A composite dressing with bidirectional fluid transport function and a preparation method and application thereof

Abstract

The application belongs to the technical field of biomedical materials, and discloses a composite dressing with bidirectional fluid transport function, a preparation method and application thereof. The composite dressing is a three-layer Janus composite fiber membrane, which comprises a hydrophobic layer, an intermediate hydrophilic layer and a hydrophilic layer from the contact side to the side away from the side in sequence. The unidirectional transmission index difference |ΔR| is 300-600%. The average pore size of the hydrophobic layer is 2-3 μm. The preparation method comprises the following steps: preparing spinning solutions of the hydrophobic layer, the intermediate hydrophilic layer and the hydrophilic layer respectively, adding small molecule active ingredients into the spinning solution of the hydrophilic layer and / or the intermediate hydrophilic layer, vacuum drying after constructing a three-layer structure through layer-by-layer electrospinning, and obtaining the composite dressing with bidirectional fluid transport function. The application is that the composite dressing can be used in biomedical scenes that need to simultaneously realize body fluid management and drug intervention. The application establishes a bidirectional transport platform, breaks through the limitation of unidirectional wetting, and the structural parameters are controllable and the performance can be accurately regulated.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of biomedical materials, and relates to a composite dressing with bidirectional fluid transport function as well as a preparation method and application thereof. BACKGROUND

[0002] Janus structure dressing can produce directional capillary pressure difference due to the asymmetric wettability gradient constructed along the thickness direction, thereby endowing the material with unidirectional liquid transport capacity, and has attracted widespread attention in the field of wound exudate management and deep tissue drainage in recent years. This strategy effectively solves the problem of wound deterioration caused by the easy “back seepage – immersion” of traditional dressings by directing the liquid from the hydrophobic side (contacting the wound) to the hydrophilic side (away from the wound).

[0003] The prior art generally adopts a “hydrophilic-hydrophobic” double-layer composite or a “hydrophobic-intermediate hydrophilic-hydrophilic” three-layer gradient structure to achieve unidirectional export of liquid from the hydrophobic side (contacting the wound) to the hydrophilic side (away from the wound), effectively preventing back seepage of exudate, contaminating the wound or the external environment. For example, the patent application with the application publication number CN118704170A is a unidirectional wetting Janus fiber membrane prepared by compounding hydrophilic cotton fiber membrane and hydrophobic polymer nanofiber membrane; the patent application with the application publication number CN116459402A is a siphon structure with “small pore hydrophilic – large pore hydrophobic” by regulating the material ratio and porosity gradient of the hydrophilic layer (pure hydrophilic material), the intermediate layer and the hydrophobic layer (hydrophilic / hydrophobic blend), to achieve unidirectional drainage of deep pus; the patent application with the application publication number CN118526624A designs a “outer hydrophobic – middle and high hydrophilic – inner hydrophilic” sandwich structure, which utilizes the synergistic effect of outer layer to block blood exudation, middle layer to store liquid with high hydrophilicity, and inner layer to absorb liquid, to improve the exudate containing capacity of the dressing.

[0004] Although the above-mentioned technologies have made significant progress in unidirectional liquid export, their functional design still has fundamental limitations: the hydrophobic layer is deliberately designed as a “barrier layer” to maximize the unidirectional wetting performance. This strong barrier property can effectively prevent back seepage of liquid, but at the same time, it blocks the active delivery path of therapeutic ingredients from the inside of the dressing to the wound.

[0005] In the complex wound scenarios such as chronic wounds and postoperative infections, it is difficult to establish an effective therapeutic concentration in the wound area by relying on the slow dissolution or passive diffusion of drugs from the hydrophilic layer, resulting in low treatment efficiency. In order to solve this problem, the patent application with the publication number CN120815206A loads drugs in the hydrophobic layer, but there are still significant defects; on the one hand, the drugs are directly exposed to the wound, which can easily cause local concentration to be too high and cause cytotoxicity; on the other hand, under the continuous perfusion of exudate, the drugs are easily washed away, causing waste. Therefore, the existing Janus dressing is still essentially a "single-function platform" and cannot meet the clinical needs of "simultaneously achieving exudate management and local precise drug intervention".

[0006] To solve the above problems, there is an urgent need for a composite dressing with bidirectional fluid transport function, its preparation method and application. While retaining the positive liquid adsorption capacity, the structure (such as pore size and thickness) of the hydrophobic layer is adjusted to weaken its liquid barrier strength, thereby constructing a controllable reverse delivery channel to enable the therapeutic ingredients to diffuse reversely to the wound along with the water. This strategy not only realizes the "positive adsorption-reverse drug release" bidirectional synergy, but also provides a structural basis for the multifunctional integration of the dressing, breaking through the functional limitations of traditional Janus dressings. SUMMARY

[0007] The purpose of the present application is to solve the technical bottleneck that the existing Janus dressing only has a single-directional wetting function and cannot achieve active delivery of therapeutic ingredients to the wound, and to provide a composite dressing with bidirectional fluid transport function and its preparation method and application. Through structural design, the composite dressing simultaneously realizes the positive adsorption of biological fluids and the reverse delivery of small molecule active ingredients, breaking through the functional limitations of traditional dressings.

[0008] To achieve the above purpose, the technical solutions adopted by the present application are as follows:

[0009] A composite dressing with bidirectional fluid transport function is a three-layer Janus composite fiber membrane, which includes a hydrophobic layer, an intermediate hydrophilic layer and a hydrophilic layer from the contact side to the side away from the side.

[0010] The contact side refers to the side that directly contacts the wound or biological fluid in the use state;

[0011] The hydrophilic layer and / or the intermediate hydrophilic layer are loaded with small molecule active ingredients;

[0012] The difference value |AR| of the one-way transmission index of the composite dressing with bidirectional fluid transport function is 300-600%; the typical one-way wetting dressing |AR| is usually ≥800%, |AR|=|R + -R - |, which is generally composed of: R + is 400-600%, R -400~500%. In contrast, the present application precisely regulates |AR| in the range of 300~600%, without significantly sacrificing the positive wicking performance, but mainly reducing the reverse barrier strength |R - |, while maintaining sufficient positive wetting ability R + ; Specifically, in the embodiments of the present application, R + > 270%, which is slightly lower than the traditional one-way wetting dressing, but still has one-way wetting effect; |R - | < 180%, indicating that the reverse resistance is greatly reduced, providing a feasible channel for the reverse diffusion of water-carrying small molecular active ingredients;

[0013] The water contact angle of the hydrophobic layer is 120~140°, the water contact angle of the intermediate hydrophilic layer is 55~80°, and the water contact angle of the hydrophilic layer is 25~55°.

[0014] The average pore size of the hydrophobic layer is 2~3 μm. The existing technology discloses a "hydrophilic-hydrophobic" double-layer composite or a "hydrophobic-intermediate hydrophilic-hydrophilic" three-layer gradient structure dressing, and the pore size of the hydrophobic layer is generally between 0.5~1.8 μm; the present application expands the average pore size of the hydrophobic layer to 2~3 μm, so that the hydrophobic layer forms a "weak barrier" rather than a "strong barrier", thereby opening a reverse channel.

