Preparation method of gamma-PGA nanofiber membrane for skin repair

Abstract

The invention discloses a preparation method of a gamma-PGA nanofiber membrane for skin repair, and relates to the technical field of nanofiber membranes, and the preparation method comprises the following steps: (1) preparing a gamma-PGA spinning solution and a drug spinning solution, and respectively filling the gamma-PGA spinning solution and the drug spinning solution into an outer cylinder and an inner cylinder which are coaxially arranged; (2) setting parameters such as the spinning voltage of 20-25kV, the distance between a needle head and a receiving disc of 16-19cm and the like; (3) a positioning cover is used for preventing wind, a shockproof mechanism is used for damping, and fiber membranes with the thickness of 50-200 microns are synchronously spun and collected; and (4) performing vacuum drying to obtain the product. A device used in the method comprises a positioning cover, double coaxial cylinders, a shockproof mechanism and the like, the thickness uniformity error of the fiber membrane is smaller than or equal to 5%, the drug encapsulation efficiency is larger than or equal to 85%, and the skin wound healing rate within 7 days is larger than or equal to 85%. The defect that the form is affected by jet flow deviation and vibration in the prior art is overcome, the synergistic function of base material supporting and medicine slow release is achieved, and the device is suitable for scenes such as skin wound repair and medical and art post-care.

Description

Technical Field

[0001] This invention relates to the field of nanofiber membrane technology, and more specifically to a method for preparing γ-PGA nanofiber membranes for skin repair. Background Technology

[0002] γ-polyglutamic acid (γ-PGA) is a natural high-molecular-weight polypeptide with excellent biocompatibility, moisturizing properties and wound healing properties. Its nanofiber membrane has broad application prospects in the field of skin repair. Electrospinning is the mainstream technology for preparing γ-PGA nanofiber membranes. Nanofibers are formed by driving the spinning solution with a high-voltage electric field. After the solvent evaporates, a three-dimensional porous network structure is formed on the receiving device.

[0003] Existing methods for preparing γ-PGA nanofiber membranes suffer from three major defects: ① During spinning, high voltage causes severe vibration of the syringe, leading to needle deviation from the receiving center and resulting in a thickness difference exceeding 50 μm, or even delamination; ② The lack of an effective windproof structure allows external airflow to cause jet deflection of 3-5 mm, resulting in poor fiber membrane integrity; ③ Single-cylinder spinning can only prepare single-component fiber membranes, failing to achieve the synergistic function of "γ-PGA substrate + drug sustained release," and lacks a targeted integrated shockproof and positioning design, making it difficult to balance morphological stability and functional diversity. For example, published patents only use single-needle spinning without a shockproof mechanism, resulting in poor fiber membrane uniformity; patent CN113863122B lacks a closed positioning cover, highlighting the jet deflection problem. This invention addresses these defects by innovatively designing an integrated solution of "positioning cover for windproofing + shockproof mechanism for vibration reduction + dual-cylinder synergistic spinning," fundamentally solving the pain points of morphological stability and functional diversity. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a γ-PGA nanofiber membrane for skin repair, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a γ-PGA nanofiber membrane for skin repair includes the following steps: (1) Place the drug (such as antibiotic) into the inner cylinder and the γ-PGA into the outer cylinder; (2) Set the spinning voltage and the distance between the second needle and the receiving plate; (3) Collect the fiber membrane onto the receiving tray and control the thickness to a reasonable range; (4) Spinning time depends on the requirements; The method for preparing the γ-PGA nanofiber membrane for skin repair requires a device for preparing the γ-PGA nanofiber membrane for skin repair. The device includes a positioning cover, a receiving plate rotatably connected to the bottom of the positioning cover, an outer cylinder and an inner cylinder provided at the top of the positioning cover, the inner cylinder and the outer cylinder being coaxially and fixedly connected, and a shock-absorbing mechanism provided inside the positioning cover.

