A nanofiber dressing and its application

Abstract

The present invention relates to a nanofiber dressing and its application, belonging to the technical field of medical materials. The dressing is constructed by nanofibers having a core-shell structure formed based on a coaxially arranged core layer and a shell layer. Among them, the shell layer of the nanofibers at least includes a first component for forming the main body of the shell layer and a second component for modifying the first component, and the core layer of the nanofibers at least includes a third component for releasing growth factors. This application can form corresponding drug release carriers based on the adjustment of the preparation parameters of the core layer and the shell layer or the construction method of the nanofiber dressing for preparing the dressing, so that the dressings located at different spatial positions of the wound can be provided with targeted release strategies and release rates based on different action stages to ensure the applicability for inducing wound repair activity and improving efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of medical materials, and particularly to a nanofiber dressing and its application. Background Art

[0002] The skin covers the whole body and becomes an important barrier to protect the internal structure of the human body and maintain the internal environment. However, the skin is vulnerable to trauma. At present, skin trauma is mainly divided into acute trauma and burns. Without intervention, scarring often occurs during the natural healing of wounds, leaving huge psychological barriers for patients. At present, the main basis for treating trauma is: inhibiting the reproduction of wound bacteria to reduce infection, increasing the concentration of active substances to accelerate wound healing, inhibiting scars or reducing patient pain based on the dressing structure and composition. For example, for skin burns, gauze and burn ointment are generally used. However, the gauze has too high porosity, too large pore size, and poor skin adhesion, which is not conducive to preventing the invasion of external bacteria. Moreover, its high absorption capacity will cause wound dehydration and promote bacterial growth, and secondary damage may also be caused when removing the gauze. The pore size of the nanofiber membrane is smaller than that of bacteria, and it has a similar structure to the extracellular matrix, making it a good substitute for gauze. Among them, the electrospun nanofiber membrane has broad prospects in the application field of wound dressings due to its inherent characteristics such as high specific surface area, high porosity, and similar structure to the skin extracellular matrix. The ointment is an exogenous drug with relatively single components, and the treatment effect varies from person to person.

[0003] Various new types of wound dressings have been developed in the prior art, such as films, hydrocolloids, hydrogels, and micro / nanofibers. Nanofiber materials include: chitosan, polycaprolactone (PCL), polylactic acid (PLA), etc. To improve the ability of the dressing to prevent bacterial infection and promote wound healing, growth factors with antibacterial effects are often loaded in the nanofibers of the dressing. For example, ε-polylysine (ε-PL) is a nutrient necessary for tissue repair. Incorporating ε-PL into the nanofibers can improve the wettability of the fibers and exhibit good antibacterial properties. Autologous platelet-rich plasma, that is, autologous PRP (Platelet Rich Plasma), not only contains abundant growth factors that can promote angiogenesis and cell proliferation, but also because it is autologous, the component ratio of each growth factor in PRP varies slightly from person to person, enabling personalized treatment and avoiding allergic reactions of the body. However, when PRP is directly applied to the affected area, after being activated, PRP releases growth factors. However, since the growth factors will be rapidly decomposed by enzymes in the wound microenvironment, it is difficult to maintain a high concentration continuously. Encapsulating PRP into nanofibers can avoid this drawback. Considering that PRP is water-soluble while most biodegradable materials are hydrophobic materials, forming a core-shell structure fiber with PRP and fibers can also avoid the problem of solvent miscibility during electrospinning.

[0004] Among the existing technical solutions for wound dressings and repair methods, for example, the patent with the publication number CN107137748B discloses a core-shell electrospun chitosan nanofiber wound dressing and its preparation method. The nanofibers of the dressing for repairing the affected area are configured in a core-shell structure. Chitosan, sodium carboxymethylcellulose, and polyethylene oxide are added to an aqueous solution containing a small amount of acetic acid and ethanol to obtain an outer layer solution. Polyethylene oxide is added to an aqueous solution to obtain solution A. Additionally, a lithothamnion solution is prepared, and a small amount of sodium pyrophosphate is added to obtain solution B. Solution A and solution B are mixed to obtain an inner layer solution. The coaxial electrospinning method is used to prepare the above outer and inner layer solutions into a core-shell nanofiber dressing. The patent with the publication number CN110464866A discloses a core-shell drug-loaded nanofiber dressing and its preparation method. The nanofibers of the dressing also adopt a core-shell structure. The core layer is composed of honey and polyvinyl alcohol, and the shell layer is composed of ε-polylysine and polycaprolactone. The patent with the publication number CN114129762B discloses an electrospun nanofiber membrane loaded with self-assembled traditional Chinese medicine components vesicles, which consists of a shell layer and a core layer. The shell layer contains a water-insoluble polymer material and phospholipids, and the core layer contains a water-soluble polymer material and traditional Chinese medicine components, and is prepared by electrospinning technology; the traditional Chinese medicine component is total asiaticoside, the water-insoluble polymer material is polycaprolactone, and the water-soluble polymer material is polyvinylpyrrolidone.

[0005] The above technical solutions are based on electrospinning technology to prepare a core-shell structure and place different substances of the nanofiber dressing in the core layer and the shell layer, so that the shell layer is prepared from a hydrophobic polymer with appropriate mechanical properties and biocompatibility and performance-improving components, and the core layer is prepared from materials or active substances that control the physical and chemical properties of the nanofibers. However, its active substances are exogenous components, which cannot overcome the possible allergic reactions of the body during use and may cause negative effects based on the specific conditions of the patient; moreover, the exogenous active substances placed in the core layer cannot be specifically set according to the differences in the internal environment of the human body, resulting in the inability of the exogenous active substances to ensure the role of inducing wound repair activity and improving efficiency.

[0006] The patent with the publication number CN108434529A discloses an in-situ autologous bionic for fat liquefaction wounds and its preparation method and application. The in-situ autologous bionic repair material for fat liquefaction wounds includes an autologous functional layer, a biological functional layer, and a surface isolation layer; among them, the autologous functional layer is PRP prepared after collecting the patient's whole blood. However, in this technical solution, the autologous functional layer directly set on the wound will cause the autologous platelet-rich plasma to directly contact the wound microenvironment and be activated, thereby releasing active positions that promote repair growth, but the active substances will be quickly decomposed by the enzymes in the wound microenvironment and it is difficult to continuously maintain a high concentration.

[0007] Based on the above analysis, in the existing nanofiber dressings for skin wound repair, the arrangement where the dressing is based on active substances or drug components in direct contact with the wound surface easily leads to the active substances or drug components being affected by the wound microenvironment and thus difficult to maintain a relatively high concentration for promoting repair and growth; when the dressing is based on a core-shell structure with exogenous active substances or drug components placed in the inner layer, the exogenous active substances cannot overcome the possible body allergic reactions during use, and the singly arranged shell structure cannot adjust the release strategy and release rate of the active substances or drug components to ensure the applicability and pertinence for wound repair activity induction and efficiency improvement.

[0008] In addition, on the one hand, there are differences in the understanding of those skilled in the art; on the other hand, although the inventor studied a large number of documents and patents when making this invention, due to space limitations, all details and content are not listed in detail. However, this by no means means that this invention does not possess the features of these prior arts. On the contrary, this invention already possesses all the features of the prior arts, and the applicant reserves the right to add relevant prior arts in the background art. Summary of the Invention

[0009] Aiming at at least some of the deficiencies of the prior art, the present invention provides a nanofiber dressing, which is constructed by nanofibers with a core-shell structure formed by a coaxially arranged core layer and shell layer. Among them, the shell layer of the nanofiber at least contains a first component for forming the main body of the shell layer and a second component for modifying the first component, and the core layer of the nanofiber at least contains a third component for releasing growth factors.

[0010] Preferably, the first component is a polymerizable organic matter that can be degraded in vivo and in vitro, the second component is a functional additive that can at least be used to adjust the antibacterial property, wettability and microscopic size of the first component, and the third component is an autogenous active substance that can release growth factors for promoting healing. For example, the first component is set as polycaprolactone, the second component is set as ε-polylysine, and the third component is set as autogenous platelet-rich plasma. That is, the present application provides a nanofiber dressing, which is constructed by nanofibers with a core-shell structure formed by a coaxially arranged core layer and shell layer. Among them, the shell layer of the nanofiber at least contains polycaprolactone for forming the main body of the shell layer and ε-polylysine for modifying polycaprolactone, and the core layer of the nanofiber at least contains autogenous platelet-rich plasma for releasing growth factors.

