Forming method of silk fibroin plate and silk fibroin plate
By mixing freeze-dried silk fibroin powder with hexafluoroisopropanol and injection molding, combined with multiple correction and soaking treatments, the problems of slow molding rate and low flatness of thin silk fibroin sheets were solved, and the thickness uniformity and mechanical properties were improved, making it suitable for medical and biomaterials fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGXI SILK BIOTECHNOLOGY CO LTD
- Filing Date
- 2026-04-23
- Publication Date
- 2026-07-28
AI Technical Summary
Existing technologies for preparing thin silk fibroin sheets have slow forming rates and low material flatness, making it difficult to guarantee thickness uniformity.
The mixture of lyophilized silk fibroin powder and hexafluoroisopropanol was injected into a sealed mold, allowed to stand to remove air bubbles, and the sealing and levelness were adjusted by gravity components. Subsequently, multiple correction and soaking treatments were performed to ensure the crystallization speed and thickness uniformity.
It significantly improves the crystallization rate and thickness uniformity of silk fibroin sheets, ensuring the flatness and mechanical properties of the sheets, making them suitable for large-scale production in the medical and biomaterials fields.
Smart Images
Figure CN122463345A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials technology, and in particular to a method for molding silk fibroin sheets and the silk fibroin sheets themselves. Background Technology
[0002] Silk fibroin is an important component of silk. It is a natural protein with good biocompatibility and biodegradability, and is widely used in the medical and biomaterials fields.
[0003] Natural silkworm cocoons can be processed into freeze-dried silk fibroin powder through a series of processes, and then into rigid silk fibroin sheets. For thicker rigid sheets, the production process is relatively simple to control. However, for the preparation of thinner sheets, the current method usually involves placing the silk fibroin solution in a sealed container and then in a completely open container to obtain the desired silk fibroin material. Although this method can achieve the crystallization of silk fibroin, the forming rate is slow and the material flatness is prone to problems. Summary of the Invention
[0004] To address the aforementioned technical problems, this application discloses, in one aspect, a method for forming silk fibroin sheets, comprising: We provide freeze-dried silk fibroin powder; The lyophilized silk fibroin powder was mixed with hexafluoroisopropanol to obtain a composite solution; The composite solution is injected into a sealed mold, and a predetermined number of gravity components are placed on the mold to allow it to stand and remove air bubbles. After a first preset time of settling, the gravity component is removed, and the material is settling for a second preset time to obtain the initial board material. The initial board material was subjected to multiple correction and soaking treatments to obtain silk fibroin board material.
[0005] In one feasible embodiment, the mixing of the lyophilized silk fibroin powder and hexafluoroisopropanol to obtain a composite solution comprises: The hexafluoroisopropanol is added to the lyophilized silk fibroin powder to dissolve the lyophilized silk fibroin powder, thereby obtaining the composite solution.
[0006] In one feasible implementation, the mold includes a base, a frame, and a top cover; The surrounding frame is a cylindrical structure; One opening of the frame is connected to the base, and the other opening of the frame can fit with the top cover to form an accommodating space; The length of at least one side of the base is greater than the length of the corresponding side of the frame.
[0007] In one feasible implementation, the top of the enclosure is provided with a sealing material.
[0008] In one feasible implementation, the mold further includes an adjusting element; The adjusting element is located on the base for adjusting the levelness of the base.
[0009] In one feasible implementation, the adjusting element includes a screw and a nut; The base is provided with mounting holes; a nut is provided in the mounting holes; The screw is threadedly connected to the nut; The length of the screw extending from the base can be adjusted by rotating the screw.
[0010] In one feasible implementation, after the gravity component is removed, there is a preset gap between the frame and the top cover.
[0011] In one feasible implementation, the process of performing multiple correction and soaking treatments on the initial board to obtain a silk fibroin board includes: The initial plate is placed in the clamp and subjected to the first correction process; The initial board material after the first correction treatment was immersed in an organic solvent for the first time. The initial board material after soaking is subjected to a second correction treatment using the clamping plate. The initial board after the second correction treatment was placed in pure water for a second immersion to remove excess organic solvent and hexafluoroisopropanol; The initial board after the second soaking is subjected to a second correction treatment using the clamping plate to obtain a silk fibroin board.
[0012] In one feasible implementation, the clamp is provided with a predetermined number of ventilation holes; During the correction process, a lint-free cloth is provided on the contact surface between the initial board and the clamping plate.
