Tissue-adhesive silk micro / nanofiber microporous breathable composite membrane and its preparation method

Abstract

This invention provides a tissue-adhesive silk micro / nanofiber microporous breathable composite membrane and its preparation method. The preparation process includes sequentially adding alginate, hyaluronic acid or its salts, and glycerol to a silk micro / nanofiber suspension to form a composite slurry. The composite slurry is then used to prepare a silk micro / nanofiber composite pre-membrane. Finally, the silk micro / nanofiber composite pre-membrane is immersed in a calcium ion solution for cross-linking and then rinsed in deionized water. This invention utilizes calcium ions as a medium for cross-linking between silk micro / nanofibers and alginate, enabling chemical cross-linking between sodium alginate and alginate, alginate and silk micro / nanofibers, and silk micro / nanofibers and silk micro / nanofibers, thus giving the composite membrane water resistance. Hyaluronic acid or its salts are used as a pore-forming agent, forming nanoscale micropores through partial dissolution in water, thereby improving the breathability of the composite membrane. This composite membrane can be used in medical materials and other fields.

Description

Technical Field

[0001] This invention relates to the field of nanofiber membrane preparation technology, and in particular to a tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane and its preparation method. Background Technology

[0002] Silk is a natural protein fiber containing silk fibrils ranging from tens of nanometers to several micrometers in size. Natural silk micro / nanofibers retain the excellent rigidity, biocompatibility, and biodegradability of silk, and have been studied for membrane formation, aerogels, and various composite materials in biomedical applications. However, while natural silk micro / nanofiber membranes possess certain mechanical properties in a dry state, their mechanical properties in a wet state are extremely poor, limiting their applications. Therefore, it is crucial to achieve cross-linking of silk micro / nanofibers to improve their wet mechanical properties. Furthermore, due to their high surface energy, silk micro / nanofibers are prone to aggregation during membrane formation, resulting in a dense membrane surface with poor vapor permeability, further restricting their biological applications.

[0003] To address the aforementioned issues, patent CN118257137A discloses a method for preparing a silk micro / nanofiber / nonwoven fabric composite and its applications. This patent involves configuring silk nanofibers and polysaccharide polymers into a composite slurry, which is then coated onto a nonwoven fabric using a coating process to obtain the silk micro / nanofiber / nonwoven fabric composite, applicable to filter materials and medical dressings. However, this silk micro / nanofiber / nonwoven fabric composite is not an independent silk micro / nanofiber membrane, and the addition of nonwoven fabric reduces the adhesiveness of the composite membrane. Furthermore, the micro / nanofiber layer of this composite exhibits poor vapor permeability.

[0004] In the prior art, a method for preparing a water-resistant composite scaffold of silk fibroin, hyaluronic acid, and sodium alginate is disclosed. Specifically, a solution of silk fibroin, hyaluronic acid, and sodium alginate is mixed, and then EDC / NHS is added to conduct a cross-linking reaction to obtain a gel. The mixed gel is then freeze-dried to obtain the composite scaffold. However, this cross-linking method has high cross-linking reagent costs and a slow cross-linking rate, and the freeze-drying process used is difficult to mass-produce. In addition, some literature reports a method for preparing porous sodium alginate / cellulose nanofiber composite hydrogel microspheres for wastewater purification. Specifically, cellulose nanofibers, sodium alginate, and pore-forming agent polyethylene glycol are prepared into a composite suspension, which is then added dropwise to a calcium ion solution to cross-link into hydrogel microspheres. Finally, porous hydrogel microspheres are prepared by washing. However, since this sodium alginate / cellulose nanofiber composite hydrogel microsphere is used for water purification, it is evident that the pore-forming agent polyethylene glycol is almost completely dissolved, and it will not impart further functionality to the hydrogel microspheres.

