Antibacterial composite promoting wound healing

Abstract

An antibacterial composite promoting wound healing, comprising at least one nanofiber layer, the nanofiber layer comprising a first fiber and a second fiber, wherein the first fiber comprises a first degradable polymer and an antibacterial agent, and the second fiber comprises a second degradable polymer and a surfactant. The antibacterial composite has good stability and hydrophilicity, and also exhibits suitable drug release properties, demonstrating excellent antibacterial and wound-healing capabilities on bacterially contaminated wounds.

Description

Antibacterial and wound-healing complex Technical Field

[0001] This invention relates to an antibacterial and wound-healing complex, and more specifically to an antibacterial and wound-healing complex containing an antibacterial agent and two or more biodegradable biomaterials. Background Technology

[0002] For any wound, whether acute or chronic, healing rate is a crucial clinical indicator. Besides healing, wound pain and infection are also significant clinical concerns. Infection is closely related to wound healing. Wounds that fail to heal for a long time are more prone to infection due to the exposure of the wound bed; infected wounds can lead to stunted healing or even further deterioration. When bacteria enter a wound, the body's immune system can eliminate all or some of them. However, when the bacteria's reproductive capacity exceeds the body's defenses, infection occurs. Once infection occurs, wound healing slows down or stops, and in severe cases, it can lead to systemic infection and even death.

[0003] Nanospinning, prepared from synthetic biodegradable polymer materials, possesses a porous structure that can mimic extracellular matrix production and promote tissue growth, and has been widely explored to accelerate wound healing. For example, the internationally marketed product Restrata (Acera Surgical, USA) is composed of independent nanofibers made from two polyester polymers: polylactic acid-glycolic acid copolymer (PLGA) and polydioxanone (PDO). While Restrata has demonstrated good wound healing capabilities in clinical studies, a drawback of this type of material is that most synthetic biodegradable polymers are polyesters, which are hydrophobic and have poor wetting properties, failing to effectively drain exudate from the wound quickly. There are indications that Restrata may increase the risk of wound infection (ClinicalTrials.gov NCT04918784; Foot & Ankle Surgery: Techniques, Reports & Cases 4 (2024) 100362). Improving the hydrophilicity of the material to reduce the accumulation of exudate in the wound and thus reduce infection is one direction for addressing this problem. While we cannot be bound by theory, existing evidence suggests that hydrophilic fibers are more conducive to cell adhesion and climbing. The fibers of the extracellular matrix, which are best suited for cell growth, are highly hydrophilic.

[0004] Another approach to preventing and managing wound infection is to use materials with antibacterial properties or to incorporate active substances with antibacterial functions. One method is to use materials with some antibacterial ability, such as chitosan, as the polymer substrate for electrospinning. However, chitosan's antibacterial ability is limited. Another approach is to add active ingredients with antibacterial functions, such as antibacterial agents or antibiotics. However, the release of these active ingredients needs to be precisely controlled. For acute surgical wounds or newly cleaned chronic wounds, the risk of infection is high in the first 24 hours after wound formation, and this risk persists for 1-2 weeks as wound healing typically takes 1-2 weeks. This requires the active substance to be continuously released for 1-2 weeks while reaching a minimum inhibitory concentration (MIC90). However, when antibacterial active substances are added to a single type of fiber, the release rate is difficult to control. Especially when the hydrophilicity of the fiber is increased, the drug is released too quickly due to the increased hydrophilicity, even resulting in a burst release, i.e., the release of a large amount of active substance in a very short time. To maintain the sustained release of active substances, the hydrophilicity of the fiber cannot be increased, thus failing to address the aforementioned problem of exudate drainage. Maintaining sustained release and hydrophilicity are two contradictory issues.

[0005] Currently, there is a lack of materials that can continuously provide anti-infective active substances and have high hydrophilicity to help wound healing and reduce the occurrence of infection.