[0013] In one feasible implementation, the first soaking time is greater than or equal to 24 hours; During the first soaking, the organic solvent can submerge the initial board material, and the organic solvent is replaced at a third preset time interval, with the number of organic solvent replacements ranging from 1 to 30 times.
[0014] In one feasible implementation, during the second soaking, the pure water can submerge the initial board material, and the pure water is replaced at fourth preset time intervals, with the number of pure water replacements ranging from 1 to 60 times.
[0015] In one feasible embodiment, the mass ratio of silk fibroin to hexafluoroisopropanol in the composite solution is 1 gram : (1-10) milliliters; The mixing temperature is 5–60°C; The mixing time is 1 to 96 hours.
[0016] In one feasible embodiment, the thickness of the silk fibroin sheet is 0.1 to 20 mm.
[0017] In another aspect, this application discloses a silk fibroin sheet, which is prepared by the above-described molding method for silk fibroin sheets.
[0018] This application embodiment provides a lyophilized silk fibroin powder; mixes the lyophilized silk fibroin powder with hexafluoroisopropanol to obtain a composite solution; injects the composite solution into a sealed mold, and places a predetermined number of gravity components on the mold to allow it to stand and remove air bubbles, thereby allowing the silk fibroin in the composite solution to crystallize. After standing for a first predetermined time, the gravity components are removed, and the mixture is left to stand for a second predetermined time to obtain an initial board. This process can accelerate the crystallization speed. The initial board is then subjected to multiple correction and soaking treatments to obtain a silk fibroin board, which can effectively improve the uniformity of the board thickness. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 A schematic flowchart illustrating a method for forming a silk fibroin board provided in this application; Figure 2 An exploded view of the mold provided in this application; Figure 3 A schematic diagram of the structure of an adjusting component provided in this application; Figure 4 An exploded view of the mold provided in this application from another perspective; Figure 5 This is a schematic diagram of the silk fibroin board corresponding to Example 1; Figure 6 This is a schematic diagram of the silk fibroin board corresponding to Example 2; Figure 7 This is a schematic diagram of the silk fibroin board corresponding to Example 3; Figure 8 This is a schematic diagram of the silk fibroin board corresponding to Example 4; Figure 9 This is a schematic diagram of the silk fibroin board corresponding to Example 5; Figure 10 This is a schematic diagram of the silk fibroin board corresponding to Example 6.
[0021] The following is supplementary explanation of the attached figures: 1-Base; 2-Frame; 3-Top cover; 4-Adjusting component; 41-Screw; 42-Nut; 5-Sealing material; 6-Gravity component. Detailed Implementation
[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0023] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of this application. In the description of this application, it should be understood that the terms "upper," "lower," "top," "bottom," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Moreover, the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein.
[0024] Although the numerical ranges and parameters illustrating the broad scope of the invention are approximate, the values listed in the specific examples are reported as precisely as possible. However, any numerical value inherently contains some error that is necessarily caused by the standard deviation found in their respective test measurements.
[0025] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to an integer, it includes every integer between the minimum and maximum values of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included. For example, a specified range from “1 to 10” should be considered to include any and all subranges between the minimum value 1 and the maximum value 10. Exemplary subranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.
[0026] Please see Figure 1 This application discloses a method for forming silk fibroin sheets, which may specifically include: S101: Provides freeze-dried silk fibroin powder.
[0027] In this embodiment, silkworm cocoons can be processed through degumming, rinsing, drying, dissolving, dialysis, centrifugation, and freeze-drying to obtain fibroin freeze-dried powder. Natural silkworm cocoons are first washed, then added to a boiling sodium carbonate solution and kept heated for a certain time to obtain degummed silk. The degummed silk is then rinsed with purified water to obtain rinsed degummed silk. The rinsed degummed silk is then dried to obtain degummed dried silk. The degummed dried silk is dissolved in a lithium salt aqueous solution until fully dissolved to obtain a fibroin lithium salt solution. The fibroin lithium salt solution is dialyzed to remove lithium salts, yielding a fibroin dialysate. The fibroin dialysate is centrifuged, and the supernatant is collected to obtain a fibroin aqueous solution. This fibroin aqueous solution is then freeze-dried in a vacuum freeze dryer to obtain fibroin freeze-dried powder.
