Ionic liquid functionalized eggshell membrane protein material as well as preparation method and application thereof

Abstract

The invention discloses an ionic liquid functionalized eggshell membrane protein material as well as a preparation method and application thereof, and belongs to the technical field of biological piezoelectric materials. Pre-treating the eggshell membrane, and grinding into powder; the preparation method comprises the following steps: treating eggshell membrane powder by using a NaOH solution, cleaning to be neutral, dissolving in an aqueous solution of 3-thiohydracrylic acid and acetic acid, reacting, adjusting the pH value to an isoelectric point, collecting precipitate, drying to obtain a soluble eggshell membrane, adding into an ionic liquid, and fully stirring and dissolving to obtain an eggshell membrane protein solution; dialyzing and freeze-drying to obtain ionic liquid functionalized eggshell membrane protein; and re-dissolving in an aqueous solution, standing, defoaming, drying, and carrying out cross-linking impregnation with absolute ethyl alcohol to obtain the ionic liquid functionalized eggshell membrane protein membrane. The eggshell membrane protein membrane prepared by the invention has good mechanical properties and relatively high thermal stability and piezoelectricity, and the degradable protein material can be applied to the fields of biological tissue engineering, intelligent sensing, energy collection and the like.

Description

Technical Field

[0001] The invention discloses an ionic liquid functionalized eggshell membrane protein material and a preparation method and application thereof, belonging to the technical field of biological piezoelectric materials. Background Art

[0002] In the field of materials science, the research and development of functionalized materials has always been an important driving force for scientific and technological progress. As a new type of green solvent, ionic liquids have unique physical and chemical properties, such as extremely low vapor pressure, high thermal stability, good solubility and designability. These properties make ionic liquids have broad application prospects in electrochemistry, electroanalysis, materials science and other fields. The functionalization of ionic liquids is mainly achieved by introducing specific functional groups or structural units to give them richer physical and chemical properties and application potential.

[0003] As a new type of green solvent, ionic liquid has the advantages of low volatility, high thermal stability and strong designability.

[0004] Eggshell membrane protein is mainly derived from the inner membrane layer of the eggshell. It is a natural polymer material rich in collagen and other bioactive ingredients. Eggshell membrane protein itself has a series of excellent biological activities and functionalities. For example, components such as protein, collagen, chondroitin sulfate and hyaluronic acid have significant effects on joint health and skin care. It not only has good biocompatibility and degradability, but also has certain mechanical strength and toughness.

[0005] Eggshell membrane protein film can be used as a drug carrier due to its good biocompatibility and biodegradability, helping drugs to be effectively released in the body and improving drug targeting and bioavailability; eggshell membrane is rich in collagen and other ingredients, which play an important role in promoting wound healing. Therefore, eggshell membrane protein film can be used as a wound dressing to accelerate the healing process of wounds. In the field of tissue engineering, eggshell membrane protein film can be used as a scaffold material to provide a suitable environment for cell growth and promote tissue regeneration and repair. Eggshell membrane protein film has high light transmittance, which makes it have potential application value in the field of optics. For example, it can be used as an optical film in the manufacture of products such as lenses and solar panels to improve the optical performance of the products. Electronic packaging materials: The high insulation of eggshell membrane protein film makes it an ideal choice for electronic packaging materials, which can effectively protect electronic components from the influence of the external environment. With the development of science and technology, wearable devices are attracting more and more attention. The flexibility and breathability of eggshell membrane protein film give it an advantage in the production of wearable devices, which can achieve a better human-computer interaction experience.

[0006] These characteristics make eggshell membrane protein have wide application potential in the fields of biomedicine, food packaging, environmental protection, etc. For example, in the field of biomedicine, eggshell membrane protein can be used to prepare tissue engineering scaffolds, drug carriers, etc.; in food packaging, its degradability and biocompatibility make it an ideal choice for green packaging materials.

[0007] However, its original performance may be difficult to fully meet the needs of specific application fields. Traditional solvents often have problems such as volatility and toxicity during material synthesis and processing, posing potential threats to the environment and operator health.

