Bio-based collagen cellulose aerogel and preparation method thereof

Abstract

The invention discloses bio-based collagen cellulose aerogel and a preparation method thereof, relates to the technical field of degradable and renewable bio-based aerogel, and aims to solve the problem of pore collapse after nano-cellulose aerogel is dissolved and regenerated. The bio-based collagen cellulose aerogel is prepared from bio-based collagen and cellulose connected with the bio-based collagen. The cellulose is connected with carboxyl, and the size of the cellulose is less than or equal to 100nn.

Description

Technical Field

[0001] This application relates to the technical field of degradable and renewable biobased aerogels, and particularly relates to a biobased collagen cellulose aerogel and a preparation method thereof. Background Art

[0002] As a novel high-performance material, nanocellulose aerogel has attracted wide attention in the field of materials science with its unique ultra-light, high porosity and multifunctional characteristics, and shows potential in multiple industrial and environmental protection fields.

[0003] However, the traditional nanocellulose aerogel will show the phenomenon of pore collapse after dissolution and regeneration, and is prone to breakage in high-strength use scenarios, which limits its application scope. Summary of the Invention

[0004] The purpose of this application is to provide a biobased collagen cellulose aerogel and a preparation method thereof, aiming to solve the problem of pore collapse that occurs after the dissolution and regeneration of nanocellulose aerogel.

[0005] To achieve the above purpose, this application adopts the following technical solutions:

[0006] In the first aspect, this application provides a biobased collagen cellulose aerogel. The biobased collagen cellulose aerogel includes: biobased collagen and cellulose connected to the biobased collagen. Carboxyl groups are connected to the cellulose, and the size of the cellulose is less than or equal to 100 nn.

[0007] In the biobased collagen cellulose aerogel provided by the embodiments of this application, the flexible three-dimensional skeleton of biobased collagen is complementary to the high-strength characteristics of cellulose, and a hierarchical pore structure can be formed to effectively disperse mechanical stress and reduce local collapse during the regeneration of the biobased collagen cellulose aerogel. At the same time, introducing carboxyl groups on the cellulose can significantly improve its hydrophilicity and enhance the interaction between it and biobased collagen, improve the crosslinking degree of the biobased collagen cellulose aerogel, thereby enhancing its stability during the regeneration process and avoiding pore collapse.

[0008] In addition, the nanoscale cellulose can provide a larger specific surface area and reaction activity, and can crosslink more densely with collagen, so that the internal structure of the biobased collagen cellulose aerogel can be better supported, improving the mechanical properties of the biobased collagen cellulose aerogel, and better maintaining the original pore structure of the biobased collagen cellulose aerogel during regeneration, reducing the probability of pore collapse.

[0009] In some embodiments, the ratio range of the mass of biobased collagen to the mass of cellulose is 0.1 to 0.4.

[0010] In some embodiments, cellulose is connected to bio-based collagen by at least one of hydrogen bonds, π-π stacking, and van der Waals forces.

[0011] In some embodiments, the bio-based collagen cellulose aerogel has three-dimensional oriented pores. The average pore diameter of the three-dimensional oriented pores ranges from 20 nm to 200 nm.

[0012] In a second aspect, the present application provides a method for preparing a bio-based collagen cellulose aerogel. The method for preparing the bio-based collagen cellulose aerogel includes:

[0013] Gelation reaction: Mix a bio-based collagen solution with a carboxylated cellulose solution and carry out a gelation reaction to obtain an initial gel; the size of the cellulose is less than or equal to 100 nn.

[0014] Freezing: Subject the initial gel to directional freezing.

[0015] Drying: Subject the frozen initial gel to freeze-drying to obtain a bio-based collagen cellulose aerogel.

[0016] In some embodiments, in the gelation reaction, the solid content range of the bio-based collagen solution is 0.5% to 1.5%. The solid content range of the cellulose solution is 0.5% to 1.5%.

[0017] The mass ratio range of the bio-based collagen solution to the cellulose solution is 5 to 9:1 to 5.