[0006] A further improvement of the technical solution of the present invention is that: a first piston is slidably connected inside the inner cylinder, a second piston is slidably connected inside the outer cylinder, a fixed seat is provided on the outside of the outer cylinder, and the first piston and the second piston are fixedly connected to the fixed seat by a push rod and a connecting rod, respectively.

[0007] A further improvement of the technical solution of the present invention is that: multiple slide rails are fixedly connected to the outer wall of the outer cylinder, the outer cylinder and the positioning cover are slidably connected through the slide rails, a first needle is connected to the end of the outer cylinder, and a second needle is connected to the end of the inner cylinder 3.

[0008] A further improvement of the technical solution of the present invention is that: a weight is sleeved on the outside of the second needle, and multiple rotating rods are rotatably connected between the weight and the positioning cover.

[0009] A further improvement of the technical solution of the present invention is that: the shock-absorbing mechanism includes a positioning seat, and multiple sets of positioning seats are provided. Each set of positioning seats has two seats, one of which is fixedly connected to the upper part of the hammer by bolts, and the other positioning seat is fixedly connected to the lower part of the hammer. A positioning frame is fixedly connected to the second needle head, and the positioning frame extends into the positioning seat. A rubber pad is provided inside the positioning seat, and the rubber pad is in contact with the positioning frame.

[0010] A further improvement of the technical solution of the present invention is that: a sliding cover is provided on the positioning cover, the sliding cover and the positioning cover are slidably connected, and a handle is fixedly connected to the sliding cover.

[0011] Due to the adoption of the above technical solution, the technical progress achieved by this invention compared to the prior art is as follows: 1. This invention provides a method for preparing a γ-PGA nanofiber membrane for skin repair. Through the design of a closed positioning cover, this invention can reduce the influence of external airflow on the jet to an offset of ≤0.5mm, which is more than 85% higher than the prior art (offset 3-5mm). The impurity content is ≤0.1wt% (the prior art is ≥0.5wt%). The positioning cover positions the outer and inner cylinders at the center of the receiving plate, the coaxiality error of the jet is ≤0.03mm (the prior art is ≥0.5mm), the fiber membrane is uninterrupted and without discontinuity, the thickness uniformity error is ≤5% (the prior art is ≥20%), and the uniformity of nanofiber diameter distribution is improved by more than 60%.

[0012] 2. The anti-vibration mechanism of the present invention, in conjunction with the weight and rotating rod, can control the vibration amplitude of spinning to ≤0.1mm (1.2-1.8mm in the prior art), with a vibration absorption efficiency of ≥90%, effectively avoiding fiber membrane defects caused by needle deviation.

[0013] 3. The dual-cylinder synergistic spinning achieves the synergistic function of "γ-PGA substrate + drug sustained release", with a drug encapsulation rate of ≥85% (previous technology ≤65%), sustained release in vitro for 72h (previous technology ≤48h), and a wound healing rate of ≥85% in rats after 7 days (previous technology ≤60%), which is significantly better than the existing technology. Attached Figure Description

[0014] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a cross-sectional structural diagram of the present invention; Figure 3 This is a partial cross-sectional view of the present invention; Figure 4 For the present invention Figure 3 Enlarged structural diagram at point A in the middle.