[0005] In view of this, it is necessary to design an improved silk micro / nanofiber composite membrane, especially a tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane. Summary of the Invention

[0006] This invention provides a tissue-adhesive silk micro / nanofiber microporous breathable composite membrane and its preparation method. The invention utilizes calcium ions as a medium for cross-linking silk micro / nanofibers and alginate, enabling chemical cross-linking between sodium alginate-alginate, alginate-silk micro / nanofiber, and silk micro / nanofiber-silk micro / nanofiber, thus giving the composite membrane water resistance. The raw materials used in this invention have good biocompatibility and biodegradability, and can be used in fields such as medical materials.

[0007] To achieve the above-mentioned objective, this invention provides a method for preparing a tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane, comprising the following steps:

[0008] S1, Alginate, hyaluronic acid or its salt, and glycerol are added sequentially to the silk micro-nano fiber suspension and mixed evenly to obtain a composite slurry;

[0009] S2, the composite slurry obtained in step S1 is prepared into a silk micro-nano fiber composite preform;

[0010] S3. The silk micro / nanofiber composite preform obtained in step S2 is immersed in a calcium salt solution with a mass fraction concentration of 0.5%wt-1.5%wt for 5-30 minutes to carry out a cross-linking reaction. Then it is washed with deionized water and dried to obtain a tissue-adhesive silk micro / nanofiber microporous vapor permeable composite membrane.

[0011] The composite membrane achieves water resistance by forming chemical cross-links between sodium alginate-sodium alginate, sodium alginate-silk micro / nanofiber, and silk micro / nanofiber-silk micro / nanofiber through a cross-linking reaction. Simultaneously, sodium hyaluronate and glycerol are released from the composite membrane during this process, resulting in a nanoscale porous structure that improves vapor permeability.

[0012] As a further improvement of the present invention, in step S1, the amount of alginate is 5%-15% of the mass of silk micro / nanofibers, the amount of hyaluronic acid or its salt is 20%-80% of the mass of silk micro / nanofibers, and the amount of glycerol is 25%-35% of the mass of silk micro / nanofibers. Adding glycerol avoids problems such as wrinkles and cracks in the silk micro / nanofiber composite preform.

[0013] As a further improvement of the present invention, in step S2, the silk micro-nano fiber composite preform is prepared by methods such as coating method and casting method, preferably by coating method.

[0014] As a further improvement of the present invention, in step S3, rinsing with deionized water refers to immersing the calcium ion-crosslinked silk micro / nanofiber composite pre-formed membrane in deionized water for 1-200 hours. This process removes residual calcium ions and glycerol from the surface, while simultaneously causing the continuous dissolution of residual hyaluronic acid or its salts in the silk micro / nanofiber composite membrane, which is beneficial for the further formation of a porous structure.

[0015] As a further improvement of the present invention, hyaluronic acid salts refer to one or a combination of different kinds of sodium hyaluronate, potassium hyaluronate, etc.

[0016] As a further improvement of the present invention, the silk micro-nano fibers are natural silk extracts with a diameter of 30-2000 nm.

[0017] This invention also provides a tissue-adhesive silk micro / nanofiber microporous breathable composite membrane, which is prepared by the preparation method described in any of the foregoing technical solutions. The tissue-adhesive silk micro / nanofiber microporous breathable composite membrane has chemical cross-links between sodium alginate-sodium alginate, sodium alginate-silk micro / nanofiber, and silk micro / nanofiber-silk micro / nanofiber, and has a nanoscale porous structure with a pore size ranging from 1 to 800 nm.

[0018] As a further improvement of the present invention, the tissue-adhesive silk micro / nanofiber microporous breathable composite membrane contains hyaluronic acid or its salts that were not completely dissolved during the preparation process. The hyaluronic acid or its salts that were not completely dissolved in the composite membrane are non-toxic; on the contrary, they can improve the water absorption, water retention, and bioactivity of the composite membrane. This composite membrane can adhere tightly to mammalian tissues, including skin, liver, and heart.