[0006] Summary of the Invention

[0007] This invention provides a highly hydrophilic composite material that can inhibit bacteria and promote wound healing. More specifically, the invention provides an effective antibacterial complex that can achieve infiltration within seconds to minutes without causing a large release of the antibacterial agent over a short period of time, such as several days. The composite of this invention aims to maintain its overall structure and continuously release the antibacterial agent for a certain period of time, such as 1-2 weeks, to achieve an antibacterial effect. Through rational design, this invention selects suitable compatibility between antibacterial agents and polymers, and between surfactants and polymers, separating the fibers containing antibacterial agents and surfactants, thus achieving a highly hydrophilic composite material with long-term sustained-release antibacterial activity.

[0008] In one aspect of the invention, an antibacterial complex for application to a wound is provided, comprising at least one nanofiber layer, the nanofiber layer comprising a first fiber and a second fiber, wherein the first fiber comprises a first degradable polymer and an antibacterial agent, and the second fiber comprises a second degradable polymer and a surfactant.

[0009] According to the composite of the present invention, the first degradable polymer and the second degradable polymer are hydrophobic synthetic degradable polymers.

[0010] According to the composite of the present invention, the first degradable polymer is a polymer with relatively low viscosity, and the second degradable polymer is a polymer with relatively high viscosity.

[0011] According to the composite of the present invention, the degradation rate of the first fiber is at least twice that of the degradation rate of the second fiber.

[0012] According to the composite of the present invention, the first degradable polymer is one or more of polylactic-co-glycolic acid copolymer (PLGA), polydioxanone (PDO), polyglycolic acid-caprolactone copolymer (PGCL), and polyglycolic acid (PGA).

[0013] According to the composite of the present invention, the second degradable polymer is one or more of polylactic acid-caprolactone copolymer (PLCL), polycaprolactone (PCL), polydioxane (PDO), polylactic acid (PLA), poly4-hydroxybutyric acid (P4HB), and polyhydroxyalkanoate (PHA).

[0014] According to the composite of the present invention, the second fiber contains PDO.

[0015] According to the composite of the present invention, the degradation time of the second fiber is twice or more than twice that of the first fiber.

[0016] In the composite according to the present invention, the surfactant is a nonionic surfactant.

[0017] According to the composite of the present invention, the nonionic surfactant is F68, P407, or Tween.

[0018] According to the composite of the present invention, the second fiber also contains an antibacterial agent.

[0019] According to the complex of the present invention, the antibacterial agent is a cationic antibacterial agent.

[0020] According to the complex of the present invention, the cationic antibacterial agent is one or more of chlorhexidine (CHG), polyhexamethylene biguanide (PHMB), silver ions, copper ions, oxytinididine hydrochloride, polylysine, and benzalkonium chloride.

[0021] According to the composite of the present invention, the antibacterial agent in the first fiber accounts for 2%-10% of the total weight of the first fiber.

[0022] According to the composite of the present invention, the intrinsic viscosity of the first biodegradable polymer is 0.3-1.0 dl / g, and the intrinsic viscosity of the second biodegradable polymer is 1.1-3.0 dl / g.

[0023] According to the composite of the present invention, the content of the surfactant in the first fiber is 0.5%-3%.

[0024] According to the composite of the present invention, the mass ratio of the first fiber and the second fiber is 1:3 to 3:1.

[0025] According to the composite of the present invention, the mass ratio of the first fiber and the second fiber is 1:2 to 2:1.

[0026] According to the composite of the present invention, at least 70% of the first and second fibers have a diameter between 100 and 4000 nanometers.

[0027] According to the composite of the present invention, the nanofiber layer can be wetted within 5 minutes when placed in a PBS solution at 25°C.

[0028] According to the composite of the present invention, the nanofiber layer is able to be wetted in PBS solution at 25°C between 1 second (1s) and 5 minutes.

[0029] According to the composite of the present invention, the antibacterial rate of the nanofiber membrane, as tested according to AATCC100, is ≥99.99%.

[0030] In another aspect, the invention also relates to a method for preparing the complex, comprising the following steps:

[0031] (1) Prepare the electrospinning mixture for the first fiber.

[0032] (2) Prepare the electrospinning mixture for the second fiber.

