CN107823694B

CN107823694B - Moisture-retaining double-layer sponge dressing and preparation method thereof

Info

Publication number: CN107823694B
Application number: CN201711096288.7A
Authority: CN
Inventors: 朱勇; 钟红荣; 徐水; 吴婷芳; 张小宁
Original assignee: Southwest University
Current assignee: Southwest University
Priority date: 2017-11-08
Filing date: 2017-11-08
Publication date: 2020-11-27
Anticipated expiration: 2037-11-08
Also published as: CN107823694A

Abstract

The invention provides a composition, which consists of Silk Fibroin (SF), glucose (Glu) and glycerol, and is preferably used for preparing wound dressings. The prepared moisture-retaining sponge dressing can support cell growth and maintain the micro-moisture environment required by wound healing under the condition of not using a cross-linking agent, so that the defects of low water absorption rate and low moisture-retaining rate of the film type dressing are overcome.

Description

Moisture-retaining double-layer sponge dressing and preparation method thereof

Technical Field

The invention relates to the technical field of biological tissue engineering and biological materials, in particular to a preparation method of a moisture-retention double-layer sponge dressing.

Background

The skin is the largest organ of the human body and is also the first barrier against external stimuli. Skin damage caused by wounds, abrasions, skin ulcerations and burns can easily result in bacterial infections, loss of body fluids and various complications. Seriously threatens the life and health of human beings. Wound dressings are commonly used to protect them from wound infection and dehydration and to provide a moist healing environment for wound repair.

The wound healing process is a complex process, with different requirements for dressings for different wounds and different stages of the same wound. Neither single material meets the complex requirements of the wound healing process. The existing wound dressing material is used for wound dressing, a single material cannot meet the complex requirement of a wound healing process, and the macromolecular composite material needs to be mixed with a cross-linking agent, for example, glutaraldehyde is added in a preparation method of a drug sustained-release membrane, so that the glutaraldehyde is a volatile toxic substance, and a certain damage is caused to a human body in the preparation process and after the glutaraldehyde is prepared. Secondly, the dressing is of a thin film type, and compared with a sponge type dressing, the dressing lacks an interconnected porous structure, so that on one hand, the water absorption rate and the air permeability are not ideal, and on the other hand, the attachment and proliferation of cells are influenced.

Disclosure of Invention

The invention aims to provide a moisturizing sponge dressing and a preparation method thereof, wherein the composite sponge dressing is prepared under the condition of not using a cross-linking agent, can support cell growth and maintain a micro-moist environment required by wound healing, and overcomes the defects of low water absorption rate and low moisturizing rate of a film type dressing.

A composition comprises Silk Fibroin (SF), glucose (Glu), and glycerol. The composition is preferably used in the preparation of wound dressings.

A moisture-retaining sponge dressing has a porous structure with interconnected pores, wherein the pore diameter of the pores is 100-300 mu m; the dressing comprises the composition.

The content of silk fibroin in the dressing is 3-8%, the content of glucose is less than 20% of the weight of silk fibroin, and the content of glycerol is less than 1% of the total volume. Preferably, the composite material has good water absorption and water retention when the content of glycerol is 0.5% and the content of glucose is 5-10%.

The dressing adopts freeze drying to form a film. Compared with the thin film type dressing, the dressing is loose and porous, is mutually communicated and has an even hole structure, is favorable for absorbing wound exudate, and is also favorable for improving the water vapor transmission rate and the growth and proliferation of cells. Specifically, the freezing film forming is to pre-freeze at-20 ℃ for 6-8h, place at-80 ℃ for 10-24h, and freeze-dry for 48-54h to form a film.

The present invention results in a flexible, strong, stable porous material. If the formula and the process are not adopted, the problems that the dressing is brittle after being formed, or the material is too soft and compact, and the pore structure is not easy to form easily occur. And phase separation can occur without the use of a crosslinking agent (e.g., glutaraldehyde).

