Absorption dressing special for laparoscopic surgery

Abstract

The invention discloses a special adsorption dressing used after a laparoscopic surgery, and belongs to the technical field of medical dressings. The dressing is of a layered composite structure and sequentially comprises a hydrophilic guide layer, an absorption foam layer and a hydrophobic protective layer from inside to outside, the hydrophilic guide layer is an electrospun fibrous membrane formed by micro / nano fibers oriented along a specific direction; the absorption foam layer is made of a foam material with high aperture ratio; the hydrophobic protective layer is a breathable hydrophobic film; the preparation method mainly comprises the steps of preparation of each functional layer and composite molding through a low-temperature hot pressing process. According to the dressing, through the synergistic effect of the three layers of materials, directional and rapid absorption and storage of percolation of a postoperative puncture hole are achieved, tissue regeneration guidance is provided, the skin around a wound is effectively prevented from being hardened, and the dressing is antibacterial, anti-inflammatory, good in fitting performance and beneficial to wound healing.

Description

Technical Field

[0001] This invention belongs to the field of medical dressing technology and relates to a special absorbent dressing for laparoscopic surgery. Background Technology

[0002] Laparoscopic cholecystectomy has become mainstream due to its minimally invasive advantages, but it requires the creation of several 5–12 mm puncture holes during the procedure. Postoperatively, these wounds have a deep channel structure, which easily retains exudate and tissue fluid. Coupled with suture irritation, this often leads to problems such as local redness, swelling, exudation, induration, and capillary hyperplasia. For such "small and deep" wounds, the selection of dressings is crucial for exudate management and tissue recovery.

[0003] Existing general-purpose dressings (such as gauze, films, foam dressings, etc.) have significant shortcomings: First, they are difficult to effectively drain and store deep exudate, leading to the risk of retention and infection; second, their shape is not suitable and they do not fit the channel tightly, affecting drainage; third, they may cause side leakage of exudate, leading to maceration of the surrounding skin; and fourth, they lack the comprehensive functions of inhibiting excessive inflammation, controlling microorganisms, and guiding orderly tissue regeneration.

[0004] Currently, layered composite dressings have been explored: foam materials can provide high absorbency, electrospun fiber membranes can achieve surface functionalization and topological guidance, and hydrophilic-hydrophobic gradient design helps with directional flow. However, for laparoscopic puncture holes, existing solutions still have significant limitations in three aspects: morphological fit (lack of short column or annular band observation port design adapted to deep channels), vertical flow guidance (lack of system design that takes into account both large-volume fluid storage and surface protection), and directional tissue guidance (difficulty in simultaneously achieving fiber orientation control and functional drug loading).

[0005] Therefore, there is an urgent need to develop an absorbent dressing specifically for this type of wound, which can achieve effective exudate management, wound protection, and microenvironment regulation through the synergistic design of materials and structure.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a special absorbent dressing for laparoscopic surgery.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A special absorbent dressing for laparoscopic surgery, the dressing having a layered composite structure, comprising, from the inside out:

[0010] A hydrophilic guiding layer that comes into direct contact with the wound surface;

[0011] An absorbent foam layer laminated to the outside of the hydrophilic guiding layer;

[0012] And a hydrophobic protective layer laminated on the outside of the absorbent foam layer;

[0013] The hydrophilic guiding layer is a fiber membrane composed of micron or nanofibers oriented in a specific direction, and the orientation of the fibers is formed by a dynamic collection process.

[0014] Preferably, the hydrophilic guiding layer is an electrospun fiber membrane, and the fiber material is one or a blend of several of polycaprolactone (PCL), polylactic acid (PLLA), polyvinyl alcohol (PVA), and silk fibroin.

[0015] By employing the above technical solution, the hydrophilic guiding layer provides a high specific surface area contact substrate for the wound surface, facilitating fibroblast attachment and migration along the fiber axis. This physical contact guidance can promote the deposition of newly formed collagen in a predetermined direction, reducing randomly tangled collagen accumulation, thereby lowering the probability of postoperative local nodular sclerosis.

[0016] Preferably, the average fiber diameter of the hydrophilic guiding layer is 200–800 nm, and the fiber orientation degree is 70%–99%.

[0017] Preferably, the absorbent foam layer is an open-cell foam material, which includes at least one of polyurethane foam, silicone gel foam or cross-linked polysaccharide-based foam, and the pore size distribution of the foam layer is 50–500 micrometers, with an overall open-cell rate of 80%–99%.