[0008] Therefore, it is of great significance to develop a new method to functionally modify this material and prepare functional materials with special properties. Summary of the invention

[0009] In order to solve the above technical problems, the technical solution of the present invention is to provide a preparation method of an ionic liquid functionalized eggshell membrane protein material and its application.

[0010] The eggshell membrane is peeled, cleaned, dried and then ground into powder; the eggshell membrane powder is pretreated with an alkaline solution, and then the eggshell membrane is cleaned to neutrality; the pretreated eggshell membrane is dissolved in an aqueous solution of 3-mercaptopropionic acid and acetic acid, fully stirred and centrifuged to obtain a clear aqueous solution on the upper layer, the pH is adjusted, a white precipitate is collected, and soluble eggshell membrane is obtained after drying; the dried soluble eggshell membrane powder is added into an ionic liquid, fully stirred and dissolved to obtain an eggshell membrane protein solution; the eggshell membrane protein solution is dialyzed and freeze-dried to obtain an ionic liquid functionalized eggshell membrane protein; the ionic liquid functionalized eggshell membrane protein is dissolved in an aqueous solution, standing for degassing, drying, and cross-linking and impregnation with anhydrous ethanol to obtain an ionic liquid functionalized eggshell membrane protein membrane.

[0011] The first object of the present invention is to provide a method for preparing an ionic liquid functionalized eggshell membrane protein material, comprising the following steps:

[0012] S1. Pre-treat the eggshell membrane powder with NaOH solution and then wash it to neutrality;

[0013] S2. The eggshell membranes pretreated in step S1 are dissolved in an aqueous solution of 3-mercaptopropionic acid and acetic acid, stirred, and separated into a solid and liquid state, and the upper clear aqueous solution is taken, the pH is adjusted, and the white precipitate is collected and dried to obtain soluble eggshell membranes;

[0014] S3. The soluble eggshell membrane powder obtained in step S2 is added to the ionic liquid and stirred to dissolve to obtain an eggshell membrane protein solution;

[0015] S4. The eggshell membrane protein solution obtained in step S3 is dialyzed and freeze-dried to obtain ionic liquid functionalized eggshell membrane protein.

[0016] Furthermore, the preparation method also includes the step of preparing the ionic liquid functionalized eggshell membrane protein into an ionic liquid functionalized eggshell membrane protein membrane (S5);

[0017] S5. The ionic liquid functionalized eggshell membrane protein obtained in step S4 is dissolved in an aqueous solution for static degassing, drying, cross-linking and immersion to obtain an ionic liquid functionalized eggshell membrane protein membrane.

[0018] Furthermore, in step S3, the mass ratio of the eggshell membrane protein to the ionic liquid is 6.0wt%-10wt%.

[0019] Further, in step S3, the ionic liquid is selected from any one of calcium chloride ionic liquid, lithium bromide ionic liquid, and sodium hypochlorite ionic liquid;

[0020] In some embodiments, the solvent system of the calcium chloride ionic liquid contains ethanol and water, the molar ratio of calcium chloride to ethanol is 1:3-1:1; the concentration is 0.3-0.5 g / ml;

[0021] In some embodiments, in step S1, the eggshell membrane powder is pretreated with a 0.2 mol / L NaOH aqueous solution;

[0022] In some embodiments, the lithium bromide ionic liquid is a lithium bromide aqueous solution with a concentration of 0.5-1.5 g / ml;

[0023] In some embodiments, the sodium hypochlorite ionic liquid is a sodium hypochlorite aqueous solution with a concentration of 0.1-0.3 g / ml.

[0024] Furthermore, in step S4, the temperature at which the eggshell membrane protein solution is dialyzed is 35°C-40°C.

[0025] Further, in step S5, the dried eggshell membrane protein membrane is cross-linked and impregnated with anhydrous ethanol;

[0026] Furthermore, the time of the anhydrous ethanol cross-linking immersion is 30-40 minutes.