The preparation method of the moisture-retaining sponge dressing comprises the following steps:

(1) preparing a regenerated fibroin solution: shearing high-quality silkworm cocoon into spiral cocoon strips with width of about 2mm, and adding Na with concentration of 0.5% according to bath ratio of 1:50₂CO₃Boiling the solution for 30min, and repeating degumming for 3 times. Detecting with picric acid carmine to obtain completely degummed silk fibroin fiber, and naturally drying and air drying.Adding completely degummed fibroin into ternary solvent (CaCl) at bath ratio of 1:10₂∶CH₃CH₂OH∶H₂O1: 2: 8), and completely dissolving in a water bath at 75 + -2 deg.C to obtain regenerated fibroin solution. The solution is dialyzed for 3d by changing distilled water at regular time (time/3 h); centrifuging the dialysate at 4 deg.C and 8000rpm for 10min, filtering, and preparing to obtain regenerated silk fibroin with certain concentration, and storing at 4 deg.C for use (time should not exceed 7d, otherwise easily precipitating silk fibroin, and changing solution concentration);

(2) preparation of fibroin/glucose/glycerol sponge dressing:

adding Glu powder (25 ℃, stirring at 300rpm for 10min, keeping constant temperature and low rotation speed to ensure uniformity of the silk fibroin solution, and ensuring stirring to form uniform sol at time span) into the silk fibroin solution with the concentration of 4%, stirring at 25 ℃ and 300rpm for 40min, defoaming, and casting to a polyacrylamide culture dish. Pre-freezing at-20 deg.C for 6 hr, standing overnight at-80 deg.C, and freeze drying for 48 hr to obtain film. Treating with 80% methanol for 30min, washing with distilled water for 3 times, and drying at room temperature.

Advantageous effects

1. The porous sponge dressing with a special structure is prepared by the invention, the pore size is uniform, and the pore distribution is uniform.

2. The hygroscopic sponge dressing obtained by the invention does not use a cross-linking agent, and has uniform texture, softness, looseness and porosity.

3. The hygroscopic sponge dressing prepared by the invention has excellent moisture absorption and retention performance, dissolution and loss performance, air permeability, mechanical property, antibacterial property and the like.

4. The film of the invention is softer, thin and transparent, and has the functions of water resistance, air permeability and bacterium resistance.

5. The invention has good effect of promoting wound healing, and is beneficial to growth, migration and the like of cells.

SF is a water-insoluble natural fibrin composed of nonpolar amino acids (e.g., glycine, alanine) that limits the ability to absorb wound exudate to some extent. The invention provides a novel wound dressing, which improves the problem and can absorb the redundant exudate of the wound so as to maintain the moist environment of the wound.

7. The sponge dressing obtained by the invention can also be used as a bottom layer, a film with waterproof, breathable and antibacterial functions is prepared by taking polyurethane as a raw material and is used as a surface layer, the sponge layer and the film layer are bonded by hot melt adhesive to obtain a double-layer dressing, the dressing is better isolated from the external environment, and the obtained material is soft, thin and transparent and has the functions of waterproofing, breathable and antibacterial.

8. The hygroscopic sponge dressing is a natural polymer biomaterial with wide source and low cost, has the advantages of easily-molded shape, ventilation, moisture retention, safety and no toxicity, and is suitable for being used as a dressing for skin wounds.