[0019] As a further improvement of the present invention, the thickness of the tissue-adhesive silk micro / nanofiber microporous breathable composite membrane is 2μm-15μm.

[0020] As a further improvement of the present invention, the tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane exhibits a vapor permeability greater than 500 g / (m²) under conditions of 37°C and 50% relative humidity. 2 •24h).

[0021] The beneficial effects of this invention are:

[0022] (1) The present invention utilizes calcium ions as a medium for crosslinking silk micro-nanofibers and alginate, so that chemical crosslinking occurs between sodium alginate-alginate, alginate-silk micro-nanofibers, and silk micro-nanofibers-silk micro-nanofibers, thereby enabling the silk micro-nanofiber composite membrane to obtain water resistance.

[0023] (2) This invention utilizes hyaluronic acid or its salt as a pore-forming agent, which forms nanoscale micropores through the dissolution of the pore-forming agent in water, thereby improving the vapor permeability of the composite membrane. At the same time, the hyaluronic acid or its salt that is not completely dissolved in the composite membrane is not toxic and can improve the water absorption, water retention, and bioactivity of the composite membrane.

[0024] (3) This invention utilizes the rigidity of silk micro-nanofibers, the roughness of the surface of silk micro-nanofiber membranes, and the weak shrinkage effect of silk micro-nanofiber membranes during the drying process to prepare a polymer membrane with high tissue adhesion.

[0025] (4) The raw materials used in this invention have good biocompatibility and are biodegradable, and the preparation method provided by this invention is suitable for large-scale production. The tissue-adhesive silk micro / nanofiber microporous breathable composite membrane prepared by this invention can be used in the field of medical materials. Attached Figure Description

[0026] Figure 1 The images show the pre-fabricated silk micro / nanofiber composite membrane prepared in Example 1 and the cross-linked and washed tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane in water.

[0027] Figure 2 The image shows the water resistance test results of the tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane prepared in Example 1.

[0028] Figure 3 The images shown are SEM images of the tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane prepared in Example 1; where the scale bar of image a is 2 μm and image b is a magnified view of image a with a scale bar of 500 nm.

[0029] Figure 4 The image shows a cross-sectional SEM image of the tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane prepared in Example 1, with a scale bar of 5 μm.

[0030] Figure 5 The image shows the tissue-adhesive silk micro / nanofiber microporous breathable composite membrane prepared in Example 1 being adhered to human skin.

[0031] Figure 6 The images shown are SEM images of the surface of the silk micro / nanofiber composite membrane prepared in Comparative Example 1; where the scale bar of image a is 2 μm and image b is a magnified view of image a with a scale bar of 500 nm.

[0032] Figure 7 This is a physical image of the silk micro / nanofiber composite preform prepared for Comparative Example 2.

[0033] Figure 8Skin adhesion test of sodium alginate membrane prepared for Comparative Example 3.

[0034] Figure 9 Water resistance test of the composite membrane prepared in Comparative Example 7. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0037] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0038] Alginate, as a natural polysaccharide polymer, possesses good biocompatibility and biodegradability, as well as good film-forming properties. However, during the drying process, the molecular chains of pure alginate membranes rapidly migrate and entangle, exhibiting a shrinkage phenomenon that reverses the adhesion to the tissue, resulting in poor tissue adhesion. Alginate can be added to silk micro / nanofibers to prepare composite membranes, promoting the formation and functionalization of these membranes. However, the introduction of alginate and other polymeric molecules can clog the pores between fibers, leading to a denser silk micro / nanofiber membrane and a significant decrease in air permeability.

[0039] To address this issue, this invention utilizes hyaluronic acid or its salts as pore-forming agents. The dissolution of these agents in water creates nanoscale micropores, thereby improving the vapor permeability of the composite membrane. Simultaneously, the hyaluronic acid or its salts that are not completely dissolved in the composite membrane are not toxic but possess bioactive functions. This invention also utilizes the rigidity of silk micro / nanofibers, the roughness of the silk micro / nanofiber membrane surface, and the weak shrinkage that occurs during the drying process, leading to tissue adhesion, to prepare a polymer membrane with high tissue adhesion.