[0015] To achieve the "positive wicking + reverse drug release" bidirectional transport effect, the key point lies in the structure and wettability of the hydrophobic layer, and the reasons are as follows: ① The present application limits the small molecular active ingredients to be loaded, and the equivalent molecular diameter thereof is usually not more than 2 nm. The average pore size of the fiber membrane prepared by electrospinning is usually not less than 100 nm, which is much larger than the size of the small molecular drug, so the hydrophilic layer and the intermediate hydrophilic layer do not constitute a physical barrier to the diffusion of small molecules. ② In the three-layer structure of the present application, the hydrophobic layer is the only functional layer with hydrophobic barrier properties, and its "weak barrier" effect determines the size of the reverse permeation resistance. In contrast, the hydrophilic layer and the intermediate hydrophilic layer are both hydrophilic porous media, and the diffusion rate of water and drugs in them is fast and the resistance is small. In summary, the bidirectional transport performance of the present application is mainly determined by the "weak barrier" property of the hydrophobic layer, and the role of the hydrophilic layer and the intermediate hydrophilic layer is to provide a wetting gradient to drive the positive wicking and to support the reverse diffusion as a drug reservoir.

[0016] And the core mechanism of being able to realize the bidirectional fluid transport function is: through the synergistic regulation of the wettability gradient along the thickness direction and the structure of the hydrophobic layer, the traditional Janus membrane "one-way barrier" transport mode is broken, and a "positive adsorption-reverse drug release" bidirectional cooperative fluid transport path is formed. The specific mechanism is as follows:

[0017] (1) Wettability gradient driven positive self-pumping adsorption:

[0018] The composite dressing has a hydrophobic layer, an intermediate hydrophilic layer and a hydrophilic layer from the side in contact with the biological fluid to the side away from the biological fluid, and the water contact angles thereof are distributed in a significant gradient. The asymmetric wettability forms a capillary pressure difference in the fiber pores, which is directed from the hydrophobic side to the hydrophilic side. When the dressing contacts the wound exudate, the liquid spontaneously migrates from the hydrophobic layer to the hydrophilic layer under the driving force of capillary force, realizing efficient positive adsorption and fixation of the exudate, i.e., a "self-pumping effect".

[0019] (2) Weak barrier realized by adjusting the pore size / thickness of the hydrophobic layer:

[0020] In the traditional Janus dressing, the hydrophobic layer is designed as a dense barrier layer to maximize the one-way wetting performance. However, by adjusting the structure (pore size, thickness) of the hydrophobic layer, the present application significantly reduces the resistance of liquid reverse osmosis. At this time, the hydrophobic layer is no longer an "ultimate barrier", but a controllable permeable "weak barrier".

[0021] (3) Concentration gradient drives reverse diffusion of small molecule active ingredients:

[0022] When the hydrophilic layer and the intermediate hydrophilic layer are water-swollen, the loaded small molecule active ingredients form a high concentration area in the hydrophilic layer, while the hydrophobic layer side (wound) is a low concentration area, thus establishing a concentration gradient from the hydrophilic side to the hydrophobic side. Under the gradient driving, the small molecule active ingredients diffuse reversely with water, cross the weak barrier of the hydrophobic layer, and are accurately delivered to the wound.

[0023] As a preferred technical solution:

[0024] The composite dressing with bidirectional fluid transport function as described above, the thickness of the hydrophobic layer is 15-22 μm, the thickness of the intermediate hydrophilic layer is 10-100 μm, the thickness of the hydrophilic layer is 10-100 μm, and the thickness of the intermediate hydrophilic layer and the hydrophilic layer can be appropriately adjusted according to the drug loading capacity and water absorption demand.

[0025] The composite dressing with bidirectional fluid transport function as described above, the small molecule active ingredients include at least one of (a), (b) and (c):

[0026] (a) small molecule drugs with a molecular weight of <1000 Da;

[0027] (b) inorganic salts that can release metal ions;

[0028] (c) metal complexes that can release metal ions.

[0029] The application further provides a preparation method of the composite dressing with the bidirectional fluid transport function as described above, spin solutions of the hydrophobic layer, the intermediate hydrophilic layer and the hydrophilic layer are respectively prepared, small molecule active ingredients are added into the spin solution of the hydrophilic layer and / or the intermediate hydrophilic layer, the three-layer structure is constructed through layer-by-layer electrospinning, and then vacuum drying is performed at 30-50 DEG C for 12-24 h, so that the composite dressing with the bidirectional fluid transport function is prepared.

[0030] The deposition sequence of the layer-by-layer electrospinning in the preparation method of the composite dressing with the bidirectional fluid transport function as described above comprises one of the following modes:

[0031] (a) the hydrophilic layer is first deposited on the receiving substrate, and then the intermediate hydrophilic layer and the hydrophobic layer are sequentially deposited;

[0032] (b) the hydrophobic layer is first deposited on the receiving substrate, and then the intermediate hydrophilic layer and the hydrophilic layer are sequentially deposited;

[0033] (c) the intermediate hydrophilic layer is first prepared, and then the hydrophilic layer is deposited on one side of the intermediate hydrophilic layer, and the hydrophobic layer is deposited on the other side.

[0034] The application further provides an application of the composite dressing with the bidirectional fluid transport function as described above, which is suitable for biomedical scenes that need to simultaneously realize body fluid management and drug intervention.

[0035] Invention principle:

[0036] The three-layer structure of the composite dressing of the application is sequentially the hydrophobic layer, the intermediate hydrophilic layer and the hydrophilic layer from the contact side to the side far away from the contact side. The wettability gradient simultaneously realizes the following: a forward capillary pressure difference: driving the exudate to migrate from the hydrophobic side to the hydrophilic side, realizing forward wetting; and a reverse concentration gradient: a concentration gradient is formed between the small molecule active ingredients loaded on the hydrophilic layer after water absorption and the contact side, driving the reverse diffusion of the small molecule active ingredients.

[0037] The traditional Janus dressing takes "strong barrier" as the core and has a single function. The application converts the hydrophobic layer from "strong barrier" to "bidirectional transport channel" through the synergy of the wettability gradient, the weak barrier structure of the hydrophobic layer and the |AR| interval, while retaining the forward liquid guiding ability, the hydrophobic layer has the function of reverse drug delivery. Any single parameter cannot realize efficient liquid guiding and effective drug release at the same time, only the synergy of multiple parameters can unlock the reverse drug delivery function while retaining sufficient forward wetting ability. Specifically:

[0038] The average pore size of the hydrophobic layer is 2-3 microns, which is much larger than the size of the small molecule active ingredient, and there is no physical barrier, and the water contact angle of the hydrophobic layer is 120-140 degrees, which maintains the positive capillary driving force while avoiding the complete rejection of water by the super-hydrophobic surface; the one-way transmission index difference |AR| is 300-600%, which is a quantitative balance interval of the two-way function: when |AR|<300%, the positive liquid guiding is insufficient, and it is difficult to deal with medium and high exudation wounds; when |AR|>600%, the reverse channel is strongly blocked, and almost no drug is released in the reverse direction; when |AR|=300-600%, the positive liquid guiding and the reverse drug release reach a balance.