[0011] In view of the problem that in the prior art, the arrangement of dressings based on active substances or drug components in direct contact with the wound surface easily leads to the active substances or drug components being affected by the wound microenvironment and it is difficult to maintain a high concentration that promotes repair and growth. In this application, the dressing applicable to wounds is nanofibers with a core-shell structure. The nanofibers are based on functional materials corresponding to the core layer and the shell layer in the core-shell structure, enabling the dressing in this application to significantly improve the repair ability and repair efficiency for wounds. Specifically, in the prior art, many polymer nanofiber materials have been proposed for dressings applicable to wounds to replace traditional gauze. To improve the repair efficiency of the nanofiber materials, the nanofiber materials are often used in combination with active substances that can release growth factors. However, in the case where the active substances are in direct contact with the wound surface microenvironment, the active substances or growth factors will be decomposed by wound enzymes and cannot maintain a high concentration that promotes wound recovery. Then, the dressing in this application can place the active substances for providing growth factors in the core layer based on the core-shell structure of the nanofibers, and arrange the nanofiber materials used as the main body of the material in the shell layer. The fiber pore size of the shell layer is smaller than that of bacteria, which can effectively isolate the external environment of the wound and prevent bacteria from invading. Moreover, the fiber pore size of the shell layer can allow the growth factors continuously released from the core layer to pass through and accumulate on the wound surface, enabling the wound surface environment to maintain a high concentration of growth factors to ensure the induction efficiency for wound repair.

[0012] To solve the problem that exogenous active substances cannot overcome the possible allergic reactions of the body during use and to improve the applicability of the dressing for wound repair. In the dressing of this application, a second component for improving physical properties is added to the first component that is the main body of the nanofiber shell layer, enabling the shell layer of the nanofiber to obtain physical properties more suitable for wound repair based on the second component. The physical properties can include antibacterial property, hydrophilicity, fiber pore size, fiber strength, processing performance, etc. For example, the first component and the second component are respectively configured as polycaprolactone and ε-polylysine. ε-Polylysine can effectively improve the wettability and antibacterial property of polycaprolactone, thereby ensuring that the shell layer including polycaprolactone and ε-polylysine is convenient for cell attachment and infiltration, is conducive to cell adhesion and proliferation, and has good biocompatibility. The active substance for releasing growth factors in this application can be autologous PRP. It not only contains rich growth factors, which can promote angiogenesis and cell proliferation, but also because it is autologous, the component ratio of each growth factor in PRP varies slightly from person to person, enabling personalized treatment and avoiding allergic reactions of the body. Considering that autologous PRP is water-soluble while most biodegradable materials are hydrophobic materials, making the nanofibers into a core-shell structure can also avoid the problem of solvent miscibility in electrospinning.

[0013] Moreover, the dressing of the present application can also form a corresponding drug release carrier based on the adjustment of the preparation parameters of the core layer and the shell layer or the construction method of the nanofiber preparation dressing, so that the core-shell structure as the drug release carrier can control the rate of growth factor release from the core layer to the wound surface and the effect of the shell layer on the wound surface, and the dressings located at different spatial positions of the wound can be set with targeted release strategies and release rates based on different action stages to ensure the applicability for wound repair activity induction and efficiency improvement.

[0014] Preferably, the diameter of the nanofibers is 0.2 - 1.2 μm, preferably 0.4 - 1.0 μm, and more preferably 0.6 - 0.9 μm.

[0015] Preferably, the diameter of the nanofiber core layer is 0.1 - 1.0 μm, preferably 0.3 - 0.8 μm, and more preferably 0.4 - 0.7 μm.

[0016] Preferably, the thickness of the nanofiber shell layer is 0.01 - 0.5 μm, preferably 0.1 - 0.3 μm.

[0017] Preferably, the shell layer of the nanofiber is a porous structure, and the fiber pore diameter of the shell layer is 4 - 10 nm, preferably 6 - 8 nm.

[0018] Preferably, the water contact angle of the nanofiber shell layer is 40 - 80 degrees, preferably 50 - 70 degrees.

[0019] By experimentally observing the microstructure of the dressing nanofibers, the overall size, core layer size, and shell layer size of the above nanofibers are based on optimized settings, enabling the nanofibers to have good mechanical properties, making the morphology of the nanofibers similar to the structure of the extracellular matrix, providing structural support and mechanical force for tissues, and ensuring that the nanofiber membrane and three-dimensional nanofiber structure prepared from the nanofibers possess excellent mechanical and physicochemical properties. The shell layer of the nanofiber is configured as a porous structure, and the fiber pore diameter of the shell layer blocks the entry of bacteria while allowing the continuous and slow release of active substances and growth factors from the core layer, thereby ensuring a relatively high concentration of active substances and growth factors on the wound surface to promote tissue healing.

[0020] The present invention also provides a method for preparing a nanofiber dressing, comprising the following steps:

[0021] a. Mix polycaprolactone and ε-polylysine in medical acetone to prepare a shell layer solution for preparing the nanofiber shell layer;

[0022] b. Dissolve autologous platelet-rich plasma in a polyvinyl alcohol solution to prepare a core layer solution for preparing the nanofiber core layer;

[0023] c. Prepare the shell solution and the core solution into nanofibers with a core-shell structure by coaxial electrospinning. The nanofibers are configured as dressings having at least one of a one-dimensional structure to a three-dimensional structure based on at least an in-situ deposition method.

[0024] Electrospinning is currently one of the simplest and most efficient methods for preparing nanofibers. Compared with traditional nanomaterial preparation technologies, electrospinning has the advantages of simple processing equipment, wide raw material sources, low spinning cost, and scalable preparation. The micro-nanofibers prepared by electrospinning technology have excellent properties such as a high specific surface area, a large length / diameter ratio, and unique physical and chemical properties, and show great application potential in the fields of biological tissue engineering, wound dressings, filtration and protection, drug slow release, flexible devices, etc. The nanofibers prepared by electrospinning technology have good biocompatibility, mechanical properties, and degradability and are widely used in biomedicine. The morphology of nanofibers has a structure similar to the extracellular matrix, which can provide structural support and mechanical force for tissues and provide a certain space for cell attachment and infiltration. Preparing the dressing of the present application based on coaxial electrospinning technology enables the dressing characteristics to obtain corresponding functional structures, which is of great significance for treating tissue wounds.

[0025] Preferably, in step a, the mass ratio of polycaprolactone, ε-polylysine to medical acetone is (3-50):(1-5):(10-300), preferably (5-30):(1-3):(20-200); the mixing is carried out using a stirrer, and the stirring time is 10-15 hours.

[0026] Preferably, in step b, the mass concentration of the polyvinyl alcohol solution is 1%-30%, preferably 3%-15%; the mass ratio of the polyvinyl alcohol solution to autologous platelet-rich plasma is (1-5):(1-20), preferably (1-3):(1-10).

[0027] Preferably, in step c, the spinning voltage of the coaxial electrospinning is 8-25 kv, preferably 10-20 kv; the flow rates of the shell solution and the core solution of the coaxial electrospinning are 0.3-0.8 ml / h and 0.8-2.0 ml / h respectively, preferably 0.4-0.6 ml / h and 1.0-1.5 ml / h; the distance between the needle and the receiving electrode of the coaxial electrospinning is 8-25 cm, preferably 10-18 cm; the diameter of the spinning nozzle of the coaxial electrospinning is 0.2-1.0 mm, preferably 0.3-0.6 mm.

[0028] Preferably, the dressing is constructed by nanofibers forming a core-shell structure based on a coaxially arranged core layer and a shell layer, wherein the shell layer of the nanofibers contains at least polycaprolactone for forming the main body of the shell layer, ε-polylysine for modifying the polycaprolactone, and zeolitic imidazolate framework material (ZIF-8), and the core layer of the nanofibers contains at least autologous platelet-rich plasma for releasing growth factors.

[0029] Preferably, the zeolitic imidazolate framework material is arranged in the shell layer of the nanofibers in a manner of coating or embedding in the ε-polylysine-modified polycaprolactone. The particle size range of the zeolitic imidazolate framework material is determined in such a way that the zeolitic imidazolate framework material can enhance the diffusion release rate of growth factors through the nanofiber shell layer without causing the wound tissue environment to extend to the inside of the nanofiber shell layer. For example, the particle size range of the zeolitic imidazolate framework material (ZIF-8) is 5 to 30 nm, preferably 7 to 15 nm. The zeolitic imidazolate framework material within the above particle size range can be used to increase the wetting area of the nanofibers and enhance the diffusion release rate of growth factors from the inside to the outside of the nanofibers. If the particle size of the zeolitic imidazolate framework material is too small, the quality of the growth factor diffusion channel cannot be improved, which is not conducive to the improvement of the growth factor diffusion release rate; if the particle size of the zeolitic imidazolate framework material is too small, it will affect the mechanical properties of the nanofiber membrane, and the tissue fluid and bioenzymes retained outside the nanofiber shell layer based on the hydrophilic adhesion of the nanofibers may act on the autologous platelet-rich plasma inside along the channels formed by the zeolitic imidazolate framework material, thus causing adverse consequences for the diffusion release of growth factors and offsetting the beneficial effects brought by the improvement of the growth factor diffusion release rate.