[0018] By adopting the above technical solution, the intermediate foam layer provides a large-capacity vertical liquid storage space and rapid capillary fluid conduction capability, which can quickly move the exudate in the deep channels of the wound from the contact surface into the foam body and seal it, reducing the retention of exudate in the channels and backflow, and reducing the risk of long-term local irritation and infection.

[0019] Preferably, the liquid absorption capacity (dry weight ratio) of the absorbent foam layer is 5-15 g / g.

[0020] Preferably, the absorbent foam layer contains at least one functional component, which includes at least one of silver ions or their nanocomposites, chitosan, antimicrobial peptides, ZnO nanoparticles, or controlled-release microcarriers loaded with nonsteroidal anti-inflammatory drugs.

[0021] Preferably, the hydrophobic protective layer is a breathable hydrophobic film or a microporous hydrophobic composite film, and the liquid penetration pressure of the hydrophobic protective layer is 5-15 kPa.

[0022] By adopting the above technical solution, the hydrophobic layer penetration pressure (LEP ≥ 5 kPa) and air permeability are limited. The outer hydrophobic layer can effectively prevent the invasion of external liquids and inhibit the lateral diffusion of exudate to the surrounding skin while allowing gas exchange, thereby protecting the surrounding skin from maceration damage and maintaining the stability of the local microenvironment.

[0023] Preferably, the overall shape of the dressing is one of the following: flat sheet, annular with a central observation hole, or short plug.

[0024] This invention also provides a method for preparing a special absorbent dressing for laparoscopic surgery, comprising the following steps:

[0025] Preparation of S1 hydrophilic guiding layer: Prepare an electrospun fiber solution, wherein the polymer concentration used in the solution is 8–20 wt% (organic solvent system) or 5–15 wt% (water-soluble system), and the organic solvent includes hexafluoroisopropanol, dichloromethane / dimethylformamide mixed solvent or water;

[0026] Electrospinning is performed using an injection pump for liquid supply and a high-voltage power supply; after electrospinning, the fiber membrane is dried.

[0027] Preparation of S2 absorbent foam layer:

[0028] Foam precursor materials are prepared according to the selected foam matrix, and open-cell foam structures are formed by physical foaming and freeze-drying.

[0029] The resulting foam is washed, dried, and heat-treated at 40–80 °C to form a stable pore structure, resulting in an overall open-cell rate of more than 80%.

[0030] S3 functional component introduction:

[0031] In or after step (S1) or step (S2), functional components are introduced into the hydrophilic guiding layer or absorbent foam layer by blending, impregnation or in-situ introduction, and then fixed by drying or crosslinking.

[0032] S4 Low-Temperature Hot Press Composite Molding:

[0033] The hydrophilic guiding layer obtained in step S1, the absorbent foam layer obtained in step S2, and the hydrophobic protective layer are accurately aligned and stacked in the inner-middle-outer order, and then composited in one step using a low-temperature hot pressing process to obtain a three-layer composite dressing blank.

[0034] S5 Forming and Slitting:

[0035] The composite dressing blank is cooled and shaped, and then die-cut into a predetermined shape.

[0036] S6 Drying, sterilization and packaging:

[0037] After the molded dressing undergoes necessary drying treatment, it is sterilized using gamma rays and then packaged and sealed in a sterile environment.

[0038] This process is advantageous in that it maintains the open pore structure and absorption properties of the foam, preserves the surface functionalization activity of the fiber layer, and avoids biocompatibility issues caused by adhesives; at the same time, it facilitates industrial roll-to-roll production and ensures quality control.

[0039] Preferably, the electrospinning parameters in step S1 are: voltage 10–25 kV, solution flow rate 0.2–2.0 mL / h, distance from needle tip to collector 10–20 cm, and the dynamic collection device is a rotating cylinder or drum with a rotation speed of 1000–5000 rpm.

[0040] In step S2, the pre-freezing temperature of the freeze-drying process is -80 to -40 °C, and after vacuum drying, the temperature is gradually increased to room temperature;

[0041] The content of the functional components in step S3 is: silver ions (0.01–0.5 wt%), chitosan (0.5–3.0 wt%), and ZnO nanoparticles (0.01–1.0 wt%).

[0042] In step S4, the hot pressing temperature is controlled at 60–120 °C, the hot pressing pressure is 0.1–2 MPa, and the hot pressing time is 10–300 s, so that the hydrophilic guiding layer and the absorbent foam layer form a stable physical lamination bond at the interface.

