Gel / peo / ca composite fiber medical dressing based on coaxial microfluidic spinning technology and preparation method thereof

Abstract

The application discloses a preparation method of a GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology, and comprises the following steps: (1) a certain amount of GEL and PEO are weighed, and an appropriate amount of acetic acid solution is added to prepare a shell spinning solution; (2) a certain amount of cinnamaldehyde and PEO are weighed, and an appropriate amount of acetic acid solution is added to prepare a core spinning solution; (3) the two kinds of spinning solutions are extracted by 10ml syringes, and a microfluidic nanospinning machine is used to form a fiber membrane under certain spinning conditions; (4) drying is carried out under a vacuum environment at 25 DEG C for 12 hours; (5) gaseous phase crosslinking is carried out on the fiber membrane by using glutaraldehyde solution at normal temperature; and (6) vacuum drying is carried out to remove residual glutaraldehyde on the fiber membrane. The application fundamentally solves the problems of high volatility of cinnamaldehyde and poor water solubility of gelatin fiber in the prior art, and the fiber is endowed with efficient, long-lasting antibacterial, antioxidant and tissue regeneration promoting functions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of medical composite materials, and particularly relates to a GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology and a preparation method thereof. BACKGROUND

[0002] In recent years, the application of fiber materials in the biomedical field continues to expand, and functionalized fiber materials have attracted much attention due to their excellent biological properties. Microfluidic spinning technology has become an important means for preparing complex structure and specific function fibers due to its high precision and controllability. With the continuous development of medical composite material technology, various new types of wound dressings such as films, hydrocolloids, hydrogels and micro / nano fibers have been developed in the field of textile medicine. Among them, electrospun nanofiber membranes have broad prospects in the application field of wound dressings due to their inherent characteristics such as high specific surface area, high porosity and structural similarity to the extracellular matrix of the skin.

[0003] Gelatin, as a natural polymer material, is widely used in medical and other fields due to its good biocompatibility, but gelatin fibers have poor structure retention under humid conditions and need to be cross-linked to improve stability. Natural antibacterial agents such as cinnamaldehyde have multiple biological activities such as antibacterial and antioxidant activities, but their high volatility and poor water solubility limit their application.

[0004] Compared with traditional drug-loaded materials, micro / nano fibers with core-shell structure can encapsulate drugs inside the fibers, which can well encapsulate drugs and maintain drug activity, and at the same time, due to the protection of the shell material, the slow release of the encapsulated drugs inside can be effectively controlled, avoiding the burst release phenomenon and reducing the toxic side effects of drugs. Therefore, micro / nano fibers with core-shell structure provide a direction for the preparation of multifunctional wound dressings. At present, the technologies for preparing functional micro / nano fiber medical dressings with core-shell structure by electrospinning technology are as follows:

[0005] CN111330063A discloses a nanofiber membrane and a preparation method thereof. The nanofiber membrane has a core-shell structure, the core layer of the core-shell structure is honey and polyvinyl alcohol, and the shell layer is cinnamaldehyde and polycaprolactone; the nanofiber membrane is prepared by coaxial electrospinning.

[0006] CN117045846A discloses a high molecular weight chitosan skin-core structure micro / nano fiber dressing. A spinning solution is prepared from high molecular weight chitosan, polyethylene oxide, acetic acid and water, and then solution jet spinning is performed to obtain the dressing. The skin-core structure has a high molecular weight chitosan as the inner core and polyethylene oxide as the outer skin.

[0007] CN119326937A discloses an antibacterial hyaluronic acid wound dressing with core-shell structure and a preparation method thereof, belonging to the field of biomedical materials. The core-shell structure nanofiber is prepared by using coaxial electrospinning technology, which is better than the solid structure nanofiber prepared by ordinary electrospinning.

[0008] From the above patent technology, the existing skin-core structure micro-nano fiber membrane for wound dressing can achieve the effect of slow release and healing promotion. At the same time, different components and drug components are added in the core-shell structure, and various advantages are combined to make it have the functions of antibiosis, hemostasis, anti-adhesion and other functions. However, electrospinning technology still has some defects in the preparation of core-shell structure nanofiber wound dressing. For example, the current dressing for wounds mainly solves the problems of antibiosis, hemostasis, anti-adhesion, antioxidant, drug release and promotion of wound repair. Of course, this is also an important function that fiber dressing must have for skin wounds. However, as for the drug-loaded nanofiber dressing for wounds at present, the most important purpose is to promote wound healing. Therefore, the absorption performance of wound exudate, the concentration and duration of drug action, the promotion of tissue regeneration, and the antibiosis and antioxidant properties are the most important functions required by wound dressings. As we all know, the electrospinning process has very strict requirements for the spinning solution and spinning parameters. Uneven distribution of electric field, uneven airflow and uneven concentration of polymer liquid can easily lead to uneven fiber diameter, even string beads, and the above parameters are not easy to control accurately. If functional polymer additives and drugs are added to the spinning solution, the content of additives and drugs in the skin-core structure micro-nano fiber will be unevenly distributed along the fiber length direction, and the functional distribution of the dressing after film formation will be uneven. In addition, the function of the skin-core drug-loaded micro-nano fiber wound dressing is determined by the addition of different additives and drugs, and the ratio and amount of additives and drugs are important factors affecting the function of the wound dressing. Although the existing technology realizes the combination of functions in the fiber according to the combination of different polymers and drugs, it is necessary to accurately match the amount and ratio of functional polymers and drugs according to the changes in the environment and requirements of the healing process at different stages of wound healing. Obviously, there is no report on this problem in the current research on skin-core drug-loaded micro-nano fiber wound dressings.