[0033] (3) The first fiber electrospinning mixture and the second fiber electrospinning mixture are mixed and electrospinned so that the fibers of the two can be mixed and intertwined.

[0034] The compound according to the present invention is used for wound healing.

[0035] The use of the compound according to the present invention in the preparation of wound healing drugs or dressings.

[0036] According to the composite of the present invention, the first fiber is composed of a first degradable polymer and an antibacterial agent, and the second fiber is composed of a second degradable polymer and a surfactant.

[0037] In another aspect, the present invention also provides a method for promoting wound healing, comprising applying and covering a wound with a complex, said complex comprising at least one nanofiber layer, the nanofiber layer comprising a first fiber and a second fiber, wherein...

[0038] The first fiber contains a first biodegradable polymer and an antibacterial agent, and the second fiber contains a second biodegradable polymer and a surfactant.

[0039] In another aspect of the invention, a method of using a dressing employing the complex of the invention is also provided, comprising the following steps: (1) wound cleaning; (2) cutting the dressing to a suitable size according to the size of the wound and applying it to the wound, wherein a small amount of saline may be used to moisten the surface of the dressing and then a secondary dressing may be used to fix it, and the dressing may be changed every 7-14 days.

[0040] These and other aspects of the invention will become apparent and will be illustrated with reference to the embodiments described below. Attached Figure Description

[0041] Embodiments of the invention will now be described by way of example only, in conjunction with the accompanying drawings, in which:

[0042] Figure 1 is a SEM image of the nanofiber layer of the composite described in this invention.

[0043] Figure 2 is a line graph showing the cumulative amount of PHMB released in vitro by samples #9 and #13 in Example 4 of the present invention over time.

[0044] Figure 3 shows the wound healing process over time in the chronic wound animal model of Example 5 of the present invention (representative photograph).

[0045] Figure 4 is a bar chart showing the change of wound area over time in the chronic wound animal model of the present invention in Example 5. Detailed Implementation

[0046] For various external and internal wounds, the key is to promote rapid healing while maintaining antibacterial effects. This invention discovered that while mixing hydrophilic materials with biodegradable polymers and then spinning them can solve the overall water permeability problem, it may lead to accelerated degradation. Through experimentation, this invention designed a composite that resolves the contradiction between sustained release and high hydrophilicity, achieving both simultaneously. This composite can be used to prepare an ideal antibacterial and wound-healing product. It can rapidly penetrate within seconds or minutes, rapidly release a certain amount of antibacterial agent within the first 24 hours, and then slowly continue to release it over 1-2 weeks.

[0047] The composite of the present invention uses two fibers with different degradation rates, which are mixed and interwoven in the same fiber layer by electrospinning. The biodegradable polymer used in the fibers is preferably a synthetic biodegradable polymer, generally a polyester polymer.

[0048] The biodegradable polymers can be, for example, polylactic-co-glycolic acid copolymer (PLGA), polydioxanone (PDO), polyglycolic acid-caprolactone copolymer (PGCL), polyglycolic acid (PGA), polylactic-co-caprolactone copolymer (PLCL), polycaprolactone (PCL), polylactic acid (PLA), poly-4-hydroxybutyric acid (P4HB), polyhydroxyalkanoates (PHA), etc., or one or more of these. These polymers are polyester-based polymers and have a certain degree of hydrophobicity. Depending on their different molecular weights, they can be used in different fibers of the composite of this invention. Generally, biodegradable polymers with relatively higher molecular weights are used in fibers that degrade relatively slowly, while biodegradable polymers with relatively lower molecular weights can be used in fibers that degrade relatively quickly. Some polymers, such as polydioxanone (PDO), can be used in both relatively slow-degrading and relatively fast-degrading fibers depending on their degree of polymerization.

[0049] The term "intrinsic viscosity" is the most commonly used expression for the viscosity of polymer solutions. It is defined as the specific viscosity when the concentration of the polymer solution approaches zero. It represents the contribution of a single molecule to the solution viscosity and reflects the properties of the polymer; its value does not change with concentration. It is often expressed as [η], and the commonly used unit is deciliters per gram (dL / g). Because intrinsic viscosity has a quantitative relationship with the relative molecular mass of the polymer, the value of [η] is often used to determine the relative molecular mass or as a measure of molecular weight. Its value is commonly measured using a capillary viscometer.