[0015] In the diagram: 1. Positioning cover; 2. Outer cylinder; 3. Inner cylinder; 4. Receiving plate; 5. Push rod; 6. First piston; 7. Second piston; 8. Connecting rod; 9. Anti-vibration mechanism; 91. Positioning seat; 92. Positioning frame; 93. Rubber pad; 10. Fixed seat; 11. Slide rail; 12. Counterweight; 13. Rotating rod; 14. First needle; 15. Second needle; 16. Slide cover; 17. Handle. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to embodiments: Example 1 like Figures 1-4 As shown, this invention provides a method for preparing a γ-PGA nanofiber membrane for skin repair, comprising the following steps: (1) Preparation of spinning solution: The inner cylinder 3 is filled with drug spinning solution. 0.5g of cefazolin sodium (antibiotic) is mixed with 4g of 12wt% PVA aqueous solution and magnetically stirred for 30min until completely dissolved. The outer cylinder 2 is filled with γ-PGA spinning solution. 2g of γ-PGA (molecular weight 800,000 Da) is dissolved in 20ml of trifluoroacetic acid / dimethylformamide mixed solvent (volume ratio 1:3) and ultrasonically dispersed for 20min to obtain a homogeneous solution. (2) Equipment parameter settings: Fix the inner cylinder 3 and the outer cylinder 2 to the center of the positioning cover 1 via the slide rail 11, set the spinning voltage to 22kV, the distance between the second needle 15 and the receiving plate 4 to 17cm, the rotation speed of the receiving plate to 600r / min, and the synchronous advance rate of the first piston 6 and the second piston 7 to 0.4ml / h; (3) Spinning and collection: Start the equipment, isolate the external airflow through the positioning cover 1, and absorb the vibration of the equipment (vibration amplitude ≤0.1mm) through the anti-vibration mechanism 9. Continue spinning for 3 hours and collect a fiber membrane with a thickness of 120μm. (4) Post-processing and testing: The fiber membrane was dried in a vacuum drying oven at 32℃ for 1.5h. The test results showed that the thickness uniformity error of the fiber membrane was ≤5%, the diameter distribution of the nanofibers was 80-150nm, the drug encapsulation rate reached 85%, and the in vitro release experiment showed that the drug could be released continuously for 72h (45% released at 24h, 68% released at 48h, and 82% released at 72h). The cytotoxicity test (CCK-8 method) showed that the relative proliferation rate of the fiber membrane extract on L929 fibroblasts was ≥90%, which met the biocompatibility standard of GB / T16886.5-2017 and had no cytotoxicity. The skin irritation test showed that there was no redness, swelling, itching or other irritation reaction when the skin of New Zealand rabbits came into contact with the fiber membrane for 72h.

[0017] In the electrospinning process, a device for preparing γ-PGA nanofiber membranes for skin repair is required. This device includes a positioning cover 1, with a receiving plate 4 rotatably connected to the bottom of the positioning cover 1. An outer cylinder 2 and an inner cylinder 3 are provided on the top of the positioning cover 1. The inner cylinder 3 and the outer cylinder 2 are coaxially fixedly connected. An anti-vibration mechanism 9 is provided inside the positioning cover 1. The positioning cover 1 positions the outer cylinder 2 and the inner cylinder 3 at the center of the receiving plate 4, ensuring that the dual-needle jet is accurately directed to the receiving area.

[0018] An apparatus for preparing γ-PGA nanofiber membranes for skin repair is provided. The positioning cover 1 prevents jet deviation caused by external airflow during spinning, and also avoids mixing of impurities in the air with the fiber membrane, thereby improving the quality of the limiting membrane. At the same time, the positioning cover 1 positions the outer cylinder 2 and inner cylinder 3 at the center of the receiving plate 4, which can prevent jet deviation during the jetting process, thus avoiding the formation of an interrupted or incomplete fiber membrane, thereby improving the quality of the limiting membrane.

[0019] The inner cylinder 2 and outer cylinder 3 are coaxially arranged, and two different spinning solutions are simultaneously delivered through double concentric needles to achieve one-step preparation of core-shell structured nanofibers. This leads to the development of complex structures such as hollow and multilayer structures, providing endless possibilities for material functional design. As a result, composite films with different compositions in the upper and lower layers can be prepared to meet the needs of different layers of the skin.

[0020] The anti-vibration mechanism 9 is designed to prevent the positioning cover 1 from vibrating when the receiving plate 4 rotates, thereby affecting the shape of the fiber membrane.

[0021] like Figure 3 As shown, a first piston 6 is slidably connected inside the inner cylinder 2, and a second piston 7 is slidably connected inside the outer cylinder 3. A fixed seat 10 is provided on the outside of the outer cylinder 3. The first piston 6 and the second piston 7 are fixedly connected to the fixed seat 10 through a push rod 5 and a connecting rod 8, respectively. Through the cooperation of the first piston 6, the second piston 7, the connecting rod 8, the push rod 5 and the fixed seat 10, the first piston 6 and the second piston 7 can be moved synchronously by voltage.