[0018] In some embodiments, in the gelation reaction, the temperature range of the gelation reaction is 0 to 6°C.

[0019] In some embodiments, the time range of the gelation reaction is 20 h to 30 h.

[0020] In some embodiments, during freezing, the pH value range of the initial gel is 4.5 to 5.0, the directional freezing rate range is 0.5°C / min to 1°C / min, and the time range is 1 h to 5 h.

[0021] In some embodiments, the freeze-drying time range is 25 h to 40 h.

[0022] In some embodiments, in the gelation reaction, an enzymatic hydrolysis process is used to prepare the bio-based collagen solution.

[0023] In some embodiments, in the gelation reaction, the bio-based collagen solution includes at least one of a type I collagen solution, a type II collagen solution, and a type III collagen solution. Description of the Drawings

[0024] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0025] Figure 1 Schematic flow chart of a preparation method for a bio-based collagen cellulose aerogel provided for the embodiments of the present application;

[0026] Figure 2 Display diagrams of the bio-based collagen cellulose aerogels of Examples 1 to 4 of the present application;

[0027] Figure 3 Display diagrams of the bio-based collagen cellulose aerogel and the regenerated bio-based collagen cellulose aerogel of Example 3 of the present application;

[0028] Figure 4 XRD diagrams of the bio-based collagen cellulose aerogel and the regenerated bio-based collagen cellulose aerogel of Example 3 of the present application;

[0029] Figure 5 Compression and rebound curve diagrams of the bio-based collagen cellulose aerogel of Example 3 of the present application under different compression times. Detailed implementation manners

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present application.

[0031] The terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0032] In the embodiments of the present application, the term "comprising", "including" or any other variant thereof is intended to cover a non-exclusive inclusion, such that a process including a series of elements not only includes those elements but also includes other elements not explicitly listed.

[0033] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0034] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any one or more embodiments or examples in a suitable manner.

[0035] As an emerging high-performance material, nanocellulose aerogel has attracted wide attention in the field of materials science and shown potential in multiple industrial and environmental protection fields with its unique ultra-light, high porosity, and multifunctional characteristics. In terms of physical properties, nanocellulose aerogel is characterized by an extremely low density (0.01 g / cm 3 ~0.1 g / cm 3 ) and an extremely high porosity (90% - 99%). Its ultra-light property is comparable to that of air, making it an ideal choice for fields with lightweight requirements such as aerospace. Its porous structure endows excellent thermal insulation performance, with a thermal conductivity of only 0.02 W / (m·K) - 0.05 W / (m·K), which is better than that of traditional polystyrene foam (0.03 = W / (m·K) - 0.041 W / (m·K)), and it has significant competitiveness in building thermal insulation walls, automotive engine compartment coatings, and spacecraft thermal protection systems.

[0036] Exemplarily, in architecture, nanocellulose aerogel can be used as an efficient thermal insulation material to reduce energy consumption.

[0037] Exemplarily, in the aerospace field, nanocellulose aerogel can be used for the thermal protection of spacecraft.

[0038] Exemplarily, in the automotive industry, using its characteristics, nanocellulose aerogel can optimize the design of the engine compartment to improve energy efficiency.

[0039] Exemplarily, in oil pollution control, nanocellulose aerogel can clean up oil spills, efficiently remove contaminants, and improve adsorption efficiency and recycling effect.

[0040] Exemplarily, in the field of flexible electronics, nanocellulose aerogel can be used as the substrate of wearable biosensors.

[0041] Exemplarily, in biomedicine, nanocellulose aerogel can be used as a carrier for controlled drug release.

[0042] Exemplarily, in environmental governance, nanocellulose aerogel can be used as biodegradable packaging to replace traditional plastics.

[0043] Exemplarily, nano-cellulose aerogel can improve soil, enhance water and fertilizer retention, and fertilizer utilization rate in agriculture.

[0044] Therefore, the breakthrough of nano-cellulose aerogel lies in performance optimization, green preparation, and sustainable application. With the reduction of cost and the maturity of technology, it will replace traditional high-pollution and high-energy-consuming materials in more fields.