[0028] Specifically, silkworm cocoons can be weighed at a ratio of 10g : (1-100)L to sodium carbonate solution volume, added to a sodium carbonate solution with a concentration of 0-100g / L, heated to 30-100℃, and degummed for 0.5-10 hours. After rinsing with water to remove sodium carbonate, the cocoons are dried. The ratio of the dried silk mass to the lithium salt solution volume is (1-100)g : 100mL to dissolve the silk. Optionally, the lithium salt can be at least one of lithium thiocyanate or lithium bromide. The dissolution temperature of the soluble fiber is room temperature, and the dissolution time is 1~24h. Then, it is placed in a dialysis bag of 1kDa~1000kDa and water is added at a volume ratio of 1:(1~1000) for dialyzing. The water is changed every 1~100h, the number of water changes is ≥3 times, and the dialysis time is ≥24h. After dialysis, it is centrifuged at 1000~20000r / min, the supernatant is collected, and it is freeze-dried in a vacuum freeze dryer at a temperature of -80~25℃ for 1~100h. The weight average molecular weight of the final freeze-dried powder is 10~300kDa.
[0029] S103: Mix the lyophilized silk fibroin powder with hexafluoroisopropanol to obtain a composite solution.
[0030] In one feasible implementation, step S103 may specifically include: adding the hexafluoroisopropanol to the lyophilized silk fibroin powder to dissolve the lyophilized silk fibroin powder and obtain the composite solution.
[0031] In one feasible embodiment, the mass ratio of silk fibroin to hexafluoroisopropanol in the composite solution is 1 gram: (1-10) milliliters; specifically, the mass ratio of silk fibroin to hexafluoroisopropanol can be 1 gram: 1 milliliter, 1 gram: 2 milliliters, 1 gram: 3 milliliters, 1 gram: 4 milliliters, 1 gram: 5 milliliters, 1 gram: 6 milliliters, 1 gram: 7 milliliters, 1 gram: 8 milliliters, 1 gram: 9 milliliters, or 1 gram: 10 milliliters. The specific amount of hexafluoroisopropanol added can be adjusted within the above ratio range. Too much hexafluoroisopropanol makes later removal difficult, while too little results in insufficient dissolution, incomplete dissolution, poor fluidity, and uneven flow across the mold.
[0032] The mixing temperature is 5 to 60°C; specifically, the mixing temperature can be 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, or 60°C.
[0033] The mixing time ranges from 1 to 96 hours; specifically, the mixing time can be 1 hour, 10 hours, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 70 hours, 80 hours, 90 hours, or 96 hours. When the mass ratio of silk fibroin to hexafluoroisopropanol is constant, the mixing time decreases with increasing temperature, and vice versa; the lower the temperature, the longer the mixing time.
[0034] S105: Inject the composite solution into a sealed mold, and place a predetermined number of gravity components on the mold to allow it to stand and remove air bubbles.
[0035] In one feasible implementation, please refer to Figure 2 The mold includes a base 1, a frame 2, and a top cover 3. The frame 2 has a cylindrical structure. One opening of the frame 2 connects to the base 1, and the other opening of the frame 2 can mate with the top cover 3 to form a receiving space. The length of at least one side of the base 1 is greater than the length of the corresponding side of the frame 2. This allows for adjustable sealing of the composite solution. Furthermore, by making the side of the base 1 slightly wider, the overall level of the mold can be determined by measuring the levelness of the surface of the base 1 using a level. If it is not level, it can be adjusted.
[0036] For details, please continue reading. Figure 2 The base 1 can be a cube, including 4 sides, and the length of each side is greater than the side of the corresponding frame 2.
[0037] The bottom of the mold should be as level as possible, with a height difference of no more than 0.02mm.
[0038] Specifically, the gravity component 6 can be a block structure, such as a metal block, providing a certain pressure. The number of gravity components 6 can be N, where N is an integer greater than or equal to 1. For example, N can be equal to 2. Each gravity component 6 has a length, width, and height of 100mm × 25mm × 25mm and a mass of 500g. If the mass is too light, the sealing effect after injection molding will be poor, causing a large number of air bubbles to be generated during the solidification process of the injection molding solution, resulting in many air bubbles in the later sheet material, which cannot be compensated for. If the mass is too heavy, the solidification time will be longer, and the material will remain in a non-solidified state for a long time, increasing time costs. This process involves sealing and standing for a period of time to allow the air bubbles to be completely removed.