[0050] The composite fibers of this invention utilize synthetic biodegradable polymer molecules as the main component. Natural polymer molecules, such as collagen, gelatin, chitosan, chitin, cellulose, and hyaluronic acid, are too hydrophilic, leading to rapid release of active substances and failing to achieve a sustained-release effect. Synthetic biodegradable polymer molecules as the main component refer to a fiber containing at least 70% hydrophobic polymer molecules by mass, which can be 75%, 80%, 85%, 88%, 90%, 92%, or 95%.

[0051] This invention prepares nanofiber membranes through a more rational structural design and material selection. By adding appropriate additives, such as surfactants and antibacterial agents, to hydrophobic and biodegradable polymers, the hydrophilicity of the dressing of this invention is greatly improved, and it also exhibits antibacterial properties and promotes wound healing. The added surfactants can be cationic, anionic, or nonionic surfactants, preferably nonionic surfactants, such as polyoxyethylene-polyoxypropylene ether block copolymers, for example: Poloxamer 188 (F68) and P407 (also known as Poloxamer 407). The added antibacterial agents can be cationic antibacterial agents, such as chlorhexidine, polyhexamethylene biguanide hydrochloride (PHMB), metal ions (e.g., silver / copper ions), oxytinididine hydrochloride, polylysine, and benzalkonium chloride, or one or more of these. Combinations of these additives can be added; some combinations can achieve complete infiltration within 1 minute (e.g., the results in Table 1), helping to rapidly drain wound exudate. Infiltration tests can be performed in PBS solution at 25°C. In fibers that degrade more slowly, the surfactant content is generally 0.5%-3%, for example, 0.8%, 1%, 1.2%, 1.5%, 1.7%, 2%, 2.2%, 2.5%, 2.7%.

[0052] F68, also known as poloxamer 188, H(C2H4O) a (C3HO) b (C2H4O) a OH, ethylene oxide unit (a) is 75-85, propylene oxide unit (b) is 25-30, CAS No.: 691397-13-4, Manufacturer: BASF.

[0053] P407, also known as poloxamer 407, H(C2H4O) a (C3H6O) b (C2H4O) a OH, ethylene oxide unit (a) is 95-105, propylene oxide unit (b) is 54-60, CAS No.: 9003-11-6, Manufacturer: BASF.

[0054] Simultaneously, this invention also achieves the slow release of additives, such as antibacterial agents (which can be demonstrated by measuring PHMB, results in Tables 3 and 4). The active substances in the complex of this invention, such as antibacterial agents, can exert their antibacterial and anti-infective effects. These antibacterial agents are preferably cationic antibacterial agents, such as chlorhexidine (CHG), polyhexamethylene biguanide (PHMB), oxytinididine hydrochloride, polylysine, benzalkonium chloride, heavy metal ion antibacterial agents (such as silver or copper ion antibacterial agents), etc. Additives, such as antibacterial agents, can be mixed into the fiber layers, for example, mixed into one type of fiber, or mixed into all fibers. The mass content of the antibacterial agent in the fiber is generally 0.5%-10%, for example, 1%, 2%, 4%, 6%, 8%, 10%.

[0055] This invention addresses the contradiction between simultaneously achieving sustained release and high hydrophilicity in order to better inhibit bacteria and induce tissue growth. By placing the antibacterial agent and surfactant separately within two different, interwoven fibers, this invention achieves independent control over the release of both hydrophilicity and antibacterial activity. This allows adjustment of one property (e.g., hydrophilicity) without affecting the other (the release rate of the antibacterial activity), resulting in a complex with both high hydrophilicity and long-lasting sustained release of antibacterial substances. Conversely, if the release of antibacterial agents and hydrophilicity are considered within the same fiber, it is difficult to simultaneously regulate these two contradictory properties.