[0045] However, the traditional nano-cellulose aerogel will experience pore collapse after dissolution and regeneration, and is prone to breakage in high-strength use scenarios, which limits its application scope.

[0046] In some examples, a water-saturated bacterial cellulose film with high water content is prepared from bacterial cellulose synthesized by Gram-negative bacterium Acetobacter xylinum. Although the mechanical properties of this bacterial cellulose film are excellent among natural cellulose fibers, its regeneration performance is poor, facing the problem of material disposal after waste, unable to effectively realize the recycling of resources, and also increasing the potential pressure on the environment, which restricts the popularization and application of the material in some fields with high requirements for sustainable development and resource recycling.

[0047] In some examples, the porosity of the regenerated cellulose aerogel decreases by 35% after the first regeneration, and the compressive strength loss exceeds 50%. The reason is that the network cannot be reconstructed after the covalent bond is broken.

[0048] Exemplarily, the degradable and regenerable cellulose fabric is of great significance in environmental protection, but has defects in mechanical properties and degradation and restoration properties. Mechanically, the interaction between internal cellulose molecules is not stable, and the molecules are prone to slip under external force, with low tensile strength and being prone to breakage in high-strength use scenarios, which limits the application scope; in terms of degradation, under natural or specific conditions, its molecular structure is destroyed and decomposed into small molecules, and the process is irreversible, unable to restore the original shape and performance, not suitable for long-term use or resource recycling scenarios, increasing costs and not conforming to the concept of sustainable development.

[0049] In some examples, for the chitosan-SiO2 aerogel / cellulose polypropylene composite spunlace material, although the material has a certain reusability, the adsorption efficiency decreases with the increase of the number of cycles. The first adsorption rate is about 99.63%, and it drops to about 80.59% after 5 cycles. This means that the ability of the material to treat organic dye wastewater gradually weakens after multiple uses, and may not be able to meet the long-term and efficient wastewater treatment requirements, and it is necessary to frequently replace or regenerate the material, increasing the use cost and operation difficulty.

[0050] Based on this, the embodiments of the present application provide a bio-based collagen cellulose aerogel. The bio-based collagen cellulose aerogel includes: bio-based collagen and cellulose connected to the bio-based collagen. Carboxyl groups are connected to the cellulose, and the size of the cellulose is less than or equal to 100 nn.

[0051] Exemplarily, the size of the cellulose can be 100 nm, 80 nm, 50 nm, 30 nm, 10 nm, etc., and there is no limitation here.

[0052] It can be understood that the flexible three-dimensional skeleton of the biobased collagen is complementary to the high-strength property of the cellulose, and can form a hierarchical pore structure, effectively dispersing mechanical stress and reducing local collapse during the regeneration of the biobased collagen-cellulose aerogel. At the same time, introducing carboxyl groups onto the cellulose can significantly improve its hydrophilicity and enhance the interaction between it and the biobased collagen, increasing the crosslinking degree of the biobased collagen-cellulose aerogel, thereby enhancing its stability during the regeneration process and avoiding pore collapse.

[0053] Moreover, the cellulose with nanoscale size can provide a larger specific surface area and reactivity, and can be more densely crosslinked with the collagen, so that the internal structure of the biobased collagen-cellulose aerogel can be better supported, improving the mechanical properties of the biobased collagen-cellulose aerogel, and being able to better maintain the original pore structure of the biobased collagen-cellulose aerogel during regeneration, reducing the probability of pore collapse.

[0054] In some embodiments, the ratio range of the mass of the biobased collagen to the mass of the cellulose is 0.1 to 0.4.

[0055] Exemplarily, the ratio of the mass of the biobased collagen to the mass of the cellulose can be 0.1, 0.15, 0.20, 0.25, 0.30, 0.35, 0.4, etc., and there is no limitation here.

[0056] Preferably, the ratio of the mass of the biobased collagen to the mass of the cellulose is 0.25.

[0057] It can be understood that the pore structure of the biobased collagen-cellulose aerogel can be optimized by adjusting the ratio of the mass of the biobased collagen to the mass of the cellulose within the above set range, avoiding pore collapse during the regeneration process.

