A super-strong adhesive hydrogel capable of delivering growth factors, its preparation method and application

Abstract

The present invention provides a super sticky hydrogel capable of delivering growth factors, a preparation method and an application thereof, which include silk fibroin after gelation, on the surface of which nano-porous calcium carbonate loaded with growth factors is provided, and the surface of the nano-porous calcium carbonate is coated with a biocompatible polymer. The present invention forms a hydrogel drug delivery system by gelating silk fibroin and loading growth factors, improves the activity of growth factors and accelerates wound healing.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedical materials, and particularly relates to a super sticky hydrogel capable of delivering growth factors, a preparation method thereof, and an application thereof. Background Art

[0002] As is well known, the skin is the natural barrier between the human body's interior and the external environment. In daily life, the skin is easily damaged to form wounds, causing bacterial infections and resulting in serious consequences. The physiological mechanisms of hemostasis and wound healing involve four stages: hemostasis, inflammation, proliferation, and remodeling. These four stages involve the interactions between various types of cells and bioactive factors. Once a certain stage cannot proceed normally, it will lead to an overly long wound healing cycle or non-healing. Only when these four processes are continuously coordinated can the rapid repair of skin wounds be promoted. Dressings can provide a temporary protective barrier for the damaged parts of the skin, preventing wounds from being infected by other microorganisms and causing serious complications. Nowadays, various types of wound dressings such as gauze, bandages, and sponges have been widely used. However, existing dressings cannot treat large or chronic wounds well due to their slow and passive healing effects. In addition, traditional dressings such as gauze have limited antibacterial ability and weak functionality. With the proposal of the theory of moist wound healing, traditional dry dressings have gradually been replaced by new dressings with more functions because they cannot provide a moist surface environment for the wound surface.

[0003] Hydrogels have shown great advantages in the field of wound dressings due to their excellent biochemical and mechanical properties. Hydrogels can absorb and retain a large amount of water, replenish water for dead tissues, and enhance the ability of autolytic debridement due to their three-dimensional polymer network similar to the natural extracellular matrix. Secondly, the permeability of hydrogels enables gas exchange between the wound and the external environment, allowing tissues to "breathe". In addition, hydrogel dressings can also act as a physical barrier to isolate the erosion of external bacteria on the wound. However, as a wound dressing, hydrogels need to exhibit appropriate adhesive strength to achieve a strong sealing effect in a dynamic environment. More and more research groups are committed to developing new and effective adhesive hydrogels. For example, cyanoacrylate-based hydrogels exhibit strong adhesiveness. However, they have certain biotoxicity and will solidify in water in a moist environment and cannot maintain adhesion. To meet the adhesion performance in a moist environment or underwater, a large number of catechol-based hydrogels have emerged. However, this material usually needs to be synthesized by oxidative polymerization under alkaline conditions, but the uncontrollable oxidation process leads to a reduction in phenolic hydroxyl groups, thus greatly reducing the adhesive strength.

[0004] The bioadhesive properties of hydrogels provide unprecedented opportunities for wound closure. However, due to the moist environment and frequent movement, skin wound healing in a dynamic environment remains a challenge. Traditional hydrogels used as wound dressings often encounter problems such as inability to completely seal the wound, poor mechanical properties, lack of self-healing ability, and poor biocompatibility. In addition, they cannot quickly deliver drugs to the wound, which further slows down the wound healing efficiency. The challenge faced by existing hydrogel adhesives is how to maintain complete wound closure and promote rapid wound healing under moist and dynamic conditions. In addition, how to ensure that drugs can be delivered to the wound in good quality and quantity without inactivation and cause the least side effects to the human body is a difficult problem in the field of wound repair in recent years. Summary of the Invention

[0005] To solve the problems in the prior art, the present invention forms a hydrogel drug delivery system by gelating silk fibroin and loading growth factors, improves the activity of growth factors, accelerates wound healing, and provides a super sticky hydrogel capable of delivering growth factors, its preparation method and application.

[0006] The present invention solves its technical problems by adopting the following technical solutions:

[0007] The first object of the present invention is to provide a super sticky hydrogel capable of delivering growth factors, which is characterized in that it includes gelated silk fibroin, and nano-porous calcium carbonate loaded with growth factors is arranged on the surface of the silk fibroin, and the surface of the nano-porous calcium carbonate is coated with a biocompatible polymer.

