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

Abstract

The application discloses an ionic liquid functionalized eggshell membrane protein material and a preparation method and application thereof, and belongs to the technical field of biological piezoelectric materials. The eggshell membrane is pretreated and then grinded into powder; the eggshell membrane powder is treated with a NaOH solution and then cleaned to neutral; the eggshell membrane powder is dissolved in an aqueous solution of 3-mercaptopropionic acid and acetic acid to react, the pH is adjusted to an isoelectric point, and a precipitate is collected and dried to obtain soluble eggshell membrane; the soluble eggshell membrane is added into ionic liquid and fully stirred and dissolved to obtain an eggshell membrane protein solution; dialysis and freeze-drying are performed to obtain ionic liquid functionalized eggshell membrane protein; and the ionic liquid functionalized eggshell membrane protein is redissolved in an aqueous solution, subjected to static defoaming, dried, and immersed in anhydrous ethanol for cross-linking to obtain an ionic liquid functionalized eggshell membrane protein film. The eggshell membrane protein film prepared by the application has good mechanical properties, high thermal stability and piezoelectricity, and the degradable protein material can be applied to the fields of biological tissue engineering, intelligent sensing and energy collection.

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 a key driver of scientific and technological progress. As a new type of green solvent, ionic liquids, due to their unique physicochemical properties, such as extremely low vapor pressure, high thermal stability, excellent solvency, and designability, have broad application prospects in fields such as electrochemistry, electroanalysis, and materials science. The functionalization of ionic liquids is primarily achieved by introducing specific functional groups or structural units to enrich their physicochemical properties and enhance their 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, primarily derived from the inner membrane of the eggshell, is a natural polymer rich in collagen and other bioactive components. It possesses a range of excellent bioactivities and functionalities, including protein, collagen, chondroitin sulfate, and hyaluronic acid, which significantly contribute to joint health and skin care. It not only exhibits excellent biocompatibility and biodegradability, but also possesses mechanical strength and toughness.

[0005] Due to its excellent biocompatibility and biodegradability, eggshell membrane protein films can be used as drug carriers, facilitating effective drug release within the body and improving drug targeting and bioavailability. Eggshell membranes are rich in components such as collagen, which play an important role in promoting wound healing. Therefore, eggshell membrane protein films can be used as wound dressings to accelerate wound healing. In tissue engineering, eggshell membrane protein films can serve as scaffolds, providing a suitable environment for cell growth and promoting tissue regeneration and repair. The high light transmittance of eggshell membrane protein films makes them promising for applications in optics. For example, they can be used as optical films in the manufacture of products such as lenses and solar panels, enhancing their optical performance. Electronic packaging materials: The high insulating properties of eggshell membrane protein films make them an ideal choice for electronic packaging, effectively protecting electronic components from environmental influences. With the advancement of technology, wearable devices are attracting increasing attention. The flexibility and breathability of eggshell membrane protein films make them advantageous in the manufacture of wearable devices, enabling a better human-computer interaction experience.

[0006] These properties give eggshell membrane protein broad application potential in biomedicine, food packaging, environmental protection, and other fields. For example, in the biomedicine field, eggshell membrane protein can be used to prepare tissue engineering scaffolds and drug carriers. In food packaging, its biodegradability and biocompatibility make it an ideal choice for green packaging materials.

[0007] However, their original performance may not fully meet the needs of specific applications. Traditional solvents often have volatility and toxicity problems 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 and application of an ionic liquid functionalized eggshell membrane protein material.

[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 dried to obtain a soluble eggshell membrane; the dried soluble eggshell membrane powder is added to an ionic liquid and 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, allowed to stand for degassing, dried, and cross-linked and impregnated 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. The upper clear aqueous solution is collected, 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 and dissolved to obtain an eggshell membrane protein solution;

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

[0016] Furthermore, the preparation method further comprises 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 and allowed to stand for degassing, drying, cross-linking and impregnation 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 6.0 wt%-10 wt%.

[0019] Furthermore, 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] Furthermore, in step S5, the dried eggshell membrane protein membrane is cross-linked and impregnated with anhydrous ethanol;

[0026] Furthermore, the time of cross-linking and dipping in anhydrous ethanol 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 membranes;

[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: The eggshell membrane is pre-treated by peeling, cleaning, etc., and then made into powder by mechanical grinding;

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

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

[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 ionic liquid-functionalized eggshell membrane protein;

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

[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 ionic liquid-functionalized eggshell membrane protein film is 1.5-2 mm.