[0039] Advantages:

[0040] (1) The application establishes a two-way transport platform in the Janus dressing, realizes the two-way cooperation of liquid forward adsorption and small molecule active ingredient reverse delivery, and solves the defects that the prior art can only guide liquid in one direction and cannot release drugs in the reverse direction.

[0041] (2) By adjusting the pore size, thickness and one-way transmission index difference |AR| of the hydrophobic layer, the quantitative design of the two-way transport performance can be realized, and the optimal transport channel can be matched for different small molecule active ingredients.

[0042] (3) The wettability of each layer can be realized by selecting or modifying the bulk material, and does not depend on the specific hydrophilic / hydrophobic material combination, which is suitable for polyvinyl alcohol, polyacrylic acid, gelatin, chitosan, thermoplastic polyurethane and other systems, and has wide material compatibility.

[0043] (4) The structure of the composite dressing of the application is not bound to a specific indication or drug type, and can be used as a universal platform to load small molecule antibacterial agents (such as ciprofloxacin), anti-inflammatory drugs (such as curcumin), metal ions (such as Ag + ) and the like, and is suitable for chronic infected wounds, postoperative wounds, burns and other biomedical scenes that require "liquid adsorption-drug intervention" cooperation.

[0044] (5) By moderately reducing |R| (i.e. reducing the barrier property of the hydrophobic layer), the two-way fluid transport function of "positive liquid guiding + reverse drug release" is realized without significantly affecting |R+|, which is not a performance "sacrifice", but a reasonable regulation to improve the function. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is a structure diagram of the composite dressing of the application; in the figure, the black arrow represents the positive liquid absorption direction, and the gray arrow represents the drug reverse release direction;

[0046] Figure 2 is a drug release curve diagram of the composite dressing prepared in Example 1 of the application;

[0047] Figure 3 Figure for the directional water transport performance test results of the composite film dressings prepared in Examples 1-7 of the present application;

[0048] Figure 4 Figure for the cytotoxicity test results of the composite dressings prepared in Examples 1-7 of the present application;

[0049] Wherein, 1-hydrophobic layer, 2-intermediate hydrophilic layer, 3-hydrophilic layer. DETAILED DESCRIPTION

[0050] The present application will be further described in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not used to limit the scope of the present application. Furthermore, it should be understood that after reading the content taught by the present application, those skilled in the art can make various alterations or modifications to the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

[0051] In order to fully disclose the properties of the substances used in each embodiment and comparative example, the manufacturer and brand of the substance are written, and the products of other manufacturers and brands that meet the definition of the present application are also feasible.

[0052] The test methods of the relevant performance indicators in each of the following embodiments and comparative examples are as follows:

[0053] Water contact angle: the sample to be tested is fixed flat on a glass slide with double-sided tape, placed on the sample stage of the contact angle measuring instrument, deionized water is used as the test liquid, the droplet volume is 2 μL, the dynamic spreading process of the droplet on the sample surface is recorded by a high-speed camera system, and the static water contact angle (WCA) is read within 1 second after the droplet contacts the surface, 5 different positions of each sample are tested, and the average value is taken as the final result.

[0054] One-way transmission index difference |ΔR|: using a liquid water management tester, the test is carried out in accordance with the AATCC TM 195-2009 standard, the test process is as follows: after the sample to be tested is cut into a 10 cm×10 cm square, it is placed between the upper and lower sensor arrays, then 0.21 g of physiological saline (0.9% NaCl) is added on the hydrophobic side (contacting the biological fluid side) of the sample, the dynamic transmission process of the liquid in the thickness direction is automatically recorded by the instrument, and the one-way transmission index (R) is calculated, the calculation formula is as follows: one-way transmission index difference |ΔR|=|R + -R - |, in the formula, R + is the transmission index of the liquid from the hydrophobic side to the hydrophilic side, and R - is the transmission index of the liquid from the hydrophilic side to the hydrophobic side.

[0055] Reverse release rate: the sample to be tested was cut into a size of 2 cm x 2 cm with the hydrophobic layer facing down on a centrifuge tube containing 1.5 mL of phosphate buffer, and the liquid in the centrifuge tube was collected at the predetermined time points (1 h, 2 h, 3 h, 4 h, 6 h, 8 h, 12 h, 18 h, 24 h), the absorbance values of ciprofloxacin and curcumin were measured by ultraviolet-visible spectrophotometer, the reverse release rate of the drug was calculated by the standard curve drawn in advance, and the reverse release rate of metal ions (silver ions) was tested by inductively coupled plasma atomic emission spectrometry (ICP-AES); wherein each group of experiments was repeated 3 times, and the results were expressed as mean ± standard deviation, and when the sample to be tested was detected by ultraviolet-visible spectrophotometer, 425 nm was used as the detection wavelength of curcumin, and 277 nm was used as the detection wavelength of ciprofloxacin.

[0056] Cell relative growth rate (RGR): before testing, the sample to be tested was cut into a disc with a diameter of 1 cm, sterilized in an alcohol fumigation jar for 24 h, then human fibroblasts (HFF) were inoculated into a 24-well plate (density of 50000 cells / well), cultured at 37°C, 5% CO2 for 24 h, then sterilized samples (experimental group) were added, and wells without samples were used as blank control group, each group had 3 parallel duplicate wells, then CCK-8 reagent was added after 24 h of continuous culture, and the absorbance at 450 nm was measured by enzyme-labeled instrument after 2 h of incubation at 37°C in the dark, and the cell relative growth rate was calculated.

[0057] Example 1

[0058] A preparation method of a composite dressing with bidirectional fluid transport function, the steps are as follows:

[0059] (1) preparing a hydrophilic layer;

[0060] (1.1) dissolving gelatin (manufacturer: National Pharmaceutical Group Chemical Reagent Co., Ltd., product number: 10010326) and ciprofloxacin (CIP, manufacturer: Shanghai Aladdin Biochemical Technology Co., Ltd., product number: C129896) in trifluoroethanol to prepare a mixed solution with a gelatin concentration of 10 wt% and a CIP concentration of 2 wt%, and then stirring in a 60°C water bath for 4 h until completely dissolved to obtain a hydrophilic layer spinning solution;

[0061] (1.2) electrospinning the spinning solution of the hydrophilic layer to deposit a hydrophilic layer with a water contact angle of 25° and a thickness of 45 μm on a receiving substrate; wherein the electrospinning parameters are set as follows: needle 21G, voltage 18 kV, injection speed 1 mL / h, receiving distance 16 cm, drum rotation speed 120 rpm, and spinning time 15 min;

[0062] (2) preparing an intermediate hydrophilic layer;

[0063] (2.1) Dissolve polyacrylonitrile (PAN, manufacturer: Shanghai Titan Co., Ltd., product number: 013358771) in N,N-dimethylformamide (DMF), add curcumin (CUR, manufacturer: Shanghai Maikelin Biochemical Technology Co., Ltd., product number: C805205) and polyvinylpyrrolidone (PVP, manufacturer: Shanghai Titan Co., Ltd., product number: 01123150), and stir at 25°C for 12h to prepare a middle hydrophilic layer spinning solution with a PAN concentration of 10wt%, a PVP concentration of 3wt%, and a CUR concentration of 2wt%;