[0027] Furthermore, the eggshell membrane powder in step S1 is obtained by peeling, washing, drying and then mechanically grinding the eggshell membrane;

[0028] Furthermore, in step S2, the pH is adjusted to the isoelectric point of the protein to form a precipitate; in some embodiments, the pH is adjusted to 4-5.

[0029] Furthermore, the eggshell membrane sources include but are not limited to eggshells of birds and oviparous reptiles; such as chicken eggshell membranes, duck eggshell membranes, ostrich eggshell membranes, quail eggshell membranes, turtle eggs, etc.

[0030] In some embodiments of the present invention, the preparation method comprises steps 1-6;

[0031] Step 1: peeling, cleaning and other pretreatment of the eggshell membrane, and making it into powder by mechanical grinding;

[0032] Step 2: pretreating the eggshell membrane powder with a NaOH solution, and then washing the eggshell membrane to neutrality;

[0033] Step 3: dissolving the pretreated eggshell membrane in an aqueous solution of 3-mercaptopropionic acid and acetic acid, stirring and centrifuging the solution to obtain a clear upper layer, adjusting the pH, collecting a white precipitate, and drying to obtain a soluble eggshell membrane;

[0034] Step 4: adding the dried soluble eggshell membrane powder into the ionic liquid and stirring and dissolving the mixture to obtain an eggshell membrane protein solution;

[0035] Step 5: dialyzing and freeze-drying the eggshell membrane protein solution to obtain the ionic liquid functionalized eggshell membrane protein;

[0036] Step 6: The eggshell membrane protein functionalized with ionic liquid is dissolved in an aqueous solution for static degassing, drying, and cross-linking and immersion in anhydrous ethanol to obtain an eggshell membrane protein film functionalized with ionic liquid.

[0037] The second object of the present invention is to provide an ionic liquid functionalized eggshell membrane protein material prepared by the preparation method, wherein the ionic liquid functionalized eggshell membrane protein material includes but is not limited to the ionic liquid functionalized eggshell membrane protein prepared in step S4, and the ionic liquid functionalized eggshell membrane protein film prepared in step S5.

[0038] In some embodiments, the thickness of the eggshell membrane protein film functionalized with ionic liquid is 1.5-2 mm.

[0039] The third object of the present invention is to provide the application of the ionic liquid functionalized eggshell membrane protein material in the fields of biological tissue engineering, intelligent sensing and energy collection.

[0040] Furthermore, the ionic liquid functionalized eggshell membrane protein material can be used to prepare bio-nano sensor devices and flexible cotton fabric-based piezoelectric sensors.

[0041] Furthermore, it is used to prepare biomedical wound dressings, flexible thin film sensors, and bio-based piezoelectric nanogenerators.

[0042] Beneficial effects of the present invention:

[0043] The eggshell membrane protein film prepared by the present invention has good mechanical properties, high thermal stability and piezoelectricity. This degradable protein material can be applied to the fields of biological tissue engineering, intelligent sensing and energy collection.

[0044] (1) Ionic liquids can improve the solubility and stability of eggshell membrane proteins by interacting with them, allowing the material to maintain excellent mechanical properties under a wider range of conditions;

[0045] (2) The structure of ionic liquids is highly designable, and their physical and chemical properties can be regulated by adjusting the types and structures of anions and cations, thereby achieving precise control of the properties of eggshell membrane protein materials;

[0046] (3) As green solvents, ionic liquids can reduce or avoid the generation and emission of harmful substances during material synthesis and processing, thereby reducing pollution and damage to the environment;

[0047] (4) The biocompatibility and piezoelectric properties of eggshell membrane protein materials functionalized with ionic liquids are improved, making them more suitable for use in biomedicine, tissue engineering, and intelligent sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0049] Figure 1 It is a schematic diagram of a process for preparing an ionic liquid functionalized eggshell membrane protein material;