[0030] Preferably, the shell layer of the nanofibers further contains polyglycidol (PGL), and the polyglycidol is uniformly arranged in the shell layer in a manner that can adjust the processability of the nanofiber shell layer and control the degradation rate in vivo and in vitro. Polycaprolactone (PCL) and its monomers are non-toxic, have good biocompatibility and biodegradability, PCL has good permeability to small molecule drugs, and can be used as an erodible drug diffusion-type sustained release carrier, while PGL-PCL (polyglycidol-polycaprolactone) can improve the processability and control the degradation rate in vivo and in vitro, enabling the drug diffusion-type sustained release carrier to be differentially set based on the different repair positions and the different repair cycles at the same position.

[0031] The present application also provides the use of the dressing as described above for tissue trauma repair or in-situ tissue trauma repair.

[0032] Preferably, the application method includes: preparing nanofibers with a core-shell structure using coaxial electrospinning, processing the nanofibers into dressings, and carrying out the processing in a manner that is set based on the difference in nanofiber functional parameters and forms at least one of a one-dimensional structure to a three-dimensional structure. For example, the one-dimensional structure includes different nanofiber segments in one dimension, the two-dimensional structure includes different nanofiber partitions on a two-dimensional plane, and the three-dimensional structure includes different nanofiber layers in a three-dimensional solid. The functional parameters may include the degradation rate of the shell layer, the pore size of the shell layer fibers, the nanofiber size, and the ratio of the core layer to the shell layer, etc.

[0033] Preferably, the application method includes: forming a partitioned setting and / or a layered setting structure for the dressing based on the difference in nanofiber functional parameters, such that the differential setting of the nanofiber functional parameters forms an associated configuration with the action position of the dressing on the tissue wound and the healing stage of the tissue wound. This associated configuration includes at least one or more of controlling the growth factor release parameters by adjusting the fiber pore size of the nanofiber shell layer, matching the degradation rate of the nanofiber shell layer with the lifespan of autologous platelet-rich plasma, and adapting the layered configuration size of the nanofibers to the duration of the healing stage. That is, the dressing of the present application specifically associates the functional parameters of the nanofibers, the one-dimensional to three-dimensional structure of the dressing, the action position of the dressing on the tissue wound, and the healing stage of the tissue wound, such that the dressing of the present application can achieve the pertinence and applicability of the repair effect for different position tissue wounds and different tissue wound healing stages based on the microscopic functional parameter settings of the nanofibers and the one-dimensional to three-dimensional structure size settings of the nanofibers that make up the dressing.

[0034] Preferably, the application method includes: in-situ depositing the aforementioned nanofibers on the tissue wound based on a handheld coaxial electrospinning device to directly form a dressing that covers and protects the tissue wound, and the dressing regulates the release rate of the growth factor in different tissue wound positions or different healing stages in a manner of layered and / or partitioned setting and differential setting of nanofiber functional parameters. Then, the release rate of the growth factor of the dressing in different tissue wound positions or different healing stages can match the degree of injury and the healing condition to improve the overall healing quality, thereby achieving the effect of reducing or inhibiting scars. Description of the Drawings

[0035] Figure 1 is the microscopic structure diagram of the dressing of a preferred embodiment of the present invention;

[0036] Figure 2 is the performance parameter diagram of the dressing of a preferred embodiment of the present invention;

[0037] Figure 3 is the antibacterial experiment comparison diagram of the dressing of a preferred embodiment of the present invention;

[0038] Figure 4It is a comparison graph of the cell proliferation experiment of the dressing of a preferred embodiment of the present invention;

[0039] Figure 5 It is an analysis graph of the cell proliferation experiment of the dressing of a preferred embodiment of the present invention;

[0040] Figure 6 It is a comparison graph of the wound of the in vivo animal experiment of the dressing of a preferred embodiment of the present invention;

[0041] Figure 7 It is a comparison graph of the HE-stained wound tissue of the histological experiment of the dressing of a preferred embodiment of the present invention;

[0042] Figure 8 It is a comparison graph of the Masson-stained wound tissue of the tissue experiment of the dressing of a preferred embodiment of the present invention. Specific embodiments

[0043] The present invention will be described in detail below with reference to the accompanying drawings.

[0044] The present application proposes a nanofiber dressing, particularly relates to a multifunctional composite nanofiber dressing, and particularly relates to an in-situ autologous bionic repair dressing, which is applicable to the repair and treatment of tissue wounds. The skin covers the whole body and becomes an important barrier to protect the internal structure of the human body and maintain the internal environment, and can protect the internal tissues of the human body from the harm of bacteria. However, the skin is vulnerable to trauma. At present, skin traumas are mainly divided into acute traumas and burns and scalds. Wounds caused by surgical operations, traumas, and superficial burns all need to be bandaged with dressings to prevent the invasion of bacteria, avoid wound inflammation, and thus accelerate the wound healing process. In order to improve the antibacterial ability of the dressing and the ability to load active substances and drug components to improve the wound recovery rate and recovery quality, nanofiber membranes for wound dressings have been proposed in the prior art. Its inherent characteristics include a high specific surface area, a high porosity, and a structure similar to the extracellular matrix of skin cells. Therefore, it can isolate bacteria based on its structural characteristics and can be used to carry active substances and drug components, making the nanofiber membrane have broad prospects in the application field of wound dressings. The dressing structure of the present invention, its preparation, performance verification experiments, and applications will be specifically described below.

[0045] Example 1

[0046] Regarding the preparation method and microstructure of the dressing, in this embodiment, a coaxial electrospinning method is used to prepare the dressing composed of core-shell structured nanofibers in the present application. For the core-shell structure of the nanofibers of the dressing, a shell solution and a core solution, which are used as the shell layer raw material and the core layer raw material respectively, need to be configured in the coaxial electrospinning method. The main active substances of the shell solution are polycaprolactone and ε-polylysine, and medical acetone is used as the solvent and the solution is uniformly mixed; the main active substance of the core solution is autologous platelet-rich plasma, and a polyvinyl alcohol solution is used as the solvent. A coaxial electrospinning method is used to prepare nanofibers with a core-shell structure, and the nanofibers are processed into a dressing. Specifically, 2 g of polycaprolactone (PCL) and 0.4 g of ε-polylysine (ε-PL) are dissolved in 10 g of medical acetone and stirred for 12 hours on a magnetic stirrer to obtain the shell solution for coaxial electrospinning; 0.5 g of polyvinyl alcohol is dissolved in 10 g of water to obtain a 5% polyvinyl alcohol solution (PVA), and the autologous platelet-rich plasma activated by CaCl2 and tested by blood routine is dissolved in the 5% polyvinyl alcohol solution (PVA). The mass ratio of autologous platelet-rich plasma (autologous PRP, hereinafter simply referred to as PRP) to the polyvinyl alcohol solution (PVA) is 2:1, which is used as the core solution for coaxial electrospinning.

[0047] To obtain targeted comparative experimental results, this embodiment sets multiple groups of nanofiber dressings based on the selection of the active substances polycaprolactone, ε-polylysine, autologous platelet-rich plasma and different coaxial electrospinning schemes. The dressings are prepared as nanofiber membranes based on the nanofibers. The coaxial electrospinning schemes include traditional electrospinning and in-situ electrospinning. Traditional electrospinning is to process the nanofiber membrane prepared based on the electrospinning device and cover it on the wound to form a nanofiber membrane similar to gauze covering; in-situ electrospinning is to directly use the prepared nanofibers as a dressing based on the coaxial electrospinning device and in-situ deposit them on the wound to directly form a nanofiber membrane that fully covers the wound.