[0008] By sucking the formic acid / calcium chloride solution into silk fibroin, during the ventilation and drying process, due to the volatilization of formic acid, the silk fibroin gradually gels, so Ca 2+ is used to modify silk fibroin to enhance the adhesion of the hydrogel, so that the gel material can tightly adhere to the skin surface in a dynamic environment, and can completely seal to prevent bacteria from invading. At the same time, the nano-porous calcium carbonate powder on the surface of silk fibroin also provides additional binding points between the polymer chains of silk fibroin, enabling physical entanglement and mechanical interlocking between the polymers, further improving the adhesiveness of the hydrogel. During use, as the biocompatible polymer dissolves, the nano-porous calcium carbonate collapses and the loaded growth factors are gradually released, improving the activity of the growth factors and being more conducive to wound healing.

[0009] Furthermore, a chitosan non-woven fabric is disposed inside the silk fibroin, and a "sandwich" structure is formed by the chitosan non-woven fabric and the silk fibroin on both sides. Adding the chitosan non-woven fabric in the middle of the silk fibroin endows the hydrogel with stronger mechanical properties due to the good permeability and stronger mechanical strength of the chitosan non-woven fabric, avoiding the rupture of the material during wound repair and maintaining good adhesiveness and strong mechanical properties even in a dynamic environment. The chitosan non-woven fabric is disposed inside the silk fibroin, enhancing the binding between the chitosan non-woven fabric and the silk fibroin and preventing the chitosan non-woven fabric from falling off.

[0010] Furthermore, the degummed silk fibroin is added to a formic acid / calcium chloride solution to form a silk fibroin solution, which is then dried in air to gel the silk fibroin. The gelled silk fibroin has better adhesiveness and can better bind to the skin.

[0011] Furthermore, the biocompatible polymer is an intestinal polymer. Preferably, the intestinal polymer is selected from L100-55. L100-55 is an anionic copolymer based on methacrylic acid and ethyl acrylate, which will dissolve at pH > 5.5, being more conducive to the release of growth factors in wound tissue fluid.

[0012] The second object of the present invention is to provide a method for preparing a super-strong adhesive hydrogel capable of delivering growth factors, which is characterized by comprising the following steps: adding the degummed silk fibroin to a formic acid / calcium chloride solution to form a silk fibroin solution, and drying to obtain a calcium-modified silk fibroin gel; loading the growth factor inside the nanoporous calcium carbonate, and then coating the nanoporous calcium carbonate with a biocompatible polymer to obtain aFGF-Ca; then dispersing aFGF-Ca into a formic acid / calcium chloride solution, and spraying the dispersion on the surface of the silk fibroin gel to obtain the hydrogel.

[0013] Furthermore, after the degummed silk fibroin forms a silk fibroin solution, it is placed in a mold, and a chitosan non-woven fabric is also disposed inside the silk fibroin to form a "sandwich" structure with the silk fibroin on both sides and then dried.

[0014] Furthermore, the growth factor is acidic fibroblast growth factor. Recombinant human acidic fibroblast growth factor (aFGF) has been clinically used to accelerate wound / burn repair. It is a class of bioactive proteins with strong antioxidant properties, having good biological activity and stability. However, when the temperature is too high or there are organic solvents, the growth factor may denature and lose its performance. The short half-life of the growth factor makes it difficult to be applied in various dressings with poor use effects. In the present invention, by coating the growth factor inside the biocompatible polymer, its activity is improved.

[0015] Furthermore, the degumming process of the silk fibroin is as follows: put the dried silkworm chrysalis into a Na2CO3 solution, take it out after boiling, wash it repeatedly with deionized water, and dry it in an oven to obtain the degummed silk fibroin.

[0016] Furthermore, the boiling time is 30 - 50 min.

[0017] Furthermore, when preparing the silk fibroin solution, the mass ratio of CaCl2, the degummed silk fibroin, and HCOOH is 1:4:40 - 5:8:100.

[0018] Furthermore, before spraying on the surface of the silk fibroin gel, first let all the formic acid in the silk fibroin volatilize completely. As the formic acid continuously volatilizes, Ca 2+ plays a modifying role on the silk fibroin, and the crystal structure of the silk fibroin is chelated by the metal and damaged by Ca 2+ and water absorption, causing the silk fibroin to gradually gelate.

[0019] Furthermore, the biocompatible polymer is an intestinal polymer. Preferably, the intestinal polymer is selected as L100 - 55.