[0043] In step S6, the gamma ray dose is 25–35 kGy.

[0044] By adopting the above technical solution and controlling the hot pressing temperature, pressure and time, the hydrophilic fiber membrane and the foam layer and hydrophobic film can form a stable bond at the interface without introducing adhesives that have the risk of migration.

[0045] The beneficial effects of this invention are:

[0046] 1) Introducing silver ions, chitosan, ZnO nanoparticles, or controlled-release drugs into the hydrophilic guiding layer or absorbent foam layer can provide chemical / biological infection control and inflammation regulation on the basis of physical absorption; by reducing microbial load and alleviating local abnormal inflammatory signals, it can reduce the tendency of abnormal angiogenesis and fibrosis caused by continuous inflammatory stimulation, and provide a favorable biochemical environment for orderly collagen deposition and soft healing.

[0047] 2) The versatile shape adaptability allows the dressing to be used not only as a regular covering dressing, but also to be made into short columns or plug modules according to the size of the puncture hole, ensuring better fit to deep channel wounds, filling dead space, improving local drainage efficiency and reducing displacement caused by movement or tension, thereby improving clinical usability and efficacy stability.

[0048] 3) The inner hydrophilic directional fibers provide spatial and mechanical cues, promoting the directional alignment of cells and collagen; at the same time, the middle foam layer reduces non-specific interference of exudate on cell behavior through effective absorption and storage; the outer hydrophobic layer maintains local humidity balance and prevents lateral maceration; the functional components regulate the intensity of biological stimulation (antibacterial / anti-inflammatory / controlled release) throughout the three-layer system; the parallel effect of these three elements forms a triple coupling control of "physical-chemical-fluid dynamics", which optimizes the wound in terms of mechanical directionality, inflammatory intensity and exudate load at the same time, thereby achieving a higher comprehensive control over the wound healing path than single-function dressings.

[0049] In summary, this invention precisely defines the materials, microstructure, and fabrication process of the hydrophilic guiding layer, absorbent foam layer, and hydrophobic protective layer, introduces necessary functional modifications, and employs low-temperature hot-pressing lamination to achieve stable, adhesive-free composite bonding. This achieves synergistic optimization across four dimensions: tissue biomechanical guidance, exudate management, infection / inflammation control, and clinical fit. This synergistic effect not only reduces postoperative local induration and exudation complications but also provides a replicable technical route in terms of manufacturing controllability and clinical adaptability, meeting both clinical needs and industrialization requirements. Attached Figure Description

[0050] Figure 1 Distribution and morphology of the absorbent dressing: SEM + EDS images;

[0051] Figure 2 This is a dynamic curve of the release of functional substances. Detailed Implementation

[0052] The present invention will be further described below through specific embodiments. To make the inventive objectives, technical solutions, and beneficial technical effects of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the embodiments described in this specification are merely for explaining the present invention and are not intended to limit the present invention.

[0053] Unless otherwise stated, all instruments and reagents used in the examples are commercially available or synthesized using conventional methods and can be used directly without further processing, and all instruments used in the examples are commercially available.

[0054] Example 1:

[0055] In S1, the electrospun fiber solution was prepared using polycaprolactone (PCL) as the substrate and a 12 wt% spinning solution was prepared in hexafluoroisopropanol (HFIP). A syringe pump was used to supply the solution at a rate of 1.0 mL / h, with the voltage set to the midpoint of 18 kV. The distance from the needle tip to the collector was 15 cm. A rotating drum dynamic collection device was used, with a rotation speed of 3000 rpm, to obtain a nanofiber membrane with an orientation degree of approximately 85% and a target fiber diameter of 400 nm. After electrospinning, the membrane was dried under normal pressure, followed by oxygen plasma surface activation treatment (100 W, 60 s) to improve hydrophilicity and subsequent chitosan impregnation.

[0056] The S2 absorbent foam layer was prepared using a freeze-drying method: a carboxymethyl cellulose solution was prepared and a sucrose pore agent was incorporated, with a particle size of 250 µm and a filler volume percentage of 45%. The gel was pre-frozen at -60 °C, followed by vacuum freeze-drying to obtain a foam layer with an open pore size of approximately 200–300 µm and an overall open porosity of 90%. The sucrose pore agent was washed off with cold water, and the structure was stabilized by drying at 60 °C.