[0064] (2.2) Electrospinning the middle hydrophilic layer spinning solution on the formed hydrophilic layer to deposit a middle hydrophilic layer with a thickness of 49μm and a water contact angle of 55°, thereby obtaining a double-layer composite film; wherein the electrospinning parameters are: needle 20G, voltage 18kV, injection speed 0.8mL / h, receiving distance 16cm, drum rotation speed 120rpm, and spinning time 15min;

[0065] (3) Prepare a hydrophobic layer;

[0066] (3.1) Dissolve polycaprolactone (PCL, manufacturer: Shanghai Yinn Chemical Technology Co., Ltd., product number: R051322) in a mixed solvent of dichloromethane (DCM) and N,N-dimethylformamide (DMF) to prepare a PCL solution with a concentration of 8wt%, and stir at 25°C for 8h until complete dissolution to obtain a hydrophobic layer spinning solution; wherein the volume ratio of dichloromethane to N,N-dimethylformamide in the mixed solvent is 7:3;

[0067] (3.2) Electrospinning the hydrophobic layer spinning solution on the double-layer composite film to deposit a hydrophobic layer with a thickness of 17μm, an average pore size of 2.6μm, and a water contact angle of 120°, thereby obtaining a three-layer composite film; wherein the electrospinning parameters are: needle 21G, voltage 20kV, injection speed 0.8mL / h, receiving distance 16cm, drum rotation speed 120rpm, and spinning time 6min;

[0068] (4) Vacuum dry the obtained three-layer composite film at 50°C for 12h to obtain a composite dressing with bidirectional fluid transport function;

[0069] The finally obtained composite dressing with bidirectional fluid transport function is a three-layer Janus composite fiber membrane, as shown in FIG. 1, which comprises a hydrophobic layer 1, a middle hydrophilic layer 2, and a hydrophilic layer 3 from the contact side to the side away from the side; Figure 1

[0070] ​The one-way transport index difference |ΔR| of the composite dressing with bidirectional fluid transport function is 380% (R Figure 3 = 311%, R + = -69%) as shown in the figure. - The 24h ciprofloxacin reverse release rate is 67.8 ± 2.4%, and the 24h curcumin reverse release rate is 65.3 ± 1.8%, which proves that the composite dressing retains the positive wetting ability while weakening the barrier effect of the hydrophobic layer, establishing a reverse diffusion channel for small molecule active ingredients, successfully realizing the reverse release of ciprofloxacin and curcumin, and verifying the feasibility of the bidirectional transport mechanism of the invention "liquid positive adsorption + drug reverse delivery". Figure 2 The relative growth rate of cells is 89.7%, which proves that the composite dressing has no cytotoxicity. Figure 4

[0071] Comparative Example 1

[0072] A preparation method of a composite dressing with bidirectional fluid transport function, which is basically the same as Example 1, except that the spinning time in step (3.2) is 9 min, and the obtained hydrophobic layer has a thickness of 25 μm and an average pore size of 1.78 μm.

[0073] The one-way transport index difference |ΔR| of the finally obtained composite dressing with bidirectional fluid transport function is 780% (R + = 464%, R - = -316%); the 24h ciprofloxacin reverse release rate is 3.5 ± 0.6%, and the 24h curcumin reverse release rate is 3.2 ± 0.4%.

[0074] Comparing Comparative Example 1 and Example 1, the one-way transport index difference of the composite dressing with bidirectional fluid transport function prepared in the present comparative example is larger, and the reverse release rates of ciprofloxacin and curcumin are significantly reduced, and the reverse drug delivery function is basically lost, because the increase in the thickness and the decrease in the pore size of the hydrophobic layer caused by the extension of the spinning time significantly increase the resistance to reverse drug transport, and this structural change also significantly increases the one-way transport index difference |ΔR|, indicating that the composite dressing of the present comparative example retains good liquid positive wetting ability, but the reverse transport channel is obviously inhibited, thereby seriously hindering the reverse release of drugs.

[0075] Comparative Example 2

[0076] A preparation method of a composite dressing with bidirectional fluid transport function, which is basically the same as Example 1, except that the spinning time in step (3.2) is 4.6 min, and the obtained hydrophobic layer has a thickness of 13 μm and an average pore size of 3.18 μm.

[0077] ​The absolute value of the one-way transport index difference |AR| of the prepared composite dressing with bidirectional fluid transport function is 213% (R + = 198%, R - = -15%); the 24 h reverse release rate of ciprofloxacin is 96.7 ± 2.1%, and the 24 h reverse release rate of curcumin is 96.2 ± 1.9%.

[0078] Comparing Comparative Example 2 and Example 1, it can be seen that the composite dressing with bidirectional fluid transport function prepared in the comparative example has a smaller one-way transport index difference, and the reverse release rates of ciprofloxacin and curcumin are greatly improved, but |R + | < 200%, indicating that the forward wetting ability of the dressing is severely limited, because the reduction of the spinning time leads to the decrease of the thickness and the increase of the pore size of the hydrophobic layer, although the reverse transport resistance of the drug is significantly reduced, the reverse release of the drug is promoted, but at the same time the capillary pressure difference required for forward wetting is weakened, leading to a significant decrease in forward wetting performance.

[0079] Example 2

[0080] A preparation method of a composite dressing with bidirectional fluid transport function, comprising the following steps:

[0081] (1) preparing a hydrophilic layer;

[0082] (1.1) dissolving polyacrylonitrile (PAN, manufacturer: Shanghai Titan Co., Ltd., product number: 013358771) in N, N-dimethylformamide (DMF), adding curcumin (CUR, manufacturer: Shanghai Maikelin Biochemical Technology Co., Ltd., product number: C805205) and polyvinylpyrrolidone (PVP, manufacturer: Shanghai Titan Co., Ltd., product number: 01123150), and stirring at 25°C for 12h to prepare a hydrophilic layer spinning solution with a PAN concentration of 10wt%, a PVP concentration of 3wt%, and a CUR concentration of 2wt%;

[0083] (1.2) electrospinning the hydrophilic layer spinning solution to deposit a hydrophilic layer with a thickness of 49μm and a water contact angle of 55° on a receiving substrate; wherein the electrospinning parameters are: needle 20G, voltage 18kV, injection speed 0.8mL / h, receiving distance 16cm, drum rotation speed 120rpm, and spinning time 15min;

[0084] (2) preparing an intermediate hydrophilic layer;

[0085] (2.1) Dissolve chitosan (CS, manufacturer: Shanghai Macklin Biochemical Technology Co., Ltd., product number: C850346) in acetic acid solution (concentration of 70 wt%) to obtain a CS solution with a concentration of 3 wt%, and dissolve polyvinyl alcohol (PVA, manufacturer: Shanghai Aldrin Chemical Reagent Co., Ltd., product number: P139533) in pure water, stir at 60°C water bath for 3h until completely dissolved, to obtain a PVA solution with a concentration of 12 wt%, mix the CS solution and the PVA solution according to the volume ratio of 1:1 and stir for 6h to obtain an intermediate hydrophilic layer spinning solution;