[0039] In this embodiment, the sealing and settling process is to prevent hexafluoroisopropanol from evaporating outside the mold. Optionally, the mold material can be PP, and the sealing area can be sealed with silicone to ensure that hexafluoroisopropanol can evaporate slowly without reacting with it.
[0040] In one feasible embodiment, a sealing material 5 is provided on the top of the frame 2 to improve sealing performance. Optionally, the sealing material 5 can be silicone or other polymer sealing materials 5.
[0041] In one feasible implementation, please refer to Figure 3 and Figure 4 The mold also includes an adjusting component 4; the adjusting component 4 is disposed on the base 1 to adjust the levelness of the base 1.
[0042] In one feasible embodiment, the adjusting member 4 includes a screw 41 and a nut 42; the base 1 is provided with a mounting hole (not shown in the figure); the nut 42 is provided in the mounting hole; the screw 41 is threadedly connected to the nut 42; by rotating the screw 41, the length of the screw 41 extending out of the base 1 can be adjusted.
[0043] In this embodiment of the application, step S105 can be left to stand at room temperature.
[0044] In steps S103-S105 above, unevenness at the bottom of the mold, poor mold sealing performance, rapid bubble formation during evaporation, uneven thickness and wrinkles after solidification, and the lack of a suitable correction process all lead to deformation and other drawbacks, making it difficult to guarantee material quality. Therefore, during the molding process, it is necessary to achieve good mold sealing and consistent horizontal leveling within the mold based on the parameters specified in the above steps.
[0045] S107: After a first preset time of settling, remove the gravity component 6 and settling for a second preset time to obtain the initial plate.
[0046] In one feasible implementation, after removing the gravity component 6, a preset gap exists between the frame 2 and the top cover 3. By setting the gravity component 6 on the mold and sealing it for a certain period of time, the composite solution can be allowed to flow fully, level out, and fill the bottom of the mold. After releasing the air bubbles, the gravity component 6 is removed, leaving a gap between the top cover 3 and the frame 2. This allows hexafluoroisopropanol to evaporate slowly at room temperature, and the material to crystallize slowly during the process. This process is to ensure that the hexafluoroisopropanol evaporates slowly. If the gap is too small, the hexafluoroisopropanol will evaporate too slowly, affecting efficiency; if the gap is too large, the hexafluoroisopropanol will evaporate too quickly, and the material is prone to bending, deformation, wrinkling, etc. Therefore, the gap size can be adjusted by adjusting the number and size of the removed gravity component 6 to leave a suitable gap in the mold, allowing the hexafluoroisopropanol to evaporate slowly at room temperature and the material to crystallize slowly. After the composite solution solidifies, a silk fibroin board is formed.
[0047] S109: The initial board material is subjected to multiple correction and soaking treatments to obtain silk fibroin board material.
[0048] In one feasible implementation, step S109 may specifically include: placing the initial board material in a clamp for a first straightening treatment; immersing the first-straightened initial board material in an organic solvent for a first immersion; performing a second straightening treatment on the immersed initial board material using the clamp; immersing the second-straightened initial board material in pure water for a second immersion to remove excess organic solvent and hexafluoroisopropanol; and performing a second straightening treatment on the second-immersion initial board material using the clamp to obtain a silk fibroin board. This three-stage straightening treatment effectively ensures the flatness and mechanical properties of the board material. The first immersion ensures uniform and stable crystallinity, and the second immersion removes excess organic solvent and hexafluoroisopropanol, thereby forming a silk fibroin thin board material with excellent chemical and physical properties.
[0049] In one feasible implementation, the clamping plate is provided with a preset number of ventilation holes; during the straightening process, a lint-free cloth is provided on the contact surface between the initial board material and the clamping plate. The ventilation holes allow for air permeability, facilitating the rapid drying of the board material.
[0050] In one feasible implementation, the first soaking time is greater than or equal to 24 hours; during the first soaking, the organic solvent can submerge the initial board material, and the organic solvent is replaced at third preset time intervals, with the number of times the organic solvent is replaced being 1 to 30. Optionally, the organic solvent can be methanol. Optionally, the third preset time can be 1 to 3 days; specifically, the organic solvent can be replaced at intervals of 1 day, 2 days, or 3 days. The first soaking can improve the crystallinity of the silk fibroin board material.