[0057] In this embodiment, a moderate loading of the S3 functional component was used: silver ions (0.10 wt%) and chitosan (1.5 wt%) were co-blended in the foam formulation to improve the antibacterial / hydrophilic properties of the substrate. The introduced chitosan was lightly cross-linked (short-term cross-linking with 0.5 wt% glutaraldehyde) to improve hot-pressing stability.

[0058] S4 One-time low-temperature hot-pressing composite molding: The hydrophilic oriented fiber membrane obtained in step S1 is placed in the mold as the inner layer, the absorbent foam layer obtained in step S2 is stacked on its outer side, and then the selected hydrophobic protective film is placed on the outermost side: temperature 90 °C, pressure 1.0 MPa, hot pressing time 60 s. After hot pressing, the hydrophobic protective film is laminated and a second lamination is performed using the same process. After completion, it is cooled to room temperature.

[0059] S5 molding and slitting is prepared by die cutting: two specifications are available: short pillars with medium puncture holes (8 mm in diameter and 4 mm in total thickness) and flat sheets (50 × 50 mm).

[0060] S6 Drying and Sterilization: The final product is dried at 60 °C for 2 hours, sterilized by gamma radiation at a dose of 30 kGy, and individually packaged in a sterile environment. This embodiment is a recommended process that balances fiber orientation, foam pore structure, and functional component loading.

[0061] Example 2:

[0062] The S1 hydrophilic layer was electrospun using an 18 wt% PLLA solution in a DCM / DMF (7:3) mixed solvent at a flow rate of 2.0 mL / h, a voltage of 25 kV, a needle pitch of 10 cm, and a collector rotation speed of 5000 rpm to obtain fibers with a diameter of approximately 200 nm and an orientation degree close to 95%. The fibers were then impregnated with 3.0 wt% chitosan and lightly crosslinked.

[0063] S2 foam is prepared by foaming polyurethane-based open-cell foam with a target pore size of small to improve capillary rate: pore size is concentrated in 50–150 µm, overall open cell ratio is 95%, and the absorption capacity is pursued to be 15 g / g.

[0064] S3 has a high loading of functional components: 0.50 wt% silver nanoparticles and 1.0 wt% ZnO nanoparticles.

[0065] S4 Low-Temperature Hot Pressing Parameters: Hot pressing temperature 120 °C, pressure 2.0 MPa, time 300 s, used for strong bonding of thicker or higher-density foams.

[0066] S5 molding: Short cylindrical shape (10 mm in diameter, 6 mm in thickness) is made to fit relatively deep puncture channels.

[0067] S6 Sterilization: Gamma rays 35 kGy.

[0068] Example 3:

[0069] S1 uses an 8 wt% PVA (highly hydrophilic) water-soluble system as the spinning solution, with a voltage of 10 kV, a flow rate of 0.2 mL / h, a distance of 20 cm, and a collector rotation speed of 1000 rpm. The target fiber diameter is close to 700–800 nm and the orientation degree is maintained at 70% to form a softer, more permeable hydrophilic membrane. Mild crosslinking is performed to increase water stability.

[0070] S2 foam is produced by freeze-drying: using sucrose pore agents with a particle size of 500 µm and a filling ratio of 20%, and a pre-freezing temperature of -40 °C, to obtain a larger pore size distribution close to the upper limit (300–500 µm), an open porosity of 80%, and an absorption capacity of 5 g / g, focusing more on softness and fit rather than extremely high absorption.

[0071] S3 low-load functional components: only 0.5 wt% chitosan is added to improve antibacterial and film-forming properties, and no metal ions are added to reduce irritation.

[0072] S4 Low-temperature hot pressing parameters: hot pressing temperature 60 °C, pressure 0.1 MPa, time 10 s, to minimize thermal damage to fiber structure and water-soluble components.

[0073] S5 is molded into a thin, flat sheet (2–3 mm thick) for patients with mild exudation or those who require high comfort.

[0074] S6 Sterilization: Ethylene oxide or gamma 25 kGy, with residual testing performed before packaging.

[0075] Example 4:

[0076] The S1 hydrophilic layer uses 15 wt% PCL (organic system), voltage 20 kV, flow rate 1.5 mL / h, distance 12 cm, and collector 3500 rpm to obtain a fiber membrane with 90% orientation.