[0009] Therefore, how to effectively control the uniformity of the diameter of the skin-core structure micro-nano fiber, realize the uniform distribution of the function of the wound dressing, and accurately match and control the amount, ratio and position of the functional polymers and drugs to provide the required wound environment and requirements for the healing process at different stages of the wound, fundamentally solve the problems of high volatility of cinnamaldehyde and poor water solubility of gelatin fiber in the existing technology, and endow the fiber with efficient, long-lasting antibacterial, antioxidant and tissue regeneration functions, have become a difficult problem that functional fiber wound dressing field technicians need to solve. SUMMARY

[0010] In view of the deficiencies of the prior art, the technical problem to be solved by the present application is to provide a GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology and a preparation method thereof, which can realize uniform distribution of the functions of the wound dressing, help provide the required wound environment and requirements in the different stages of the healing process, and solve the problems of high volatility of cinnamaldehyde and poor water solubility of gelatin fibers.

[0011] To solve the above technical problems, the technical solution adopted by the present application is: a preparation method of a GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology, comprising the following steps:

[0012] (1) A certain amount of GEL and PEO are weighed, and an appropriate amount of acetic acid solution is added to prepare a shell spinning solution, wherein the concentration of GEL in the spinning solution is 7.5-9.5wt%, and the concentration of PEO is 5.5-7.5wt%;

[0013] (2) A certain amount of cinnamaldehyde and PEO are weighed, and an appropriate amount of acetic acid solution is added to prepare a core spinning solution, wherein the concentration of cinnamaldehyde in the spinning solution is 3-7wt%, and the concentration of PEO is 4-8wt%;

[0014] (3) After the two spinning solutions are extracted with 10ml syringes, the microfluidic nanospinning machine is used to extrude the spinning solutions through the coaxial spinning needle under certain spinning conditions, and the extruded spinning solutions contact the rotating collection plate, and the fibers with a skin-core structure are formed at the outlet of the needle after stretching and refining, and are wound on the collection plate, and the fiber membrane is formed under room temperature drying conditions;

[0015] (4) The fiber membrane is dried in a vacuum environment at 25℃ for 12 hours to remove excess acetic acid and water;

[0016] (5) The fiber membrane is placed in a fumigation pot, and gaseous crosslinking is performed with a 25-75%mv glutaraldehyde solution at room temperature, and the crosslinking time is 6-12h;

[0017] (6) The residual glutaraldehyde on the fiber membrane is removed by vacuum drying again to obtain the GEL / PEO / CA composite fiber medical dressing.

[0018] The preparation method of the GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology, wherein the concentration of GEL in the shell spinning solution of step (1) is 8.5wt%, and the concentration of PEO is 6.4wt%.

[0019] The preparation method of the GEL / PEO / CA composite fiber medical dressing based on the coaxial microfluidic spinning technology, in the acetic acid solution of the step (1), the mass ratio of acetic acid to water is 4:1.

[0020] The preparation method of the GEL / PEO / CA composite fiber medical dressing based on the coaxial microfluidic spinning technology, in the core layer spinning solution of the step (2), the concentration of cinnamaldehyde is 5wt%, and the concentration of PEO is 6wt%.

[0021] The preparation method of the GEL / PEO / CA composite fiber medical dressing based on the coaxial microfluidic spinning technology, in the acetic acid solution of the step (2), the mass ratio of acetic acid to water is 5:4.

[0022] The preparation method of the GEL / PEO / CA composite fiber medical dressing based on the coaxial microfluidic spinning technology, in the step (3), the spinning conditions are as follows: the core layer spinning solution pushing speed is 0.1-0.3ml / h, the skin layer spinning solution is 0.6-1.2ml / h, the collection plate rotating speed is 200-400r / min, the coaxial spinning needle specification is 30G / 21G, and the spinning humidity is 20-40%.

[0023] The preparation method of the GEL / PEO / CA composite fiber medical dressing based on the coaxial microfluidic spinning technology, in the step (5), the concentration of glutaraldehyde solution is 50%mv, and the crosslinking time is 9h.

[0024] The preparation method of the GEL / PEO / CA composite fiber medical dressing based on the coaxial microfluidic spinning technology, in the step (6), the vacuum drying time is set to 8h.

[0025] The preparation method of the GEL / PEO / CA composite fiber medical dressing based on the coaxial microfluidic spinning technology, the core layer spinning solution pushing speed is 0.2ml / h, the skin layer spinning solution is 0.8ml / h, the collection plate rotating speed is 300r / min, and the spinning humidity is 30%.