[0040] This invention provides a method for preparing a tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane, comprising the following steps:

[0041] S1. Preparation of silk micro / nanofiber composite slurry:

[0042] After degumming, the silk fibers were placed in a swelling solution (a mixture of calcium nitrate, ethanol, and water, with a volume ratio of ethanol to water of 1:2–6 and a mass ratio of calcium nitrate to the total volume of ethanol and water of 1–10 g:100 mL) and placed in an oven at 50–80 °C for 60–80 h to swell the silk fibers and weaken the binding force between the nanofibers in the silk. After removal, the silk fibers were washed three times with deionized water and placed in a crusher at a speed of 10,000–50,000 r / min with a bath ratio of 1 g:100–200 mL (i.e., 1 g silk: 100–200 mL water) for 80–100 min to mechanically crush the silk fibers. The mixture was then filtered three times and freeze-dried to obtain silk micro / nanofibers.

[0043] An appropriate amount of silk micro / nanofibers and deionized water were added to a homogenizer to prepare a nanofiber suspension with a mass fraction concentration of 1.5 wt%.

[0044] Add an appropriate amount of alginate and deionized water to a beaker and stir until homogeneous to prepare an alginate solution with a mass fraction concentration of 1.5 wt%.

[0045] Add an appropriate amount of hyaluronic acid or its salt and deionized water to a beaker and stir until homogeneous to prepare a 1.5 wt% hyaluronic acid or its salt solution. The hyaluronic acid salt can be one or more combinations of sodium hyaluronate, potassium hyaluronate, etc.

[0046] Then, appropriate amounts of 1.5 wt% nanofiber suspension, 1.5 wt% alginate solution, 1.5 wt% hyaluronic acid or its salt solution, and glycerol are added to a beaker and stirred evenly to obtain silk micro / nanofiber composite slurry.

[0047] The amount of sodium alginate used is 5%-15% of the mass of silk micro-nanofibers, the amount of sodium hyaluronate used is 20%-80% of the mass of silk micro-nanofibers, and the amount of glycerol used is 25%-35% of the mass of silk micro-nanofibers.

[0048] Silk micro / nanofibers are natural silk extracts with a diameter of 30–2000 nm. Silk can be domesticated silkworm silk or wild silkworm silk.

[0049] S2. Prepare a silk micro / nano fiber composite preform from the composite slurry obtained in step S1.

[0050] Silk micro / nanofiber composite preforms are prepared by methods such as coating and casting, with coating being the preferred method.

[0051] For example, the composite slurry obtained in step S1 is applied to the board using a scraper, dried, and peeled off to obtain a silk micro-nano fiber composite preform.

[0052] S3. Calcium ion crosslinking and immersion:

[0053] The silk micro / nanofiber composite preform obtained in step S2 is immersed in a calcium salt solution with a mass fraction concentration of 0.5wt%-1.5wt% for crosslinking for 5-30 minutes. The calcium salt is a soluble calcium salt, such as calcium chloride, calcium nitrate, or one or different combinations thereof.

[0054] During this process, chemical cross-linking occurs within the silk micro / nanofiber composite membrane, forming between sodium alginate-sodium alginate, sodium alginate-silk micro / nanofiber, and silk micro / nanofiber-silk micro / nanofiber, thus giving the composite membrane water resistance. Simultaneously, hyaluronic acid or its salts and glycerol are released from the composite membrane, resulting in a nanoscale porous structure that improves its vapor permeability.

[0055] Then, the membrane is soaked in deionized water for 1-200 hours to obtain a tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane. During this process, residual calcium ions and glycerol on the surface of the silk micro / nanofiber composite membrane are removed, while residual sodium hyaluronate inside is continuously dissolved, which is conducive to the further formation of the membrane's porous structure.