[0020] Furthermore, the preparation method of the nano - porous calcium carbonate is as follows: mix calcium chloride and dopamine in absolute ethanol, then mix with NH4HCO3 and place it in a sealed container, leave it at 37 °C for 24 hours, and wash it with alcohol to obtain the nano - porous calcium carbonate.

[0021] Furthermore, the process of loading the growth factor is as follows: form an aqueous calcium carbonate solution from the nano - porous calcium carbonate, add the growth factor to a buffer solution for mixing, stir and dissolve it, then mix it with the aqueous calcium carbonate solution and stir, and centrifuge to obtain the nano - porous calcium carbonate loaded with the growth factor.

[0022] Furthermore, the mass ratio of the added growth factor to the nano - porous calcium carbonate is 1:6 - 8.

[0023] Furthermore, the buffer solution is a PBS solution or a phosphate buffer solution.

[0024] Furthermore, the process of coating is as follows: dissolve the biocompatible polymer in a small amount of alcohol solution, then add the nano - porous calcium carbonate loaded with the growth factor, stir rapidly and centrifuge, and then evaporate the alcohol to obtain the aFGF - Ca powder. The addition of a small amount of alcohol does not affect the activity of the growth factor, is more conducive to the dissolution of the biocompatible polymer, and is conducive to the progress of coating.

[0025] Furthermore, the mass ratio of the added biocompatible polymer to the nano-porous calcium carbonate loaded with growth factors is 8-12:1. Preferably, the mass ratio of the added biocompatible polymer to the nano-porous calcium carbonate loaded with growth factors is 10:1.

[0026] Furthermore, the coating process is carried out at -5 to 10 °C.

[0027] The third object of the present invention is to provide an application of a super-strong adhesive hydrogel capable of delivering growth factors as a drug delivery carrier.

[0028] Furthermore, an application of a super-strong adhesive hydrogel capable of delivering growth factors in a wound dressing.

[0029] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0030] In the present invention, silk fibroin absorbs formic acid / calcium chloride solution, and during the ventilation and drying process, due to the volatilization of formic acid, silk fibroin gradually gels. Therefore, Ca 2+ is used to modify silk fibroin to enhance the adhesion of the gel dressing, so that the gel material tightly adheres to the skin surface in a dynamic environment, can completely seal to prevent bacterial invasion, and accelerate healing. By assembling a chitosan non-woven fabric with permeability and mechanical strength in the middle of silk fibroin, the hydrogel has stronger mechanical properties, avoids the rupture of the dressing during wound repair, and can still maintain good adhesion and strong mechanical properties even in a dynamic environment, better protecting the wound.

[0031] The present invention adds growth factors, loads them with nano-porous calcium carbonate and coats them with an intestinal polymer, which improves the activity of the growth factors and avoids affecting their activity due to the very short half-life of the growth factors. In use, the intestinal polymer is utilized to dissolve when the environmental pH>5.5. Under the condition that the pH of the tissue fluid of the ruptured wound>5.5, the intestinal polymer gradually dissolves and releases nano-porous calcium carbonate, and the nano-porous calcium carbonate collapses in the tissue fluid to release growth factors. The continuous release improves the activity of the growth factors in the wound dressing and is more conducive to wound healing. In addition, the aFGF-Ca powder on the surface of silk fibroin also provides additional binding points between the polymer chains of silk fibroin, forming physical entanglement and mechanical interlocking between the polymers, further improving the adhesion of the hydrogel.

[0032] The above description is only an overview of the technical solution of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. And in order to make the above and other objects, features and advantages of the present invention more obvious and understandable, the following specifically illustrates the embodiments of the present invention. Brief Description of the Drawings

[0033] Figure 1 This is the preparation flow chart of a super sticky hydrogel capable of delivering growth factors, its preparation method and application according to the present invention.

[0034] Figure 2 This is the transmission electron microscope image of different materials in a super sticky hydrogel capable of delivering growth factors, its preparation method and application according to the present invention.

[0035] Figure 3 This is the wound healing image under different materials in a super sticky hydrogel capable of delivering growth factors, its preparation method and application according to the present invention.

[0036] Figure 4 This is the wound healing image under different materials in a super sticky hydrogel capable of delivering growth factors, its preparation method and application according to the present invention. Detailed implementation manners

[0037] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are only for illustrative and explanatory purposes of the present invention, and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0038] In addition, unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the present invention can be obtained through market purchase or prepared by existing methods.

