic acid suture into a serine protease solution, adding cassia oil and baking soda, sealing, performing constant-temperature oscillation treatment, fully washing with distilled water, airing, and drying; the serine protease surface modified polylactic acid suture line is twisted by using twisting equipment, and the mechanical property of the suture line is adjusted by adjusting the number of twists to form a gradient. According to the biodegradable medical suture with the gradient mechanical property, the high-strength end has the high mechanical property, and wound closure can be effectively maintained; the mechanical property of the low-strength end is low, the degradation rate is gradually increased, and wound healing is promoted.

Description

Technical Field

[0001] This invention relates to the field of medical materials, and in particular to a method for preparing biodegradable medical sutures with gradient mechanical properties. Background Technology

[0002] Medical sutures are essential materials for closing wounds during surgery. Traditional non-biodegradable sutures require a second surgery for removal, causing additional pain and infection risks for patients. Biodegradable sutures, on the other hand, gradually degrade and are absorbed by the body, avoiding the need for secondary surgery and showing great promise for future applications.

[0003] Chinese Patent CN115874297A discloses a method and apparatus for preparing medical absorbable antibacterial sutures. In this method, biocompatible biodegradable polymers are used as raw materials, and inorganic nanoparticles are used as fillers and antibacterial agents. Medical absorbable antibacterial sutures are prepared using a self-made electrospinning device.

[0004] Chinese Patent CN111840630B discloses an antibacterial absorbable medical soft tissue suture, its preparation method, and its application. This method uses carboxymethyl chitosan as the main carrier, carbon-loaded copper, and low-molecular-weight aldehyde-modified chitosan as chelating agents to prepare a chitosan copper-based hydrogel. This hydrogel is then formed into an antibacterial absorbable medical soft tissue suture with a diameter of 0.01–3 mm through mechanical stretching or syringe injection.

[0005] Chinese Patent CN105497974B discloses a silk-woven medical suture with both color recognition and antibacterial functions, and its preparation method. This method uses single-strand silk thread as raw material, employing a two-step dyeing process using natural dyes and a mordant. Then, food-grade beeswax is used to wax the dyed silk thread while simultaneously rewinding it. The core and shell threads are arranged with a core / shell ratio of 0.083–0.25, and the thread is woven on an automatic braiding machine to obtain the silk-woven thread. Finally, the silk-woven thread undergoes high-temperature rapid heat setting treatment, followed by Co60 irradiation sterilization.

[0006] However, current biodegradable sutures often exhibit limited mechanical properties, failing to meet the varying mechanical support requirements of sutures at different stages of wound healing. In the early stages of wound healing, sutures require high strength to maintain wound closure. As healing progresses, the mechanical properties of the sutures gradually decrease, while the degradation rate accelerates. Therefore, developing a biodegradable medical suture with gradient mechanical properties is of significant practical importance. Summary of the Invention

[0007] To address the above problems, this invention provides a method for preparing biodegradable medical sutures with gradient mechanical properties, the operation steps of which are as follows:

[0008] S1: Place 10-20 parts of polylactic acid suture into 500-700 parts of a serine protease solution with a mass percentage of 0.01-0.05%, then add 0.3-0.8 parts of rosemary oil (containing rosmarinal), 0.1-0.5 parts of tea polyphenols (containing polyphenolic hydroxyl groups), and 0.2-0.5 parts of baking soda. After sealing, place the suture in a 40-50℃ water bath constant temperature shaker and sonicate for 1-3 hours. Then remove the suture, wash it thoroughly with distilled water, air dry, and then bake it.

[0009] S2: Twisting: The suture is twisted using a twisting device. The mechanical properties of the suture are adjusted by changing the number of twists to create a gradient.

[0010] Furthermore, the ultrasonic treatment conditions are 20°C and 40kHz.

[0011] Furthermore, the washing process is repeated at least three times.

[0012] Furthermore, the drying temperature is 50-60℃ until the suture reaches a constant weight.

[0013] Furthermore, the twisting device has a twist rate of 200-600 twists / m, and the twisting device has an adjustable twist rate with an adjustment accuracy of ±10 twists / m, and can maintain uniform tension of the suture during the twisting process.

[0014] Beneficial effects:

[0015] Gradient mechanical properties: The suture prepared by the method of this invention possesses gradient mechanical properties, enabling it to provide appropriate mechanical support according to the different stages and locations of wound healing. In the early stages of wound healing, the suture has high strength, effectively maintaining wound closure and preventing wound dehiscence; as the wound gradually heals, the mechanical properties of the suture gradually decrease, avoiding excessive pressure and damage to newly formed tissue, and promoting normal wound healing.