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

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

[0041] Furthermore, it can be 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 fields such as 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 its 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 The figure is a schematic diagram of a process for preparing an ionic liquid functionalized eggshell membrane protein material;

[0050] Figure 2 Scanning electron micrographs 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 Examples 2, 3, and 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 relates to the application of the ionic liquid functionalized eggshell membrane protein membrane prepared by the present invention in the fields of biomedicine, optics and sensing. DETAILED DESCRIPTION

[0057] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. 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 making creative efforts are within the scope of protection of the present invention.

[0058] Example 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: The eggshell membrane is pre-treated by peeling, cleaning, etc., and then made into powder by mechanical grinding;

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

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

[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 ionic liquid-functionalized eggshell membrane protein;

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

[0066] Example 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 membranes from the eggshell, rinse thoroughly with distilled water, and allow to dry naturally at room temperature. Grind the dried eggshell membranes 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 and pretreated for 24 h. The alkaline solution was replaced every 6 h to clean the eggshell membrane until it was neutral to remove impurities in the eggshell membrane.

[0070] (3) The pretreated eggshell membranes were dissolved in an aqueous solution of 1.2 mol / L 3-mercaptopropionic acid and 0.5 mol / L acetic acid, stirred and centrifuged to obtain a clear upper aqueous solution, which was adjusted to pH 5 with 5 mol / L NaOH. The white precipitate was collected and dried to obtain the desired eggshell membrane protein;

[0071] (4) The eggshell membrane protein was dissolved in a ternary solution of CaCl2 / C2H5OH / H2O (molar ratio 1:2:8) and stirred under a magnetic stirrer for 6 h until 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 8000 Da). The deionized water was changed every 12 hours and the magnetic stirring speed was 300 rpm. The dialyzate was freeze-dried to obtain the ionic liquid functionalized eggshell membrane protein;

[0073] (6) The ionic liquid-functionalized eggshell membrane protein 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 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.

[0074] Example 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 membranes from the eggshell, rinse thoroughly with distilled water, and allow to dry naturally at room temperature. Grind the dried eggshell membranes 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 and pretreated for 24 h. The alkaline solution was replaced every 6 h to clean the eggshell membrane until it was neutral to remove impurities in the eggshell membrane.

[0078] (3) The pretreated eggshell membranes were dissolved in an aqueous solution of 1.2 mol / L 3-mercaptopropionic acid and 0.5 mol / L acetic acid, stirred and centrifuged to obtain a clear upper aqueous solution, which was adjusted to pH 5 with 5 mol / L NaOH. The white precipitate was collected and dried 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 8000 Da). The deionized water was changed every 12 hours and the magnetic stirring speed was 300 rpm. The dialyzate was freeze-dried to obtain the ionic liquid functionalized eggshell membrane protein;

[0081] (6) The ionic liquid-functionalized eggshell membrane protein 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] Example 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 membranes from the eggshell, rinse thoroughly with distilled water, and allow to dry naturally at room temperature. Grind the dried eggshell membranes 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 and pretreated for 24 h. The alkaline solution was replaced every 6 h to clean the eggshell membrane until it was neutral to remove impurities in the eggshell membrane.

[0086] (3) The pretreated eggshell membranes were dissolved in an aqueous solution of 1.2 mol / L 3-mercaptopropionic acid and 0.5 mol / L acetic acid, stirred and centrifuged to obtain a clear upper aqueous solution, which was adjusted to pH 5 with 5 mol / L NaOH. The white precipitate was collected and dried 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 8000 Da). The deionized water was changed every 12 hours and the magnetic stirring speed was 300 rpm. The dialyzate was freeze-dried to obtain the ionic liquid functionalized eggshell membrane protein;

[0089] (6) The ionic liquid functionalized eggshell membrane protein 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 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.

[0090] Test example:

[0091] Figure 2 Scanning electron micrographs of ionic liquid-functionalized eggshell membrane protein films prepared in Examples 2, 3, and 4 of the present invention. As can be seen from the figure, the CaCl2 / C2H5OH / H2O ternary solution has little effect on the microscopic morphology of the eggshell membrane protein, resulting in a relatively smooth surface. After the eggshell membrane protein is treated with a lithium bromide solution, the lithium bromide solution has a certain solubility capacity and is able to dissolve some of the components of the eggshell membrane protein. Furthermore, the lithium bromide molecules in the solution interact with the protein molecules, weakening the bonding between the protein molecules and causing some protein components to dissolve in the solution, resulting in the appearance of tiny pores on the surface of the eggshell membrane protein. Sodium hypochlorite has strong oxidizing properties and can break chemical bonds in organic molecules, including peptide bonds in protein molecules. Under the action of sodium hypochlorite, secondary bonds such as hydrophobic bonds and hydrogen bonds within the protein molecules are destroyed, causing the protein molecules to transform from an ordered three-dimensional structure to a disordered, coiled structure, forming voids and pores. Because the effect of sodium hypochlorite on the membrane surface may not be uniform, but rather proceeds along certain specific paths or directions, resulting in long strips of holes on the surface of the eggshell membrane protein.