Drawings

FIG. 1 sponge dressing forming diagram

FIG. 2 is a diagram showing the results of an experiment for the water absorption of sponge

FIG. 3 is a graph showing the results of the sponge dissolution rate test

FIG. 4 is a diagram showing the results of the sponge water retention test

FIG. 5 is a graph showing the results of an experiment for the water vapor permeability of sponge

FIG. 6 is a chart showing the results of the sponge mechanics experiment

FIG. 7 is a graph showing the results of the antibacterial property of the sponge

FIG. 8 shows the results of scanning electron microscopy of sponges (SF (A), SF-Glu 0% -Gly0.5% (B), SF-Glu 5% -Gly0.5% (C), SF-Glu 10% -Gly0.5% (D), SF-Glu 15% -Gly0.5% (E), SF-Glu 20% -Gly0.5% (F))

FIG. 9 Water absorption results for example 7;

FIG. 10 Water Retention results for example 7;

FIG. 11 results for solvent loss of example 7;

FIG. 12 Water vapor Transmission Rate results for example 7;

FIG. 13 mechanical results for example 7;

FIG. 14 shows the results of inhibiting bacteria in example 7;

FIG. 15A diagram of a double-layered dressing

FIG. 16 is an experimental observation of the mouse of example 6;

figure 17 wound healing rates of example 6;

FIG. 18 wound shrinkage of example 6;

Detailed Description

The process of the present invention is described in detail below with reference to examples, which are intended to further illustrate the invention, but are not to be construed as limiting the invention.

Example 1

A preparation method of the moisture-retaining sponge dressing comprises the following steps:

(1) preparing a regenerated fibroin solution:

shearing high-quality silkworm cocoons into a spiral shape, degumming, drying in the air, dialyzing, centrifuging and filtering to obtain regenerated silk fibroin with a certain concentration, and keeping the regenerated silk fibroin at 4 ℃ for later use;

(2) preparation of fibroin/glucose/glycerol sponge dressing:

adding Glu powder (0%, 5%, 10%, 15%, 20%) in a certain mass ratio into the fibroin solution, and stirring at 25 deg.C and 300rpm for 10 min; stirring at 25 deg.C and 300rpm for 40 min; defoaming and casting to a polyacrylamide culture dish. Prefreezing at-20 deg.C for 6 hr, standing overnight at-80 deg.C, and freeze drying for 48 hr to obtain membrane (desktop freeze dryer Thermo, Modulyo-d model). Treating with 80% methanol for 30min, washing with distilled water for 3 times, and drying at room temperature.

The appearance and the shape of the sponge dressing are described as follows: uniform texture, brittle material, poor flexibility and unobvious pore structure.

And (3) performance detection:

(1) water absorption Performance test

According to the method for testing the water absorption performance of the wound dressing, which is commonly used internationally, namely the method established by British pharmacopoeia for medical dressings: cutting the material into 2cm multiplied by 2cm, balancing at 25 ℃ and 65% humidity for 24h, weighing and recording as W; preparing simulated wound exudate A solution (142mmol NaCl, 2.5mmol CaCl)₂) The material was incubated in solution A40 times its weight at 37 ℃ for 24 hours, and the wet weight of the material was measured after 30 seconds of suspension and was designated as Wt. The calculation is as follows:

water absorption/% (Wt-W)/Wx100% (1)

The results show that: the water absorption performance of the sponge dressing is remarkably improved by adding Glu, wherein when the adding amount is 15%, the water absorption capacity can reach 11.8 times of the volume of the sponge.

(2) And (3) detecting the dissolution loss performance:

taking a material with the size of 2cm multiplied by 2cm, balancing the material at 25 ℃ and 65% humidity for 24h, and weighing and recording the material as Wa; placing the material in a weighing bottle containing 100 times of the solution A, performing shaking culture at 37 ℃ for 24h, taking out the sponge, drying at 37 ℃ under 50% humidity, balancing for 24h again, and weighing as Wb. The calculation is as follows:

hot Water loss Rate/% (Wa-Wb)/Wa × 100% (2)

The results show that: the addition of low amounts (5%, 10%) of Glu effectively reduced the leaching loss of SF sponge, with a leaching rate of 0, but if Glu was further added, the leaching rate increased sharply to 9.26% at more than 15%.