[0022] like Figure 3 As shown, multiple slide rails 11 are fixedly connected to the outer wall of the outer cylinder 2. The outer cylinder 2 and the positioning cover 1 are slidably connected through the slide rails 11. The slide rails 11 can restrict the axial rotation of the outer cylinder 2, thereby affecting the shape of the fiber membrane. A first needle 14 is connected to the end of the outer cylinder 2, and a second needle 15 is connected to the end of the inner cylinder 3.

[0023] Example 2 like Figures 3-4 As shown, based on Embodiment 1, the present invention provides a technical solution: preferably, a weight 12 weighing 500-800g is sleeved on the outside of the second needle 15, and three rotating rods 13 made of carbon fiber (5mm in diameter and 60mm in length) are rotatably connected between the weight 12 and the positioning cover 1. Comparative experiment: Fiber membranes were prepared using the device of this invention (with shockproof mechanism + positioning cover) and a conventional device (without shockproof mechanism + positioning cover), and the results are as follows: | Testing Items | Apparatus of the Invention | Conventional Apparatus | |------------------|---------------------------|---------------------------| Vibration amplitude | ≤0.1mm | 1.2-1.8mm | | Fiber membrane thickness error | ≤5% | ≥22% | | Drug release duration | 72h | 48h | | Skin repair experiment (rat wound) | 7-day healing rate ≥85% | 7-day healing rate ≤60% |

[0024] like Figures 3-4 As shown, the shock-absorbing mechanism 9 includes a positioning seat 91. Multiple sets of positioning seats 91 are provided, and each set has two positioning seats 91. One of them is fixedly connected to the upper part of the counterweight 12 by bolts, and the other positioning seat 91 is fixedly connected to the lower part of the counterweight 12. A positioning frame 92 is fixedly connected to the second needle 15. The positioning frame 92 extends into the positioning seat 91. A rubber pad 93 is provided inside the positioning seat 91, and the rubber pad 93 contacts the positioning frame 92.

[0025] The positioning seat 91 located on the upper part of the hammer 12 is connected by bolts. The purpose is to allow the outer cylinder 2 to be installed and disassembled at any time. When it is necessary to disassemble the outer cylinder 2, the positioning seat 91 can be removed to take out the outer cylinder 2 and the inner cylinder 3.

[0026] The positioning seat 91 is set at the same time to position the outer cylinder 2 and the inner cylinder 3 between the two positioning seats 91, so as to prevent the outer cylinder 2 and the inner cylinder 3 from moving during the spinning process, thereby affecting the shape of the fiber membrane.

[0027] like Figure 1 As shown, a sliding cover 16 is provided on the positioning cover 1, and the sliding cover 16 and the positioning cover 1 are slidably connected. A handle 17 is fixedly connected to the sliding cover 16.

[0028] The anti-vibration mechanism 9, in conjunction with the counterweight 12 and the rotating rod 13, effectively prevents vibrations caused to the outer cylinder 2 and inner cylinder 3 when the receiving plate 4 rotates. When the counterweight 12 is subjected to vibration, some of the vibration is absorbed by its inertia, while the other part of the vibration energy is transmitted to the positioning cover 1 via the rotating rod 13. The anti-vibration mechanism 9 inside the positioning cover 1 absorbs and disperses this vibration energy through the elastic action of the positioning seat 91 and the rubber pad 93, thereby preventing the vibration from being directly transmitted to the outer cylinder 2 and inner cylinder 3 and ensuring the stability of the spinning process. In addition, the sliding cover 16 not only provides extra protection for the entire preparation device, preventing external dust and impurities from entering, but also facilitates the maintenance and repair of the device by the operator through its sliding connection design. When it is necessary to clean or inspect the inside of the device, the positioning cover 1 can be easily opened by sliding the sliding cover 16 with the handle 17 to perform the relevant operations. This design ensures the sealing of the device and improves its ease of use.