[0048] Specifically, three groups of nanofiber membranes, namely PCL, PCL + ε-PL, and PCL + PRP + ε-PL, were prepared using traditional electrospinning. The electrospinning voltage for the above three groups was 17.6 KV, and the flow rates of the electrospinning core layer solution and the shell layer solution were 0.5 ml / h and 1.2 ml / h, respectively. The distance between the electrospinning needle and the receiving electrode was about 15 cm, and all electrospinning processes were carried out under the conditions of 25°C and 50% humidity. An in-situ PCL + PRP + ε-PL (In-situ PCL + PRP + ε-PL) group of nanofiber membranes was prepared using in-situ electrospinning and based on the preparation method of the present application. In step a, the mass ratio of polycaprolactone, ε-polylysine, and medical acetone was 5:1:25, and the mixture was mixed using a stirrer for 12 hours. In step b, the mass concentration of the polyvinyl alcohol solution was 5%; the mass ratio of the polyvinyl alcohol solution to autologous PRP was 1:2. In step c, the electrospinning voltage of the coaxial electrospinning was 10 kv; the flow rates of the shell layer solution and the core layer solution of the coaxial electrospinning were 0.5 ml / h and 1.2 ml / h, respectively; the distance between the needle and the receiving electrode of the coaxial electrospinning was 10 cm; and the diameter of the electrospinning nozzle of the coaxial electrospinning was 0.4 mm.

[0049] Then, the above four groups of dressings, namely the PCL, PCL + ε-PL, PCL + PRP + ε-PL group nanofiber membranes and the In-situ PCL + PRP + ε-PL group nanofiber membranes, can obtain targeted comparative analysis results based on experiments to clarify the active substances and the contribution of the electrospinning scheme to the dressings.

[0050] Regarding the microstructure of the nanofiber membrane prepared in the In-situ PCL + PRP + ε-PL group, Figure 1 a is the SEM image of the nanofibers of the present application. The diameter range of the nanofibers is 0.2 to 1.2 μm, most of the diameters are between 0.4 and 1.0 μm, the median and average values are between 0.6 and 0.9 μm, and the average diameter of the nanofibers is about 0.7 μm. Figure 1 b is the TEM image of such nanofibers. It can be seen from the figure that the nanofibers have a coaxial structure, that is, the nanofibers of the dressing of the present application have a coaxial core-shell structure. Further, the nanofibers were stained, and the corresponding solutions of the core layer and the shell layer were labeled with calcein and rhodamine B, respectively. Figure 1When observed under a confocal microscope with excitation at a wavelength of 495 nm, the nuclear layer appears green, and when excited at a wavelength of 540 nm, the shell layer appears red, confirming the core-shell structure of the nanofibers and the concentrated distribution of PRP in the nuclear layer. Regarding the size ratio of the nuclear layer diameter to the nanofiber diameter of the nanofibers, the nuclear layer diameter of the nanofibers is 0.1 to 1.0 μm, preferably 0.3 to 0.8 μm, more preferably 0.4 to 0.7 μm; while the shell layer thickness of the nanofibers is 0.01 to 0.5 μm, preferably 0.1 to 0.3 μm. That is, the nuclear layer in the nanofibers is located inside and the shell layer coaxially wraps the nuclear layer on the outside to form nanofibers with a coaxial core-shell structure. The nuclear layer is used to provide growth factors, and the shell layer allows the growth factors to pass through and be released to act on the wound tissue. The first component as the main body of the shell layer in the shell layer is polycaprolactone, and the second component used to modify the first component in the shell layer is ε-PL. The action of ε-PL on PCL at least includes the improvement of wettability and the improvement of antibacterial ability. The third component of the nuclear layer is PRP. In the traditional single-needle electrospinning process, PRP will be directly mixed and contacted with organic solvents, resulting in the inactivation and denaturation of biological proteins and cytokines in PRP. Designing it into a core-shell structure allows PRP to use an aqueous solvent for electrospinning inside the nanofibers while the outer shell layer of the fiber uses an organic solvent for electrospinning, which can well protect the activity of PRP biological proteins and cytokines. In addition, compared with the traditional single-needle electrospinning, the coaxial electrospinning method for preparing the core-shell structure can usually slow down the release rate of doped substances in the fibers, such as growth factors, drugs, etc., based on the porous structure of the nanofiber shell layer. The slow and continuous release can usually meet the requirements of tissue repair for drug concentration.

[0051] Figure 2 a is the FTIR spectrum of the nanofiber membrane of the In-situ PCL+PRP+ε-PL group. The nanofibers (green line) have a carboxyl stretching vibration peak of the ester group at 1725 cm -1 and a stretching vibration peak of -C-O-C- at 1245 cm -1 These vibration peaks originate from PCL (blue line). At the same time, the vibration peaks at 1640 cm -1 and 1520 cm -1 come from ε-PL (red line), which proves that the main body of the nanofibers is composed of PCL and ε-PL. Since PRP rich in growth factors is distributed inside the nuclear layer of the nanofibers, in order to allow the drugs and active substances in the nuclear layer of the nanofibers to be released more easily, the nanofibers should have a porous structure and good wettability, so that after the tissue fluid infiltrates the nanofibers, the drugs and active substances can diffuse out in time. First, the N2 adsorption-desorption curve of the nanofibers was tested. From Figure 2As can be seen from b, an obvious hysteresis loop appears between the adsorption and desorption curves, indicating that the nanofibers have a porous structure with a fiber pore size of 4 to 10 nm, preferably 6 to 8 nm. Second, the water contact angle was measured. As can be seen from Figure 2 c, the water contact angle of the PCL group is about 109°, making it a hydrophobic material. After adding ε-PL, the water contact angle changed from 109° to about 62°. Based on the different proportions of the active ingredients, the water contact angle can be controlled between 40 and 80 degrees, preferably 50 to 70 degrees, successfully changing the hydrophilicity of the nanofiber membrane. The nanofiber membrane has good hydrophilicity, which can form a moist microenvironment on the wound surface, effectively absorb the exudate at the wound, and is beneficial to wound repair. Third, the release curves of several growth factors that play a positive role in burns and scalds were evaluated. Figure 2 As can be seen from d, the release rate of platelet-derived growth factor PDGF-BB in tissue fluid is faster than that of transforming growth factor TGF-β and vascular endothelial growth factor VEGF. This may be because PDGF-BB is more water-soluble, while TGF-β and VEGF are more lipid-soluble. In addition, it can be seen that the content of PDGF-BB is higher than that of TGF-β and VEGF. Considering that for different people, the contents of these three growth factors are different, and the specific content ratio of autologous growth factors is the optimal content ratio for this person and can effectively reduce the rejection, which is also the reason for using autologous PRP in this application.

[0052] Based on the experimental results of microstructure and spectral analysis, the nanofibers prepared by the in-situ coaxial electrospinning method in this application have a core-shell structure. The first component of the shell layer is polycaprolactone, and polycaprolactone can form a nanofiber shell layer with fiber pore size based on electrospinning. When the nanofibers made of polycaprolactone cover the wound, the size of the fiber pore is smaller than the size of bacteria, thus blocking the invasion of bacteria into the wound. However, polycaprolactone is a hydrophobic material, making it difficult for wound tissues to adhere. The second component of the shell layer is ε-polylysine, which is used to modify polycaprolactone, including at least improving the antibacterial property and wettability of polycaprolactone. As can be seen from the above experimental data, the improvement of wettability is reflected in that ε-polylysine can significantly reduce the water contact angle of polycaprolactone, enabling the wound tissue to adhere effectively, which is beneficial to cell adhesion and proliferation. Moreover, the preparation parameters in the preparation method of this application are also the optimized implementation parameters and preferred implementation schemes for making the nanofibers of the dressing in this application based on experimental design and debugging. The selection of the preparation parameters determines the ranges of material parameters such as nanofiber diameter, core layer diameter, shell layer thickness, shell layer fiber pore size, and water contact angle. The ranges of the above material parameters determine the antibacterial property, wettability, growth factor release and distribution of the dressing in this application, that is, the realization of the technical effects of the dressing in this application is closely related to the material parameters and preparation parameters in this application, making the nanofiber dressing with a core-shell structure prepared based on the preparation method of this application applicable to wound repair and having excellent antibacterial and wound-healing promoting properties.