[0016] Reaction mechanism

[0017] Synergistic effects of enzymatic hydrolysis and composite components: Under a weakly alkaline environment (regulated by baking soda), serine proteases specifically hydrolyze the ester bonds of polylactic acid (PLA) molecular chains, generating hydroxyl and carboxyl groups on the PLA surface. Rosmarin in rosemary oil forms hydrogen bonds with the carboxyl groups of PLA through its aldehyde groups, and the polyphenolic hydroxyl groups of tea polyphenols interact with the hydroxyl groups of PLA, constructing a complex hydrogen bond network. This synergistic effect not only modifies the PLA surface and enhances its hydrophilicity but also stabilizes the material structure through antioxidant components, preventing excessive degradation. For example, similar hydrogen bonding interactions between polyphenols and polymers have significantly improved the performance of PLA / tannic acid composite membranes.

[0018] Ultrasound-enhanced reaction process: The cavitation effect induced by ultrasound treatment generates an instantaneous high-temperature, high-pressure microenvironment in the solution, accelerating the diffusion and adsorption of serine protease molecules onto the polylactic acid (PLA) surface and promoting ester bond hydrolysis. Simultaneously, the microjets generated by the rupture of cavitation bubbles allow rosemary oil and tea polyphenols to disperse more uniformly and come into contact with PLA, enhancing their interaction. In protein-related research, the cavitation effect of ultrasound can alter protein structure; here, it similarly promotes mass transfer and chemical reactions throughout the reaction system through mechanical and thermal effects.

[0019] Technical effect

[0020] Customized mechanical properties: By controlling the treatment time and concentration of the serine protease solution, as well as the number of twists during the twisting process, the mechanical property gradient of the suture can be precisely controlled. For example, in the early stage of wound healing, areas with high twist and low enzymatic hydrolysis provide high-strength support to prevent wound dehiscence; as time progresses, areas with low twist and high enzymatic hydrolysis gradually adapt to tissue repair, and the mechanical properties decrease gradually, reducing stimulation to newly formed tissue and meeting the mechanical needs of different stages of wound healing.

[0021] Enhanced bioactivity and safety: The microstructures produced by enzymatic hydrolysis promote cell adhesion and growth, thus accelerating tissue healing; rosemary oil and tea polyphenols endow the sutures with antibacterial, antioxidant, and anti-inflammatory properties, reducing the risk of infection and alleviating inflammatory responses. Furthermore, the entire preparation process utilizes biodegradable raw materials and mild reaction conditions, leaving no harmful chemical residues, ensuring the biosafety of the sutures for in vivo use and providing a more reliable option for clinical applications. Detailed Implementation

[0022] To further illustrate the technical means and effects adopted by the present invention in order to achieve the intended purpose, a detailed description is provided below.

[0023] 1. Mechanical property testing: The suture was subjected to tensile testing using an electronic universal testing machine to test its breaking strength.

[0024] 2. Degradation rate test: Weigh the suture sample and record the initial weight W0; place the sample in phosphate buffer solution and degrade it at 37℃; after 10 days, remove the sample, rinse it with distilled water, and then dry it at low temperature to constant weight, and weigh it Wt; the degradation rate is calculated using the formula: Degradation rate (%) = (W0 - Wt) / W0 × 100%

[0025] Example 1:

[0026] Preparation of modified solution: In a clean beaker, accurately measure 500g of 0.01% serine protease solution, add 0.3g of rosemary oil and 0.1g of tea polyphenols, stir thoroughly to disperse the cinnamon oil into fine droplets, then add 0.2g of baking soda, stir to dissolve completely, mix evenly at room temperature to obtain the modified solution;

[0027] Suture preparation: Take 10g of medical-grade polylactic acid suture with a diameter of 3-0 and place it in the above-mentioned modified solution, ensuring that the suture is completely submerged, and seal the beaker.

[0028] Oscillation and ultrasonic treatment: Place the sealed beaker in a 40℃ water bath constant temperature shaker and set the oscillation frequency to 100 rpm. At the same time, set the ultrasonic cleaner temperature to 20℃ and the frequency to 40 kHz, and perform ultrasonic treatment on the solution for 1 hour.

[0029] Washing and drying: After ultrasonic treatment, remove the sutures, wash them with plenty of distilled water at least 3 times, blot the surface moisture with filter paper, and then dry them in a 50°C oven until constant weight.