[0029] The working principle of the preparation method for the γ-PGA nanofiber membrane used for skin repair is described in detail below. In the preparation process of the γ-PGA nanofiber membrane for skin repair, the drug (such as antibiotics) is first placed in the inner cylinder 3, and γ-PGA is placed in the outer cylinder 2. Next, a suitable spinning voltage and the distance between the second needle 15 and the receiving plate 4 are set. The precise setting of this distance is crucial for the forming quality of the fiber membrane. During the spinning process, the voltage synchronously drives the first piston 6 and the second piston 7 to move, ensuring a stable output of the spinning solution in the inner cylinder 2 and the outer cylinder 3. The coaxially arranged inner cylinder 2 and outer cylinder 3 simultaneously deliver two different spinning solutions through dual concentric needles, achieving one-step preparation of core-shell structured nanofibers, thereby deriving complex structures such as hollow and multilayered structures to meet the needs of different skin layers. The positioning cover 1 positions the outer cylinder 2 and inner cylinder 3 at the center of the receiving plate 4, preventing jet deviation due to external airflow during the spinning process, avoiding the mixing of air impurities with the fiber membrane, and preventing interruption or incomplete formation of the fiber membrane due to jet deviation, thus improving the quality of the fiber membrane. The outer cylinder 2 and the positioning cover 1 are slidably connected by a slide rail 11, restricting the axial rotation of the outer cylinder 2 and ensuring the stability of the fiber membrane morphology. The counterweight 12 sleeved on the outside of the second needle 15 and multiple rotating rods 13 rotatably connected to the positioning cover 1, together with the shock-absorbing mechanism 9, effectively prevent vibration of the outer cylinder 2 and inner cylinder 3 when the receiving tray 4 rotates. When the counterweight 12 is vibrated, part of the vibration is absorbed by inertia, and the other part is transmitted to the positioning cover 1 through the rotating rods 13. The shock-absorbing mechanism 9 inside the positioning cover 1 absorbs and disperses the vibration energy through the elastic action of the positioning seat 91 and the rubber pad 93, ensuring the stability of the spinning process. Finally, the fiber membrane is collected onto the receiving tray 4, and the thickness is controlled to a reasonable range. The spinning time depends on the requirements.

[0030] The present invention has been described in detail above. However, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, any modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing a γ-PGA nanofiber membrane for skin repair, characterized in that: To address the technical shortcomings of existing electrospinning methods for preparing γ-PGA nanofiber membranes, such as vibration deviation caused by high voltage, interference of external airflow with the jet, and single-component single-function, the following steps are included: (1) Preparation of spinning solution: The inner cylinder (3) is filled with a drug spinning solution, which is a mixture of antibiotic (such as cefazolin sodium, purity ≥98%) and 10-15wt% PVA aqueous solution (PVA molecular weight 100,000-150,000 Da) at a mass ratio of 1:5-1:8, and magnetically stirred for 30-40 min until completely dissolved; The outer cylinder (2) is filled with a γ-PGA spinning solution, which is a homogeneous solution obtained by ultrasonically dispersing 8-12wt% γ-PGA (molecular weight 800,000-1,000,000 Da) with a trifluoroacetic acid / dimethylformamide mixed solvent (volume ratio 1:3) for 20-30 min; (2) Set electrospinning parameters: the spinning voltage is 20-25kV, the distance between the second needle (15) and the receiving plate (4) is 16-19cm, the rotation speed of the receiving plate is 500-800r / min, the ambient temperature is controlled at 23-27℃ and the humidity is 40%-60%; (3) Synchronous spinning and collection: the first piston (6) and the second piston (7) are driven by voltage to advance synchronously at a speed of 0.3-0.6ml / h, and the fiber membrane is collected onto the receiving plate (4), and the thickness of the fiber membrane is controlled at 50-200μm; (4) Post-processing: the spinning time is 2-4h, and after collection, it is dried in a vacuum drying oven at 30-35℃ for 1-2h to obtain a γ-PGA nanofiber membrane for skin repair; the preparation method requires a special device, which includes a positioning cover (1), the bottom of the positioning cover (1) is rotatably connected to the receiving plate (4), and the top is provided with a coaxially fixed outer cylinder (2). The inner cylinder (3) is equipped with an anti-vibration mechanism (9). The anti-vibration mechanism (9) absorbs ≥90% of the spinning vibration through the cooperation of the positioning seat (91), the positioning frame (92) and the rubber pad (93), ensuring that the coaxiality error of the jet is ≤0.03mm.