Example 2

(1) preparing a regenerated fibroin solution:

(2) preparation of fibroin/glucose/glycerol sponge dressing:

adding Glu powder (0%, 5%, 10%, 15%, 20%) in a certain mass ratio into the fibroin solution, and stirring at 25 deg.C and 300rpm for 10 min; adding 0.25% glycerol (75% glycerol prepared in advance) at 25 deg.C, stirring at 300rpm for 40 min; defoaming and casting to a polyacrylamide culture dish. Pre-freezing at-20 deg.C for 6 hr, standing overnight at-80 deg.C, and freeze drying for 48 hr to obtain film. Treating with 80% methanol for 30min, washing with distilled water for 3 times, and drying at room temperature.

The appearance and the shape of the sponge dressing are described as follows: the texture is uniform, the material is soft, loose and porous.

And (3) detecting the performance (the detection method is the same as the example 1), wherein the detection result is as follows:

(1) water absorption Performance results: when the Glu content is 5%, the water absorption capacity is the highest and reaches 12.4 times of the volume of the sponge; the water absorption capacity of the water-absorbing agent is reduced by continuously adding Glu, and when the content of Glu is 20%, the water absorption capacity is 10 times of the volume of the water-absorbing agent.

(2) Loss on dissolution performance results: when the addition amount of Glu is 0-10%, the dissolution rate is basically zero; however, when Glu exceeds 10%, the dissolution rate slightly increases to 3.9%.

Example 3

(1) preparing a regenerated fibroin solution:

(2) preparation of fibroin/glucose/glycerol sponge dressing:

adding Glu powder (0%, 5%, 10%, 15%, 20%) in a certain mass ratio into the fibroin solution, and stirring at 25 deg.C and 300rpm for 10 min; adding 0.5 vol% glycerol (75 vol% glycerol prepared in advance), and stirring at 25 deg.C and 300rpm for 40 min; defoaming and casting to a polyacrylamide culture dish. Pre-freezing at-20 deg.C for 6 hr, standing overnight at-80 deg.C, and freeze drying for 48 hr to obtain film. Treating with 80% methanol for 30min, washing with distilled water for 3 times, and drying at room temperature.

The appearance and the shape of the sponge dressing are described as follows: uniform texture, good softness of the material, looseness and porosity.

(1) water absorption Performance results: the water absorption of the sponge can be increased by adding Glu less than 15%, and when the Glu content is 5%, the water absorption capacity can reach 12.5 times of the self volume. When the Glu content is 20%, the water absorption capacity is not 10 times of its volume.

(2) Loss on dissolution performance results: the rate of dissolution increased gradually with increasing Glu content, up to 7.5% when Glu content was 20%.

Example 4

(1) preparing a regenerated fibroin solution:

(2) preparation of fibroin/glucose/glycerol sponge dressing:

adding Glu powder (0%, 5%, 10%, 15%, 20%) in a certain mass ratio into the fibroin solution, and stirring at 25 deg.C and 300rpm for 10 min; adding 0.75% glycerol (75% glycerol prepared in advance) at 25 deg.C, stirring at 300rpm for 40 min; defoaming and casting to a polyacrylamide culture dish. Pre-freezing at-20 deg.C for 6 hr, standing overnight at-80 deg.C, and freeze drying for 48 hr to obtain film. Treating with 80% methanol for 30min, washing with distilled water for 3 times, and drying at room temperature.

(1) and (3) detecting the water absorption performance: the water absorption of the sponge is reduced by adding Glu, and when the Glu content is 20%, the sponge can only absorb liquid with the volume about 10 times of the self volume.

(2) And (3) detecting the dissolution loss performance: the dissolution rate increases with the increase of the content of Glu, and when the content of Glu is added to be 20%, the dissolution rate can reach 12%.