[0058] In some embodiments, the cellulose and the biobased collagen are connected by at least one of hydrogen bonds, π-π stacking, and van der Waals forces.

[0059] It can be understood that the amino or carboxyl groups in the biobased collagen form a hydrogen bond network with the hydroxyl groups in the cellulose, which can significantly enhance the binding strength between the biobased collagen and the cellulose, and further effectively improve the structural integrity of the biobased collagen-cellulose aerogel, preventing pore collapse during the dissolution and regeneration process.

[0060] Aromatic amino acids (such as tyrosine) in bio-based collagen can produce π-π interactions with cellulose, enhancing the molecular orientation stability, promoting the interaction between bio-based collagen and cellulose, and thus enhancing the overall mechanical strength and thermal stability of the bio-based collagen-cellulose aerogel.

[0061] The high specific surface area of nanoscale cellulose (≤100 nm) fills the micro-gaps between bio-based collagen through van der Waals forces, forming small-scale bindings, and thus reducing structural defects.

[0062] Through the action of at least one of hydrogen bonds, π-π stacking and van der Waals forces, the overall strength and toughness of the bio-based collagen-cellulose aerogel can be significantly enhanced.

[0063] In some embodiments, the bio-based collagen-cellulose aerogel has three-dimensional oriented pores. The average pore diameter of the three-dimensional oriented pores ranges from 20 nm to 200 nm.

[0064] Exemplarily, the average pore diameter of the three-dimensional oriented pores can be 20 nm, 50 nm, 150 nm, 180 nm, 200 nm, etc., and there is no limitation here.

[0065] It can be understood that the three-dimensional oriented pores indicate that the shape and arrangement of the internal pores of the bio-based collagen-cellulose aerogel are ordered, usually showing a specific directionality. The pore walls arranged along the pore direction of the three-dimensional oriented pores form a continuous support network, enhancing the compressive strength and tensile strength of the bio-based collagen-cellulose aerogel; moreover, the oriented pores provide a straight-through channel with low resistance, significantly enhancing the efficiency of mass transfer (such as gas adsorption, liquid penetration) or heat conduction. Also, by regulating the pore direction, local stress concentration or pore blockage easily generated by disordered pores can be avoided, and the oriented structure is evenly distributed, reducing defects and enhancing the reliability of the bio-based collagen-cellulose aerogel.

[0066] In addition, the average pore diameter of the above three-dimensional oriented pores in the range of 20 nm to 200 nm can meet various application requirements, especially playing a key role in mass transfer (such as the flow, adsorption and release of gases and liquids), and enabling the interaction between the material and the organism at the cellular level to become more effective.

[0067] In some examples, the preparation method of renewable cellulose foamed aerogel materials has several potential drawbacks: in terms of mechanical properties, improper control of the reaction conditions during the cross-linking process can lead to uneven cross-linking, and high-speed shearing will damage the fiber structure and cause uneven dispersion of cellulose. During the foaming process, fluctuations in the amount of foaming agent or shear rate make the pore size uncontrollable, affecting the structural stability, resilience, mechanical strength, and uniformity of the cellulose foamed aerogel materials; in terms of regeneration performance and environmental protection, chemical reagent residues during the preparation process will affect biodegradability and environmental friendliness, and the use of organic solvents will increase safety risks and treatment costs; as well as the preparation method with high energy consumption, which limits the large-scale production of cellulose foamed aerogel materials and results in low economic efficiency.

[0068] An embodiment of the present application provides a method for preparing a bio-based collagen cellulose aerogel. As Figure 1 shown, the method for preparing the bio-based collagen cellulose aerogel includes: S1 to S3.

[0069] S1: Gelation reaction, mixing the bio-based collagen solution with the carboxylated cellulose solution, and performing a gelation reaction to obtain an initial gel; the size of the cellulose is less than or equal to 100 nn.

[0070] Exemplarily, the bio-based collagen includes at least one of type I collagen solution, type II collagen solution, and type III collagen solution.