[0056] This invention provides a suitable range of formulation ratios for various fibers, enabling the composite to have sufficient hydrophilicity while continuously releasing antibacterial active substances for 1-2 weeks.

[0057] The composite material of this invention contains an active material-carrying layer, which is composed of two or more biodegradable biomaterials. The two materials exist independently as fibers with diameters ranging from nanometers to micrometers. Preferably, the two fibers are arranged in an interwoven manner, for example, they can be intertwined and entangled within the same fiber layer through blending. Upon use, the two fibers exhibit different degradation rates; for example, the faster-degrading fiber degrades at least twice, or even 2.5 times, 3 times, 3.5 times, 4 times, 4.5 times, or 5 times, faster-degrading fibers. The faster-degrading fibers, after degradation, release more space for tissue growth, and the fiber degradation is synchronized with the rate at which cells enter the scaffold. The faster-degrading fibers can degrade completely within 1-4 weeks, while the slower-degrading fibers require at least 2-8 weeks to degrade completely.

[0058] The mass ratio of the two fibers can be adjusted within a certain range. For example, the mass ratio of the fiber with a relatively fast degradation rate to the fiber with a relatively slow degradation rate can be 1:3, 1:2.5, 1:2, 1:1.5, 1:1, 1.5:1, 2:1, 2.5:1, or 3:1.

[0059] There is no significant difference in the diameter of fibers that degrade quickly and slowly. All or most of the fibers, for example, at least 60%, at least 70%, at least 80% of the fibers, have a diameter between 100 and 4000 nanometers, preferably between 200 and 2000 nanometers, more preferably between 400 and 1000 nanometers, for example, around 500, 600, 700, 800, or 900 nanometers.

[0060] The degradation rate of fibers depends on their composition. Natural polymers, or simply natural polymers, are high-molecular-weight compounds formed in nature or minerals through biochemical processes or photosynthesis, as opposed to synthetic polymers. Natural polymers exist in animals, plants, or minerals, such as gelatin, hyaluronic acid, cellulose, starch, collagen, chitosan, and fibrinogen. Experiments have shown that the biodegradable polymers in the fiber layer of the composite of this invention should be synthetic polymers, not natural polymers. This is not only because natural polymers are immunogenic, but also because their high hydrophilicity causes the antibacterial agent in this invention to be released too quickly, at a rate measured in seconds per minute, with almost no slow release.

[0061] In this way, the product of the present invention achieves two seemingly contradictory technical effects simultaneously: ideal immersion and sustained antibacterial effect. That is, it can achieve the immersion effect in a short time, such as within a few seconds or minutes, while maintaining a certain supporting structure. In the early stage, such as the first 24 hours, it can quickly release a certain amount of antibacterial agent and then release it slowly and continuously.

[0062] Electrospinning is a highly efficient spinning and film-forming process used to prepare fibrous polymer membranes with fiber diameters ranging from nanometers to micrometers. Electrospinning typically uses a high-voltage electric field to inject a current of a specific polarity into a polymer solution / melt, causing the solution / melt to be accelerated and sprayed towards a collection surface of opposite polarity, thereby forming solid fibers. The relative motion between the nozzle and the collection surface can form a fiber layer. The fiber matrix formed by electrospinning has a three-dimensional porous structure with a relatively large surface area. Good fiber formation requires optimization of solution parameters and electrospinning configuration. Controllable parameters during the electrospinning process affect the fiber diameter and the drug release pattern from the membrane matrix. In this way, the electrospinned membrane matrix can be customized to achieve the desired drug release pattern. The polymers described above for electrospinning, mixed with one or more active substances, such as drugs, solvents, and excipients, in the form of a solution, suspension, emulsion, or melt, can be subjected to a voltage from about 5-30 kV, preferably 10-25 kV, more preferably 11-20 kV, to the polymer solution, suspension, emulsion, or melt. Active substances can be incorporated through direct dissolution, suspension, or emulsion. Suitable solvents for preparing electrospinning solutions include water and organic solvents. This invention utilizes the biodegradability of biomedical polymers and the differences in biodegradation rates between different materials of fibers prepared by electrospinning. By considering and utilizing the influence of additives incorporated into the fibers on fiber diameter and degradation, the degradation rate of the dressing material of this invention can be controlled, as well as the release of additives, such as antibacterial agents, within a certain time period.