[0039] Example 1:

[0040] See attached Figure 1 , a preparation method of a super sticky hydrogel capable of delivering growth factors, comprising the following steps:

[0041] 1) Preparation of silk fibroin hydrogel:

[0042] (1) Degumming: Cut open the dry cocoon shell, take out the silkworm pupa, weigh a certain amount of dry cocoon shell, put it into a Na2CO3 solution with a bath ratio of 1:100, a temperature of 100 °C, and a mass fraction of 0.2%, boil for 40 minutes and then take out, wash repeatedly with deionized water, dry in an oven, and check the degumming degree until the degumming is completed.

[0043] (2) Subsequently, in order to prepare a silk fibroin solution, first add CaCl2 to HCOOH, and then gradually add the degummed silk fibroin (SF) strand by strand to the FA-Ca solution under magnetic stirring (mass ratio of CaCl2:SF:HCOOH = 5:8:85). Stir the resulting mixture at a speed of 500 rpm for 2 hours.

[0044] (3) Pour the silk fibroin solution into a mold, place the chitosan non-woven fabric on the surface, and then cover the surface of the non-woven fabric with the same volume of silk fibroin solution to form a "sandwich" structure. Then transfer it to a fume hood until the formic acid completely volatilizes to obtain the MSC hydrogel.

[0045] 2) Preparation of nano-porous CaCO3:

[0046] (1) Preparation of Nano-CaCO3: Mix 200 mg of CaCl2·2H2O and 4 mg of dopamine uniformly with 100 ml of absolute ethanol. Then place this mixture together with 5 g of NH4HCO3 in a sealed container and leave it at 37 °C for 24 hours. After 24 hours, collect the obtained nanoparticles, wash them three times with alcohol, and then dry the washed CaCO3 nanoparticles for subsequent use.

[0047] (2) Coating: First, dissolve 0.1 g of growth factor (aFGF) in phosphate buffer solution to make a dispersion. Combine the washed 0.7 g of nano-porous CaCO3 made into an aqueous solution with the 10 μg / ml growth factor (aFGF) dispersion, stir horizontally for 1 hour, and then centrifuge at 10,000 rpm for 10 minutes to produce nano-CaCO3 loaded with aFGF. After that, take 0.1 g L 100-55 and mix it evenly in a small amount of alcohol solution. Also add 0.01 g of Nano-CaCO3 loaded with growth factor to the solution. Stir magnetically at 0 °C for 30 minutes. Subsequently, centrifuge at 10000 rpm for 5 minutes and wait for the alcohol to volatilize completely at room temperature to obtain the aFGF-Ca powder.

[0048] 3) Preparation of aFGF-Ca@MSC gel:

[0049] Mix the aFGF-Ca powder obtained in step 2) with the FA-Ca solution and evenly coat it on the surface of the MSC hydrogel to obtain the aFGF-Ca@MSC gel.

[0050] Example 2:

[0051] A preparation method of a super-strong adhesive hydrogel capable of delivering growth factors, comprising the following steps:

[0052] 1) Preparation of silk fibroin hydrogel:

[0053] (1) Degumming: Cut open the dry cocoon shell, take out the silkworm pupa, weigh a certain amount of dry cocoon shell, put it into a Na2CO3 solution with a bath ratio of 1:100, a temperature of 100 °C, and a mass fraction of 0.2%, boil for 40 minutes and then take it out, wash it repeatedly with deionized water, dry it in an oven, and check the degumming degree until the degumming is complete.

[0054] (2) Subsequently, to prepare the silk fibroin solution, first, CaCl2 was added to HCOOH, and then the degummed silk fibroin (SF) was added strand by strand to the FA-Ca solution under magnetic stirring (mass ratio of CaCl2:SF:HCOOH = 1:2:20). The resulting mixture was stirred at 500 rpm for 2 hours.

[0055] (3) The silk fibroin solution was poured into a mold and then transferred to a fume hood until the formic acid completely volatilized to obtain the MS hydrogel.

[0056] 2) Preparation of nanoporous CaCO3:

[0057] (1) Preparation of Nano-CaCO3: 200 mg of CaCl2·2H2O and 4 mg of dopamine were uniformly mixed with 100 ml of absolute ethanol. Then, the mixture was placed in a sealed container together with 5 g of NH4HCO3 and incubated at 37 °C for 24 hours. After 24 hours, the obtained nanoparticles were collected, washed three times with alcohol, and then the washed CaCO3 nanoparticles were dried for subsequent use.