[0026] A GEL / PEO / CA composite fiber medical dressing based on a coaxial microfluidic spinning technology, prepared by the preparation method.

[0027] The application is based on the advantages of the GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology and a preparation method thereof, which are as follows: firstly, the coaxial spinning technology realizes the coaxial spinning of two or more kinds of fluids with different properties through a microfluidic chip, which ensures the accurate separation and synchronous spinning of the skin layer and the core layer spinning solution, so that the composite fiber with a skin-core structure can be formed. This technology not only improves the controllability of the spinning process, but also makes the composite fiber more uniform in structure and more diversified in performance. Secondly, in the design of the composite fiber, gelatin and PEO are selected as the skin layer material, which fully utilizes the biocompatibility, degradability and cell affinity of gelatin, and the stability and processability of PEO. At the same time, the spinning solution containing cinnamaldehyde is used as the core layer, and through accurate control of the fluid dynamics parameters in the spinning process, the uniform distribution of cinnamaldehyde in the fiber is realized. The application not only retains the excellent performance of gelatin, but also endows the fiber with the functions of antibacterial, antioxidant and promoting tissue regeneration through the introduction of cinnamaldehyde. The diameter uniformity of the skin-core structure micro-nano fiber is effectively controlled, the functional distribution of the wound dressing is uniform, and through accurate matching and control of the amount, ratio and position of the functional polymers and drugs, the required wound environment and requirements are provided for the wound healing process at different stages, which fundamentally solves the problems of high volatility of cinnamaldehyde and poor water solubility of gelatin fiber in the prior art, and endows the fiber with efficient, long-lasting antibacterial, antioxidant and tissue regeneration promoting functions. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The preparation process flow chart of the GEL / PEO / CA composite fiber medical dressing of the application is shown in the figure;

[0029] Figure 2 The SEM images and diameter distribution graphs of the medical dressings prepared under different glutaraldehyde crosslinking times are shown in the figure;

[0030] Figure 3 The TEM image of the medical dressing prepared in Example 2 of the application is shown in the figure;

[0031] Figure 4 The FTIR-ATR spectrum and XRD spectrum of the medical dressings prepared under different glutaraldehyde crosslinking times are shown in the figure;

[0032] Figure 5 The XPS-nitrogen spectrum of the medical dressings prepared under different glutaraldehyde crosslinking times is shown in the figure;

[0033] Figure 6 The stress-strain curve of the medical dressings prepared under different glutaraldehyde crosslinking times is shown in the figure;

[0034] Figure 7 The morphology of the water droplet contact of the medical dressings prepared under different glutaraldehyde crosslinking times is shown in the figure;

[0035] Figure 8 The water absorption rate test diagram of the medical dressing prepared at different glutaraldehyde crosslinking times after being soaked in PBS for 24 hours;

[0036] Figure 9 The drug release performance test diagram of the core-shell structure nanofiber in the medical dressing prepared in Example 2 of the application;

[0037] Figure 10 The antibacterial property test diagram of the fibers with different contents of cinnamaldehyde in the core liquid against Staphylococcus aureus and Escherichia coli;

[0038] Figure 11 The DPPH clearance rate test diagram of the medical dressings prepared at different contents of cinnamaldehyde in the core liquid and different glutaraldehyde crosslinking times;

[0039] Figure 12 The hemolysis effect test diagram and the cytotoxicity test diagram of the medical dressings prepared at different cinnamaldehyde concentrations. DETAILED DESCRIPTION

[0040] The application will be further described in detail below in combination with the drawings and specific examples.

[0041] The GEL / PEO / CA nanofiber dressing of the application is prepared by using the microfluidic spinning technology by a microfluidic nanospinning machine (JNS-SBS-01, Nanjing Janus New Material Co., Ltd.). The spinning liquid for the skin layer and the core layer is prepared respectively, and stirred for eight hours to make GEL, PEO and CA completely dissolved to obtain a uniform spinning solution. The prepared two kinds of spinning liquid are extracted by 10ml syringes, and the ejection flow of the spinning liquid is controlled by using the microfluidic nanospinning machine. The shell liquid and the core liquid are respectively introduced into the outer channel and the inner channel of the coaxial spinning needle by catheter. The needle extrudes the spinning liquid to contact with the collection plate in rotation, and the skin-core structure fiber is formed at the outlet of the needle after the stretching and refining process, and is wound on the collection plate. The fiber membrane is formed under the condition of room temperature drying, and is dried overnight to remove the residual solvent. The fiber membrane is placed in a smoking oven, and is crosslinked by using glutaraldehyde solution at room temperature. After crosslinking, it is placed in a vacuum drying oven for eight hours to remove the residual glutaraldehyde on the fiber membrane.