[0050] Figure 2 The present invention is a scanning electron micrograph of freeze-dried samples of ionic liquid functionalized eggshell membrane protein membranes prepared in Examples 2, 3 and 4 of the present invention, wherein (a) and (a') are freeze-dried samples prepared in Example 2, (b) and (b') are freeze-dried samples prepared in Example 3, and (c) and (c') are freeze-dried samples prepared in Example 3;

[0051] Figure 3 Transmission electron micrographs of ionic liquid functionalized eggshell membrane protein solutions prepared in Example 2 (a), Example 3 (b), and Example 4 (c) of the present invention;

[0052] Figure 4 Surface morphology test images (AFM, atomic force microscopy analysis) of ionic liquid functionalized eggshell membrane protein membranes prepared in Example 2 (a), Example 3 (b), and Example 4 (c) of the present invention;

[0053] Figure 5This is a particle size distribution diagram of the ionic liquid functionalized eggshell membrane protein solution prepared in Example 2, Example 3, and Example 4 of the present invention;

[0054] Figure 6 The secondary structure content of the ionic liquid functionalized eggshell membrane protein membrane prepared in Example 2, Example 3, and Example 4 of the present invention;

[0055] Figure 7 The piezoelectric constant of the ionic liquid functionalized eggshell membrane protein membrane prepared in Example 2, Example 3, and Example 4 of the present invention;

[0056] Figure 8 The invention discloses the application of the ionic liquid functionalized eggshell membrane protein film prepared by the invention in the fields of biomedicine, optics and sensing. DETAILED DESCRIPTION

[0057] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] Embodiment 1:

[0059] Figure 1 A schematic flow chart of a method for preparing an ionic liquid functionalized eggshell membrane protein material provided by an exemplary embodiment of the present application is shown, the method comprising:

[0060] Step 1: peeling, cleaning and other pretreatment of the eggshell membrane, and making it into powder by mechanical grinding;

[0061] Step 2: pretreating the eggshell membrane powder with a NaOH solution, and then washing the eggshell membrane to neutrality;

[0062] Step 3: dissolving the pretreated eggshell membrane in an aqueous solution of 3-mercaptopropionic acid and acetic acid, stirring and centrifuging the solution to obtain a clear upper layer, adjusting the pH, collecting a white precipitate, and drying to obtain a soluble eggshell membrane;

[0063] Step 4: adding the dried soluble eggshell membrane powder into the ionic liquid and stirring and dissolving the mixture to obtain an eggshell membrane protein solution;

[0064] Step 5: dialyzing and freeze-drying the eggshell membrane protein solution to obtain the ionic liquid functionalized eggshell membrane protein;

[0065] Step 6: The eggshell membrane protein functionalized with ionic liquid is dissolved in an aqueous solution for static degassing, drying, and cross-linking and immersion in anhydrous ethanol to obtain an eggshell membrane protein film functionalized with ionic liquid.

[0066] Embodiment 2:

[0067] This embodiment provides a method for preparing an ionic liquid functionalized eggshell membrane protein material, and the specific steps are as follows:

[0068] (1) Manually peel the eggshell membrane from the eggshell, rinse thoroughly with distilled water, and dry naturally at room temperature. Grind the dried eggshell membrane into fine particles, seal and store for later use;

[0069] (2) The dried eggshell membrane powder was suspended in a 0.2 mol / L NaOH aqueous solution at a solid-solvent ratio of 1:10, pretreated for 24 h, and the alkali solution was replaced every 6 hours to clean the eggshell membrane until it was neutral to remove foreign proteins in the eggshell membrane;

[0070] (3) dissolving the pretreated eggshell membrane in an aqueous solution of 1.2 mol / L 3-mercaptopropionic acid and 0.5 mol / L acetic acid, stirring and centrifuging the solution to obtain a clear upper layer, adjusting the pH to 5 with 5 mol / L NaOH, collecting the white precipitate, and drying to obtain the desired eggshell membrane protein;

[0071] (4) dissolving the eggshell membrane protein in a ternary solution of CaCl2 / C2H5OH / H2O (molar ratio 1:2:8) and stirring under a magnetic stirrer for 6 h until it is completely dissolved;