[0058] (2) Coating: First, 0.1 g of growth factor (aFGF) was dissolved in phosphate buffer solution to prepare a dispersion. The washed 0.7 g of nanoporous CaCO3 was made into an aqueous solution and combined with the 10 μg / ml growth factor (aFGF) dispersion, stirred horizontally for 1 hour, and then centrifuged at 10,000 rpm for 10 minutes to produce aFGF-loaded nano-CaCO3. After that, 0.1 g L 100-55 was put into a small amount of alcohol solution and mixed evenly. 0.01 g of growth factor-loaded Nano-CaCO3 was also added to the solution. It was magnetically stirred at 0 °C for 30 minutes. Subsequently, it was centrifuged at 10,000 rpm for 5 minutes, and after the alcohol volatilized completely at room temperature, the aFGF-Ca powder was obtained.

[0059] 3) Preparation of aFGF-Ca@MS gel:

[0060] The aFGF-Ca powder obtained in step 2) was mixed with the FA-Ca solution and evenly coated on the surface of the MS hydrogel obtained in step 1) to obtain the aFGF-Ca@MS gel.

[0061] Example 3:

[0062] A method for preparing a super-strong adhesive hydrogel capable of delivering growth factors, comprising the following steps:

[0063] 1) Preparation of silk fibroin hydrogel:

[0064] (1) Degumming: Cut the dried cocoon shells, take out the silkworm pupae, weigh a certain amount of dry cocoon shells, put them into a Na2CO3 solution with a bath ratio of 1:100, a temperature of 100 °C, and a mass fraction of 0.2%, boil for 45 minutes, then take them out, wash repeatedly with deionized water, dry in an oven, and check the degumming degree until degumming is complete.

[0065] (2) Subsequently, to prepare the silk fibroin solution, first add CaCl2 to HCOOH, and then gradually add the degummed silk fibroin (SF) strand by strand to the FA-Ca solution under magnetic stirring (mass ratio of CaCl2:SF:HCOOH = 1:3:30). Stir the resulting mixture at a speed of 500 rpm for 2 hours.

[0066] (3) Pour the silk fibroin solution into a mold, place the chitosan non-woven fabric on the surface, and then cover the surface of the non-woven fabric with the same volume of silk fibroin solution to form a "sandwich" - like structure, and then move it to a fume hood until the formic acid completely volatilizes to obtain the MSC hydrogel.

[0067] 2) Preparation of nano - porous CaCO3:

[0068] (1) Preparation of Nano - CaCO3: Uniformly mix 200 mg of CaCl2·2H2O and 4 mg of dopamine with 100 ml of absolute ethanol. Then place this mixture together with 5 g of NH4HCO3 in a sealed container and leave it at 37 °C for 24 hours. After 24 hours, collect the obtained nanoparticles, wash them three times with alcohol, and then dry the washed CaCO3 nanoparticles for subsequent use.

[0069] (2) Coating: First, dissolve 0.1 g of growth factor (aFGF) in PBS buffer solution to make a dispersion, combine the washed 0.6 g of nano - porous CaCO3 made into an aqueous solution with 10 μg / ml of growth factor (aFGF), stir horizontally for 1 hour, and then centrifuge at 10,000 rpm for 10 minutes to produce aFGF - loaded nano - CaCO3. After that, take 0.12 g L100 - 55 and put it into a small amount of alcohol solution to mix evenly, and also add 0.01 g of growth factor - loaded Nano - CaCO3 to the solution. Stir magnetically at 0 °C for 30 minutes. Subsequently, centrifuge at 10000 rpm for 5 minutes, and wait for the alcohol to volatilize at room temperature to obtain the aFGF - Ca powder.

[0070] 3) Preparation of aFGF - Ca@MSC gel:

[0071] Mix the aFGF-Ca powder obtained in step 2) with the FA-Ca solution and evenly coat it on the surface of the MSC hydrogel to obtain the aFGF-Ca@MSC gel.

[0072] Comparative Example 1:

[0073] Compared with Example 1, prepare the MSC hydrogel according to the method of step 1) in Example 1. Then directly spray the FA-Ca solution evenly on the surface of the MSC hydrogel to obtain the MSC@Ca gel.