[0051] In this embodiment of the application, the first correction process involves clamping the initial board material in the middle with a clamp and a lint-free cloth, clamping it tightly, and letting it air dry at natural temperature to correct the deformation during the solidification process and accelerate the volatilization of residual hexafluoroisopropanol. The drying time is 1 to 30 days.
[0052] The second correction process involves using a splint and a lint-free cloth to clamp the initial board in the middle, securing it with clips, and allowing it to air dry at natural temperature to correct the deformation caused by the methanol soaking process. The drying time is 1 to 30 days.
[0053] In one feasible implementation, during the second soaking, the pure water can submerge the initial board material, and the pure water is replaced at a fourth preset time interval, with the number of water replacements ranging from 1 to 60 times. Optionally, the pure water used for the second soaking is ultrapure water, and the fourth preset time interval can be 1 to 30 days; specifically, the pure water can be replaced at intervals of 1 day, 5 days, 10 days, 15 days, 20 days, 25 days, or 30 days. Afterwards, a third correction is performed, using a clamp and a lint-free cloth to sandwich the initial board material in the middle, securing it with clips, and allowing it to air dry at natural temperature to correct any deformation caused during the soaking process. The drying time is 1 to 30 days.
[0054] In one feasible embodiment, the thickness of the silk fibroin sheet is 0.1–20 mm. Specifically, the thickness of the silk fibroin sheet is 0.1 mm, 1 mm, 5 mm, 10 mm, 15 mm, or 20 mm. This solution is particularly effective for sheets with a thickness of less than 1 mm, resulting in better thickness uniformity and crystallinity.
[0055] The silk fibroin content of the material is not less than 90% when it is demolded after crystallization.
[0056] The rigid thin-sheet silk fibroin material prepared by this application allows for precise control of the injection molding amount by calculating volume and expansion ratio, resulting in a thickness ranging from 0.1 to 20 mm with a tolerance within ±0.05 mm. The material exhibits uniform crystalline molecular distribution, high crystallinity, and good mechanical strength. As a natural protein, it is biodegradable, and the process is simple and highly operable, suitable for large-scale production. It can be widely used in the medical and biomaterials fields.
[0057] In another aspect, this application discloses a silk fibroin sheet, which is prepared by the above-described molding method for silk fibroin sheets.
[0058] The following are several specific embodiments provided in this application: Example 1 Weigh 10g of silkworm cocoons, take 4L of purified water, add 8.48g of sodium carbonate to dissolve it, and obtain a sodium carbonate solution of 2.12g / L. Heat to boiling, add the weighed silkworm cocoons, and continue heating to degumme for 30 minutes. Remove, rinse with water to remove sodium carbonate, and air dry at room temperature to obtain degummed dry silk.
[0059] 273.7 g of lithium bromide was weighed and dissolved in 280 mL of water to obtain a lithium bromide solution. 70 g of the degummed dried silk fibers was weighed and dissolved in the lithium bromide solution, and dissolved at 60 °C for 3 hours to obtain a solution. The solution was placed in a dialysis bag, sealed, and dialyzed in 5 L of ultrapure water for 72 hours, changing the water every 6 hours. After dialysis, the solution was removed, centrifuged, and the supernatant was collected and freeze-dried at -40 °C to 25 °C for 72 hours. The result was the lyophilized silk fibroin powder.
[0060] Accurately weigh 15.5g of the lyophilized silk fibroin powder, add it to 100ml of hexafluoroisopropanol, seal it, and let it dissolve at room temperature for 72h to obtain a composite solution.
[0061] The obtained composite solution is injected into the mold and pressed down with an iron block (i.e., a gravity component). It is then left to stand at room temperature until the air bubbles are completely released.
[0062] After releasing the bubbles, remove the iron block from the mold, leaving a gap between the mold cover and the mold box to allow for the slow evaporation of hexafluoroisopropanol. After the silk fibroin recrystallizes and solidifies, it is demolded, placed on a clamp to dry, and then soaked in methanol for a certain period (no less than 2 days). It is then placed on the clamp again to dry for at least 3 days. Next, it is placed in ultrapure water for immersion and washing, changing the water every day for 10 days. After this, it is removed and dried again at room temperature on a clamp, yielding the silk fibroin board. This process ultimately produces the desired product. Figure 5 The 0.2mm silk fibroin board shown.