Example 5

(1) preparing a regenerated fibroin solution:

(2) preparation of fibroin/glucose/glycerol sponge dressing:

adding Glu powder (0%, 5%, 10%, 15%, 20%) in a certain mass ratio into the fibroin solution, and stirring at 25 deg.C and 300rpm for 10 min; adding 1% glycerol (75% glycerol prepared in advance) at 25 deg.C, stirring at 300rpm for 40 min; defoaming and casting to a polyacrylamide culture dish. Pre-freezing at-20 deg.C for 6 hr, standing overnight at-80 deg.C, and freeze drying for 48 hr to obtain film. Treating with 80% methanol for 30min, washing with distilled water for 3 times, and drying at room temperature.

(1) and (3) detecting the water absorption performance: glu is added to the sponge, so that the influence on the water absorption of the sponge is small, and the water absorption capacity of the Glu is not 10 times of the volume of the sponge.

(2) And (3) detecting the dissolution loss performance: the total dissolution rate increases with Glu, and the maximum value of Glu is about 12% when Glu is 20%.

Example 6

Preparation of a moisture sponge dressing (the same method and ratio design as in example 3)

And (3) performance testing:

(1) and (3) detecting the water retention performance:

2cm × 2 material was incubated at 37 deg.C for 24h, and the wet weight is recorded as W₀. Transferring the water-saturated material to a dry weighing bottle, placing the bottle in an incubator at 37 ℃ and 35% humidity for water loss test, measuring and weighing every 1h (cumulative time 24h), and recording as W₂T is calculated. The water retention at time t per unit weight is calculated as follows:

water retention ratio/% (W)₀-W₂/t)/W₀×100％ (3)

The results show that: glu with different concentrations is added, the final water retention time is not obviously different and can reach 7h, and the water retention rate is 10%. At 4h, the sponge added with Glu has a higher water retention rate of about 40%.

(2) Moisture permeability detection:

a proper columnar container is selected to be filled with 10mL of distilled water, and the cross section area of the opening of the container is smaller than that of the dressing. The dressing with area A is covered on a container, the cup mouth is sealed by a sealing film, the whole device is placed in an environment with 37 ℃ and 35% relative humidity, and the weight of the whole device is measured at regular time. The calculation is as follows:

water vapor transmission rate/percent Slope × 24/A g/m²/day (4)

In the calculation formula, Slope is the Slope of the change of the device quality along with the time extension; a is the air permeable area of the sample.

The results show that: the water vapor transmission rates of the sponges added with Glu 5% and 10% relative to the sponge without GluIncreased by about 1.6 times to 1600g/m²And/day. When the Glu content exceeds 10%, the water vapor transmission rate tends to decrease.

(3) And (3) mechanical property detection:

the material was cut to a size of 3cm × 1cm, equilibrated at 25 ℃ for 24h with 65% humidity, and its thickness was measured. The breaking strength and breaking elongation of the material were measured at a tensile rate of 10mm/min on a universal mechanical tester.

The results show that: the maximum breaking strength reaches 0.45MPa when the Glu content is 5 percent. With the addition of Glu, the breaking strength tended to decrease. And the addition of Gly0.5% obviously increases the elongation at break of the sponge, but if 5% of Glu is added, the elongation at break is greatly reduced, and the elongation at break of the sponge can be improved by continuously adding Glu.

(4) And (3) detecting the antibacterial performance:

taking the prepared sponge, performing ultraviolet sterilization, performing water bath for 24h at 37 ℃ by using a PBS solution, filtering by using a 0.22 mu m filter head to obtain a leaching solution, and placing the leaching solution in a refrigerator at 4 ℃ for later use. Co-culturing the leaching liquor with Escherichia coli (Escherichia coli) bacterial liquid and Staphylococcus aureus (Staphylococcus aureus) bacterial liquid for 12h, diluting, inoculating on LB agar plate, culturing for 12h, and recording the colony number. The bacteriostatic rate was calculated as follows:

bacteriostasis rate/% (A-B)/A × 100% (5)

In the calculation formula, A is the average colony number of the control group; b is the average colony number of the test sample.