[0086] (2.2) On the formed hydrophilic layer, the intermediate hydrophilic layer spinning solution is spun by electrospinning, and after depositing an intermediate hydrophilic layer with a thickness of 46μm and a water contact angle of 80° on the hydrophilic layer, a double-layer composite membrane is obtained; wherein the electrospinning parameters are: needle 21G, voltage 18kV, injection speed 0.6mL / h, receiving distance 15cm, drum rotating speed 120rpm, and spinning time 15min;

[0087] (3) Prepare a hydrophobic layer;

[0088] (3.1) Dissolve polycaprolactone (PCL, manufacturer: Shanghai Yinn Chemical Technology Co., Ltd., product number: R095677) in a mixed solvent of dichloromethane (DCM) and N,N-dimethylformamide (DMF) to prepare a PCL solution with a concentration of 16wt%, and stir at 25°C for 12h until completely dissolved to obtain a hydrophobic layer spinning solution; wherein the volume ratio of dichloromethane to N,N-dimethylformamide in the mixed solvent is 7:3;

[0089] (3.2) On the basis of the double-layer composite membrane, the hydrophobic layer spinning solution is spun by electrospinning to deposit a hydrophobic layer with a thickness of 16.4μm, an average pore size of 2.69μm, and a water contact angle of 140°, thereby obtaining a three-layer composite membrane; wherein the electrospinning parameters are: needle 20G, voltage 20kV, injection speed 0.6mL / h, receiving distance 17cm, drum rotating speed 120rpm, and spinning time 5.5min;

[0090] (4) The obtained three-layer composite membrane is vacuum dried at 30°C for 24h to obtain a composite dressing with bidirectional fluid transport function;

[0091] The finally obtained composite dressing with bidirectional fluid transport function is a three-layer Janus composite fiber membrane, which comprises a hydrophobic layer, an intermediate hydrophilic layer and a hydrophilic layer from the contact side to the side away from the side;

[0092] The unidirectional transmission index difference |ΔR| of the composite dressing with bidirectional fluid transport function is 365% (as shown in FIG. 2B, R Figure 3 ​+ =309%, R - =-56%)); the 24h curcumin reverse release rate reached 67.5±2.1%, proving that the composite dressing, while retaining its forward moisture-wicking ability, weakened the barrier effect of the hydrophobic layer, established a reverse diffusion channel for small molecule active ingredients, and successfully achieved the reverse release of curcumin, verifying the feasibility of the "liquid forward adsorption + drug reverse delivery" bidirectional transport mechanism of this invention; such as Figure 4 As shown, the relative cell proliferation rate was 90.2%, proving that the composite dressing was non-cytotoxic.

[0093] Example 3

[0094] A method for preparing a composite dressing with bidirectional fluid transport function, comprising the following steps:

[0095] (1) Preparation of a hydrophobic layer;

[0096] (1.1) Polycaprolactone (PCL, manufacturer: Shanghai Yien Chemical Technology Co., Ltd., item number: R095677) was dissolved in a mixed solvent of dichloromethane (DCM) and N,N-dimethylformamide (DMF) to prepare a PCL concentration of 16wt%. The solution was stirred at 25°C for 12 h until completely dissolved to obtain a hydrophobic spinning solution. The volume ratio of dichloromethane to N,N-dimethylformamide in the mixed solvent of dichloromethane and N,N-dimethylformamide was 7:3.

[0097] (1.2) The hydrophobic spinning solution was spun by electrospinning to deposit a hydrophobic layer with a thickness of 16.4 μm, an average pore size of 2.69 μm, and a water contact angle of 140° on the receiving substrate; wherein, the electrospinning parameters were: needle 20G, voltage 20kV, injection speed 0.6mL / h, receiving distance 17cm, roller speed 120rpm, and spinning time 5.5min;

[0098] (2) Preparation of the intermediate hydrophilic layer;

[0099] (2.1) Chitosan (CS, manufacturer: Shanghai Maclean Biochemical Technology Co., Ltd., item number: C850346) was dissolved in acetic acid solution (concentration of 70wt%) to obtain a CS solution with a concentration of 3wt%. Polyvinyl alcohol (PVA, manufacturer: Shanghai Aladdin Chemical Reagent Co., Ltd., item number: P139533) was dissolved in pure water and stirred in a 60℃ water bath for 3h until completely dissolved to obtain a PVA solution with a concentration of 12wt%. The CS solution and PVA solution were mixed at a volume ratio of 1:1 and stirred for 6h to obtain the intermediate hydrophilic layer spinning solution.

[0100] (2.2) On the formed hydrophobic layer, the intermediate hydrophilic layer spinning solution was spun by electrospinning to deposit an intermediate hydrophilic layer with a thickness of 46 μm and a water contact angle of 80°, thus obtaining a double-layer composite film; wherein, the electrospinning parameters were: needle 21G, voltage 18kV, injection speed 0.6mL / h, receiving distance 15cm, roller speed 120rpm, and spinning time 15min;

[0101] (3) Prepare the hydrophilic layer;

[0102] (3.1) Polyacrylonitrile (PAN, manufacturer: Shanghai Titan Co., Ltd., item number: 013358771) was dissolved in N,N-dimethylformamide (DMF), and curcumin (CUR, manufacturer: Shanghai Maclean Biochemical Technology Co., Ltd., item number: C805205) and polyvinylpyrrolidone (PVP, manufacturer: Shanghai Titan Co., Ltd., item number: 01123150) were added. The mixture was stirred at 25°C for 12 hours to prepare a hydrophilic spinning solution with a PAN concentration of 10wt%, a PVP concentration of 3wt%, and a CUR concentration of 2wt%.

[0103] (3.2) Based on the double-layer composite membrane, the hydrophilic layer spinning solution was spun by electrospinning to deposit a hydrophilic layer with a thickness of 49 μm and a water contact angle of 55°; wherein, the electrospinning parameters were: needle 20G, voltage 18kV, injection speed 0.8mL / h, receiving distance 16cm, roller speed 120rpm, and spinning time 15min;

[0104] (4) The obtained three-layer composite film was vacuum dried at 30°C for 24 hours to obtain a composite dressing with bidirectional fluid transport function;

[0105] The final composite dressing with bidirectional fluid transport function is a three-layer Janus composite fiber membrane, which includes a hydrophobic layer, an intermediate hydrophilic layer and a hydrophilic layer from the contact side to the far side.

[0106] The unidirectional transport index difference |ΔR| of composite dressings with bidirectional fluid transport function is 361% (e.g. Figure 3 As shown, R + =306%, R - =-55%)); the 24h curcumin reverse release rate reached 67.6±1.9%, proving that the composite dressing, while retaining its forward moisture-wicking ability, weakened the barrier effect of the hydrophobic layer, established a reverse diffusion channel for small molecule active ingredients, and successfully achieved the reverse release of curcumin, verifying the feasibility of the "liquid forward adsorption + drug reverse delivery" bidirectional transport mechanism of this invention; such as Figure 4 As shown, the relative cell proliferation rate was 90.5%, proving that the composite dressing was non-cytotoxic.