[0063] Another pair of comparative examples 1, 2, 3 and 4 are provided. The difference between comparative example 1 and example 1 is that the ratio of the mass of the lyophilized silk fibroin powder to the volume of hexafluoroisopropanol in the preparation of the composite solution is 1g:6mL. All other steps are the same as in example 1. Due to the reduced content of the solvent hexafluoroisopropanol, the reconstituted solution has poor fluidity, higher viscosity during injection molding, and poor mold sealing, making it difficult to level and solidify into a single piece of rigid silk fibroin sheet.
[0064] The difference between Comparative Example 2 and Example 1 is that the mold in Comparative Example 2 has poor sealing performance, causing many air bubbles to solidify before they can escape during the solidification process. After solidification, air bubbles are visible to the naked eye inside the board. It can be seen that the initial sealing condition significantly affects the material's performance.
[0065] The difference between Comparative Example 3 and Example 1 is that in the step of preparing the composite solution, the ratio of the mass of the lyophilized silk fibroin powder to the volume of hexafluoroisopropanol is 1g: 15mL. This process doubles the solidification time. Most parts have solidified, resulting in curling and bending, while some parts are still relatively viscous and not solidified.
[0066] The difference between Comparative Example 4 and Example 1 is that the bottom level of the mold is ±5°, while the rest is the same as Example 1. The result is that the thickness of the rigid board is uneven. The thinnest part of the final silk fibroin rigid board is 0.1mm and the thickest part is 0.9mm. The uneven thickness leads to unstable product performance.
[0067] This demonstrates that the preparation parameters and steps described in this scheme can yield silk fibroin sheets with uniform thickness and stable performance.
[0068] Example 2 Weigh 10g of silkworm cocoons, take 4L of purified water, add 8.48g of sodium carbonate to dissolve, and obtain a sodium carbonate solution of 2.12g / L. Heat to boiling, add the weighed silkworm cocoons, and continue heating to degumme for 30 minutes. Remove, rinse with water to remove sodium carbonate, and air dry at room temperature to obtain degummed dry silk.
[0069] 273.7 g of lithium bromide was dissolved in 280 mL of water to obtain a lithium bromide solution. 70 g of the degummed dried silk fibers was weighed and dissolved in the lithium bromide solution, then dissolved at 60°C for 3 hours to obtain a solution. The solution was placed in a dialysis bag, sealed, and dialyzed in 5 L of ultrapure water for 72 hours, changing the water every 6 hours. The solution was then removed, centrifuged, and the supernatant was collected and freeze-dried at -40°C to 10°C for 72 hours. The resulting lyophilized silk fibroin powder was obtained.
[0070] Accurately weigh 15.5g of the lyophilized silk fibroin powder, add it to 80ml of hexafluoroisopropanol, seal it, and let it dissolve at room temperature for 72h to obtain a composite solution.
[0071] The composite solution is injected into a mold, allowed to solidify, then clamped and dried. It is then soaked in methanol to solidify again, clamped a second time, and dried. Next, it is rinsed with ultrapure water, clamped a third time, and dried to obtain the final product. Figure 6 The 0.4mm silk fibroin board shown.
[0072] Example 3 This embodiment follows the same steps as Embodiment 2, except for the injection volume and the parameters for subsequent bubble release, soaking, and correction steps, in order to obtain the desired result. Figure 7 The 0.8 mm thick silk fibroin sheet is shown. By processing the materials of Examples 1-3 into dumbbell-shaped tensile samples and testing their mechanical properties, the performance results shown in Table 1 below can be obtained.
[0073]
[0074] As can be seen from the table above, since the rigid sheet prepared in Example 1 is 0.2 mm thick and the injection molding volume is relatively small, the content of the solvent hexafluoroisopropanol needs to be increased to make the solution easier to level. At the same time, considering the solidification efficiency and the removal of impurities later, the proportion of hexafluoroisopropanol content cannot be too high. The rigid sheets in Examples 2 and 3 are 0.4 mm and 0.8 mm thick, respectively, and the injection molding volume is relatively large. There is no need to worry too much about the leveling problem, so the solvent content can be reduced. The results above show that, compared with Examples 2 and 3, Example 1 has lower tensile strength and elongation at break, which reflects the positive correlation between the thickness of the sheet and the injection volume. The amount of hexafluoroisopropanol solvent will also vary with the injection volume, thus affecting the mechanical properties of sheets of different thicknesses.