[0072] (5) The eggshell membrane protein solution was placed in a constant temperature water bath at 37°C, and the dialyzate was dialyzed in deionized water using a dialysis membrane (cutoff value of 8000Da), and the deionized water was changed every 12 hours. The magnetic stirring speed was 300 rpm. The dialyzate was freeze-dried to obtain the ionic liquid functionalized eggshell membrane protein;

[0073] (6) The eggshell membrane protein functionalized with ionic liquid was dissolved in an aqueous solution to prepare an eggshell membrane protein solution with a mass fraction of 12% (4 ml, cast in a glass culture dish with a diameter of 6 mm, and the prepared membrane thickness was about 1.2 mm). After static degassing, drying, and cross-linking immersion in anhydrous ethanol for 30 minutes, an ionic liquid-functionalized eggshell membrane protein membrane was obtained.

[0074] Embodiment 3:

[0075] This embodiment provides a method for preparing an ionic liquid functionalized eggshell membrane protein material, and the specific steps are as follows:

[0076] (1) Manually peel the eggshell membrane from the eggshell, rinse thoroughly with distilled water, and dry naturally at room temperature. Grind the dried eggshell membrane into fine particles, seal and store for later use;

[0077] (2) The dried eggshell membrane powder was suspended in a 0.2 mol / L NaOH aqueous solution at a solid-solvent ratio of 1:10, pretreated for 24 h, and the alkali solution was replaced every 6 hours to clean the eggshell membrane until it was neutral to remove foreign proteins in the eggshell membrane;

[0078] (3) dissolving the pretreated eggshell membrane in an aqueous solution of 1.2 mol / L 3-mercaptopropionic acid and 0.5 mol / L acetic acid, stirring and centrifuging the solution to obtain a clear upper layer, adjusting the pH to 5 with 5 mol / L NaOH, collecting the white precipitate, and drying to obtain the desired eggshell membrane protein;

[0079] (4) Dissolve the eggshell membrane protein in 1.5 g / ml lithium bromide solution and stir under a magnetic stirrer for 6 h until it is completely dissolved;

[0080] (5) The eggshell membrane protein solution was placed in a constant temperature water bath at 37°C, and the dialyzate was dialyzed in deionized water using a dialysis membrane (cutoff value of 8000Da), and the deionized water was changed every 12 hours. The magnetic stirring speed was 300 rpm. The dialyzate was freeze-dried to obtain the ionic liquid functionalized eggshell membrane protein;

[0081] (6) The eggshell membrane protein functionalized with ionic liquid was dissolved in an aqueous solution to prepare an eggshell membrane protein solution with a mass fraction of 12% (4 ml, cast in a glass culture dish with a diameter of 6 mm, and the prepared membrane thickness was about 1.1 mm). After standing for degassing, drying, and cross-linking and immersion in anhydrous ethanol for 30 minutes, an ionic liquid-functionalized eggshell membrane protein membrane was obtained.

[0082] Embodiment 4:

[0083] This embodiment provides a method for preparing an ionic liquid functionalized eggshell membrane protein material, and the specific steps are as follows:

[0084] (1) Manually peel the eggshell membrane from the eggshell, rinse thoroughly with distilled water, and dry naturally at room temperature. Grind the dried eggshell membrane into fine particles, seal and store for later use;

[0085] (2) The dried eggshell membrane powder was suspended in a 0.2 mol / L NaOH aqueous solution at a solid-solvent ratio of 1:10, pretreated for 24 h, and the alkali solution was replaced every 6 hours to clean the eggshell membrane until it was neutral to remove foreign proteins in the eggshell membrane;

[0086] (3) dissolving the pretreated eggshell membrane in an aqueous solution of 1.2 mol / L 3-mercaptopropionic acid and 0.5 mol / L acetic acid, stirring and centrifuging the solution to obtain a clear upper layer, adjusting the pH to 5 with 5 mol / L NaOH, collecting the white precipitate, and drying to obtain the desired eggshell membrane protein;