[0092] Figure 3Transmission electron micrographs 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 in a ternary solution of CaCl2 / C2H5OH / H2O are both greater than those obtained by dissolving silk fibroin in a solution of lithium bromide and sodium hypochlorite. This indicates that CaCl2 has less detrimental effect on the dissolution of the eggshell membrane protein, preserving more of the fibrous structure within the eggshell membrane protein. This is beneficial for preparing regenerated eggshell membrane protein materials with excellent performance. After treatment with lithium bromide solution, the diameter and length of the eggshell membrane protein fibers decrease, indicating that the lithium bromide solution dissolves some of the components of the eggshell membrane protein. After treatment with sodium hypochlorite solution, the eggshell membrane protein is broken down into more fragmented, flaky structures.

[0093] Figure 4 Figure 3 shows the surface morphology of ionic liquid-functionalized eggshell membrane protein membranes prepared in Examples 2, 3, and 4 of the present invention (AFM analysis). The surface roughness of the eggshell membrane protein membranes functionalized with sodium hypochlorite solution was greater than that of the membranes functionalized with lithium bromide and the ternary solution. This is due to the different interactions and effects of the three different ionic liquid solvent systems on eggshell membrane proteins, which is consistent with the micromorphology and transmission electron microscopy results of the three previous 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 proteins (prepared in step 5) prepared in Examples 2, 3, and 4 of the present invention are shown. The amide I band in the Fourier spectrum includes α-helix, β-sheet, β-turn, and random coil structures, which are commonly used to analyze the secondary structure of proteins. The amide I band was subjected to peak fitting, and the secondary structure content of each material was quantitatively analyzed. 1640-1655 cm -1 α-helix and random coil, 1610~1635cm -1 β-folding, 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 promote 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 changes 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 were measured. 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 As can be seen, the β-sheet content of Examples 2, 3, and 4 follows the order: Example 4 > Example 3 > Example 2. The molecular chain arrangement within the β phase enables the material to more efficiently generate charge when subjected to mechanical stress, resulting in higher piezoelectric properties. With increasing β-sheet content, eggshell membrane protein generates more charge when subjected to mechanical stress. The accumulation and transfer efficiency of these charges within the material also improves, leading to an increase in the piezoelectric constant. Therefore, the piezoelectric constants of Examples 2, 3, and 4 also exhibit a similar trend to the changes in β-sheet 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. This material not only inherits the advantages of both, but also may produce new synergistic effects, thereby giving the material even better performance. The ionic liquid used can improve its solubility and stability through interaction with the eggshell membrane protein, allowing the material to maintain excellent mechanical properties under a wider range of conditions. The structure of the ionic liquid has great designability, and its physical and chemical properties can be regulated by adjusting the type and structure 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 material synthesis and processing process, reducing pollution and damage to the environment. The eggshell membrane protein material functionalized with ionic liquid has improved biocompatibility and piezoelectric properties, making it more suitable for use in biomedicine, tissue engineering, and intelligent sensing.

[0098] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined 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. The upper clear aqueous solution is collected, 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 and dissolved to obtain an eggshell membrane protein solution; S4. The eggshell membrane protein solution obtained in step S3 was dialyzed and freeze-dried to obtain ionic liquid-functionalized eggshell membrane protein; In step S3, the ionic liquid is selected from any one of lithium bromide ionic liquid and sodium hypochlorite ionic liquid; 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.

2. The method for preparing the ionic liquid functionalized eggshell membrane protein material according to claim 1, characterized in that: The method further includes the steps of preparing an ionic liquid functionalized eggshell membrane protein membrane from an ionic liquid functionalized eggshell membrane protein membrane; S5. The ionic liquid-functionalized eggshell membrane protein obtained in step S4 is dissolved in an aqueous solution and allowed to stand for degassing, drying, cross-linking and impregnation 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 the eggshell membrane protein to the ionic liquid is 6.0 wt%-10 wt%.

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

5. 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.

6. 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 prepared by peeling, washing, drying and then mechanically grinding the eggshell membranes; In step S2, the pH is adjusted to 4-5.

7. The ionic liquid functionalized eggshell membrane protein material prepared by the preparation method according to any one of claims 1 to 6, 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.

8. Use of the ionic liquid functionalized eggshell membrane protein material according to claim 7 in the preparation of biological tissue engineering products, intelligent sensing products and energy harvesting products.

9. The use according to claim 8, 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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