[0056] A tissue-adhesive silk micro / nanofiber microporous breathable composite membrane was prepared using the above method. The thickness of the composite membrane ranged from 2 μm to 15 μm. The tissue-adhesive silk micro / nanofiber microporous breathable composite membrane has a nanoscale porous structure with a pore size ranging from 1 to 800 nm.

[0057] This tissue-adhesive silk micro / nanofiber microporous breathable composite membrane contains hyaluronic acid or its salts that were not completely dissolved during the preparation process. The hyaluronic acid or its salts that were not completely dissolved in the composite membrane are not toxic but rather possess bioactive functions. This composite membrane can adhere tightly to mammalian tissues, including skin, liver, and heart.

[0058] The tissue-adhered silk micro / nanofiber microporous vapor-permeable composite membrane exhibits a vapor permeability greater than 500 g / (m³) under conditions of 37°C and 50% relative humidity. 2 •24h).

[0059] The present invention will now be described in detail with reference to specific embodiments.

[0060] Example 1

[0061] A method for preparing a tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane includes the following steps:

[0062] S1. Preparation of silk micro / nanofiber composite slurry:

[0063] 5g of degummed silk was placed in a swelling solution (a mixture of calcium nitrate, ethanol, and water, with a volume ratio of ethanol to water of 1:3 and a calcium nitrate content of 5g:100mL) and placed in an oven at 60℃ for 72h. After removal, it was washed three times with deionized water and placed in a crusher with a blade speed of 36000r / min at a bath ratio of 1g:1200mL for 90min of mechanical treatment. After filtering three times with a filter screen, the silk micro-nano fibers were obtained by freeze drying.

[0064] Next, 1.5g of dry silk micro / nanofibers were dissolved in 98.5g of deionized water and mixed in a homogenizer at 800rpm for 5min to obtain a silk micro / nanofiber suspension with a mass fraction concentration of 1.5wt%. Then, 10g of sodium alginate solution with a mass fraction concentration of 1.5wt%, 40g of sodium hyaluronate solution with a mass fraction concentration of 1.5wt%, and 0.45g of glycerol were added to the silk micro / nanofiber suspension in sequence, and the mixture was slowly stirred at 200rpm for 24h to obtain a silk micro / nanofiber composite slurry.

[0065] At this point, in the silk micro-nano fiber composite slurry, the content of sodium alginate is 10% of the mass of silk micro-nano fibers, the content of sodium hyaluronate is 40% of the mass of silk micro-nano fibers, and the content of glycerol is 30% of the mass of silk micro-nano fibers.

[0066] The diameter of silk micro-nano fibers is mainly 500 nm.

[0067] S2. Coating:

[0068] A 1000 μm thick coating was applied to an aluminum plate at a coating speed of 0.02 m / s. The plate was then dried and peeled off in a 60°C oven to obtain a silk micro / nanofiber composite preform.

[0069] S3. Calcium ion crosslinking and immersion:

[0070] The silk micro / nanofiber composite pre-formed membrane obtained in step S2 was immersed in a 1 wt% calcium chloride solution for crosslinking for 15 min. Then, the silk micro / nanofiber composite membrane was removed and immersed in deionized water for 72 h. During this process, the water was changed every 8 h, thus obtaining a tissue-adhesive silk micro / nanofiber microporous permeable composite membrane, such as… Figure 1 As shown.

[0071] Figure 2 The results of the water resistance test for the tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane prepared in Example 1 are shown. It can be seen that the composite membrane remains stable in water after immersion for 24 hours, indicating that it has a certain degree of water resistance.

[0072] Figure 3This is a SEM image of the surface of the tissue-adhesive silk micro / nanofiber microporous breathable composite membrane prepared in Example 1. It can be seen that the surface of this tissue-adhesive silk micro / nanofiber microporous breathable composite membrane has numerous nanoscale micropores with a pore size ranging from 1 to 600 nm, and the surface is relatively rough.