[0087] (4) Dissolve the eggshell membrane protein in 0.2 g / ml sodium hypochlorite solution and stir under a magnetic stirrer for 6 h until it is completely dissolved;

[0088] (5) The eggshell membrane protein solution was placed in a constant temperature water bath at 37°C, and the dialyzate was dialyzed in deionized water using a dialysis membrane (cutoff value of 8000Da), and the deionized water was changed every 12 hours. The magnetic stirring speed was 300 rpm. The dialyzate was freeze-dried to obtain the ionic liquid functionalized eggshell membrane protein;

[0089] (6) The eggshell membrane protein functionalized with ionic liquid was dissolved in an aqueous solution to prepare an eggshell membrane protein solution with a mass fraction of 12% (4 ml, cast in a glass culture dish with a diameter of 6 mm, and the prepared membrane thickness was about 1.3 mm). After static degassing, drying, and cross-linking immersion in anhydrous ethanol for 30 minutes, an ionic liquid-functionalized eggshell membrane protein membrane was obtained.

[0090] Test example:

[0091] Figure 2 The scanning electron microscope images of the ionic liquid functionalized eggshell membrane protein membranes prepared in Examples 2, 3 and 4 of the present invention. As can be seen from the figure, the ternary solution of CaCl2 / C2H5OH / H2O has little effect on the microscopic morphology of the eggshell membrane protein, and the surface is relatively flat; after the eggshell membrane protein is treated with lithium bromide solution, the lithium bromide solution has a certain solubility and can dissolve some components in the eggshell membrane protein. And the lithium bromide molecules in the solution will interact with the protein molecules, resulting in the weakening of the bonding between the protein molecules, and then some of the protein components are dissolved in the solution, resulting in the appearance of tiny holes on the surface of the eggshell membrane protein. Sodium hypochlorite has a strong oxidizing property and can destroy the chemical bonds in organic molecules, including peptide bonds in protein molecules. Under the action of sodium hypochlorite, the secondary bonds such as hydrophobic bonds and hydrogen bonds inside the protein molecules are destroyed, so that the protein molecules are transformed from an ordered three-dimensional structure to a disordered coil-like structure, forming gaps and holes. Because the effect of sodium hypochlorite on the membrane surface may not be uniform, but along certain specific paths or directions, resulting in long strips of holes on the surface of the eggshell membrane protein.

[0092] Figure 3Transmission electron microscope images of ionic liquid functionalized eggshell membrane protein solutions prepared in Examples 2, 3 and 4 of the present invention. The length and diameter of the eggshell membrane protein fibers obtained by dissolving silk fibroin with the CaCl2 / C2H5OH / H2O ternary solution are greater than the length and diameter of the eggshell membrane protein fibers obtained by dissolving silk fibroin with lithium bromide and sodium hypochlorite solutions, indicating that CaCl2 has less damage to the dissolution of eggshell membrane protein, and more fibrous structures inside the eggshell membrane protein are retained, which is conducive to the preparation of regenerated eggshell membrane protein materials with excellent performance. After the eggshell membrane protein is treated with lithium bromide solution, the diameter and length of the eggshell membrane protein fibers become smaller, indicating that the lithium bromide solution dissolves some components in the eggshell membrane protein. After being treated with sodium hypochlorite solution, the eggshell membrane protein is decomposed into more fragmented flaky structures.

[0093] Figure 4 The surface morphology test diagram (AFM, atomic force microscope analysis) of the ionic liquid functionalized eggshell membrane protein membrane prepared in Example 2, Example 3, and Example 4 of the present invention. The surface roughness of the eggshell membrane protein membrane functionalized with sodium hypochlorite solution is greater than the surface roughness of the eggshell membrane protein membrane functionalized with lithium bromide and ternary solution. This is also due to the different interactions and effects of the three different ionic liquid solvent systems on eggshell membrane proteins, which is consistent with the microscopic morphology and transmission electron microscopy analysis results of the previous three ionic liquid functionalized eggshell membrane protein membranes.