[0053] Example 2

[0054] Comparative analysis of the antibacterial properties of the dressing: To compare and test the antibacterial properties of three groups of nanofiber membranes of PCL, PCL+ε-PL, PCL+PRP+ε-PL prepared by traditional electrospinning equipment and the nanofiber membrane of In-situ PCL+PRP+ε-PL. The disk agar diffusion method was used to evaluate the antibacterial effect. First, in a sterile environment, a suspension of Escherichia coli and Staphylococcus aureus with about 1×10 8 cells was inoculated onto a ready-to-use nutrient agar medium (9 cm×9 cm). The several groups of nanofiber membranes used in the experiment were cut into nanofiber pads with a radius of 1 cm, and then the nanofiber pads were placed at the center of the 9 cm×9 cm agar medium coated with bacteria and cultured in a constant temperature and pressure box at 30 °C for 18 hours. Since burn wounds are extremely vulnerable to bacterial infection, if the nanofibers can kill Gram-negative bacteria and Gram-positive bacteria, it will be beneficial to burn treatment. Therefore, in vitro antibacterial evaluation was carried out by the disk agar diffusion method. Figure 3The control group in a was untreated Escherichia coli and Staphylococcus aureus. No antibacterial ring appeared after covering with PCL fibers, indicating that PCL has no bactericidal effect on bacteria. In the other three groups, including PCL+ε-PL, PCL+PRP+ε-PL, and In-situ PCL+PRP+ε-PL, very obvious antibacterial rings appeared and the radii were basically the same, indicating that the antibacterial effect should come from ε-PL. ε-PL can interfere with the normal synthesis of the microbial cell wall, reduce the osmotic pressure resistance of the bacterial cells, and cause the bacterial cells to deform, rupture, and die. From the further SEM images of Escherichia coli and Staphylococcus aureus ( Figure 3 b, d), it can be confirmed that untreated Escherichia coli has a rod-shaped structure, a smooth surface, and a plump morphology without cell damage ( Figure 3 b). After treatment with PCL+PRP+ε-PL nanofibers, the cell membrane of the bacteria showed shrinkage, without a plump feeling, and constriction marks appeared on the cell membrane surface ( Figure 3 c). Staphylococcus aureus showed similar results to Escherichia coli ( Figure 3 d, e). This can confirm that after adding ε-PL, it can damage the cell membrane structure of microorganisms, cause bacterial lysis, and thus achieve a bactericidal effect.

[0055] Comparative analysis of the cytotoxicity of dressings: Since the nanofiber membrane containing PRP is ultimately used in the human body, it is required to be non-toxic. Therefore, fibroblasts were inoculated onto different 4 groups of slides and the control group slides, and their cell responses were detected. After alcohol disinfection and ultraviolet irradiation of the nanofiber membrane, the cell metabolic activity was measured using CCK-8. All experimental steps need to be carried out under a sterile laminar flow hood. This experiment was divided into the above 5 groups, including the traditional electrospinning group PCL, PCL+ε-PL group, PCL+PRP+ε-PL group, and In-situ PCL+ε-PL+PRP group. There were 4 replicate wells in each group. The above 5 groups of nanofiber membranes and the control group empty slides were placed in a 24-well plate, washed once with phosphate buffer solution (PBS), washed three times with serum-free medium, then 100 μl of complete medium was added, and then placed in an incubator at 37 °C. Next, fibroblasts with a confluence of 90% were taken out of the incubator, rinsed 3 times with phosphate buffer solution PBS, then 200 μl of trypsin was added and placed in the incubator to digest the cells. After 3 minutes, it was taken out and the digestion was terminated with 1 ml of complete medium (DMEM high glucose hyclone, 10% fetal bovine serum, 1% double antibody). The cells were repeatedly pipetted until they detached and then placed in a 1.5 ml EP tube and centrifuged (900 rmp, 5 min). The supernatant was discarded, and the cells were resuspended in 1 ml of complete medium. 10 μl of the cell suspension was taken for counting, and the number of cells obtained was 80×10 4 cells / ml. The number of cells seeded in each well was approximately 10 5cells / ml. After preparing the required cell suspension, use a pipette to aspirate 100 μl of the cell suspension and seed it into each well. After 2 hours, supplement the culture medium to 700 μl. Measure the cell proliferation numbers at 4 hours, 12 hours, 1 day, 3 days, and 5 days respectively. After removing the old culture medium, rinse it once with phosphate buffer solution (PBS), and add complete medium containing 10% CCK-8 reagent (400 μl per well). Note that when adding the liquid, it is necessary to avoid light. Incubate at 37 °C in a humidified atmosphere of 5% CO2 for 2 h. Transfer 100 μL of the liquid in the 24-well plate to a 96-well plate, with 3 replicates for each group, wrap it with tin foil, and monitor the absorbance at 450 nm using a microplate reader.

[0056] Due to further in vivo applications, it is required that the PRP-containing nanofibers are not cytotoxic. Therefore, human fibroblasts were seeded on the nanofiber membranes to evaluate their cellular responses. Polystyrene tissue culture plates (TCPs) were incubated with fibroblasts on the same day as a control group. The attachment and morphology of human fibroblasts were determined by double-label fluorescence staining of the actin cytoskeleton and the nucleus. Figure 4 a - e show the cells on the nanofiber membranes of different groups. Figure 5 The proliferation of human foreskin fibroblasts (HSFs) cultured on the control group, PCL, PCL + ε-PL, PCL + ε-PL + PRP, and In-situ PCL + ε-PL + PRP for 1, 3, and 5 days is shown. The control group is the positive control group, and the proliferation shows an upward trend from day 1 to day 5 for each group. The PCL group exhibits more significant proliferation than the control group, indicating that the fibers spun from pure PCL itself have good biocompatibility. When HSFs were cultured on different samples for 1 day, the proliferation effect of HSFs on different samples was not obvious. After culturing for 3 days, the proliferation of HSFs on PCL + ε-PL was better than that of HSFs on PCL. This indicates that although ε-PL is an antibacterial substance, it has no toxic effect on cells. After HSFs were cultured on different samples for 5 days, the proliferation of HSFs on PCL + ε-PL + PRP and In-situ PCL + ε-PL + PRP was significantly (P < 0.01) better than that of HSFs on the PCL and PCL + ε-PL groups. These experimental results indicate that PRP promotes the proliferation of HSFs, and these nanofibers are non-toxic and have no side effects on cells.

[0057] Comparative analysis of in vivo experiments on dressings: To test the efficacy, 40 SD rats were randomly divided into 5 groups. Appropriate-shaped PCL, PCL + ε-PL, and PCL + ε-PL + PRP fiber scaffolds were cut according to the shape of the skin burn wound surface. In the In-situ PCL + PRP + ε-PL group, a PCL + PRP + ε-PL nanofiber membrane was directly deposited in situ on the wound surface of the rat back skin using a handheld electrospinning device. The wound surfaces of each group were covered with gauze and fixed with silk sutures. To avoid interference between animals, they were housed individually. After the burn wounds of the rats were covered with scaffolds or treated with natural healing, photographs were taken and the healing conditions were observed on days 1, 3, 5, 7, 9, 14, and 21. The wound recovery of second-degree burns was evaluated using SD rats, and the recovery conditions were photographed and recorded on days 3, 5, 7, 9, 11, 14, and 21. Second-degree burns affect the upper and deep dermis, appear white or yellow, blister, and have a moist appearance. As Figure 6 shown in Figure a, 3 days after scalding, the swelling and redness around the wound of the control group were the most obvious, followed by the PCL group. This is because the PCL nanofiber membrane can prevent bacterial infection of the wound from the air and protect the wound. On the 5th day after scalding, compared with the PCL group, the recovery effect of the PCL + ε-PL group was significantly better, which can be attributed to the antibacterial ability of ε-PL, which reduces bacterial infection and thus facilitates wound recovery. On the 14th day, obvious scabs could still be seen in the PCL + ε-PL group. In sharp contrast, the scabs on the wound of the PCL + ε-PL + PRP group had completely disappeared, and it had almost completely recovered on the 21st day. This shows that the various growth factors contained in PRP are very helpful for wound healing and can effectively promote wound repair.

[0058] The nanofiber membrane obtained by traditional electrospinning involves two processes: spinning and use. After the nanofiber membrane is cut, it is then covered on the wound surface. However, the nanofiber membrane obtained by this traditional method, similar to the use of gauze, has a poor fit with the wound. Figure 6 Figure c shows the traditional nanofiber membrane covered on the skin. After testing, the adhesion force between the nanofiber membrane and the skin is 0.02 N. In contrast, the handheld device based on in situ electrospinning directly deposits fibers on the skin. After testing, the adhesion force between the nanofiber membrane and the skin is 0.18 N. A better fit will have a positive impact on repair. Therefore, based on the PCL + ε-PL + PRP group, the differences between the traditional method and the in situ electrospinning method for burn repair were further compared. From Figure 6As can be seen from Figure b, the In-situ PCL+PRP+ε-PL group showed a faster recovery rate than the traditional spinning group. This may be due to better adhesion, which can effectively prevent external bacteria from invading the wound through the adhesion gap at the nanofiber membrane-skin interface, thus accelerating the recovery of burns and scalds. This shows that the in-situ deposition method can further improve the effect of dressings containing antibacterial and growth factors. Better adhesion not only reduces the gap and the probability of bacterial infection, but also reduces the distance from the skin, which is beneficial to the timely and effective delivery of growth factors to the wound, while enhancing the efficacy of antibacterial and growth factors.