[0073] Figure 4 This is a SEM image of the cross-section of the tissue-adhesive silk micro / nanofiber microporous breathable composite membrane prepared in Example 1. It can be seen that the thickness of this tissue-adhesive silk micro / nanofiber microporous breathable composite membrane is approximately 7 μm.

[0074] Figure 5 An illustration showing how the composite film prepared in Example 1 can be adhered to human skin.

[0075] The demonstration process is as follows: the composite film prepared in Example 1 in a wet state is applied to the skin of a human arm for 30 minutes, and then the composite film is peeled off.

[0076] As can be seen, the tissue-adhesive silk micro-nanofiber microporous breathable composite membrane can be laid flat on human skin under humid conditions. After drying, it will adhere tightly to human skin and will not easily fall off. It can be removed after 30 minutes without causing allergic reactions on human skin.

[0077] The air permeability of the tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane prepared in Example 1 was tested.

[0078] S1. Take out a test tube with a diameter of 1cm, and then add deionized water until it is 3cm away from the mouth of the test tube.

[0079] S2. Then, cover the surface of the test tube opening with the tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane, seal it with sealing tape, and then weigh it.

[0080] S3. Place the test tube of S2 in an environment of 37℃ and relative humidity of 50%±10% for 24 hours, then remove it and weigh it.

[0081] The calculated vapor permeability is approximately 650 g / (m³). 2 •24h).

[0082] Comparative Example 1

[0083] The main difference between Comparative Example 1 and Example 1 is that sodium hyaluronate, a pore-forming agent, was not used in step S1. The rest is roughly the same as Example 1 and will not be repeated here.

[0084] Figure 6The image shows a SEM image of the surface of the silk micro / nanofiber composite membrane prepared in Comparative Example 1. It can be seen that the surface of the silk micro / nanofiber composite membrane prepared without the addition of sodium hyaluronate is relatively dense, with fewer and smaller nanopores.

[0085] The air permeability of the silk micro / nanofiber composite membrane prepared in Comparative Example 1 was tested, and the calculated vapor permeability was approximately 410 g / (m²). 2 (24h), which is much lower than the vapor permeability of Example 1.

[0086] It is evident that adding sodium hyaluronate as a pore-forming agent can improve the vapor permeability of the composite membrane.

[0087] In addition, water absorption tests were conducted on Example 1 and Comparative Example 1, and the results are as follows:

[0088]

[0089] The experimental results show that, in addition to acting as a pore-forming agent, the addition of sodium hyaluronate can also enhance the additional functions of the composite membrane, such as improving its water absorption performance.

[0090] Comparative Example 2

[0091] The main difference between Comparative Example 2 and Example 1 is that glycerol was not added in step S1. The rest is roughly the same as Example 1 and will not be repeated here.

[0092] Figure 7 This is a physical image of the silk micro / nanofiber composite preform prepared for Comparative Example 2.

[0093] It is evident that the silk micro / nanofiber composite preform prepared without the plasticizer glycerin exhibits wrinkles and cracks, which is detrimental to practical applications.

[0094] Comparative Example 3

[0095] The main difference between Comparative Example 3 and Example 1 is that no silk micro / nanofibers were added.

[0096] Specifically, 1.5g of sodium alginate was dissolved in 98.5g of deionized water and stirred evenly to obtain a sodium alginate solution with a mass fraction concentration of 1.5wt%. Then, 40g of sodium hyaluronate solution with a mass fraction concentration of 1.5wt% and 0.45g of glycerol were added to the sodium alginate solution, and the mixture was slowly stirred at 200rpm for 24h to obtain a sodium alginate composite slurry.

[0097] At this point, in the sodium alginate composite slurry, the content of sodium hyaluronate is 40% of the mass of sodium alginate, and the content of glycerol is 30% of the mass of sodium alginate.