[0071] Exemplarily, the type I collagen solution can be a porcine-derived collagen solution, a bovine tendon solution, a fish skin solution, etc.

[0072] Exemplarily, the type II collagen solution can be a chicken breast cartilage solution.

[0073] Exemplarily, the type III collagen solution can be a humanized collagen solution.

[0074] Exemplarily, the temperature range of the gelation reaction is 0 to 6 °C.

[0075] Exemplarily, the temperature of the gelation reaction can be 0 °C, 1 °C, 2 °C, 3 °C, 4 °C, 5 °C, or 6 °C, etc., and there is no limit here.

[0076] Exemplarily, the time range of the gelation reaction is 20 h to 30 h.

[0077] Exemplarily, the time of the gelation reaction can be 20 h, 22 h, 24 h, 26 h, 28 h, or 30 h, etc., and there is no limit here.

[0078] S2: Freezing, subjecting the initial gel to directional freezing.

[0079] Exemplarily, the pH value of the initial gel ranges from 4.5 to 5.0.

[0080] Exemplarily, the pH value of the initial gel can be 4.5, 4.6, 4.7, 4.8, 4.9, 5, etc., without limitation here.

[0081] Exemplarily, the rate of directional freezing ranges from 0.5 °C / min to 1 °C / min.

[0082] Exemplarily, the rate of directional freezing can be 0.5 °C / min, 0.6 °C / min, 0.7 °C / min, 0.8 °C / min, 0.9 °C / min, 1 °C / min, etc., without limitation here.

[0083] Exemplarily, the time of directional freezing ranges from 1 h to 5 h.

[0084] Exemplarily, the time of directional freezing can be 1 h, 2 h, 3 h, 4 h, 5 h, etc., without limitation here.

[0085] S3: Drying. The frozen initial gel is freeze-dried to obtain a bio-based collagen cellulose aerogel.

[0086] Exemplarily, the time of freeze-drying ranges from 25 h to 40 h.

[0087] Exemplarily, the time of freeze-drying can be 25 h, 27 h, 30 h, 35 h, 40 h, etc., without limitation here.

[0088] It can be understood that the gelation reaction in S1 enables the bio-based collagen and cellulose to form a three-dimensional network structure, laying a foundation for subsequent freeze-drying. In S2, the initial gel is frozen in a specific direction (such as the vertical or horizontal direction), enabling the ice crystals to grow along a specific direction to form an oriented pore structure. In S3, the frozen gel is subjected to sublimation drying to remove the ice crystals and retain the porous structure. Freeze-drying avoids the pore collapse caused by surface tension in traditional drying methods and maintains the high porosity and low density of the bio-based collagen cellulose aerogel.

[0089] The porosity of the bio-based collagen cellulose aerogel prepared in this application reaches 98.2%. The mild conditions of the supramolecular method (room temperature, aqueous phase reaction) not only avoid the use of toxic reagents but also retain the triple helix structure of collagen and the crystalline region of cellulose, endowing the material with excellent biological activity and mechanical properties (the compressive modulus reaches 12.5 MPa, which is 3.8 times higher than that of pure cellulose aerogel).

[0090] After five regenerations, the porosity of the regenerated bio-based collagen cellulose aerogel is still >95%, and the compression-recovery rate is >92% (the residual deformation after 100 cycles of compression <8%), while the residual deformation of traditional materials is usually >30% under the same conditions.

[0091] The initial thermal decomposition temperature of the regenerated bio-based collagen cellulose aerogel is maintained above 320 °C (only a decrease of <5%), which is significantly better than that of chemically cross-linked cellulose aerogels (the thermal decomposition temperature decreases by 15% - 20% after regeneration). This performance stability stems from the "self-healing" property of the supramolecular network: the temporary dissociation of non-covalent bonds such as hydrogen bonds during the dissolution process of the bio-based collagen cellulose aerogel does not damage the chemical structure of the molecular chain. When the S2 freezing step and S3 drying step are carried out again, cross-linking points can be re-formed through thermodynamic driving, thereby restoring the original network topology. In contrast, once the chemical bonds of traditional cellulose aerogels (such as chitosan-SiO2 aerogel / cellulose polypropylene composite spunlace materials) are broken, they are irreversible, resulting in a significant attenuation of the regeneration performance. The bio-based collagen cellulose aerogel prepared in this application relies on the dynamic reversible property of supramolecular interactions and exhibits excellent structural recovery ability during the dissolution and regeneration process.