[0107] Example 4

[0108] A method for preparing a composite dressing with bidirectional fluid transport function, the steps are as follows:

[0109] (1) preparing a hydrophilic layer;

[0110] (1.1) dissolving polyacrylonitrile (PAN, manufacturer: Shanghai Titan Co., Ltd., item number: 013358771) in N,N-dimethylformamide (DMF), adding curcumin (CUR, manufacturer: Shanghai Maikelin Biochemical Technology Co., Ltd., item number: C805205) and polyvinylpyrrolidone (PVP, manufacturer: Shanghai Titan Co., Ltd., item number: 01123150), and stirring at 25°C for 12h to prepare a hydrophilic layer spinning solution with a PAN concentration of 10wt%, a PVP concentration of 3wt%, and a CUR concentration of 2wt%;

[0111] (1.2) electrospinning the hydrophilic layer spinning solution to deposit a hydrophilic layer with a thickness of 10μm and a water contact angle of 55° on a receiving substrate; wherein the electrospinning parameters are: needle 20G, voltage 18kV, injection speed 0.8mL / h, receiving distance 16cm, drum rotation speed 120rpm, and spinning time 3.1min;

[0112] (2) preparing an intermediate hydrophilic layer;

[0113] (2.1) dissolving chitosan (CS, manufacturer: Shanghai Maikelin Biochemical Technology Co., Ltd., item number: C850346) in acetic acid solution (concentration of 70wt%) to obtain a CS solution with a concentration of 3wt%, dissolving polyvinyl alcohol (PVA, manufacturer: Shanghai Aldrin Chemical Reagent Co., Ltd., item number: P139533) in pure water, stirring at 60°C for 3h until completely dissolved to obtain a PVA solution with a concentration of 12wt%, mixing the CS solution and the PVA solution in a volume ratio of 1:1 and stirring for 6h to obtain an intermediate hydrophilic layer spinning solution;

[0114] (2.2) electrospinning the intermediate hydrophilic layer spinning solution on the formed hydrophilic layer to deposit an intermediate hydrophilic layer with a thickness of 10μm and a water contact angle of 80°, thereby obtaining a double-layer composite film; wherein the electrospinning parameters are: needle 21G, voltage 18kV, injection speed 0.6mL / h, receiving distance 15cm, drum rotation speed 120rpm, and spinning time 3.3min;

[0115] (3) preparing a hydrophobic layer;

[0116] (3.1) Polycaprolactone (PCL, manufacturer: Shanghai Yien Chemical Technology Co., Ltd., item number: R095677) was dissolved in a mixed solvent of dichloromethane (DCM) and N,N-dimethylformamide (DMF) to prepare a PCL concentration of 16wt%. The solution was stirred at 25°C for 12 h until completely dissolved to obtain a hydrophobic spinning solution. The volume ratio of dichloromethane to N,N-dimethylformamide in the mixed solvent of dichloromethane and N,N-dimethylformamide was 7:3.

[0117] (3.2) Based on the bilayer composite membrane, the hydrophobic layer spinning solution was spun by electrospinning to deposit a hydrophobic layer with a thickness of 15 μm, an average pore size of 3 μm, and a water contact angle of 140°, thus obtaining a three-layer composite membrane; wherein, the electrospinning parameters are: needle 20G, voltage 20kV, injection speed 0.6mL / h, receiving distance 17cm, roller speed 120rpm, and spinning time 5min;

[0118] (4) The obtained three-layer composite film was vacuum dried at 30°C for 24 hours to obtain a composite dressing with bidirectional fluid transport function;

[0119] The final composite dressing with bidirectional fluid transport function is a three-layer Janus composite fiber membrane, which includes a hydrophobic layer, an intermediate hydrophilic layer and a hydrophilic layer from the contact side to the far side.

[0120] The unidirectional transport index difference |ΔR| of composite dressings with bidirectional fluid transport function is 300% (e.g. Figure 3 As shown, R + =274%, R - =-26%)); the 24h curcumin reverse release rate reached 89.7±2.6%, proving that the composite dressing, while retaining its forward moisture-wicking ability, weakened the barrier effect of the hydrophobic layer, established a reverse diffusion channel for small molecule active ingredients, and successfully achieved the reverse release of curcumin, verifying the feasibility of the "liquid forward adsorption + drug reverse delivery" bidirectional transport mechanism of this invention; such as Figure 4 As shown, the relative cell proliferation rate was 90.8%, proving that the composite dressing was non-cytotoxic.

[0121] Example 5

[0122] A method for preparing a composite dressing with bidirectional fluid transport function, comprising the following steps:

[0123] (1) Preparation of the hydrophilic layer;

[0124] (1.1) Polyacrylonitrile (PAN, manufacturer: Shanghai Titan Co., Ltd., product number: 013358771) was dissolved in N,N-dimethylformamide (DMF), and after adding curcumin (CUR, manufacturer: Shanghai Macklin Biochemical Technology Co., Ltd., product number: C805205) and polyvinylpyrrolidone (PVP, manufacturer: Shanghai Titan Co., Ltd., product number: 01123150), it was stirred at 25°C for 12h to prepare a hydrophilic layer spinning solution with a PAN concentration of 10wt%, a PVP concentration of 3wt%, and a CUR concentration of 2wt%;

[0125] (1.2) The hydrophilic layer spinning solution was spun by electrospinning to deposit a hydrophilic layer with a thickness of 100μm and a water contact angle of 55° on a receiving substrate; wherein the electrospinning parameters were: needle 20G, voltage 18kV, push injection speed 0.8mL / h, receiving distance 16cm, drum rotation speed 120rpm, and spinning time 31.5min;

[0126] (2) Preparation of an intermediate hydrophilic layer;

[0127] (2.1) Chitosan (CS, manufacturer: Shanghai Macklin Biochemical Technology Co., Ltd., product number: C850346) was dissolved in acetic acid solution (concentration of 70wt%) to obtain a CS solution with a concentration of 3wt%, and polyvinyl alcohol (PVA, manufacturer: Shanghai Aldrin Chemical Reagent Co., Ltd., product number: P139533) was dissolved in pure water and stirred at 60°C for 3h until completely dissolved to obtain a PVA solution with a concentration of 12wt%. The CS solution and the PVA solution were mixed in a volume ratio of 1:1 and stirred for 6h to obtain an intermediate hydrophilic layer spinning solution;

[0128] (2.2) The intermediate hydrophilic layer spinning solution was spun by electrospinning on the formed hydrophilic layer to deposit an intermediate hydrophilic layer with a thickness of 100μm and a water contact angle of 80°, and a double-layer composite membrane was obtained; wherein the electrospinning parameters were: needle 21G, voltage 18kV, push injection speed 0.6mL / h, receiving distance 15cm, drum rotation speed 120rpm, and spinning time 33.5min;