[0094] Figure 5 The particle size distribution diagram of the ionic liquid functionalized eggshell membrane protein solution prepared in Example 2, Example 3, and Example 4 of the present invention. The average particle sizes of the solutions in Example 2, Example 3, and Example 4 are 31849nm, 12843nm, and 3997nm, respectively, indicating that the CaCl2 / C2H5OH / H2O ternary solution has a smaller effect on protein molecules and a larger molecular particle size; the sodium hypochlorite solution has the greatest damage to protein molecules and has the smallest molecular particle size. This result is also consistent with Figure 4 , Figure 5 The experimental test results are consistent with the analysis.

[0095] Figure 6 The secondary structure test results of the functionalized eggshell membrane protein (prepared in step 5) prepared in Example 2, Example 3, and Example 4 of the present invention. The amide I band in the Fourier spectrum includes α-helix, β-fold, β-turn and random coil structures, which are often used to analyze the secondary structure of proteins. The amide I band was peak fitted and the secondary structure content of each material was quantitatively analyzed. 1640~1655cm -1 α-helix and random coil, 1610~1635cm -1 β-fold, 1660~1700cm -1is a β-turn. As can be seen from the figure, the β-folding contents of Example 2, Example 3 and Example 4 are 31.14%, 36.48% and 41.89% respectively. The addition of calcium chloride increases the ionic strength of the solvent, affecting the interactions between protein molecules, including electrostatic interactions and hydrophobic interactions. Changes in these interactions cause conformational changes in protein molecules, thereby increasing the content of β phase. The bromide ions in lithium bromide can interact with charged groups (such as amino groups and carboxyl groups) on the surface of eggshell membrane proteins. This interaction will change the charge distribution and conformation of the protein, thereby affecting its secondary structure, including the content of β phase. Sodium hypochlorite can oxidize certain amino acid residues in proteins, especially those containing easily oxidized elements such as sulfur and nitrogen. This oxidation may cause the chemical bonds within the protein molecules to break or recombine, thereby changing their conformation.

[0096] Figure 7 The piezoelectric constants of the functionalized eggshell membrane protein films prepared in Examples 2, 3 and 4 of the present invention are tested. The piezoelectric constants d of Example 2 (1.2 mm), Example 3 (1.1 mm) and Example 4 (1.3 mm) are 33 They are 18.53pC / N, 13.75pC / N and 24.12pC / N respectively. The piezoelectric constant is usually closely related to factors such as the crystal structure, charge distribution and intermolecular interaction of the material. The change of the piezoelectric constant of eggshell membrane protein is affected by its secondary structure (such as α-helix, β-fold, etc.) and the interaction between protein molecules. Figure 6 It can be seen that the β-fold content of Example 2, Example 3 and Example 4 is: Example 4> Example 3> Example 2. The arrangement of molecular chains in the β phase enables the material to generate charges more efficiently when subjected to mechanical stress, thereby exhibiting higher piezoelectric properties. As the β-fold content increases, the eggshell membrane protein can generate more charges when subjected to mechanical stress. The accumulation and transmission efficiency of these charges in the material are also improved, resulting in an increase in the piezoelectric constant. Therefore, the piezoelectric constants of Example 2, Example 3 and Example 4 also show a trend similar to the change in β-fold content.

[0097] The present invention combines the functionality of ionic liquids with the biological properties of eggshell membrane proteins to prepare ionic liquid functionalized eggshell membrane protein materials, which can not only inherit the advantages of both, but also produce new synergistic effects, thereby giving the material more excellent performance. The ionic liquid used can improve its solubility and stability through interaction with the eggshell membrane protein, so that the material maintains excellent mechanical properties under a wider range of conditions; the structure of the ionic liquid has greater designability, and its physical and chemical properties are regulated by adjusting the types and structures of anions and cations, thereby achieving precise control of the performance of the eggshell membrane protein material; as a green solvent, the ionic liquid can reduce or avoid the generation and emission of harmful substances during the synthesis and processing of the material, and reduce pollution and damage to the environment; the eggshell membrane protein material functionalized with ionic liquids has improved biocompatibility and piezoelectric properties, and is more suitable for use in biomedicine, tissue engineering, intelligent sensing and other fields.