[0059] Regarding the comparative analysis of the tissue reaction of the dressing: Histological analysis was performed. After taking frozen sections of the newly formed tissue, methods such as HE staining and Masson staining were used to observe the healing process of the rat skin wound surface (such as wound inflammatory reaction, fibroblast proliferation, collagen secretion and typing, epidermal layer differentiation, etc.). The scalded tissues of SD rats on the 1st day, 7th day, 14th day, and 21st day were fixed on glass slides for hematoxylin-eosin (H&E) and Masson staining. HE and Masson staining were used to evaluate the number of bacteria around the wound and the progress of wound recovery, respectively. The histopathological changes of the wound were observed under a microscope.

[0060] The repair of burns and scalds wounds is a very complex process. In order to analyze the relationship between wound infection and recovery from a microscopic perspective, HE staining ( Figure 7 ) was used to evaluate the state of wound repair. From the 3rd day to the 7th day after scalding, a large number of lymphocytes were seen in the control group, while relatively fewer in the PCL group. This shows that the PCL group can protect the wound from bacterial invasion due to the coverage of the nanofiber membrane, so there are fewer lymphocytes. On the 7th day, the PCL+ε-PL group showed fewer lymphocytes than the PCL group. This is because ε-PL has antibacterial properties and can lyse bacteria, thus reducing the bacteria at the wound. On the 14th day, the PCL+ε-PL+PRP group significantly had more blood vessels than the PCL+ε-PL group. This is because PRP contains various growth factors. When PRP encounters tissue fluid, Ca2+ in the tissue fluid activates PRP to release growth factors, accelerating tissue repair and regeneration. On the 21st day, the In-situ PCL+ε-PL+PRP group showed more blood vessels and fewer neutrophils than the PCL+ε-PL+PRP group. This is because the fibers deposited in-situ on the wound have better adhesion, which can effectively prevent external bacteria from invading the wound through the adhesion gap at the nanofiber membrane-skin interface, enhancing antibacterial ability, and reducing the gap distance from the skin, which is beneficial to the timely and effective delivery of growth factors to the wound, while enhancing the repair effect of growth factors on tissues. This confirms from a microscopic perspective that the in-situ deposition method can further improve the effect of dressings containing antibacterial and growth factors. Further through Masson's trichrome staining (Figure 8 ) Observe the collagen deposition in the wound tissue. It can be seen that on the 3rd day, only a small amount of collagen fibers appeared in all groups. On the 7th day, the arrangement of collagen fibers in all wound groups was irregular. On the 14th day, the PCL + ε-PL group had less blue collagen fibers and granulation tissue, while the PCL + ε-PL + PRP group and the In-situ PCL + PRP + ε-PL group had relatively dense collagen fibers. On the 21st day, the In-situ PCL + ε-PL + PRP group took the lead in forming a complete epithelial tissue on the surface of the wound tissue, indicating that tissue repair had been completed. These experimental results show that relying solely on antibacterial action is far from enough to achieve wound healing. Wound repair not only requires bactericidal action to eliminate bacteria and reduce inflammation, but also needs the combined action of various growth factors to promote wound healing. The in-situ deposition method can further enhance the effect of dressings containing antibacterial and growth factors.

[0061] Based on the above performance comparison experiments such as antibacterial property / cytotoxicity / in vivo experiment / tissue examination, etc., the technical effect of the dressing of the present application is closely related to the acting substances such as ε-polylysine, autologous platelet-rich plasma, etc. and material parameters. For example, for ε-polylysine, ε-polylysine not only improves the wettability of the polycaprolactone in the dressing shell layer and enhances the antibacterial property, but also the shell layer structure formed by ε-polylysine and polycaprolactone is of great significance for the release rate and distribution of growth factors in autologous platelet-rich plasma. The dressing shell layer formed by ε-polylysine and polycaprolactone coaxially wraps the autologous platelet-rich plasma located in the core layer and has fiber pores that allow the growth factors in the autologous platelet-rich plasma to pass through. Wound tissue cells adhere and proliferate on the outer surface of the shell layer, and the growth factors move from the inner side of the shell layer to the outer side to maintain a high concentration of growth factors near the tissue cells. The shell layer serves as a degradable organic barrier that isolates the wound environment and autologous platelet-rich plasma, which can prevent autologous platelet-rich plasma from being decomposed by enzymes on the wound surface and unable to continuously release growth factors. The fiber pore size of the shell layer matches the size of the growth factors, and the degradation rate of the shell layer also adapts to the life cycle of the release of growth factors from autologous platelet-rich plasma, enabling the autologous platelet-rich plasma located in the core layer to continuously and stably release growth factors to maintain a high concentration of growth factors for tissue cells.

[0062] In summary, the dressing of the present application has excellent antibacterial properties under the combined use of polycaprolactone and ε-polylysine, and can improve the wettability of polycaprolactone, enabling wound tissue cells to exhibit good biocompatibility with the shell layer of the dressing, which is conducive to cell adhesion and proliferation. This also provides an active induction environment for the synergistic effect with the growth factors released from the core layer of the dressing. Moreover, the autologous PRP in the core layer can slowly and continuously release growth factors. The autologous PRP fits perfectly with the patient's wound environment without causing allergic reactions, and the content ratio of each growth factor meets the requirements of the wound environment, effectively ensuring the pertinence and applicability of the growth factors for inducing the activity of wound tissue cells.

[0063] Example 3

[0064] The dressing of this example is constructed by forming a core-shell structure nanofiber based on a coaxially arranged core layer and shell layer. Among them, the shell layer of the nanofiber at least contains polycaprolactone for forming the main body of the shell layer, ε-polylysine for modifying polycaprolactone, and zeolitic imidazolate framework material (ZIF-8), and the core layer of the nanofiber at least contains autologous platelet-rich plasma for releasing growth factors.

[0065] Preferably, the zeolitic imidazolate framework material is arranged in the shell layer of the nanofiber in a manner of coating or embedding in the polycaprolactone modified by ε-polylysine. The particle size range of the zeolitic imidazolate framework material is determined in such a way that the zeolitic imidazolate framework material can improve the diffusion release rate of growth factors through the nanofiber shell layer without causing the wound tissue environment to extend to the inner side of the nanofiber shell layer. For example, the particle size range of the zeolitic imidazolate framework material (ZIF-8) is 5 to 30 nm, preferably 7 to 15 nm. The zeolitic imidazolate framework material within the above particle size range can be used to increase the wetted area of the nanofiber and improve the diffusion release rate of growth factors from the inner side to the outer side of the nanofiber. If the particle size of the zeolitic imidazolate framework material is too small, the quality of the growth factor diffusion channel cannot be improved, which is not conducive to the improvement of the growth factor diffusion release rate; if the particle size of the zeolitic imidazolate framework material is too small, it will affect the mechanical properties of the nanofiber membrane, and the tissue fluid and bioenzymes retained on the outer side of the nanofiber shell layer based on the hydrophilic adhesion of the nanofiber may act on the autologous platelet-rich plasma inside along the channels formed by the zeolitic imidazolate framework material, thus causing adverse consequences for the diffusion release of growth factors and offsetting the beneficial effects brought by the improvement of the growth factor diffusion release rate.

[0066] Preferably, the shell layer of the nanofibers further contains polyglycidol (PGL), and the polyglycidol is uniformly arranged in the shell layer in a manner that can adjust the processability of the nanofiber shell layer and control the degradation rate in vivo and in vitro. Polycaprolactone (PCL) and its monomer are non-toxic, have good biocompatibility and biodegradability. PCL has good permeability to small molecule drugs and can be used as an erodible drug diffusion-type sustained release carrier. PGL-PCL (polyglycidol-polycaprolactone) can improve the processability and control the degradation rate in vivo and in vitro, enabling the drug diffusion-type sustained release carrier to be differentially set based on the differences in the repair location and the repair cycle at the same location.