[0129] (3) Preparation of a hydrophobic layer;

[0130] (3.1) Polycaprolactone (PCL, manufacturer: Shanghai Yinn Chemical Technology Co., Ltd., product number: R095677) was dissolved in a mixed solvent of dichloromethane (DCM) and N,N-dimethylformamide (DMF) to prepare a PCL solution with a concentration of 16wt%, and the solution was stirred at 25°C for 12h until completely dissolved to obtain a hydrophobic layer spinning solution; wherein in the mixed solvent of dichloromethane and N,N-dimethylformamide, the volume ratio of dichloromethane to N,N-dimethylformamide was 7:3;

[0131] (3.2) Based on the bilayer composite membrane, the hydrophobic layer spinning solution was spun by electrospinning to deposit a hydrophobic layer with a thickness of 22 μm, an average pore size of 2 μm, and a water contact angle of 140°, thus obtaining a three-layer composite membrane; wherein, the electrospinning parameters were: needle 20G, voltage 20kV, injection speed 0.6mL / h, receiving distance 17cm, roller speed 120rpm, and spinning time 7.4min;

[0132] (4) The obtained three-layer composite film was vacuum dried at 30°C for 24 hours to obtain a composite dressing with bidirectional fluid transport function;

[0133] The final composite dressing with bidirectional fluid transport function is a three-layer Janus composite fiber membrane, which includes a hydrophobic layer, an intermediate hydrophilic layer and a hydrophilic layer from the contact side to the far side.

[0134] The unidirectional transport index difference |ΔR| of composite dressings with bidirectional fluid transport function is 600% (R + =425%, R - =-175%)); the 24h curcumin reverse release rate reached 35.4±1.2%, proving that the composite dressing, while retaining its forward moisture-wicking ability, weakened the barrier effect of the hydrophobic layer, established a reverse diffusion channel for small molecule active ingredients, and successfully achieved the reverse release of curcumin, verifying the feasibility of the "liquid forward adsorption + drug reverse delivery" bidirectional transport mechanism of this invention; such as Figure 4 As shown, the relative cell proliferation rate was 89.1%, proving that the composite dressing was non-cytotoxic.

[0135] Example 6

[0136] A method for preparing a composite dressing with bidirectional fluid transport function, comprising the following steps:

[0137] (1) Preparation of the intermediate hydrophilic layer;

[0138] (1.1) Thermoplastic polyurethane (TPU, manufacturer: BASF, brand name: Elastollan® 1185A) was dissolved in a mixed solution of chloroform and N,N-dimethylformamide (DMF), and stirred at 25°C for 12 h to prepare a spinning solution with a TPU concentration of 10 wt% to obtain the intermediate hydrophilic layer spinning solution; wherein, in the mixed solution of chloroform and N,N-dimethylformamide, the volume ratio of chloroform to N,N-dimethylformamide is 8:2;

[0139] (1.2) The intermediate hydrophilic layer spinning solution is spun into a fiber membrane by electrospinning, and then the spun fiber membrane is placed in a vacuum dryer at 80°C for 2h to remove residual solvent, then immersed in a Tris-HCl solution containing 0.2wt% dopamine hydrochloride (pH=8.5), reacted at 37°C in the dark for 24h, washed with pure water three times, and placed in a vacuum dryer at 30°C for 24h to obtain an intermediate hydrophilic layer with a thickness of 61μm and a water contact angle of 70°; wherein the electrospinning parameters are: needle 21G, voltage 20kV, injection speed 1mL / h, receiving distance 16cm, drum speed 120rpm, and spinning time 20min;

[0140] (2) Preparation of the hydrophilic layer;

[0141] (2.1) Chitosan (CS, manufacturer: Shanghai Aladdin Bio-Chem Technology Co., Ltd., product number: C105799) is dissolved in 5% acetic acid solution to prepare a solution with a CS concentration of 5wt%, polyvinyl alcohol (PVA, manufacturer: Shanghai Aladdin Bio-Chem Technology Co., Ltd., product number: P105124) is dissolved in pure water under stirring at 70°C for 2h until completely dissolved to prepare a solution with a PVA concentration of 5wt%, the CS solution and the PVA solution are mixed in a volume ratio of 1:1, 1wt% silver nitrate is added, and stirring is carried out at 25°C in the dark for 8h to obtain a spinning solution;

[0142] (2.2) After spinning the spinning solution of the hydrophilic layer on one side of the formed intermediate hydrophilic layer by electrospinning, a hydrophilic layer with a water contact angle of 37° and a thickness of 63μm is obtained; wherein the electrospinning parameters are set as follows: needle 21G, voltage 18kV, injection speed 1mL / h, receiving distance 16cm, drum speed 120rpm, and spinning time 20min;

[0143] (3) Preparation of the hydrophobic layer;

[0144] (3.1) Polycaprolactone (PCL, manufacturer: Shanghai Yinn Chemical Technology Co., Ltd., product number: R095677) is dissolved in a mixed solvent of dichloromethane (DCM) and N,N-dimethylformamide (DMF) to prepare a solution with a PCL concentration of 12wt%, and stirring is carried out at 25°C for 12h until complete dissolution to obtain a hydrophobic layer spinning solution; wherein the volume ratio of dichloromethane to N,N-dimethylformamide in the mixed solvent is 7:3;

[0145] (3.2) Based on the bilayer composite membrane, the hydrophobic layer spinning solution is electrospun on the other side of the middle hydrophilic layer to deposit a hydrophobic layer with a thickness of 17.3 μm, an average pore size of 2.52 μm, and a water contact angle of 132°, thus obtaining a three-layer composite membrane; wherein, the electrospinning parameters are: needle 20G, voltage 20kV, injection speed 0.8mL / h, receiving distance 17cm, roller speed 120rpm, and spinning time 6min;

[0146] (4) The obtained three-layer composite film was vacuum dried at 40°C for 18 hours to obtain a composite dressing with bidirectional fluid transport function;

[0147] The final composite dressing with bidirectional fluid transport function is a three-layer Janus composite fiber membrane, which includes a hydrophobic layer, an intermediate hydrophilic layer and a hydrophilic layer from the contact side to the far side.

[0148] The unidirectional transport index difference |ΔR| of composite dressings with bidirectional fluid transport function is 427% (e.g., Figure 3 As shown, R + =332%, R - =-95%)); 24h Ag + The reverse release rate reached 57.3±1.6%, demonstrating that the composite dressing, while retaining its forward moisture-wicking ability, weakened the barrier effect of the hydrophobic layer, established a reverse diffusion channel for small molecule active ingredients, and successfully achieved Ag... + The reverse release verifies the feasibility of the bidirectional transport mechanism of "liquid forward adsorption + drug reverse delivery" of this invention; such as Figure 4 As shown, the relative cell proliferation rate was 87.9%, proving that the composite dressing was non-cytotoxic.