[0092] Here, the specific regeneration method is as follows: The prepared bio-based collagen cellulose aerogel is ultrasonically dispersed in an ice-water bath (0 - 6 °C) for 2 h - 10 h, then ball-milled for 2 h - 8 h to dissolve the prepared bio-based collagen cellulose aerogel, and then dispersed in an acetic acid solution with a concentration of 0.5 mol / L - 1 mol / L. The S2 freezing step and S3 drying step are carried out again to obtain the regenerated bio-based collagen cellulose aerogel.

[0093] In some embodiments, in the S1 gelation reaction, an enzymatic hydrolysis process is used to prepare the bio-based collagen solution.

[0094] In some examples, the bio-based collagen solution can be prepared through the following steps (1) - (5).

[0095] Step (1): The bio-based collagen raw material soaked in acetic acid solution under the condition of 0 - 6 °C is separated to obtain a first supernatant and a first solid. Then the first solid is minced and mixed with the first supernatant to obtain a first mixture.

[0096] Exemplarily, the bio-based collagen source can be subjected to defatting and depilation treatment to remove hair and fat, then washed with distilled water to remove residual depilatory and other impurities, and then soaked in acetic acid (CH3COOH) solution to help soften the skin particles and promote subsequent mechanical mincing and enzymatic hydrolysis.

[0097] Exemplarily, the temperature for soaking in the acetic acid solution can be 0, 1 °C, 3 °C, 5 °C, 6 °C, etc., and there is no limitation here.

[0098] Step (2): Add pepsin to the first mixture and stir. Stir and enzymatically hydrolyze at 0-6 °C for 48 h-96 h to obtain a second mixture.

[0099] Step (3): Freeze and centrifuge the second mixture to obtain a second supernatant.

[0100] Step (4): Add a salt solution to the second supernatant for salting out at a pH range of 7-8 to obtain a third mixture.

[0101] Step (5): Centrifuge the third mixture to obtain a second solid, and dissolve the second solid in an acetic acid solution to obtain a bio-based collagen solution.

[0102] It can be understood that pepsin hydrolyzes the protein of the bio-based collagen source to obtain a second mixture. Freezing and centrifuging removes the solid residues and impurities that are not completely enzymatically hydrolyzed in the second mixture to obtain a second supernatant. Then, salting out is carried out on the second supernatant under near-neutral conditions, so that collagen will precipitate at the salt concentration. Then, centrifugation is carried out to separate the salted-out collagen precipitate (the second solid). Dissolving the second solid in an acetic acid solution helps the stability and dissolution of collagen.

[0103] Here, steps (3) and (4) can also be cycled to improve the purity of collagen, and at the same time, washing with distilled water is carried out to remove residual salts and other impurities.

[0104] In some embodiments, in the S1 gelation reaction, the solid content range of the bio-based collagen solution is 0.5%-1.5%.

[0105] Exemplarily, the solid content of the bio-based collagen solution can be 0.5%, 0.75%, 1%, 1.25%, 1.5%, etc., and there is no limitation here.

[0106] The solid content range of the cellulose solution is 0.5%-1.5%.

[0107] Exemplarily, the solid content of the cellulose solution can be 0.5%, 0.75%, 1%, 1.25%, 1.5%, etc., and there is no limitation here.

[0108] The mass ratio range of the bio-based collagen solution to the cellulose solution is 5-9:1-5.

[0109] Exemplarily, the mass ratio of the bio-based collagen solution to the cellulose solution can be 9:1, 8:2, 7:3, 6:4, 5:5, etc., and there is no limitation here.

[0110] Understandably, through the above settings, the skeletal support between bio-based collagen and cellulose can be balanced.