[0042] As shown in Figure 1 , a preparation method of a GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology includes the following steps:

[0043] (1) A certain amount of GEL and PEO is weighed, and an appropriate amount of acetic acid solution is added to prepare a shell spinning solution. The spinning solution is stirred in a magnetic stirrer at room temperature for 8 hours until it is completely dissolved to obtain a uniform spinning solution. The concentration of GEL in the spinning solution is 7.5-9.5wt%, and the concentration of PEO is 5.5-7.5wt%;

[0044] (2) A certain amount of cinnamaldehyde and PEO is weighed, and an appropriate amount of acetic acid solution is added to prepare a core spinning solution. The spinning solution is stirred in a magnetic stirrer at room temperature for 8 hours until it is completely dissolved to obtain a uniform spinning solution. The concentration of cinnamaldehyde in the spinning solution is 3-7wt%, and the concentration of PEO is 4-8wt%;

[0045] (3) After the two spinning solutions are extracted with 10ml syringes, the microfluidic nanospinning machine is used to extrude the spinning solutions through the coaxial spinning needle under certain spinning conditions. The extruded spinning solution contacts the rotating collection plate, and after stretching and refining, a skin-core structure fiber is formed at the outlet of the needle, which is wound on the collection plate. The fiber membrane is formed under room temperature drying conditions;

[0046] (4) The fiber membrane is dried in a vacuum environment at 25°C for 12 hours to remove excess acetic acid and water;

[0047] (5) The fiber membrane is placed in a fumigation pot and subjected to gas-phase crosslinking with 25-75% mv glutaraldehyde solution at room temperature for 6-12h;

[0048] (6) The residual glutaraldehyde on the fiber membrane is removed by vacuum drying again to obtain a GEL / PEO / CA composite fiber medical dressing.

[0049] Among them, the materials used in the product: pigskin gelatin (Gel, gel strength 300, class A, CAS: 9000-70-8) is purchased from Sigma-Aldrich Company, polyoxyethylene (PEO, MV=600000, powder, CAS: 68441-17-8), cinnamaldehyde (CA, 98%, CAS: 104-55-2) and glutaraldehyde (high-purity medical grade, 50%, CAS: 111-30-8) are purchased from Shanghai Maikelin Biotechnology Co., Ltd. Acetic acid (analytical pure AR, CAS: 64-19-7) is purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd.

[0050] The antibacterial dressing of the application overcomes the problem that the active substance or the drug component of the dressing in the prior art is difficult to maintain the promotion of the repair growth due to the influence of the wound microenvironment, fully utilizes the biocompatibility, degradability and cell affinity of gelatin, the stability and processability of PEO, and the uniform distribution and slow release performance of cinnamaldehyde in the fiber, not only avoids the influence of the wound environment on the drug and the polymer, but also solves the problem of fast drug release speed in the initial use of the drug-loaded medical dressing, improves the functionality and quality of the wound dressing. Meanwhile, the polymer and gelatin effectively absorb tissue exudate, keep the wound moist, avoid the problem of wound adhesion, and further promote the healing of the wound.

[0051] The application will be specifically described below through specific examples. The following examples are only part of the examples of the application and are not a limitation of the application.

[0052] Example 1:

[0053] A preparation method of a GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology, comprising the following steps:

[0054] (1) A certain amount of GEL and PEO are weighed, and an appropriate amount of acetic acid solution is added to prepare a shell spinning solution. The concentration of GEL in the spinning solution is 7.5wt%, and the concentration of PEO is 5.5wt%. In the acetic acid solution, the mass ratio of acetic acid to water is 4:1;

[0055] (2) A certain amount of cinnamaldehyde and PEO are weighed, and an appropriate amount of acetic acid solution is added to prepare a core spinning solution. The concentration of cinnamaldehyde in the spinning solution is 3wt%, and the concentration of PEO is 4wt%. In the acetic acid solution, the mass ratio of acetic acid to water is 5:4;

[0056] (3) After the two spinning solutions are extracted with 10ml syringes, a microfluidic nanospinning machine is used, the pushing speed of the core spinning solution is set to 0.1ml / h, the pushing speed of the shell spinning solution is set to 0.6ml / h, the rotation speed of the collection plate is set to 200r / min, the specification of the coaxial spinning needle is 30G / 21G, the spinning humidity is 20%, and the spinning solution is extruded through the coaxial spinning needle and contacted with the rotating collection plate. After being stretched and refined, the fiber with a skin-core structure is formed at the outlet of the needle and wound on the collection plate. The fiber membrane is formed under room temperature drying conditions;

[0057] (4) The fiber membrane is dried in a vacuum environment at 25℃ for 12 hours to remove excess acetic acid and water;

[0058] (5) The fiber membrane is placed in a fumigation pot and subjected to gas phase crosslinking with 25%mv glutaraldehyde solution at room temperature, and the crosslinking time is 12h;

[0059] (6), vacuum drying for 8h again to remove residual glutaraldehyde on the fiber membrane, to obtain GEL / PEO / CA composite fiber medical dressing.

[0060] The GEL / PEO / CA composite fiber medical dressing based on the coaxial microfluidic spinning technology of the application is prepared by the preparation method described above in this embodiment.