[0067] In this embodiment, the nanofiber dressing is further improved to enhance the antibacterial performance and tissue adhesion of the dressing and improve the drug diffusion and sustained release characteristics. For the above-mentioned nanofiber dressing prepared from polycaprolactone, ε-polylysine and autologous platelet-rich plasma, the autologous platelet-rich plasma rich in growth factors is distributed inside the nanofiber core layer, so that the growth factors need to use the nanofiber shell layer composed of polycaprolactone and ε-polylysine as a drug diffusion and sustained release carrier, enabling the growth factors located inside the nanofiber shell layer to stably and continuously diffuse and release to the outside of the nanofiber shell layer. To improve the diffusion range and release rate of the growth factors in the nanofiber core layer and other characteristics, the fiber pore size of the nanofiber shell layer should be suitable for autologous platelet-rich plasma and the nanofibers should have good wettability; to promote the interaction between the growth factors and the wound tissue to improve the wound healing rate, the nanofibers should have a larger wettable area to increase the space for wound tissue cell adhesion and proliferation, so that the nanofibers can also increase the interaction efficiency between the growth factors and the wound tissue based on the increase in the wettable area.

[0068] As Figure 2 shown in d, the growth factors released by autologous platelet-rich plasma for promoting tissue repair are mainly platelet-derived growth factor PDGF-BB, transforming growth factor TGF-β, and vascular endothelial growth factor VEGF. Among them, platelet-derived growth factor PDGF-BB has mitogenic, differentiating, chemotactic, and angiogenic effects, and transforming growth factor TGF-β is used to regulate cell growth and differentiation; vascular endothelial growth factor VEG is highly specific for vascular endothelial cells and has important biological functions such as promoting vascular permeability and promoting the proliferation of endothelial cells. According to Figure 2From the cumulative release curves of different growth factors in d, it can be seen that the different growth factors released from autologous platelet-rich plasma diffuse and release from the nanofiber shell to the outside of the nanofiber shell and show curves with varying contents over time in the tissue fluid. Since PDGF-BB is more water-soluble, while TGF-β and VEGF are more lipid-soluble, the release rate of PDGF-BB in the tissue fluid is faster than that of TGF-β and VEGF; and the content of PDGF-BB is higher than that of TGF-β and VEGF. The content difference and specific ratio are determined by the autologous platelet-rich plasma from the patient itself, and its specific ratio is the optimal ratio for the patient and can effectively avoid rejection. However, for the drug diffusion and sustained-release carrier composed of polycaprolactone and ε-polylysine, it takes a long time for the growth factors to reach a stable high content or high concentration. For example, the times for PDGF-BB, TGF-β, and VEGF to reach 80% of the maximum concentration are 15 days, 10 days, and 10 days respectively. That is, in the initial stage of wound healing when the demand for growth factors is the greatest, the drug diffusion and sustained-release carrier composed of polycaprolactone and ε-polylysine has a slow diffusion and release rate of growth factors and cannot provide a high concentration of growth factors in the initial stage of healing. Therefore, it is considered to improve the nanofiber shell to improve the release rate of growth factors and the efficiency of promoting healing of the drug diffusion and sustained-release carrier composed of polycaprolactone and ε-polylysine.

[0069] Metal-Organic Frameworks (MOFs) are porous, crystalline materials formed by the self-assembly of metal ions or metal clusters with multidentate organic ligands. This inorganic-organic hybrid material combines the excellent properties of inorganic and organic materials. It not only has a high specific surface area, adjustable size and porosity, but also has a high drug loading rate and is easy to modify on the surface. Therefore, it is widely used in fields such as catalysis, gas capture, sensors, and drug delivery. Zeolitic Imidazolate Framework-8 (ZIF-8) is a type of metal-organic framework coordinated by zinc ions (Zn 2+ ) and 2-methylimidazole (2-MiM), showing good biocompatibility and acid environment sensitivity. It remains stable under physiological conditions and disintegrates under acidic conditions. It is an ideal carrier for drug transport and sustained release. Moreover, the size of the nanomaterial is crucial for its performance. A slight change in size can have a decisive impact on the performance of the material, making the control of the particle size of ZIF-8 and the functional size composite regulation of ZIF-8 with other materials of great significance for the application of ZIF-8 and its composites in the process of biomolecular transport. The preparation methods of ZIF-8 include solvothermal synthesis, microwave-assisted method, and microfluidic method. Its particle size regulation methods include the adjustment of reaction parameters, the regulation of surfactants, and the participation of crystallization regulators, and ZIF-8 with a particle size range of 10 nm - 1 μm can be prepared.

[0070] Therefore, ZIF-8 within a selected particle size range is added to the shell solution and mixed evenly, and a shell of nanofibers is prepared based on coaxial electrospinning, such that the PCL-ε-PL nanofibers coated or embedded with ZIF-8 exhibit a large specific surface area, thereby increasing the drug loading capacity of the nanofibers from 15% to 25%. ZIF-8 can also increase the number and quality of channels for the diffusion release of growth factors from the inner side to the outer side of the nanofiber shell based on the selection of a specific range of particle size dimensions. The PCL-ε-PL nanofibers coated or embedded with ZIF-8 also significantly increase the infiltration area and adhesion space of tissue cells on the nanofiber shell, enhancing the interaction between growth factors and wound tissue. Antibacterial experiments have found that ZIF-8 and ε-PL exhibit dual antibacterial properties. ε-PL, as a polypeptide, is loaded onto ZIF-8 to further kill residual bacteria, enabling the dressing prepared from such PCL-ZIF-8-εPL nanofibers to enhance the barrier ability against external bacteria and the killing effect on internal bacteria, and to prevent external bacteria from infecting the wound, thus exhibiting efficient bactericidal properties. Then, the drug diffusion and sustained release carrier based on PCL-ZIF-8-εPL nanofibers can shorten the wound healing time from 22 days to 17 days by enhancing antibacterial performance, increasing the infiltration area, and enhancing the release rate of growth factors.

[0071] Example 4

[0072] This example provides the application of the dressing as described above for tissue trauma repair. The application method includes: using coaxial electrospinning to prepare nanofibers with a core-shell structure, processing the nanofibers into a dressing and carrying out in a manner that is set based on the difference in nanofiber functional parameters to form at least one of a one-dimensional structure to a three-dimensional structure. For example, the one-dimensional structure includes different nanofiber segments in one dimension, the two-dimensional structure includes different nanofiber partitions on a two-dimensional plane, and the three-dimensional structure includes different nanofiber layers in a three-dimensional solid. The functional parameters can include the shell degradation rate, the shell fiber pore size, the nanofiber size, and the ratio of the core layer to the shell layer, etc.

[0073] Preferably, the dressing is partitioned and / or layered based on different settings of nanofiber functional parameters, so that the different settings of nanofiber functional parameters are associated with the action position of the dressing on the tissue wound and the healing stage of the tissue wound. The association configuration includes at least one or more of the following: the nanofiber shell layer controls the growth factor release parameters by adjusting the fiber pore size, the degradation rate of the nanofiber shell layer matches the life cycle of autologous platelet-rich plasma, and the nanofiber layered configuration size is adapted to the duration of the healing stage. That is, the dressing of the present application specifically associates the functional parameters of the nanofibers, the one-dimensional to three-dimensional structure of the dressing, the action position of the dressing on the tissue wound, and the healing stage of the tissue wound. Therefore, the dressing of the present application can achieve the targeting and applicability for the repair of different tissue wounds and different tissue wound healing stages based on the settings of the nanofiber microscopic functional parameters and the one-dimensional to three-dimensional structure size of the nanofiber constituting the dressing.

[0074] This embodiment also provides the application of the dressing as described above in in-situ tissue trauma repair. The application method includes: based on a handheld coaxial electrospinning device, depositing the nanofibers as described above in-situ on the tissue wound to directly form a dressing that covers and protects the tissue wound, and the dressing regulates the release rate of growth factors at different tissue wound positions or different healing stages in a manner of layered and / or partitioned setting and different settings of nanofiber functional parameters. Then, the release rate of the growth factor of the dressing at different tissue wound positions or different healing stages can match the degree of injury and the healing condition to improve the overall healing quality, thereby achieving the effect of reducing or inhibiting scars.