The results show that: the antibacterial rate of escherichia coli is increased along with the increase of the concentration of the leaching liquor, and the antibacterial property of the sponge on the escherichia coli is not hindered by adding low-content Glu, but the antibacterial rate is increased; for materials without Glu, the sponge has the capacity of resisting staphylococcus aureus only when the concentration of the leaching liquor is 0.8%, and the leaching liquor with low concentration can also show certain antibacterial property when Glu is added. In general, sponges have less antimicrobial effect than E.coli against S.aureus.

(5) And (3) detection by a scanning electron microscope:

and (3) carrying out gold spraying on the sample for 2 times by adopting an SBC-12 ion sputtering instrument, wherein each time is 50s, and the sample is placed in a JEOL, JSM-6610 scanning electron microscope for scanning and shooting in a low-voltage environment, the voltage is 20kV, and the magnification is shown in the figure.

The results show that: the pure SF sponge is in a sheet curl shape, has low porosity and poor connectivity, and does not have a typical pore structure. When Gly was added, the lamellar structure disappeared and pores began to appear relative to the pure SF material. Then, Glu is gradually added, and an obvious porous structure is formed inside the material, the shape of the pores is regular, the thickness of the pore walls is uniform, and the pore size is about 100-200 μm.

Example 7

A double-layer dressing is prepared by using the sponge dressing obtained in example 3 as a bottom layer, using a polyurethane film as a surface layer, and adhering the sponge layer and the film layer by using a hot melt adhesive.

(1) Preparing a polyurethane film: polyurethane is used as solute, N-N-Dimethylformamide (DMF) is used as solvent, and polyurethane films with different concentrations (2% -20%) are prepared. The method comprises the following specific steps: adding a certain amount of polyurethane particles into a DMF solution, mixing for 3h at the temperature of 60 ℃ by a magnetic stirrer at 400rpm, defoaming, pouring into a mold (the mold is 5cm multiplied by 5cm), and drying in an oven at the temperature of 60 ℃ to form a film.

The experimental results are as follows:

1. and (3) morphology observation: when the concentration of the polyurethane is below 8%, the complete and uniform film formation can not be realized due to the low concentration of the solute; when the concentration of the polyurethane exceeds 12%, the film thickness is thick, the flexibility is poor, and the function of surface layer ventilation cannot be achieved. Therefore, the concentration of the primary screened polyurethane is 8%, 10% and 12%.

2. Water absorption results (fig. 9): when the concentration of the polyurethane is 8 percent, the liquid absorption amount only reaches 0.4 time of the volume of the polyurethane, and the waterproof effect is achieved.

3. Water retention results (fig. 10): when the concentration of the polyurethane is 8%, the water retention rate can reach 70%; the concentration of polyurethane is 12 percent, and the water retention rate is 80 percent. This is because polyurethane itself has poor water absorption and therefore can emit relatively little water.

4. Loss on dissolution results (fig. 11): when the concentration of the polyurethane is 8-12%, the dissolution rate is lower than 2%.

5. Water vapor transmission results (fig. 12): at a polyurethane concentration of 8%, the maximum water vapor transmission rate is 600g/m 2/day.

6. Mechanical results (fig. 13): when the concentration of the polyurethane is 8%, the lowest breaking strength is 9MPa, and the breaking elongation is 380%.

When the concentration of the screened polyurethane is 8 percent, the performance is optimal, and the following bacteria-resistant experimental research is carried out:

the method comprises the following steps: cutting a polyurethane film into 1 multiplied by 1em, placing the film on an LB solid culture medium, adding escherichia coli and staphylococcus aureus on the film respectively, culturing for 24h, cutting the culture medium below the film, eluting a bacterial colony by PBS, diluting and coating, and observing the growth condition of the bacterial colony.

Inhibition results (fig. 14): the polyurethane film has the function of bacterium resistance, and does not grow bacteria.