[0061] Example 2:

[0062] A preparation method of a GEL / PEO / CA composite fiber medical dressing based on the coaxial microfluidic spinning technology, comprising the following steps:

[0063] (1), a certain amount of GEL and PEO is weighed, and an appropriate amount of acetic acid solution is added to prepare a shell spinning solution, the concentration of GEL in the spinning solution is 8.5wt%, the concentration of PEO is 6.4wt%, and the mass ratio of acetic acid to water in the acetic acid solution is 4:1;

[0064] (2), a certain amount of cinnamaldehyde and PEO is weighed, and an appropriate amount of acetic acid solution is added to prepare a core spinning solution, the concentration of cinnamaldehyde in the spinning solution is 5wt%, the concentration of PEO is 6wt%, and the mass ratio of acetic acid to water in the acetic acid solution is 5:4;

[0065] (3), after the two kinds of spinning solutions are extracted by 10ml syringes, a microfluidic nanospinning machine is used, the pushing speed of the core spinning solution is set to 0.2ml / h, the skin layer spinning solution is 0.8ml / h, the rotating speed of the collection plate is 300r / min, the coaxial spinning needle specification is 30G / 21G, the spinning humidity is 30%, and the spinning solution is extruded through the coaxial spinning needle and contacted with the rotating collection plate, and after stretching and refining, the fiber membrane with a skin-core structure is formed at the needle outlet and wound on the collection plate, and the fiber membrane is dried under room temperature conditions;

[0066] (4), the fiber membrane is dried in a vacuum environment at 25℃ for 12 hours to remove excess acetic acid and water;

[0067] (5), the fiber membrane is placed in a fumigation pot, and 50%mv glutaraldehyde solution is used for gas phase crosslinking at room temperature, and the crosslinking time is 9h;

[0068] (6), vacuum drying for 8h again to remove residual glutaraldehyde on the fiber membrane, to obtain GEL / PEO / CA composite fiber medical dressing.

[0069] The GEL / PEO / CA composite fiber medical dressing based on the coaxial microfluidic spinning technology of the application is prepared by the preparation method described above in this embodiment.

[0070] Example 3:

[0071] A preparation method of a GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology, comprising the following steps:

[0072] (1) A certain amount of GEL and PEO is weighed, and an appropriate amount of acetic acid solution is added to prepare a shell spinning solution, wherein the concentration of GEL in the spinning solution is 9.5wt%, the concentration of PEO is 7.5wt%, and the mass ratio of acetic acid to water in the acetic acid solution is 4:1;

[0073] (2) A certain amount of cinnamyl aldehyde and PEO is weighed, and an appropriate amount of acetic acid solution is added to prepare a core spinning solution, wherein the concentration of cinnamyl aldehyde in the spinning solution is 7wt%, the concentration of PEO is 8wt%, and the mass ratio of acetic acid to water in the acetic acid solution is 5:4;

[0074] (3) After the two spinning solutions are extracted by 10ml syringes, a microfluidic nanospinning machine is used, the pushing speed of the core spinning solution is set to 0.3ml / h, the skin layer spinning solution is 1.2ml / h, the rotating speed of the collection plate is 400r / min, the coaxial spinning needle specification is 30G / 21G, the spinning humidity is 40%, and the spinning solution is extruded through the coaxial spinning needle and contacted with the rotating collection plate, and after stretching and refining, the fiber membrane is formed on the needle outlet, and the fiber membrane is dried under room temperature conditions;

[0075] (4) The fiber membrane is dried in a vacuum environment at 25℃ for 12 hours to remove excess acetic acid and water;

[0076] (5) The fiber membrane is placed in a fumigation pot, and gaseous crosslinking is carried out with 75%mv glutaraldehyde solution at room temperature, and the crosslinking time is 6h;

[0077] (6) Vacuum drying for 8h to remove residual glutaraldehyde on the fiber membrane to obtain a GEL / PEO / CA composite fiber medical dressing.

[0078] The GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology of the application is prepared by the preparation method.

[0079] The performance test results of the GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology of the application are as follows:

[0080] 1. About the fiber morphology:

[0081] As shown in Figure 2 , wherein, Figure 2 a-e are respectively the SEM images and diameter distribution graphs of each GEL / PEO / CA composite fiber medical dressing prepared under the conditions of glutaraldehyde crosslinking for 0h, 3h, 6h, 9h and 12h under the basic conditions of Example 2. Figure 2As can be seen, all the fibers are uniform in morphology, without droplets and beading, and are aligned in the same direction. When the glutaraldehyde crosslinking time is varied from 0 hour to 12 hours, the average diameter of the fibers varies from 1.85 ± 0.12 μm to 2.21 ± 0.25 μm, the uniformity decreases, and the fibers appear to swell and curl to some extent. These changes in microstructure with reaction time are mainly due to the reaction of glutaraldehyde molecules with the amino groups (-NH2) on the gelatin molecular chains to form Schiff base structures -RC=N-, which causes the fibers to stick together. The longer the crosslinking time, the greater the diameter and the degree of fiber curling, and a large number of fibers stick together to gradually form a dense network structure.

[0082] As shown in Figure 3 , the skin-core structure of the fibers is confirmed by TEM images, and the results show that the core layer is well wrapped by the skin layer, and the skin-core fiber structure is uniformly distributed inside and outside.