[0030] Twisting: The treated suture is fixed on a twisting device. The initial twist number of the device is set to 200 twists / m. The twist number is gradually increased so that the twist of the suture gradually changes from one end to the other. Finally, the twist number reaches 400 twists / m, forming a suture with gradient mechanical properties.

[0031] Example 2:

[0032] Preparation of modified solution: Measure 600g of 0.03% serine protease solution, add 0.5g rosemary oil, 0.2g tea polyphenols, and 0.3g baking soda, and mix evenly according to the above method.

[0033] Suture treatment: Take 15g of polylactic acid suture with a diameter of 4-0 and put it into the modification solution, then seal it.

[0034] Oscillation and ultrasonic treatment: The ultrasonic treatment was carried out at 20℃, 40kHz, and 2 hours in a 45℃ water bath constant temperature oscillator with an oscillation frequency of 100rpm.

[0035] Washing and drying: Wash and absorb moisture as required, then dry in an oven at 55°C until constant weight.

[0036] Twisting: Using twisting equipment, the initial twist number is set to 300 twists / m, and the final twist number reaches 600 twists / m, forming a suture with gradient mechanical properties.

[0037] Example 3:

[0038] Preparation of modified solution: Measure 700g of 0.05% serine protease solution, add 0.8g rosemary oil, 0.5g tea polyphenols, and 0.5g baking soda, and mix well.

[0039] Suture treatment: Take 20g of polylactic acid suture with a diameter of 2-0 and put it into the modification solution, then seal it.

[0040] Oscillation and ultrasonic treatment: The ultrasonic treatment was carried out at 20℃, 40kHz, and 3 hours in a 50℃ water bath constant temperature oscillator with an oscillation frequency of 100rpm.

[0041] Washing and drying: Wash and absorb moisture as required, then dry in a 60℃ oven to constant weight.

[0042] Twisting: The initial twist number of the twisting equipment is set to 400 twists / m, and the final twist number reaches 500 twists / m, forming a suture with gradient mechanical properties.

[0043] Comparative Example 1

[0044] The polylactic acid sutures were not modified with serine protease, otherwise the same as in Example 1.

[0045] Comparative Example 2

[0046] No tea polyphenols were added; otherwise, the same as in Example 1.

[0047] Comparative Example 3

[0048] Rosemary oil was not added; otherwise, the process was the same as in Example 1.

[0049] Table 1: Test Results of Examples and Comparative Examples

[0050]

[0051] Based on the data analysis of the above embodiments and comparative examples, the biodegradable medical suture with gradient mechanical properties prepared by the present invention has high mechanical properties at the high-strength end, which can effectively maintain wound closure; and low mechanical properties at the low-strength end, while the degradation rate gradually accelerates, promoting wound healing.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing biodegradable medical sutures with gradient mechanical properties, characterized in that, The operation steps are as follows: S1: Place 10-20 parts of polylactic acid suture into 500-700 parts of a serine protease solution with a mass percentage of 0.01-0.05%, then add 0.3-0.8 parts of rosemary oil (containing rosmarinal), 0.1-0.5 parts of tea polyphenols, and 0.2-0.5 parts of baking soda. After sealing, place the suture in a 40-50℃ water bath constant temperature shaker and sonicate for 1-3 hours. Then remove the suture, wash it thoroughly with distilled water, air dry, and then bake it. S2: Twisting: The suture is twisted using a twisting device, and the mechanical properties of the suture are adjusted by adjusting the number of twists.

2. The method for preparing a biodegradable medical suture with gradient mechanical properties according to claim 1, characterized in that: The ultrasonic treatment conditions for S1 are 20℃ and 40kHz.

3. The method for preparing a biodegradable medical suture with gradient mechanical properties according to claim 1, characterized in that: The twisting device of S2 has a twist count of 200-600 twists / m.

4. The method for preparing a biodegradable medical suture with gradient mechanical properties according to claim 1, characterized in that, The washing process must be repeated at least three times.

5. The method for preparing a biodegradable medical suture with gradient mechanical properties according to claim 1, characterized in that, The drying temperature is 50-60℃ until the sutures reach a constant weight.

6. The method for preparing a biodegradable medical suture with gradient mechanical properties according to claim 1, characterized in that, The twisting device has an adjustable twist rate with an adjustment accuracy of ±10 twists / m, and can maintain uniform tension of the suture during the twisting process.

7. A biodegradable medical suture with gradient mechanical properties prepared by the preparation method according to any one of claims 1-6.

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