[0098] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A method for preparing an ionic liquid functionalized eggshell membrane protein material, characterized in that: The following steps are involved: S1. Pre-treat the eggshell membrane powder with NaOH solution and then wash it to neutrality; S2. The eggshell membranes pretreated in step S1 are dissolved in an aqueous solution of 3-mercaptopropionic acid and acetic acid, stirred, and separated into a solid and liquid state, and the upper clear aqueous solution is taken, the pH is adjusted, and the white precipitate is collected and dried to obtain soluble eggshell membranes; S3. The soluble eggshell membrane powder obtained in step S2 is added to the ionic liquid and stirred to dissolve to obtain an eggshell membrane protein solution; S4. The eggshell membrane protein solution obtained in step S3 is dialyzed and freeze-dried to obtain ionic liquid functionalized eggshell membrane protein.

2. The method for preparing the ionic liquid functionalized eggshell membrane protein material according to claim 1, characterized in that: The invention also includes the steps of preparing an ionic liquid functionalized eggshell membrane protein membrane by ionic liquid functionalized eggshell membrane protein; S5. The ionic liquid functionalized eggshell membrane protein obtained in step S4 is dissolved in an aqueous solution and subjected to static degassing, drying, cross-linking and immersion to obtain an ionic liquid functionalized eggshell membrane protein membrane.

3. The method for preparing the ionic liquid functionalized eggshell membrane protein material according to claim 1 or 2, characterized in that: In step S3, the mass ratio of eggshell membrane protein to ionic liquid is 6.0wt%-10wt%.

4. The method for preparing an ionic liquid functionalized eggshell membrane protein material according to claim 1 or 2, characterized in that: In step S3, the ionic liquid is selected from any one of calcium chloride ionic liquid, lithium bromide ionic liquid, and sodium hypochlorite ionic liquid; The solvent system of the calcium chloride ionic liquid contains ethanol and water, the molar ratio of calcium chloride to ethanol is 1:3-1:1; the concentration is 0.3-0.5 g / ml; The lithium bromide ionic liquid is a lithium bromide aqueous solution with a concentration of 0.5-1.5 g / ml; The sodium hypochlorite ionic liquid is a sodium hypochlorite aqueous solution with a concentration of 0.1-0.3 g / ml.

5. The method for preparing the ionic liquid functionalized eggshell membrane protein material according to claim 1 or 2, characterized in that: In step S4, the temperature at which the eggshell membrane protein solution is dialyzed is 35°C-40°C.

6. The method for preparing the ionic liquid functionalized eggshell membrane protein material according to claim 2, characterized in that: In step S5, the dried eggshell membrane protein membrane is cross-linked and impregnated with anhydrous ethanol; And / or, the time of cross-linking and dipping in anhydrous ethanol is 30-40 minutes.

7. The method for preparing an ionic liquid functionalized eggshell membrane protein material according to claim 1 or 2, characterized in that: The eggshell membrane powder in step S1 is obtained by peeling, washing, drying and then mechanically grinding the eggshell membrane; In step S2, the pH is adjusted to 4-5.

8. The ionic liquid functionalized eggshell membrane protein material prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The method comprises the ionic liquid functionalized eggshell membrane protein prepared in step S4, or the ionic liquid functionalized eggshell membrane protein membrane prepared in step S5.

9. Application of the ionic liquid functionalized eggshell membrane protein material according to claim 8 in the fields of biological tissue engineering, intelligent sensing and energy harvesting.

10. The use according to claim 9, characterized in that: Applied to the preparation of flexible thin film sensors and bio-based piezoelectric nanogenerators; Or its application in the preparation of biomedical wound dressings.

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