Double-layer composite experiment: the hot melt adhesive dot matrix compounding technology is adopted to compound SF-Glu 5% -Gly0.5% sponge and SF-Glu 10% -Gly0.5% polyurethane film, the sponge is arranged at the lower part, the film is arranged at the upper part, the hot melt adhesive is compounded in a double layer mode, the compounding effect is good, the pasting is tight, the double-layer dressing is used for animal experiments, and the obtained double-layer dressing is shown in figure 15.

Animal experiments:

balb/c mice (weight about 25 g) were used to prepare a full-thickness defect wound model of skin. Photographs were taken 3d, 7d and 11d after injury, respectively, and wound healing rate and wound shrinkage were calculated using IPP 6.0.

The wound healing rate is (original wound area-the area of the residual wound on the nth day after injury)/original wound area × 100%

The wound surface shrinkage rate is the area of wound surface shrinkage on the nth day after injury/original wound surface area multiplied by 100%

The results are as follows: mouse experimental observation picture (fig. 16)

Wound healing rate (fig. 17): at 3d after injury, the wound healing rate of the dressings of all groups is less than 20%, while at 7d, the wound healing is remarkably accelerated, and the average wound healing rates of sterile gauze, SF-Glu 0% -Gly0.5%, SF-Glu 5% -Gly0.5% and SF-Glu 10% -Gly0.5% dressings are 35.48%, 18.87%, 83.79% and 44.68% respectively. At 11d, the healing rate of the wound surface of the two dressings added with Glu reaches about 90%.

(2) Wound surface shrinkage (fig. 18): the wound surface shrinkage rate of each group is not greatly different at 3d after injury, but at 7d, the shrinkage rate of the SF-Glu 5% -Gly0.5% dressing is as high as 80%. Up to 11d, the wound healing rate was over 50% for all groups, also the two dressing groups with Glu added reached the highest level.

Claims

1. The moisture-retention sponge dressing has a porous structure with interconnected pores, and the pore size of the pores is 100-300 mu m; the dressing comprises a composition consisting of silk fibroin, glucose, glycerol.

2. The sponge dressing of claim 1, wherein the weight of the silk element in the dressing is 3-8%, the glucose content is less than 20% of the weight of the silk element, and the glycerol content is less than 1% of the total volume.

3. The sponge dressing of claim 1 or 2, formed into a film by freeze drying.

4. The sponge dressing as claimed in claim 3, wherein the freeze-dried film is formed by pre-freezing at-20 ℃ for 6-8h, standing at-80 ℃ for 10-24h, and freeze-drying for 48-54 h.

5. The sponge dressing of claim 1 prepared by a process comprising the steps of:

(1) preparing a regenerated fibroin solution: cutting high-quality silkworm cocoon into spiral cocoon strips with width of 2mm, and adding Na with concentration of 0.5% according to bath ratio of 1:50₂CO₃Boiling in the solution for 30min, and repeating degumming for 3 times; detecting with picric acid carmine to obtain completely degummed silk fibroin fiber, and naturally drying and air drying; adding completely degummed fibroin into CaCl at bath ratio of 1:10₂:CH₃CH₂OH:H₂Completely dissolving in ternary solvent O =1:2:8 in water bath at 75 + -2 deg.C to obtain regenerated fibroin solution; dialyzing the solution for 3d by periodically changing distilled water; centrifuging the dialysate at 4 deg.C and 8000rpm for 10min, filtering, and preparing to obtain regenerated fibroin with certain concentration, and storing at 4 deg.C;

(2) preparation of fibroin/glucose/glycerol sponge dressing: adding Glu powder and 75% Gly solution into 4% silk fibroin solution in sequence, defoaming, and casting to a polyacrylamide culture dish; pre-freezing at-20 deg.C for 6 hr, standing overnight at-80 deg.C, and freeze drying for 48 hr to form film; treating with 80% methanol for 30min, washing with distilled water for 3 times, and drying at room temperature.