[0149] Example 7

[0150] A method for preparing a composite dressing with bidirectional fluid transport function, comprising the following steps:

[0151] (1) Preparation of the hydrophilic layer;

[0152] (1.1) Polyacrylonitrile (PAN, manufacturer: Shanghai Titan Co., Ltd., item number: 013358771) was dissolved in N,N-dimethylformamide (DMF), and curcumin (CUR, manufacturer: Shanghai Maclean Biochemical Technology Co., Ltd., item number: C805205) and polyvinylpyrrolidone (PVP, manufacturer: Shanghai Titan Co., Ltd., item number: 01123150) were added. The mixture was stirred at 25°C for 12 hours to prepare a hydrophilic spinning solution with a PAN concentration of 10 wt%, a PVP concentration of 3 wt%, and a CUR concentration of 1 wt%.

[0153] (1.2) The hydrophilic layer spinning solution is spun by electrospinning to deposit a hydrophilic layer with a thickness of 48 pm and a water contact angle of 51° on the receiving substrate; wherein the electrospinning parameters are: needle 20G, voltage 18 kV, push injection speed 0.8 mL / h, receiving distance 16 cm, drum rotation speed 120 rpm, and spinning time 15 min;

[0154] (2) Preparation of an intermediate hydrophilic layer;

[0155] (2.1) Polyvinyl alcohol (PVA, manufacturer: Shanghai Maikelin Biochemical Technology Co., Ltd., product number: P815723) is dissolved in pure water to obtain a PVA solution with a concentration of 14 wt%, which is stirred at 90°C for 4 h until completely dissolved. After the solution is cooled to 25°C, 1 wt% of silver nitrate is added, and the mixture is stirred at 25°C for 6 h in the dark to obtain an intermediate hydrophilic layer spinning solution;

[0156] (2.2) The intermediate hydrophilic layer spinning solution is spun by electrospinning on the formed hydrophilic layer to deposit an intermediate hydrophilic layer with a thickness of 46 pm and a water contact angle of 78°, thereby obtaining a double-layer composite film; wherein the electrospinning parameters are: needle 20G, voltage 25 kV, push injection speed 1 mL / h, receiving distance 18 cm, drum rotation speed 120 rpm, and spinning time 15 min;

[0157] (3) Preparation of a hydrophobic layer;

[0158] (3.1) Polycaprolactone (PCL, manufacturer: Shanghai Yinn Chemical Technology Co., Ltd., product number: R095677) is dissolved in a mixed solvent of dichloromethane (DCM) and N,N-dimethylformamide (DMF) to prepare a PCL solution with a concentration of 12 wt%, which is stirred at 25°C for 12 h until completely dissolved to obtain a hydrophobic layer spinning solution; wherein the volume ratio of dichloromethane to N,N-dimethylformamide in the mixed solvent is 7:3;

[0159] (3.2) The hydrophobic layer spinning solution is spun by electrospinning on the double-layer composite film to deposit a hydrophobic layer with a thickness of 17.3 pm, an average pore size of 2.52 pm, and a water contact angle of 132°, thereby obtaining a three-layer composite film; wherein the electrospinning parameters are: needle 20G, voltage 20 kV, push injection speed 0.8 mL / h, receiving distance 17 cm, drum rotation speed 120 rpm, and spinning time 6 min;

[0160] (4) The obtained three-layer composite film is vacuum dried at 30°C for 24 h to prepare a composite dressing with bidirectional fluid transport function;

[0161] The final composite dressing with bidirectional fluid transport function is a three-layer Janus composite fiber membrane, which includes a hydrophobic layer, an intermediate hydrophilic layer and a hydrophilic layer from the contact side to the far side.

[0162] The unidirectional transport index difference |ΔR| of composite dressings with bidirectional fluid transport function is 406% (e.g. Figure 3 As shown, R + =320%, R - =-86%)); the 24h curcumin reverse release rate reached 59.8±1.4%, 24h Ag + The reverse release rate reached 61.2±1.6%, proving that the composite dressing, while retaining its forward moisture-wicking ability, weakened the barrier effect of the hydrophobic layer, established a reverse diffusion channel for small molecule active ingredients, and successfully achieved the reverse release of curcumin, verifying the feasibility of the "liquid forward adsorption + drug reverse delivery" bidirectional transport mechanism of this invention; Figure 4 As shown, the relative cell proliferation rate was 88.4%, proving that the composite dressing is non-cytotoxic.

Claims

1. A composite dressing with bidirectional fluid transport function, characterized in that: It is a three-layer Janus composite fiber membrane, which consists of a hydrophobic layer, an intermediate hydrophilic layer and a hydrophilic layer from the contact side to the far side; The contact side refers to the side that comes into direct contact with the wound or bodily fluids during use; The hydrophilic layer and / or intermediate hydrophilic layer are loaded with small molecule active ingredients; the small molecule active ingredients are ciprofloxacin, curcumin or silver nitrate. The unidirectional transport index difference |ΔR| of the composite dressing with bidirectional fluid transport function is 300~600%. The unidirectional transport index difference |ΔR| is tested using a liquid moisture management tester, referring to the AATCC TM 195-2009 standard. The test procedure is as follows: the sample to be tested is cut into a 10cm×10cm square and placed between the upper and lower sensor arrays. Then, 0.21g of physiological saline is dropped onto the hydrophobic side of the sample. The instrument automatically records the dynamic transport process of the liquid in the thickness direction and calculates the unidirectional transport index difference |ΔR|. The calculation formula is: unidirectional transport index difference |ΔR|=|R₊−R₋|, where R+ is the liquid transport index from the hydrophobic side to the hydrophilic side, and R- is the liquid transport index from the hydrophilic side to the hydrophobic side. The water contact angle of the hydrophobic layer is 120~140°, the water contact angle of the intermediate hydrophilic layer is 55~80°, and the water contact angle of the hydrophilic layer is 25~55°. The average pore size of the hydrophobic layer is 2~3μm.

2. The composite dressing with bidirectional fluid transport function according to claim 1, characterized in that, The thickness of the hydrophobic layer is 15~22μm, the thickness of the intermediate hydrophilic layer is 10~100μm, and the thickness of the hydrophilic layer is 10~100μm.

3. A method for preparing a composite dressing with bidirectional fluid transport function as described in claim 1 or 2, characterized in that: Spinning solutions for a hydrophobic layer, an intermediate hydrophilic layer, and a hydrophilic layer were prepared separately. Small molecule active ingredients were added to the spinning solutions of the hydrophilic layer and / or the intermediate hydrophilic layer. The three-layer structure was constructed by electrospinning layer by layer. The solution was then vacuum dried at 30-50℃ for 12-24 hours to obtain a composite dressing with bidirectional fluid transport function.

4. The method for preparing a composite dressing with bidirectional fluid transport function according to claim 3, characterized in that, The deposition sequence of layer-by-layer electrospinning includes one of the following methods: (a) First, a hydrophilic layer is deposited on the receiving substrate, and then an intermediate hydrophilic layer and a hydrophobic layer are deposited sequentially; (b) First, a hydrophobic layer is deposited on the receiving substrate, and then an intermediate hydrophilic layer and a hydrophilic layer are deposited sequentially; (c) First, prepare an intermediate hydrophilic layer, then deposit a hydrophilic layer on one side and a hydrophobic layer on the other side.

Images