[0083] As shown in Figure 4 , among them, Figure 4 (a) is the amide A band spectrum of Gel, Figure 4 (b) is the amide I, II, III band spectrum of Gel. Figure 4 (c) is the XRD spectrum under different glutaraldehyde crosslinking times. Figure 4 (d) is the XRD spectrum of Gel and PEO. The FTIR-ATR spectrum of the glutaraldehyde crosslinked Gel / PEO / Ca fiber membrane is as shown in Figure 4 (a). All samples have a wide absorption peak at 3296 cm -1 , corresponding to the stretching vibration of O-H and N-H. However, with the extension of the crosslinking time, the intensity of the peak gradually decreases. This can be due to the reaction of free amino groups in the Gel / PEO / Ca fiber with the aldehyde groups in glutaraldehyde, and the greater the degree of crosslinking, the more the amino groups on the surface of the fiber are consumed. In addition, in Figure 4 (b), all FTIR spectra show three characteristic absorption peaks at 1636 cm -1 , 1538 cm -1 and 1466 cm -1 , respectively, corresponding to the Gel amide I band (C=O stretching vibration), the Gel amide II band (N-H bending vibration and C-N stretching vibration), and the Gel amide III band (C=O bending vibration and C-N stretching vibration). With the extension of the glutaraldehyde crosslinking time, the intensity of these characteristic peaks gradually decreases. These changes also confirm the crosslinking effect of glutaraldehyde on the Gel / PEO / Ca fiber, reducing the number of free amino groups.

[0084] The x-ray diffraction pattern (XRD) is as shown in Figure 4The aggregate structure of the nanofiber was studied as shown in (c), (d). In the Gel diffraction pattern, a broad characteristic peak was observed at 20°. For the PEO diffraction pattern, two sharp peaks were observed at 2θ = 19.2° and 23.3° due to the crystalline nature of PEO. In the fiber membrane sample without glutaraldehyde crosslinking, three distinct characteristic peaks appeared at 15.3°, 19.0° and 22.5°, which did not coincide with the diffraction bands of pure PEO and Gel, indicating that PEO and CS macromolecules interacted to form a new molecular structure. With the increase of glutaraldehyde crosslinking time, the intensity of the three characteristic peaks at 15.3°, 19.0° and 22.5° decreased to varying degrees and the peak position shifted to the right, because the crosslinking of glutaraldehyde changed the triple helix structure of gelatin macromolecules, reducing the crystallinity. The longer the crosslinking time, the smaller the diffraction peak intensity. The possible reason is that the higher the crosslinking degree, the tighter the network structure, which further destroys the crystal structure of the fiber membrane and reduces the crystallinity.

[0085] As shown in Figure 5 , the chemical bond types and contents on the surface of the sample were determined by XPS. With the extension of crosslinking time, a new peak appeared in the N spectrum, which was an unsaturated N bond with higher energy than -NH2. This is because the glutaraldehyde molecules react with the amino groups (-NH2) on the gelatin molecular chain to form a new Schiff base structure -RC=N.

[0086] 2. About physical properties:

[0087] As shown in Figure 6 , the stress-strain curve can show that the tensile strength of GEL / PEO / CA fiber membrane is about 1 MPa. After glutaraldehyde crosslinking treatment, the tensile strength of the fiber membrane is significantly improved, reaching 3-4 MPa, meeting the requirements of wound dressings. The crosslinking reaction forms a chemical bond network inside the gelatin fiber, significantly enhancing the interaction force between the fiber molecular chains. When the fiber is stretched by external force, these chemical bond networks can effectively resist the stretching force, thereby improving the tensile strength of the fiber. The elongation at break of the fiber membrane is about 0.5%, and the toughness is low.

[0088] As shown in Figure 7 , wherein, Figure 7 a-e are the morphology diagrams of water droplet contact of medical dressings prepared under crosslinking time of 0 h, 3 h, 6 h, 9 h and 12 h, respectively. As we know, wettability is crucial for dressings to maintain a proper moist wound environment, and the water contact angle (WCA) in the range of 0-80° is necessary for cell adhesion and proliferation during the wound healing process. As shown in Figure 7 a-e, the initial WCA is 48.2°, and after glutaraldehyde crosslinking treatment, the WCA increases to 88° with the extension of crosslinking time, achieving a slightly hydrophilic effect Figure 7e), indicating a decrease in wettability. This is because when glutaraldehyde is used as a crosslinking agent to treat gelatin fibers, the crosslinking reduces the number of hydrophilic groups (such as hydroxyl and amino groups) exposed in the gelatin molecules, making it more difficult for water molecules to interact with the surface of the gelatin fibers. As the degree of glutaraldehyde crosslinking increases, the hydrophilicity of the gelatin fiber membrane will further decrease. This is because high crosslinking makes the interaction between gelatin molecular segments more tight, limiting the penetration and diffusion of water molecules. Due to the decrease in hydrophilicity, the contact angle of the gelatin fiber membrane will increase accordingly.