[0111] Example 1

[0112] Example 1 provides a bio-based collagen cellulose aerogel. The preparation method of the bio-based collagen cellulose aerogel includes the following steps (1) to (4).

[0113] (1) Wash the dehaired and degreased skin particles with distilled water, soak them in acetic acid solution at 4°C, pour out the supernatant, mechanically crush the soaked skin particles, transfer the fully crushed skin particles into the previously poured out supernatant, add pepsin and stir evenly, and place them in an environment at 4°C with intermittent stirring for enzymatic hydrolysis for 72 h.

[0114] (2) Place the mixture obtained by enzymatic hydrolysis in a refrigerated centrifuge for refrigerated centrifugation, and take the supernatant. Adjust the pH = 7 with NaOH solution, add NaCl solution for salting out. Centrifuge again, discard the supernatant, dissolve the precipitate in acetic acid solution and repeat the previous steps for further purification. Finally, briefly wash the obtained collagen precipitate with distilled water and dissolve it in a certain amount of acetic acid solution for standby.

[0115] (3) Mix the bio-based collagen prepared by enzymatic hydrolysis and the carboxylated nanofibrillated cellulose solution in a ratio of 9:1. The collagen and cellulose are evenly mixed under mechanical stirring, and the mixed solution is placed in a low-temperature environment (4°C) for gelation reaction for 25 h.

[0116] Exemplarily, the cellulose is an aqueous dispersion of cotton fibers with a solid content of 1%.

[0117] Exemplarily, the bio-based collagen is an acetic acid solution of porcine-derived collagen with a solid content of 1%.

[0118] (4) Place the copper stage in liquid nitrogen solution to cool it sufficiently, keep the surrounding environment temperature stable, place the gelated sample on the copper stage to freeze it directionally for 3 h. Subsequently, place the directionally gelled sample with ice microcrystals filled in the pores in a freeze dryer, and freeze-dry the frozen gel in a low-pressure environment for 20 h to finally obtain the bio-based collagen cellulose aerogel.

[0119] As Figure 2 Figure A shows the bio-based collagen cellulose aerogel of Example 1. It can be seen that the bio-based collagen cellulose aerogel presents a white porous structure without collapse and shrinkage.

[0120] Example 2

[0121] Example 2 provides a bio-based collagen cellulose aerogel. The preparation method of the bio-based collagen cellulose aerogel includes the following steps (1) to (4).

[0122] (1) Wash the dehaired and degreased skin particles with distilled water, soak them in acetic acid solution at 0 °C, pour out the supernatant, mechanically crush the soaked skin particles, transfer the fully crushed skin particles into the previously poured out supernatant, add pepsin and stir evenly, and place them in an environment at 0 °C for intermittent stirring and enzymatic hydrolysis for 48 h.

[0123] (2) Place the mixture obtained by enzymatic hydrolysis in a refrigerated centrifuge for refrigerated centrifugation, and take the supernatant. Adjust the pH = 7 with NaOH solution, and add NaCl solution for salting out. Centrifuge again, discard the supernatant, dissolve the precipitate in acetic acid solution and repeat the previous steps for further purification. Finally, briefly wash the obtained collagen precipitate with distilled water and dissolve it in a certain amount of acetic acid solution for standby.

[0124] (3) Mix the bio-based collagen prepared by enzymatic hydrolysis and the carboxylated nanofibrillated cellulose solution in a ratio of 8:2. The collagen and cellulose are evenly mixed under mechanical stirring, and the mixed solution is placed in a low-temperature environment (0 °C) for gelation reaction for 20 h.

[0125] Exemplarily, the cellulose is an aqueous dispersion of cotton fibers with a solid content of 1%.

[0126] Exemplarily, the bio-based collagen is an acetic acid solution of porcine-derived collagen with a solid content of 1%.

[0127] (4) Place the copper stage in liquid nitrogen solution to cool it sufficiently, keep the surrounding environmental temperature stable, place the gelation sample on the copper stage for directional freezing and icing for 1 h. Subsequently, place the directional gel with ice microcrystals filled in the pores in a freeze dryer, and freeze-dry the frozen gel in a low-pressure environment for 25 h to finally obtain the bio-based collagen cellulose aerogel.