[0075] Example 4 The steps for preparing the silk fibroin sheet in this embodiment are basically the same as in Example 1, so the similarities will not be repeated. The differences lie in the injection volume and the amount of hexafluoroisopropanol solvent, to obtain the desired result. Figure 8 The 3mm silk fibroin board shown.
[0076] Example 5 The steps for preparing the silk fibroin sheet in this embodiment are basically the same as in Example 1, so the similarities will not be repeated. The differences lie in the injection volume and the amount of hexafluoroisopropanol solvent, to obtain the desired result. Figure 9 The 5mm silk fibroin board shown.
[0077] Example 6 The steps for preparing the silk fibroin sheet in this embodiment are basically the same as in Example 1, so the similarities will not be repeated. The differences lie in the injection volume and the amount of hexafluoroisopropanol solvent, to obtain the desired result. Figure 10 The 10mm silk fibroin board shown.
[0078] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for forming silk fibroin sheets, characterized in that, include: We provide freeze-dried silk fibroin powder; The lyophilized silk fibroin powder was mixed with hexafluoroisopropanol to obtain a composite solution; The composite solution is injected into a sealed mold, and a predetermined number of gravity components are placed on the mold to allow it to stand and remove air bubbles. After a first preset time of settling, the gravity component is removed, and the material is settling for a second preset time to obtain the initial board material. The initial board material was subjected to multiple correction and soaking treatments to obtain silk fibroin board material.
2. The molding method according to claim 1, characterized in that, The step of mixing the lyophilized silk fibroin powder with hexafluoroisopropanol to obtain a composite solution includes: The hexafluoroisopropanol is added to the lyophilized silk fibroin powder to dissolve the lyophilized silk fibroin powder, thereby obtaining the composite solution.
3. The molding method according to claim 1, characterized in that, The mold includes a base, a frame, and a top cover; The surrounding frame is a cylindrical structure; One opening of the frame is connected to the base, and the other opening of the frame can fit with the top cover to form an accommodating space; The length of at least one side of the base is greater than the length of the corresponding side of the frame.
4. The molding method according to claim 3, characterized in that, The top of the enclosure is covered with sealing material.
5. The molding method according to claim 3, characterized in that, The mold also includes an adjusting component; The adjusting element is located on the base for adjusting the levelness of the base.
6. The molding method according to claim 5, characterized in that, The adjusting components include screws and nuts; The base is provided with mounting holes; a nut is provided in the mounting holes; The screw is threadedly connected to the nut; The length of the screw extending from the base can be adjusted by rotating the screw.
7. The molding method according to claim 3, characterized in that, After the gravity component is removed, there is a preset gap between the frame and the top cover.
8. The molding method according to any one of claims 1-7, characterized in that, The process of performing multiple correction and soaking treatments on the initial board material to obtain silk fibroin board material includes: The initial plate is placed in the clamp and subjected to the first correction process; The initial board material after the first correction treatment was immersed in an organic solvent for the first time. The initial board material after soaking is subjected to a second correction treatment using the clamping plate. The initial board after the second correction treatment was placed in pure water for a second immersion to remove excess organic solvent and hexafluoroisopropanol; The initial board after the second soaking is subjected to a second correction treatment using the clamping plate to obtain a silk fibroin board.
9. The molding method according to claim 8, characterized in that, The clamp is provided with a preset number of ventilation holes; During the correction process, a lint-free cloth is provided on the contact surface between the initial board and the clamping plate.
10. The molding method according to claim 8, characterized in that, The first soaking time is greater than or equal to 24 hours; During the first soaking, the organic solvent can submerge the initial board material, and the organic solvent is replaced at a third preset time interval, with the number of organic solvent replacements ranging from 1 to 30 times.
11. The molding method according to claim 8, characterized in that, During the second soaking, the pure water can submerge the initial board material, and the pure water is replaced at a fourth preset time interval, with the number of pure water replacements ranging from 1 to 60 times.
12. The molding method according to claim 1, characterized in that, The mass ratio of silk fibroin to hexafluoroisopropanol in the composite solution is 1 gram: (1-10) milliliters; The mixing temperature is 5–60°C; The mixing time is 1 to 96 hours.
13. The molding method according to claim 1, characterized in that, The thickness of the silk fibroin board is 0.1 to 20 mm.
14. A silk fibroin board, characterized in that, It is prepared by the molding method of silk fibroin sheet according to any one of claims 1 to 13.