[0089] As Figure 8 shown, good absorbency is another important feature of wound dressings, which can allow the dressing to absorb wound exudates in time, create a better microenvironment, and promote wound healing. The water absorption rate of the dressing was measured after soaking in PBS buffer for 24 h, as Figure 6 shown. All samples showed high water absorption rate > 300%. At the same time, as the glutaraldehyde treatment time increases, the water absorption rate of the nanofiber dressing decreases slowly, with the most significant decrease at 9 hours. This is because ① reduction of hydrophilic groups: crosslinking reaction consumes hydrophilic groups (such as hydroxyl and amino groups) in gelatin molecules, resulting in a decrease in the number of these groups exposed on the fiber surface. Hydrophilic groups are the main sites for attracting water molecules, and their reduction will lead to a decrease in fiber water absorption. ② Network structure restriction: the network structure formed by crosslinking will limit the entry and diffusion of water molecules, making it more difficult for water molecules to penetrate into the fiber interior, thereby reducing the water absorption rate. ③ The higher the degree of crosslinking, the tighter the connection between gelatin molecules, and the more dense the network structure formed. This will further limit the penetration and diffusion of water molecules, leading to a further decrease in water absorption rate.

[0090] 3. Drug release effect:

[0091] As Figure 9 shown, among them, Figure 9 (a) is the linear relationship diagram of the ultraviolet absorbance and concentration of cinnamaldehyde, Figure 9 (b) is the curve diagram of the change of the release concentration of cinnamaldehyde in nanofiber with time. As Figure 9 (a) shown, the absorbance of the solution with known concentration of cinnamaldehyde was tested by ultraviolet absorbance method, and the linear relationship equation between ultraviolet absorbance and cinnamaldehyde concentration was established. The release effect of the core-sheath structure fiber was determined, as Figure 9 (b), the cinnamaldehyde was basically released completely at the eighth day, with a concentration of 1.05 mg / L, which reached the optimal concentration for promoting cell growth. The core-sheath structure fiber can continuously and stably release the drug, ensuring that the wound site maintains an effective drug concentration for a long time. This sustained release property helps to maintain long-term antibacterial effect while reducing the frequency of drug administration, improving patient comfort.

[0092] 4. Regarding antibacterial properties:

[0093] Preventing bacterial infection is essential for wound healing. The inhibitory rates of dressings against Staphylococcus aureus and Escherichia coli were evaluated. Figure 10 As shown, for Staphylococcus aureus, the inhibition rates of cinnamaldehyde in the core solution were 98.51%, 99.50%, and 99.99% at concentrations of 3%, 5%, and 7%, respectively. For Escherichia coli, the inhibition rates were 99.73%, 99.93%, and 99.99% at concentrations of cinnamaldehyde in the core solution. The control sample agar plates showed dense colonies. This is because the aldehyde group in the cinnamaldehyde molecule is a nucleophilic group, which is easily adsorbed by the hydrophilic groups on the bacterial surface and penetrates the cell wall. Cinnamaldehyde can destroy the polysaccharide structure of the cell walls of bacteria and fungi, thereby achieving antibacterial or bactericidal effects. Since mammals do not have cell walls, cinnamaldehyde will not damage human and animal cells. It can not only destroy cell structure but also interact with proteins and enzymes in bacteria, interfering with normal bacterial physiological metabolism, further exerting antibacterial or bactericidal effects.

[0094] 5. Regarding antioxidant properties:

[0095] like Figure 11 As shown, where Figure 11 (a) is a graph showing the DPPH removal rate test when the cinnamaldehyde content in the core solution of the spinning solution is 3 wt% and 5 wt%. Figure 11 (b) DPPH scavenging rate of wound dressings prepared at glutaraldehyde crosslinking times of 3h, 6h, and 9h. The antioxidant activity of the wound dressings of the present invention was determined by the DPPH scavenging rate. Figure 11 (a) shows that the higher the cinnamaldehyde content in the spinning solution core fluid, the stronger the antioxidant properties of the dressing, with a DPPH scavenging rate exceeding 90%. This is because the aldehyde group of cinnamaldehyde can react with free radicals to form stable compounds, thereby scavenging free radicals within the wound. Wound dressings with antioxidant activity can promote wound healing because neutrophils and leukocytes aggregate at the injury site and attack microorganisms through phagocytosis. During wound healing, excessive free radicals are generated at the wound site, which disrupts the cellular oxidation / antioxidant balance, leading to enzyme inactivation, lipid peroxidation, and DNA breaks, causing damage and expansion of the skin around the wound and slowing wound healing. The benzene ring structure of cinnamaldehyde can interact with proteases, thereby affecting their activity and helping to regulate the intracellular redox state, further exerting its antioxidant effect. Figure 11 (b) As the cross-linking time of glutaraldehyde increases, the time required for the antioxidant performance of the fiber membrane to reach its maximum is longer, meaning the cinnamaldehyde release rate is slower. Therefore, the appropriate sustained-release rate of cinnamaldehyde can be selected to address different wounds by controlling the cross-linking time of glutaraldehyde.