[0074] Experimental Example 1:

[0075] Perform transmission electron microscopy observations on the MSC hydrogel obtained in step 1) of Example 1, the aFGF-Ca obtained in step 2), the aFGF-Ca@MSC gel obtained in step 3), the MS hydrogel obtained in step 1) of Example 2, and the MSC@Ca gel obtained in Comparative Example 1, respectively.

[0076] See Appendix Figure 2 , it can be seen that the nanoporous calcium carbonate is circular, with porous surfaces, no adhesion between particles, and poor agglomeration; the nanoporous calcium carbonate coated with a biocompatible polymer is irregularly circular, with no obvious pores on the surface, adhesion between particles, and they are connected to each other.

[0077] Silk fibroin without chitosan non-woven fabric is prone to breakage and has poor mechanical strength; after adding chitosan non-woven fabric, silk fibroin has strong adhesiveness, no breakage phenomenon, and high mechanical strength. The MSC hydrogel with only the FA-Ca solution sprayed on its surface causes the MSC to absorb too much water, reducing the mechanical properties of the gel, resulting in breakage and making the material too soft to protect the wound easily. The aFGF-Ca@MSC gel sprayed in Example 1 of the present application, which is coated with nanoporous calcium carbonate, has better adhesiveness and mechanical strength. This is mainly because the aFGF-Ca powder provides additional binding points between the polymer chains of silk fibroin under the action of metal chelation and Ca 2+ , enabling physical entanglement and mechanical interlocking to form between the polymers, forming a network structure. A large mechanical strength is formed between the networks, making the hydrogel have good adhesiveness and mechanical strength, and being more conducive to protecting the wound.

[0078] Experimental Example 2:

[0079] See Appendix Figure 3, four rabbits of similar age, size, and weight were selected. Circular wounds with a diameter of 2 cm and a depth of 0.2 cm were cut at the same location to establish an animal bleeding model. After hemostasis was performed in the same manner, the first rabbit was sprayed with a bactericide regularly every day, the second rabbit was treated with a commercially available 3M dressing, the third rabbit was treated with the MSC gel obtained in step 1) of Example 1 of the present invention, and the fourth rabbit was treated with the aFGF-Ca@MSC gel obtained in Example 1 of the present invention. It can be seen that the healing degree of the wound with the commercially available 3M dressing is basically the same as that of the blank sample. Although the 3M dressing can prevent the wound from coming into direct contact with external objects, it cannot prevent the invasion of bacteria, and the influence of bacteria reduces the wound healing speed. The silk fibroin after gelation in the present invention has stronger adhesiveness, so that the gel adheres tightly to the skin surface, can be completely sealed to prevent the invasion of bacteria, accelerates wound healing, the wound has basically healed on the 11th day, and is completely healed on the 13th day, leaving only a very small mark.

[0080] Compared with the MSC gel without loaded growth factor, the aFGF-Ca@MSC gel loaded with growth factor has a faster wound healing speed, especially on the 3rd - 7th days, the wound healing speed is accelerated. It can be seen from the figure that on the third day, the wound coagulation is good, but the healing degree of both wounds is very poor, and there is almost no healing phenomenon. On the 7th day, obvious wound healing appears in the aFGF-Ca@MSC gel loaded with growth factor, and the wound area is less than half of the original, and the healing speed is significantly faster compared with other groups; although the healing speed is faster than other groups after 7 days, the speed is not obvious. This is mainly because the growth factor is coated by the coating and cannot play a role at the beginning of use. As the wound tissue fluid exudes, the biocompatible polymer gradually dissolves, and the nanoporous calcium carbonate gradually collapses in the tissue fluid, so that the loaded growth factor is released, and the growth factor acts on the wound to promote wound healing, and the wound healing speed gradually accelerates. After the 7th day, the growth factor loaded in the hydrogel is basically completely released, and the wound healing speed is basically the same as that of the wound without loaded growth factor again.

[0081] Experimental Example 3:

[0082] See Appendix Figure 4 , four rabbits of similar age, size, and weight were selected. Wounds with a length of 2 cm and a depth of 0.5 cm were cut at the same location to establish an animal bleeding model. After hemostasis was performed in the same manner, the first rabbit was sprayed with a bactericide regularly every day, the second rabbit was treated by surgical suture, the third rabbit was treated with a commercially available 3M biomedical glue, and the fourth rabbit was treated with the aFGF-Ca@MSC gel obtained in Example 3 of the present invention.