[0077] S2 foam employs a pore-forming agent method: a salt / sucrose composite pore-forming agent is selected, with particle sizes of 100 µm (low-end), 250 µm (mid-range), or 400 µm (high-end), which can be used alone or in combination, with filling ratios of 30% (low-end), 50% (mid-range), and 70% (high-end); after gel cross-linking, the pore-forming agent is washed away with water and then freeze-dried to produce a two-dimensional interconnected pore structure. The pore size distribution can be precisely controlled by the combination of pore-forming agent particle sizes, with a target overall open porosity of 85–95%.

[0078] S3 Functional Component: A controlled-release microcarrier (with a drug loading of 2 mg / cm²) is added to the foam precursor to sustain the release of a low dose of nonsteroidal anti-inflammatory drug, while the surface of the hydrophilic layer is impregnated with 1.0 wt% chitosan.

[0079] S4 Low-Temperature Hot Pressing: The oriented fiber membrane of S1, the foam formed by the S2 pore-forming method and washed / dried, and the hydrophobic film are layered and stacked, placed in a mold for displacement correction, and then fed into the hot pressing equipment in one go. Hot pressing parameters: 80 °C, 0.8 MPa, 120 s. To maintain the integrity of the pore structure, the foam should be pre-cured at 40–60 °C for 30–60 min before hot pressing to reduce the impact of thermal stress. After hot pressing, cool under pressure for 30–60 s, remove, and die-cut.

[0080] S5 molding: Complex shapes (ring-shaped with observation holes) are machined using CNC die cutting to facilitate postoperative observation of sutures and exudation.

[0081] S6 sterilization: 30 kGy gamma rays.

[0082] Example 5:

[0083] The S1 hydrophilic layer was electrospun using a 10 wt% PCL / PLLA blend solution (voltage 15 kV, flow rate 0.8 mL / h, distance 14 cm, collector 2500 rpm) to obtain medium fiber diameter and orientation.

[0084] S2 foam is prepared by chemical foaming to produce polyurethane foam. The amount of foaming agent and the degree of foam crosslinking are controlled to achieve a structure with a pore size of 80–200 µm and an open porosity of 88%, which results in a faster capillary conduction rate and a certain liquid storage capacity (absorption of 8–12 g / g).

[0085] S3 introduces 0.2 wt% ZnO nanoparticles into the foam via in-situ deposition to achieve long-term antibacterial effects, while simultaneously coating the hydrophilic layer surface with controlled-release microcarriers (0.5–2 mg / cm²).

[0086] S4 hot pressing parameters: 100 °C, 1.2 MPa, 120 s, followed by lamination and die cutting.

[0087] The S5 is molded as a short-pole plug type (6 mm in diameter) to be used with flat plates.

[0088] S6 Sterilization at 30 kGy. This embodiment is suitable for scenarios requiring rapid initial absorption and good long-term antimicrobial control.

[0089] Example 6: Blending of functional components in S1

[0090] Blending method: Prepare polycaprolactone (PCL) spinning solution in HFIP, and add silver ion solution (by mass of silver) directly to the spinning solution. The rest is the same as in Example 1.

[0091] Example 7: In-situ blending of functional components in S2

[0092] In preparing the PCL / PLLA hydrophilic layer, functional component ZnO nanoparticles were added to the solution, and the rest was the same as in Example 5.

[0093] Example 8: Introducing "Post-S2 Impregnation Load" via impregnation after S2

[0094] To prepare the antibacterial solution, the foam sample was immersed in the solution and evacuated and circulated in a vacuum chamber 3–5 times to promote the solution to enter the micropores. After immersion, the sample was centrifuged.

[0095] Example 9:

[0096] The hydrophobic protective layer may be selected from one or more of thermoplastic polyurethane (TPU) microporous membrane, polytetrafluoroethylene (PTFE) microporous membrane, or polyethylene / polypropylene porous membrane;

[0097] In this embodiment, the hydrophobic protective layer is made of medical-grade thermoplastic polyurethane (TPU) microporous membrane. The TPU microporous membrane is prepared by phase separation-stretching process, with a thickness of 20–40 μm and an average pore size of 0.2–1.0 μm, and has good waterproof and breathable properties.

[0098] The water vapor transmission rate of the hydrophobic protective layer was 2000–3500 g / m²·24 h when tested at 23 ± 2 °C, and its liquid penetration pressure was 8–12 kPa when tested by hydrostatic pressure method.