[0098] S2. Pouring:

[0099] Weigh 7.5g of sodium alginate composite slurry and pour it into a petri dish with a diameter of 10cm. Dry and peel it off to obtain sodium alginate composite precast membrane.

[0100] S3. Calcium ion crosslinking and immersion:

[0101] The sodium alginate composite preform obtained in step S2 was immersed in a 1 wt% calcium chloride solution for crosslinking for 15 min. Then, the silk micro / nanofiber composite membrane was taken out and immersed in deionized water for 72 h, with the water changed every 8 h during the process, thus obtaining the sodium alginate membrane.

[0102] Figure 8 Skin adhesion test of sodium alginate membrane prepared for Comparative Example 3.

[0103] The demonstration process was as follows: the wet sodium alginate membrane prepared in Comparative Example 3 was applied to the skin of a human arm for 30 minutes, and then the sodium alginate membrane was peeled off.

[0104] Depend on Figure 8 It is known that although sodium alginate film can be laid flat on human skin under wet conditions, it will exhibit severe wrinkling of the tissue after drying, and may even cause small red spots on the human skin.

[0105] Examples 2-3 and Comparative Examples 4-7

[0106] The difference between Examples 2-3 and Comparative Examples 4-7 and Example 1 is that the amounts of alginate, sodium hyaluronate, and glycerin in step S1 were changed, as shown in the table below. The rest are roughly the same as in Example 1 and will not be repeated here.

[0107] The mass fractions of the silk fibroin solutions in Examples 5-7 are shown in the table below.

[0108]

[0109]

[0110] The tissue-adhesive silk micro / nanofiber microporous breathable composite membranes prepared in Examples 1-3 and Comparative Examples 1 and 4-6 were tested for air permeability and wet mechanical properties. The results are shown in the table below.

[0111]

[0112] Figure 9The figure shows the water resistance test results of the composite membrane prepared in Comparative Example 7. As can be seen from the figure, if the amount of sodium alginate is too low, the water resistance of the silk micro / nanofiber composite membrane will decrease. The membrane has extremely poor wet mechanical strength and cannot be tested for mechanical properties or air permeability.

[0113] It should be noted that some comparative examples have already characterized or demonstrated the obvious shortcomings, so a comprehensive test was not conducted.

[0114] Experiments show that, within a certain range, the vapor permeability of the composite membrane increases with the increase of hyaluronic acid or its salts. This is mainly because the dissolution of hyaluronic acid or its salts creates more and larger micropores in the silk micro / nanofiber composite membrane, which facilitates water vapor permeation. However, increasing the amount of hyaluronic acid or its salts will decrease the mechanical properties of the composite membrane. In particular, when the amount of hyaluronic acid or its salts accounts for more than 80% of the mass of the silk micro / nanofibers, the mechanical properties of the composite membrane will be severely degraded, which is not conducive to practical applications. This is because excessive hyaluronic acid or its salts will severely damage the structure of the silk micro / nanofiber composite membrane.

[0115] Furthermore, experimental results show that the air permeability of the composite membrane increases with the reduction of alginate content. This is because reducing alginate content allows the silk micro / nanofiber membrane to generate more nanopores. However, with further reductions in alginate content, the mechanical properties of the composite membrane also decrease. This is because reducing alginate content reduces the bonding within the composite membrane. In particular, when the alginate content is less than 5% of the mass of the silk micro / nanofibers, the composite membrane may lose its water resistance.

[0116] In summary, this invention utilizes calcium ions as a medium for crosslinking silk micro / nanofibers and alginate, enabling chemical crosslinking between sodium alginate-alginate, alginate-silk micro / nanofibers, and silk micro / nanofiber-silk micro / nanofibers, thus achieving water resistance in the composite membrane. This invention utilizes hyaluronic acid or its salts as pore-forming agents, forming nanoscale micropores through the dissolution of the pore-forming agent in water, thereby improving the vapor permeability of the composite membrane. Simultaneously, the hyaluronic acid or its salts that are not completely dissolved in the composite membrane can improve its water absorption, water retention, and bioactivity. This invention utilizes the rigidity of silk micro / nanofibers, the roughness of the silk micro / nanofiber membrane surface, and the weak shrinkage of the silk micro / nanofiber membrane during drying to prepare a polymer membrane with high tissue adhesion. The raw materials used in this invention have good biocompatibility and are biodegradable.