[0096] 6. On the effect of promoting tissue regeneration:

[0097] As shown in Figure 12 , wherein, Figure 12 (a) is a hemolysis effect test diagram of the fiber membrane with different cinnamaldehyde concentrations, Figure 12 (b) is a cytotoxicity diagram of the fiber membrane with different cinnamaldehyde concentrations determined by cck-8 method. Figure 12 The hemolysis effect of the fiber membrane was determined in (a). When the core layer cinnamaldehyde concentration of the fiber membrane was 3% and 5%, there was no hemolysis effect, which was the same as the blank control group, but there was a small amount of hemolysis effect when the concentration was 7%. Cytotoxicity is an important requirement for biomedical materials. The in vitro cytotoxicity of the fiber membrane was evaluated by using L929 cells, because fibroblasts play a key role in the wound healing process. As shown in Figure 12 (b), the L929 cell survival rate of the fiber membrane with a core layer cinnamaldehyde concentration of 3% and 5% was more than 100% at 24h, while the survival rate of the part group with a concentration of 7% was less than 100%. This shows that the fiber membrane has no cytotoxicity and can promote cell proliferation when the core layer cinnamaldehyde concentration is 3% and 5%, and has a small amount of cytotoxicity when it is 7%.

[0098] In summary, to solve the problems existing in the prior art, the coaxial extension spinning technology is used to perform coaxial co-spinning through a microfluidic chip, and a composite fiber with a skin-core structure is formed by stretching force. The advantages of different materials are fully utilized to realize the diversification of fiber structure and function. Through the application of coaxial extension spinning technology and the careful design of composite fiber, the core innovation points of the technical scheme are formed, so that the prepared gelatin cinnamaldehyde composite fiber has a broad application prospect in the biomedical field.

[0099] Of course, the above description is not a limitation on the present application, and the present application is not limited to the above examples. Within the essential scope of the present application, changes, modifications, additions or substitutions made by ordinary skilled in the art should be within the protection scope of the present application.

Claims

1. A method for preparing a GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology, characterized in that, Includes the following steps: (1) Weigh a certain amount of GEL and PEO, add an appropriate amount of acetic acid solution, and prepare a shell spinning solution. The concentration of GEL in the spinning solution is 7.5-9.5wt%, and the concentration of PEO is 5.5-7.5wt%. (2) Weigh a certain amount of cinnamaldehyde and PEO, add an appropriate amount of acetic acid solution, and prepare a core spinning solution. The concentration of cinnamaldehyde in the spinning solution is 3-7 wt%, and the concentration of PEO is 4-8 wt%. (3) After the two spinning solutions were extracted with a 10ml syringe, a microfluidic nanospinning machine was used. Under certain spinning conditions, the spinning solution was squeezed out through the coaxial spinning needle and came into contact with the rotating collection plate. After being stretched and refined, the core-sheath structure fibers were formed at the needle outlet and wrapped around the collection plate. The fiber membrane was formed under the drying conditions at room temperature. (4) Dry the fiber membrane in a vacuum environment at 25°C for 12 hours to remove excess acetic acid and water; (5) Place the fiber membrane in a fumigation oven and perform gas-phase crosslinking with 25-75% mv glutaraldehyde solution at room temperature for 6-12 hours. (6) Vacuum drying is performed again to remove residual glutaraldehyde from the fiber membrane, resulting in GEL / PEO / CA composite fiber medical dressing.

2. The method for preparing GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology according to claim 1, characterized in that: In the shell spinning solution of step (1), the concentration of GEL is 8.5 wt% and the concentration of PEO is 6.4 wt%.

3. The method for preparing GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology according to claim 1, characterized in that: In the acetic acid solution of step (1), the mass ratio of acetic acid to water is 4:

1.

4. The method for preparing GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology according to claim 1, characterized in that: In the core spinning solution of step (2), the concentration of cinnamaldehyde is 5 wt% and the concentration of PEO is 6 wt%.

5. The method for preparing GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology according to claim 1, characterized in that: In the acetic acid solution of step (2), the mass ratio of acetic acid to water is 5:

4.

6. The method for preparing GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology according to claim 1, characterized in that: In step (3), the spinning conditions are as follows: the core spinning solution feed rate is 0.1-0.3 ml / h, the skin spinning solution is 0.6-1.2 ml / h, the collecting plate rotation speed is 200-400 r / min, the coaxial spinning needle specification is 30G / 21G, and the spinning humidity is 20-40%.

7. The method for preparing GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology according to claim 1, characterized in that: In step (5), the concentration of glutaraldehyde solution is 50% mv, and the crosslinking time is 9 h.

8. The method for preparing GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology according to claim 1, characterized in that: In step (6), the vacuum drying time is set to 8 hours.

9. The method for preparing GEL / PEO / CA composite fiber medical dressing based on coaxial microfluidic spinning technology according to claim 6, characterized in that: The core spinning solution feed rate is 0.2 ml / h, the sheath spinning solution feed rate is 0.8 ml / h, the collecting plate rotation speed is 300 r / min, and the spinning humidity is 30%.

10. A medical dressing made of GEL / PEO / CA composite fiber based on coaxial microfluidic spinning technology, characterized in that: It is prepared by the preparation method according to any one of claims 1-9.

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