[0099] During the preparation process, the TPU microporous membrane is used as the outer protective layer and is laminated with the absorbent foam layer by hot pressing. The hot pressing temperature is controlled at 80–110 °C, the pressure is 0.1–0.3 MPa, and the time is 5–20 s to ensure that the interlayer bonding is strong and the TPU microporous structure is not damaged.

[0100] Comparative Example 1: Control of unoriented fibers

[0101] Prepared according to the steps of Example 1, but the collector is not rotated in S1 (static plate collection) to obtain a non-oriented random fiber membrane; the remaining steps are the same as in Example 1.

[0102] Comparative Example 2: A control group using adhesive bonding instead of low-temperature hot pressing

[0103] In the composite step S4, instead of low-temperature hot pressing, medical-grade pressure-sensitive adhesive or solvent-based adhesive is used to bond the hydrophilic layer, foam layer and hydrophobic membrane.

[0104] Comparative Example 3: Control with no functional components

[0105] Prepared according to the parameters of Example 1, but without the addition of functional components such as silver, chitosan or ZnO in S3, in order to evaluate the differences in the effects of functional components on antibacterial and inflammation control.

[0106] Performance comparison of Examples 1-5 with Comparative Examples 1-3:

[0107] 1. Material and fluid properties (mean ± SD, n = 5), results are shown in Table 1:

[0108]

[0109] As shown in Table 1, smaller pore size / higher open porosity (Example 2) improved the absorption rate and total absorption; Comparative Example 2 (adhesive composite) showed higher interlayer bonding strength but lower LEP, slightly worse air permeability and liquid conductivity, demonstrating the advantage of low-temperature hot pressing without adhesive. 2. Antibacterial properties (in vitro, strains: S. aureus and E. coli, n = 6) Method points: Following the direct contact method or plate count method similar to ISO 20743 or JIS L 1902, the sample was contacted with the standard bacterial solution (≈10^6 CFU / mL) for 24 h, the sample was diluted and plate counted, and the log10 reduction (log10 CFU reduction) was calculated, as shown in Table 2 below:

[0110]

[0111] The table above shows that the examples with high silver / nano ZnO loading (especially Example 2) exhibited significantly stronger antibacterial activity (p < 0.01 compared with Comparative Example 3); Comparative Examples 2 and 3 had limited antibacterial effects with no / weak additives.

[0112] 3. In vitro cell functional tests (fibroblasts, n = 6) to evaluate the effects of hydrophilic oriented fibers on fibroblast adhesion, orientation and biocompatibility (compared with disordered fiber control).

[0113] Methods: Human skin fibroblasts were seeded onto samples and cultured for 72 h; the cytoskeleton (phalloidin) and DAPI were fluorescently labeled, and the results are shown in Table 3 below:

[0114]

[0115] The data in the table above show that oriented fibers significantly improve cell orientation (p < 0.001 for non-oriented controls in Examples 1 / 2 / 4); cell compatibility was good in all groups (>85%), indicating that the materials / process conditions maintained acceptable biocompatibility after sterilization.

[0116] 4. Small animal (rodent) puncture site healing model—Histological and mechanical parameters (n = 6 / group). A puncture channel was simulated in the skin / subcutaneous tissue of the rat abdominal wall. A short cylindrical dressing was inserted, and standard postoperative care was followed. Histological parameters at the endpoint assessment day 14 (representing mid-healing): collagen orientation index (0–1), scar hardness (by tissue indentation test or microindentation device, kPa), and microvessel density (vessels / mm², counted by CD31 immunostaining). Results are shown in Table 4 below.

[0117]

[0118] Note: The rating system (levels 0–3) is as follows:

[0119]

[0120] The data above indicate that, compared to the comparative group, the example group had a significantly higher collagen arrangement index (p < 0.01), lower scar hardness, and lower microvascular density that was close to the mature repair range (indicating vascular maturation and inhibition of excessive pathological angiogenesis). Comparative Example 2 (using an adhesive) showed higher hardness and higher microvascular density, suggesting that adhesive bonding may be detrimental to tissue maturation.

[0121] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A special absorbent dressing for laparoscopic surgery, characterized in that, The dressing has a layered composite structure, comprising, from the inside out: A hydrophilic guiding layer that comes into direct contact with the wound surface; An absorbent foam layer laminated to the outside of the hydrophilic guiding layer; And a hydrophobic protective layer laminated on the outside of the absorbent foam layer; The hydrophilic guiding layer is a fiber membrane composed of micron or nanofibers oriented in a specific direction, and the orientation of the fibers is formed by a dynamic collection process.