[0063] Each composite of the present invention can be composed of two or more fibers. The fibrous membrane of the present invention primarily acts as a scaffold, facilitating cell adhesion, migration, and proliferation. The mass ratio of the two fibers can be from 1:3 to 3:1. This porous structure and stepwise degradation characteristics promote cell proliferation within the matrix and its continued development into new tissues.

[0064] Example 1

[0065] Taking Experiment 1 in Example 2 as an example, PLGA (all specifications are 50 / 50) and PHMB were added to a glass bottle according to the mass ratio in Table 1. Hexafluoroisopropanol (HFIP) was added and stirred on a magnetic stirrer until it was transparent and free of impurities. Then it was added to a disposable syringe to prepare spinning solution A.

[0066] Another polymer and surfactant F68 were added to a glass bottle according to the mass ratio in Table 1. HFIP was added and stirred on a magnetic stirrer until the mixture was transparent and free of impurities. The mixture was then added to a disposable syringe to prepare spinning solution B.

[0067] Spinning solutions A and B were placed on the feed pump of an electrospinning machine, respectively, to begin electrostatic blending, resulting in a nanofiber layer in which the two fibers were blended together. The positive voltage was 10-20 kV, the negative voltage was 2-8 kV, and the drum speed was 50-300 rpm; the flow rate of spinning solution A (first fiber) was 4-10 ml / h; and the flow rate of spinning solution B (second fiber) was 10-20 ml / h. In the same fiber layer, the mass ratio of the two fibers was 1:1. Figure 1 shows that the two fibers are mixed and interwoven, with most fibers exhibiting a basically straight shape.

[0068] Example 2

[0069] Following the preparation method in Example 1, various formulations as shown in the table below were prepared, and the wetting rate of the resulting samples was then evaluated.

[0070] Table 1. Effect of antibacterial agent concentration

[0071] From the four experimental groups numbered 1-4, it can be seen that the solution provided by this invention has high hydrophilicity, and can achieve rapid wetting of the complex at different concentrations of antibacterial agent, which is very beneficial for the drainage of exudate. Of course, it can also be seen that different concentrations of antibacterial agent have a relatively small impact on the wetting speed (unlike surfactants).

[0072] Example 3

[0073] The antibacterial test was performed using a modified AATCC 100 method. Preparation of simulated wound fluid (SWF): Sodium chloride: 8.035 g; Sodium bicarbonate: 0.035 g; Potassium chloride: 0.225 g; Potassium phosphate trihydrate: 0.231 g; Magnesium chloride hexahydrate: 0.311 g; Hydrochloric acid: 0.039 mol; Calcium chloride: 0.292 g; Sodium sulfate: 0.072 g; Tris(hydroxymethyl)aminomethane: 0.6118 g; Bovine serum albumin: 80 g; Sterile water: 1 L.

[0074] Bacterial culture preparation: The *Staphylococcus aureus* for testing was inoculated into the corresponding culture medium and incubated at the appropriate temperature for the specified time. After incubation, the cultures were eluted with 0.9% sterile physiological saline and diluted to a concentration greater than 2 × 10⁻⁶. 6 CFU / mL.

[0075] 1) "Zero" contact time: The three test samples and three negative control samples were pretreated (the samples were placed in sterile containers, and 5 mL of SWF was added to each sample to ensure that the test samples were kept moist). Then, they were incubated at (37±2)℃ for (24±1) hours, and then inoculated (the SWF absorbed by the sample was squeezed out, and 1±0.1 mL of test microorganisms was pipetted and added to the corresponding sample, ensuring that there was no excess liquid leakage, and then the sterile container was sealed). The samples were then collected and counted.