[0075] Specifically, the nanofiber dressing of the present application has excellent antibacterial properties, drug loading properties, and wound healing and repair promoting effects. Therefore, the nanofiber dressing of the present application can be applied to the repair of tissue wounds at different positions, enabling the nanofiber shell structure to serve as an organic biodegradable drug diffusion and sustained release carrier to provide antibacterial support and drug support for tissues in the wound repair period. Due to the differences in the positions of tissue wounds, the nanofiber dressing of the present application needs to be processed into a form suitable for tissue wounds with different body positions, different shapes, and different depth distribution characteristics. Then, in the process of using the coaxial electrospinning method to prepare nanofibers with a core-shell structure and processing the nanofibers into a dressing, the dressing should have a structure suitable for tissue wounds with different characteristics, and this structure is formed based on the parameter settings of the nanofibers and includes at least one of a one-dimensional structure to a three-dimensional structure. For example, the one-dimensional structure includes different nanofiber segments in one dimension, the two-dimensional structure includes different nanofiber partitions on a two-dimensional plane, and the three-dimensional structure includes different nanofiber layers in a three-dimensional solid. Clinically, wounds are classified into ordinary linear wounds, ramp-shaped linear wounds, V-shaped wounds, triangular-like wounds, U-shaped flap wounds, circular-like or irregular wounds, etc. according to their morphological characteristics. Then, for tissue wounds with different morphological characteristics, dressings of corresponding shapes should be configured to achieve good coverage and protection, and the functional parameters of the nanofibers serving as the drug diffusion and sustained release carrier can be controlled based on the settings of the one-dimensional structure to the three-dimensional structure. The functional parameters can include the shell degradation rate, the pore size of the shell fibers, the nanofiber size, and the ratio of the core layer to the shell layer, etc.

[0076] For example, for circular or quasi-circular burn or scald tissue wounds, the burn / scald center spreads outwards and forms a distribution pattern in which the degree of wound damage changes radially, such that the morphological characteristics of the tissue wound show a differential distribution along the radial direction on a plane. To ensure the applicability of the dressing to different positions of the tissue wound, the dressing acts on wound positions with different degrees of damage in a manner of differentially setting the functional parameters of the nanofibers in a two-dimensional structure and can finely adjust the healing speed of each position. The differential setting of the functional parameters of the nanofibers in the two-dimensional structure may include: the pore size of the shell layer fibers is arranged to decrease radially from the center, and the ratio of the core layer to the shell layer is arranged to decrease radially from the center. Thus, the pore size of the shell layer fibers and the ratio of the core layer to the shell layer are larger at the center of the tissue wound and smaller at the edge. This setting method mainly considers the characteristic of the change in the degree of tissue wound damage along the radial direction. The larger the pore size of the shell layer fibers, the faster the growth factor release rate. The increase in the ratio of the core layer to the shell layer will also bring an increase in the release concentration of the growth factor, such that the growth factor concentration and release speed can match the damage state at the center of the tissue wound, accelerate the repair speed at the center of the tissue wound, and combine with the healing speed of other positions to achieve an improvement in the overall healing effect. Then, the dressing can not only specifically promote wound repair, but also achieve coordinated control of the healing speed of each position based on the overall regulation of the wound healing speed to reduce or inhibit scars, thereby significantly improving the quality of the effect of the dressing of the present application on the repair and healing of tissue wounds.

[0077] Wound healing is generally divided into a coagulation phase, an inflammation phase, a repair phase, and a maturation phase. The coagulation phase varies from a few minutes to dozens of minutes based on individual differences and the degree of the wound. After the formation of the wound surface, the first reaction of the body is to initiate the coagulation mechanism for its own hemostasis process. Platelets on the wound surface aggregate and a blood clot appears, which can effectively prevent the wound from bleeding. The inflammation phase lasts about 4 - 6 days. In this stage, mainly bacteria are destroyed and necrotic tissue is removed. The permeability of tissue blood vessels increases, body fluids exude, and coagulation factors, fibrin, etc. participate in the hemostasis process, while neutrophils and macrophages, etc. participate in the inflammatory reaction, phagocytosing necrotic tissue cells, laying a foundation for the regeneration and repair of the tissue. The repair phase is mainly tissue hyperplasia and granulation formation, the generation of new capillaries, blood vessel reconstruction, and the formation of new granulation tissue. The maturation phase is mainly a process of scar remodeling, tissue connection repair, the wound gradually shrinks and closes, epithelial cells crawl along the wound, gradually covering the wound to form a scar. As time goes by, the scar tissue, scab, etc. that repair the wound are gradually adjusted, and the repair tissue adapts to the physiological function, ultimately achieving an improvement in the appearance and function of the injured part.

[0078] Therefore, the repair effects of dressings on wounds at different healing stages should be configured with targeted functional parameters in combination with tissue morphology and physiological characteristics. For example, based on the duration of different healing stages and the degradation rate of nanofiber dressings, dressings acting on different healing stages are configured in layers. The layered dressings are set to adapt to the tissue morphology and physiological characteristics of different wound healing stages based on the differences in nanofiber functional parameters, so that the nanofibers as drug diffusion and sustained-release carriers have a specific association with the healing stage in terms of functional parameters. This specific association includes at least one or more of the following: the nanofiber shell layer controls the growth factor release parameters by adjusting the fiber pore size, the degradation rate of the nanofiber shell layer matches the lifespan of autologous platelet-rich plasma, and the size of the nanofiber layered configuration adapts to the duration of the healing stage. This enables the nanofiber dressings of the present application to achieve the pertinence and applicability of the repair effects on wounds of different tissue locations and different tissue wound healing stages in terms of the setting of nanofiber microscopic functional parameters and the setting of the one-dimensional to three-dimensional structural sizes of nanofibers forming the dressings.

[0079] It should be noted that the above specific embodiments are exemplary. Those skilled in the art can come up with various solutions inspired by the disclosure of the present invention, and these solutions also fall within the scope of the disclosure of the present invention and within the protection scope of the present invention. Those skilled in the art should understand that the description and drawings of the present invention are illustrative and do not constitute a limitation on the claims. The protection scope of the present invention is defined by the claims and their equivalents.

Claims

1. A nanofiber dressing, characterized in that, The dressing is constructed by nanofibers forming a core-shell structure based on coaxially arranged core layer and shell layer, wherein, the shell layer of the nanofibers contains a first component for forming the main body of the shell layer and a second component for modifying the first component; the core layer of the nanofibers contains a third component for releasing growth factors, wherein, the nanofiber dressing forms a two-dimensional structure based on the differential setting of nanofiber functional parameters, the dressing acts on wound positions with different degrees of injury in a manner of differential setting according to the functional parameters of the nanofibers on the two-dimensional structure and can finely adjust the healing speed of each position, and the functional parameters of the nanofibers are differentially set on the two-dimensional structure as follows: the fiber pore diameter of the shell layer decreases radially from the center and the ratio of the core layer to the shell layer decreases radially from the center.

2. The dressing according to claim 1, characterized in that, The first component is a polymerizable organic matter that can be degraded in vivo and in vitro, the second component is a functional additive that can be used to adjust the antibacterial property, wettability and microscopic size of the first component, and the third component is an autologous active substance that can release pro-healing growth factors.

3. The dressing according to claim 1 or 2, characterized in that, The first component is set as polycaprolactone, the second component is set as ε-polylysine, and the third component is set as autologous platelet-rich plasma.

4. The dressing according to claim 1, characterized in that The diameter of the nanofibers is 0.2 - 1.2 μm, the diameter of the nanofiber core layer is 0.1 - 1.0 μm, and the thickness of the nanofiber shell layer is 0.01 - 0.5 μm.

5. The dressing according to claim 1, characterized in that The shell layer of the nanofibers is a porous structure, and the fiber pore diameter of the shell layer is 4 - 10 nm; The water contact angle of the shell layer of the nanofibers is 40 - 80 degrees.

6. The dressing according to claim 1, wherein, the shell layer of the nanofibers contains polycaprolactone for forming the main body of the shell layer, ε-polylysine for modifying polycaprolactone, and zeolitic imidazolate framework material ZIF-8; the core layer of the nanofibers contains autologous platelet-rich plasma for releasing growth factors.

7. The dressing according to claim 6, characterized in that, The zeolitic imidazolate framework material is arranged in the shell layer of the nanofibers in a manner of coating or embedding in the polycaprolactone modified by ε-polylysine; The particle size range of the zeolitic imidazolate framework material is determined in a manner that the zeolitic imidazolate framework material can enhance the diffusion release rate of growth factors through the nanofiber shell layer without causing the wound tissue environment to extend to the inner side of the nanofiber shell layer.

8. The dressing according to claim 1, characterized in that, The shell layer of the nanofibers further contains polyglycidol, and polyglycidol is uniformly arranged in the shell layer in a manner that can adjust the processability of the nanofiber shell layer and control the in vivo and in vitro degradation rate.

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