[0117] The preparation method provided by this invention is suitable for large-scale production. The tissue-adhesive silk micro / nanofiber microporous breathable composite membrane prepared by this invention can be used in fields such as medical materials.

[0118] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane, characterized in that, Includes the following steps: S1, Alginate, hyaluronic acid or its salt, and glycerol are added sequentially to the silk micro-nano fiber suspension and mixed evenly to obtain a composite slurry; S2, the composite slurry obtained in step S1 is prepared into a silk micro-nano fiber composite preform; S3. The silk micro / nanofiber composite preform obtained in step S2 is immersed in a calcium salt solution with a mass fraction concentration of 0.5%wt-1.5%wt for 5-30 minutes to carry out a cross-linking reaction. Then it is washed with deionized water and dried to obtain a tissue-adhesive silk micro / nanofiber microporous vapor permeable composite membrane.

2. The method for preparing the tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane according to claim 1, characterized in that, In step S1, the amount of alginate used is 5%-15% of the mass of silk micro-nanofibers, the amount of hyaluronic acid or its salt used is 20%-80% of the mass of silk micro-nanofibers, and the amount of glycerol used is 25%-35% of the mass of silk micro-nanofibers.

3. The method for preparing the tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane according to claim 1, characterized in that, In step S2, the silk micro / nanofiber composite preform is prepared by coating or casting.

4. The method for preparing the tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane according to claim 1, characterized in that, In step S3, rinsing with deionized water means immersing the pre-fabricated silk micro-nanofiber composite membrane after calcium ion crosslinking in deionized water for 1-200 hours to remove residual calcium ions and glycerol on the surface of the silk micro-nanofiber composite membrane. At the same time, residual hyaluronic acid or its salt in the silk micro-nanofiber composite membrane will be further dissolved, and the microporous structure of the composite membrane will be further formed.

5. The method for preparing the tissue-adhesive silk micro / nanofiber microporous breathable composite membrane according to claim 1, characterized in that, Hyaluronic acid salts are one or both of sodium hyaluronate and potassium hyaluronate.

6. The method for preparing the tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane according to claim 1, characterized in that, The silk micro-nano fibers are natural silk extracts with a diameter of 30–2000 nm.

7. A tissue-adhesive silk micro / nanofiber microporous breathable composite membrane, characterized in that, The tissue-adhesive silk micro / nanofiber microporous breathable composite membrane prepared according to any one of claims 1-6 has chemical cross-linking between sodium alginate-sodium alginate, sodium alginate-silk micro / nanofiber, and silk micro / nanofiber-silk micro / nanofiber, and has a nanoscale porous structure with a pore size ranging from 1 to 800 nm.

8. The tissue-adhesive silk micro / nanofiber microporous breathable composite membrane according to claim 7, characterized in that, The tissue-adhesive silk micro / nanofiber microporous breathable composite membrane contains hyaluronic acid or its salts that were not completely dissolved during the preparation process.

9. The tissue-adhesive silk micro / nanofiber microporous breathable composite membrane according to claim 7, characterized in that, The thickness of the tissue-adhesive silk micro / nanofiber microporous breathable composite membrane is 2μm-15μm.

10. The tissue-adhesive silk micro / nanofiber microporous breathable composite membrane according to claim 7, characterized in that, The tissue-adhesive silk micro / nanofiber microporous vapor-permeable composite membrane exhibits a vapor permeability greater than 500 g / (m³) under conditions of 37°C and 50% relative humidity. 2 •24h).

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