[0076] 2) "168H" contact time: The three test samples and three negative control samples were pretreated (the samples were placed in sterile containers, and 5 mL of SWF was added to each sample to ensure that the test samples were kept moist). They were then incubated at (37±2)℃ for (168±1) hours and inoculated (the SWF absorbed by the sample was squeezed out, and 1±0.1 mL of test microorganisms was pipetted and added to the corresponding samples to ensure that there was no excess liquid leakage, and then the sterile container was sealed). After inoculation, the samples were incubated at (37±2)℃ for (24±1) hours, and then collected and counted.

[0077] 3) Uninoculated “168H” contact time: The three test group samples and three negative control samples were pretreated (the samples were placed in sterile containers and 5 mL of SWF was added to each sample to ensure that the test samples were kept moist), and then incubated at (37±2)℃ for (48±1) hours, and then collected and counted.

[0078] A = Colony count of the test sample after inoculation and exposure for 168 hours;

[0079] B = Colony count of the negative control sample that was inoculated and had a contact time of "0".

[0080] Table 2. Antibacterial effects of different types of antibacterial agents

[0081] Based on experimental groups 5-8, with other components remaining constant, at the same concentration of antibacterial agent, the anionic antibacterial agent was less effective than the cationic antibacterial agent; furthermore, when the concentration of the cationic antibacterial agent was ≥3%, its antibacterial rate was ≥99.99%. The samples with added antibacterial agents showed better antibacterial effects than those without.

[0082] Example 4

[0083] Measurement of PHMB sustained release

[0084] A portion of the sample containing PHMB was placed in 50 ml of pH 7.4 phosphate buffer solution at 37°C. At 2 hours and 24 hours, appropriate amounts of this solution were measured as test solutions, and the PHMB content was then determined using high-performance liquid chromatography (HPLC). The HPLC method used octadecylsilane-bonded silica gel as the stationary phase (Xtimate C18 100★4.6 mm 5 μm); 0.05 M dipotassium hydrogen phosphate solution-methanol (50:50) as the mobile phase; a detection wavelength of 236 nm; a column temperature of 35°C; and an injection volume of 20 μl.

[0085] Compared with the control, all samples prepared according to this invention, except for the sample in experimental group 12, showed a certain release at 2 hours, and also had a certain amount of PHMB at 24 hours for subsequent continuous release.

[0086] Table 3. PHMB release measurement results of different samples

[0087] Adding surfactant F68 to the second fiber can increase the release of antibacterial agents. However, if too much surfactant is added, such as in experimental group 11 where the mass ratio is 10% of the second fiber, PHMB will be released too quickly, completing its release within 2 hours. Therefore, the amount of surfactant added should not be too large.

[0088] The in vitro release rate at other time points was further observed in the experimental group with slower release within 24 hours, and the results are as follows:

[0089] Table 4. Long-term release in experimental groups 9 and 13

[0090] As can be seen from the comparison of data in the table above and Figure 2 (A represents experimental group 9; B represents experimental group 13), PHMB can be slowly released from the wound within 14 or 28 days by changing the proportion of various components in the fiber, so that it can continuously exert its antibacterial effect on the wound and prevent wound infection.

[0091] Example 5

[0092] Wound healing experiment containing bacterial colonies

[0093] A type 1 diabetes model was established in male Sprague-Dawley (SD) rats of specific pathogen-free (SPF) grade by intraperitoneal injection of streptozotocin (STZ). The successfully modeled rats were randomly divided into four groups. Each group of rats had lesions on their dorsal skin. Full-thickness skin excision, injection of Staphylococcus aureus (5x10) 5 -107 CFU). Control and / or test samples were applied, secured with secondary dressings, and then bandaged with elastic bandages; one dressing was applied each time, changed every 3 days for weeks 1-2, and every 7 days for weeks 3-4. Each time the dressing was changed, the wound was cleaned, and the secondary dressing and bandage were replaced. If the wound became contaminated, the dressing was replaced earlier. To ensure consistency, if early replacement was necessary, all animals were treated once. Samples were collected for analysis after 4 weeks. Rats were observed daily for vital signs, wound exudate, and healing progress. The wound was photographed each time the dressing was changed to observe healing. In Figures 3 and 4, sample #1 is sample group 9 of this invention; control #2 is ordinary petroleum jelly (Zhende Medical Supplies Co., Ltd.); and control #3 is silver ion dressing (Atrauman Ag, German wet silver, Germany).