[0083] It can be seen that the blank sample still had an obvious wound on the 18th day, and the wound healing speed was slow; for the second sample sutured surgically, the wound was obvious at the suture site after the stitches were removed on the 18th day, the degree of healing at the suture was poor, and the scar was deep. Compared with the blank sample, the commercially available biomedical glue significantly accelerated the wound healing speed. Obvious healing phenomenon occurred on the 7th day, which was 4 days faster than that of the blank sample. By the 18th day, the wound had basically completely healed, but there was an obvious scar. After using the aFGF-Ca@MSC gel of the present invention, the wound healing speed was fast. Obvious healing phenomenon occurred after the 3rd day, and the wound had basically healed by the 11th day. By the 18th day, the wound had completely healed and there was no obvious scar. This was mainly because the biocompatible polymer and the gelled silk fibroin had an obvious adsorption effect on the exuded tissue fluid, preventing the tissue fluid from exuding and coagulating, which would otherwise affect the wound healing and leave scars; coupled with the action of the released growth factors, the wound healing was accelerated.

[0084] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages and disadvantages of the embodiments.

[0085] The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative rather than restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the purpose of the present invention and the scope protected by the claims. All of these fall within the protection scope of the present invention.

Claims

1. A hydrogel capable of delivering growth factors, characterized in that: It includes silk fibroin after gelation. On the surface of the silk fibroin, nano-porous calcium carbonate loaded with growth factors is provided, and the surface of the nano-porous calcium carbonate is coated with a biocompatible polymer; a chitosan non-woven fabric is also arranged inside the silk fibroin, and the chitosan non-woven fabric and the silk fibroin on both sides form a "sandwich" structure.

2. The hydrogel capable of delivering growth factors according to claim 1, wherein: The degummed silk fibroin is added to a formic acid / calcium chloride solution to form a silk fibroin solution, and dried in air to gelate the silk fibroin.

3. A method for preparing a hydrogel capable of delivering growth factors according to any one of claims 1-2, characterized in that, It includes the following steps: The degummed silk fibroin is added to a formic acid / calcium chloride solution to form a silk fibroin solution, and after drying, a calcium-modified silk fibroin gel is obtained; the growth factor is loaded inside the nano-porous calcium carbonate, and then the nano-porous calcium carbonate is coated with a biocompatible polymer to obtain aFGF-Ca; then aFGF-Ca is dispersed into a formic acid / calcium chloride solution, and the dispersion is sprayed on the surface of the silk fibroin gel to obtain a hydrogel.

4. The preparation method of a hydrogel capable of delivering growth factors according to claim 3, wherein: After the degummed silk fibroin forms a silk fibroin solution, it is put into a mold, and a chitosan non-woven fabric is also arranged inside the silk fibroin, so that the chitosan non-woven fabric and the silk fibroin on both sides form a "sandwich" structure and are dried.

5. The preparation method of a hydrogel capable of delivering growth factors according to claim 3, characterized in that: When preparing the silk fibroin solution, the mass ratio of CaCl2, degummed silk fibroin, and formic acid is 1:4:40 to 5:8:

100.

6. The preparation method of a hydrogel capable of delivering growth factors according to claim 3, wherein: Before spraying on the surface of the silk fibroin gel, first make all the formic acid in the silk fibroin volatilize completely.

7. The preparation method of a hydrogel capable of delivering growth factors according to claim 3, wherein The process of loading the growth factor is: forming an aqueous calcium carbonate solution of nano-porous calcium carbonate, adding the growth factor to a buffer solution for mixing, stirring and dissolving, and then mixing and stirring with the aqueous calcium carbonate solution, and centrifuging to obtain nano-porous calcium carbonate loaded with the growth factor.

8. The preparation method of a hydrogel capable of delivering growth factors according to claim 3, characterized in that, The process of coating is: adding the biocompatible polymer to a small amount of alcohol solution to dissolve, then adding the nano-porous calcium carbonate loaded with the growth factor, quickly stirring and centrifuging, and then evaporating the alcohol to obtain aFGF-Ca powder.

9. Use of a hydrogel capable of delivering growth factors obtained by the preparation method according to any one of claims 3-8 in the preparation of a drug delivery carrier.

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