2. The absorbent dressing specifically for laparoscopic surgery according to claim 1, characterized in that, The hydrophilic guiding layer is an electrospun fiber membrane, and the fiber material is one or a blend of several of the following: polycaprolactone (PCL), polylactic acid (PLLA), polyvinyl alcohol (PVA), and silk fibroin.

3. The absorbent dressing specifically for laparoscopic surgery according to claim 2, characterized in that, The average diameter of the fibers in the hydrophilic guiding layer is 200–800 nm, and the fiber orientation degree is 70%–99%.

4. The absorbent dressing specifically for laparoscopic surgery according to claim 1, characterized in that, The absorbent foam layer is an open-cell foam material, which includes at least one of polyurethane foam, silicone gel foam or cross-linked polysaccharide-based foam, and the pore size distribution of the foam layer is 50–500 micrometers, with an overall open-cell rate of 80%–99%.

5. The absorbent dressing specifically for laparoscopic surgery according to claim 4, characterized in that, The liquid absorption capacity (dry weight ratio) of the absorbent foam layer is 5-15 g / g.

6. The absorbent dressing specifically for laparoscopic surgery according to claim 5, characterized in that, The absorbent foam layer contains at least one functional component, which includes at least one of silver ions or their nanocomposites, chitosan, antimicrobial peptides, ZnO nanoparticles, or controlled-release microcarriers loaded with nonsteroidal anti-inflammatory drugs.

7. The absorbent dressing specifically for laparoscopic surgery according to claim 1, characterized in that, The hydrophobic protective layer is a breathable hydrophobic film or a microporous hydrophobic composite film, and the liquid penetration pressure of the hydrophobic protective layer is 5-15 kPa.

8. The absorbent dressing specifically for laparoscopic surgery according to claim 7, characterized in that, The dressing is in one of the following shapes: flat sheet, annular with a central observation hole, or short plug.

9. A method for preparing a special absorbent dressing for laparoscopic surgery as described in any one of claims 1-8, characterized in that, Includes the following steps: Preparation of S1 hydrophilic guiding layer: Prepare electrospun fiber solution, use dynamic collection device to perform electrospinning to form a fiber membrane with fibers oriented along the collection direction, and obtain hydrophilic guiding layer after drying; Preparation of S2 absorbent foam layer: A foam precursor is prepared, and a foam preform with an open-cell structure is formed by physical foaming or freeze-drying processes. A stable absorbent foam layer is obtained through post-processing. S3 functional component introduction: In or after step (S1) or step (S2), functional components are introduced into the hydrophilic guiding layer or absorbent foam layer by blending, impregnation or in-situ introduction, and then fixed by drying or crosslinking. S4 Low-Temperature Hot Press Composite Molding: The hydrophilic guiding layer obtained in step S1, the absorbent foam layer obtained in step S2, and the hydrophobic protective layer are accurately aligned and stacked in the inner-middle-outer order, and then composited in one step using a low-temperature hot pressing process to obtain a three-layer composite dressing blank. S5 Forming and Slitting: The composite dressing blank is cooled and shaped, and then die-cut into a predetermined shape. S6 Drying, sterilization and packaging: After the molded dressing undergoes necessary drying treatment, it is sterilized using gamma rays and then packaged and sealed in a sterile environment.

10. A method for preparing a special absorbent dressing for laparoscopic surgery according to claim 9, characterized in that, In step S1, the electrospinning parameters are: voltage 10–25 kV, solution flow rate 0.2–2.0 mL / h, distance from needle tip to collector 10–20 cm, and the dynamic collection device is a rotating cylinder or drum with a rotation speed of 1000–5000 rpm. In step S2, the pre-freezing temperature of the freeze-drying process is -80 to -40 °C, and after vacuum drying, the temperature is gradually increased to room temperature; The content of the functional components in step S3 is: silver ions (0.01–0.5 wt%), chitosan (0.5–3.0 wt%), and ZnO nanoparticles (0.01–1.0 wt%). In step S4, the hot pressing temperature is controlled at 60–120 °C, the hot pressing pressure is 0.1–2 MPa, and the hot pressing time is 10–300 s, so that the hydrophilic guiding layer and the absorbent foam layer form a stable physical lamination bond at the interface. In step S6, the gamma ray dose is 25–35 kGy.

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