[0094] Figure 3 shows the wound healing process over time in an animal model of chronic wounds (representative photographs). From top to bottom, the first row shows sample #1 and experimental group 9, the second row shows control #2, and the third row shows control #3. From left to right, the photographs are taken on days 3, 6, 13, and 20. It can be seen that the photograph on day 3 shows that experimental group 9 healed relatively quickly, by day 13 it was almost completely healed, and by day 20 it was completely healed. The other two control groups healed much more slowly.

[0095] Figure 4 shows the change in wound area over time in an animal model of chronic wound. The horizontal axis represents the number of experimental days, and the vertical axis represents the wound area (square centimeters). In each bar chart, the left column represents sample #1 and experimental group 9, the middle column represents control #2, and the right column represents control #3. It can be seen that the wound areas of the three groups are basically the same at the beginning. The area of ​​experimental group 9 decreases slowly at first, but by day 9, it has become the smallest.

[0096] Those skilled in the art will understand that various components / parts of the products, formulations, apparatuses, methods, systems, and embodiments described in this application may be modified (added and / or removed) without departing from the full scope and spirit of the invention, and such modifications are covered by the scope and spirit of the invention.

Claims

1. A bacteriostatic and wound healing promoting composite comprising at least one nanofiber layer, the nanofiber layer comprising first fibers and second fibers, wherein the first fibers comprise a first degradable polymer and a bacteriostatic agent, and the second fibers comprise a second degradable polymer and a surfactant.

2. The composite of claim 1, wherein the first degradable polymer is one or more of polylactic-co-glycolic acid, polydioxanone, polyhydroxybutyric acid, polyhydroxybutyric acid-co-caprolactone.

3. The composite of claim 1, wherein the second degradable polymer is one or more of polylactic-co-caprolactone, polydioxanone, polycaprolactone, polylactic acid, poly-4-hydroxybutyric acid, polyhydroxyalkanoate.

4. The composite of claim 1, wherein the mass ratio of the first fibers to the second fibers is 1:3 to 3:

1.

5. The composite of claim 1, wherein the second fibers have a degradation time that is two times or more than that of the first fibers.

6. The composite of claim 1, wherein the surfactant is a non-ionic surfactant.

7. The composite of claim 6, wherein the non-ionic surfactant is F68, P407 or Tween.

8. The composite of claim 1, wherein the second fibers also contain a bacteriostatic agent.

9. The composite of claim 1 or 8, wherein the bacteriostatic agent is one or more of chlorhexidine (CHG), polyhexamethylene biguanide (PHMB), silver ions, copper ions, octenidine hydrochloride, polylysine, benzalkonium chloride.

10. The composite of claim 1, wherein the first degradable polymer has an intrinsic viscosity of 0.3 to 1.0 dl / g, and the second degradable polymer has an intrinsic viscosity of 1.1 to 3.0 dl / g.

11. The composite of claim 1, wherein the second fibers contain the surfactant in an amount of 0.5% to 3%.

12. The composite of claim 8, wherein the surfactant plus the bacteriostatic agent in the second fibers is 1% to 15% of the total weight of the second fibers.

13. The composite of claim 1, wherein at least 70% of the fibers in the first fibers and the second fibers have a diameter of 100 to 4000 nanometers.

14. The composite of claim 1, wherein the nanofiber layer is capable of achieving wet-out in 1 second to 5 minutes when placed in a PBS solution at 25°C.

15. A method of making the composite of claim 1, comprising the steps of: (1) preparing a first fiber electrospinning mixture, (2) preparing a second fiber electrospinning mixture, and (3) mixing the first fiber electrospinning mixture and the second fiber electrospinning mixture and electrospinning the mixture so that the two types of fibers are intermingled in the same fiber layer.

16. Use of the composite of claim 1 in the manufacture of a wound healing promoting medicament or dressing. ​ ​ ​ ​

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