2. The apparatus for preparing γ-PGA nanofiber membranes for skin repair according to claim 1, characterized in that: The first piston (6) slidably connected inside the inner cylinder (3) and the second piston (7) slidably connected inside the outer cylinder (2) are rigidly connected to the fixed seat (10) through the push rod (5) and the connecting rod (8); the coaxiality error of the rigid connection is ≤0.05mm, which can ensure that the synchronous advance rate deviation of the two pistons is ±0.02ml / h, avoiding uneven output of spinning solution due to asynchronous advance, and thus ensuring the integrity of the core-shell structure of the fiber membrane.

3. The apparatus for preparing γ-PGA nanofiber membranes for skin repair according to claim 1, characterized in that: The outer cylinder (2) is fixedly connected with 2-3 axial slide rails (11). The length of the slide rails (11) is 80-100mm and the guiding accuracy is ≤0.02mm. The outer cylinder (2) is slidably connected to the positioning cover (1) through the slide rails (11). The sliding resistance is ≤5N. This design can realize the precise positioning and convenient disassembly of the outer cylinder and the inner cylinder. The inner diameter of the first needle (14) is 0.3-0.5mm (used to transport γ-PGA spinning solution), and the inner diameter of the second needle (15) is 0.15-0.25mm (used to transport drug spinning solution). The coaxiality error of the two needles is ≤0.03mm, which can ensure that the two spinning solutions form a continuous core-shell structure and avoid delamination or breakage.

4. The apparatus for preparing γ-PGA nanofiber membranes for skin repair according to claim 1, characterized in that: The second needle (15) is fitted with a weight (12), and a plurality of rotating rods (13) are rotatably connected between the weight (12) and the positioning cover (1).

5. The apparatus for preparing γ-PGA nanofiber membrane for skin repair according to claim 4, characterized in that: The shock-absorbing mechanism (9) includes 3-4 sets of positioning seats (91), with a distance of 15-20mm between the two seats in each set of positioning seats (91). The upper positioning seat is detachably connected to the counterweight (12) by M5 bolts, and the lower positioning seat is integrally formed with the counterweight (12). The positioning frame (92) is made of stainless steel with a U-shaped cross-section and is embedded in the positioning seat (91) to a depth of 8-10mm, which can limit the radial displacement of the needle. The rubber pad (93) is made of silicone rubber with a Shore hardness of 30-40° and a thickness of 5-8mm. The contact area with the positioning frame (92) is ≥80%, which can absorb ≥90% of the spinning vibration energy. The shock-absorbing mechanism works in conjunction with the counterweight (12) and the rotating rod (13) to control the vibration amplitude to ≤0.1mm through the dual mechanism of "counterweight inertial shock absorption + rubber pad elastic shock absorption".

6. The apparatus for preparing γ-PGA nanofiber membrane for skin repair according to claim 1, characterized in that: The positioning cover (1) is provided with a transparent polycarbonate sliding cover (16). The sliding stroke of the sliding cover (16) is 100-150mm. The sliding is smooth and without jamming. After closing, the sealing degree of the positioning cover (1) is ≥95%, which can effectively isolate the external airflow and particles in the air, and avoid jet deviation and fiber membrane contamination. The sliding cover (16) is fixedly connected with an ABS handle (17). The length of the handle (17) is 80-100mm, and the surface is provided with anti-slip texture for easy operation.

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