[0128] As Figure 2 In B of, which is the display diagram of the bio-based collagen cellulose aerogel of Example 2, it can be seen that the bio-based collagen cellulose aerogel presents a white porous structure, without collapse and shrinkage phenomena, and the surface pore distribution is denser and more uniform, and the surface smoothness increases.

[0129] Example 3

[0130] Example 3 provides a bio-based collagen cellulose aerogel. The preparation method of the bio-based collagen cellulose aerogel includes the following steps (1) to (4).

[0131] (1) Wash the pretreated skin particles after hair removal and degreasing with distilled water, soak them in acetic acid solution at 4°C, pour out the upper clear liquid, mechanically crush the soaked skin particles, transfer the fully crushed skin particles into the previously poured upper clear liquid, add pepsin and stir evenly, and place them in a 4°C environment with intermittent stirring for enzymatic hydrolysis for 72 h.

[0132] (2) Place the mixture obtained by enzymatic hydrolysis in a refrigerated centrifuge for refrigerated centrifugation, and take the upper clear liquid. Adjust the pH = 7 with NaOH solution, add NaCl solution for salting out. Centrifuge again, discard the upper clear liquid, dissolve the precipitate in acetic acid solution and repeat the previous steps for further purification. Finally, briefly wash the obtained collagen precipitate with distilled water and dissolve it in a certain amount of acetic acid solution for standby.

[0133] (3) Mix the bio-based collagen prepared by the enzymatic method and the carboxylated nanocellulose solution in a ratio of 7:3. The collagen and cellulose are evenly mixed under mechanical stirring, and the mixed solution is placed in a low-temperature environment (4°C) for gelation reaction for 20 h.

[0134] Exemplarily, the cellulose is an aqueous dispersion of cotton fibers with a solid content of 1%.

[0135] Exemplarily, the bio-based collagen is an acetic acid solution of porcine-derived collagen with a solid content of 1%.

[0136] (4) Place the copper stage in liquid nitrogen solution to cool it sufficiently, keep the surrounding environmental temperature stable, place the gelated sample on the copper stage to freeze it directionally for 2 h. Subsequently, place the directionally gelated sample with ice microcrystals filled in the pores in a freeze dryer, and freeze-dry the frozen gel in a low-pressure environment for 30 h to finally obtain the bio-based collagen cellulose aerogel.

[0137] As Figure 2 In the figure, C is the display diagram of the bio-based collagen cellulose aerogel of Example 3. It can be seen that the bio-based collagen cellulose aerogel presents a white porous structure, without collapse and shrinkage phenomena, and the surface pore distribution is dense and uniform, the surface is flat and smooth, and the void distribution is uniform and dense, and the three-dimensional skeleton network structure is stable.

[0138] Example 4

[0139] Example 4 provides a bio-based collagen cellulose aerogel, and the preparation method of the bio-based collagen cellulose aerogel includes the following steps (1) to (4).

[0140] (1) Wash the pretreated dehaired and degreased skin particles with distilled water, soak them in acetic acid solution at 6 °C, pour out the supernatant, mechanically crush the soaked skin particles, transfer the fully crushed skin particles into the previously poured-out supernatant, add pepsin and stir evenly, and place them in an environment at 6 °C with intermittent stirring for enzymatic hydrolysis for 96 h.

[0141] (2) Place the mixture obtained by enzymatic hydrolysis in a refrigerated centrifuge for refrigerated centrifugation, and take the supernatant. Adjust the pH = 8 with NaOH solution, add NaCl solution for salting out. Centrifuge again, discard the supernatant, dissolve the precipitate in acetic acid solution and repeat the previous steps for further purification. Finally, briefly wash the obtained collagen precipitate with distilled water and dissolve it in a certain amount of acetic acid solution for standby.

[0142] (3) Mix the bio-based collagen prepared by enzymatic hydrolysis and the carboxylated nanocellulose solution in a ratio of 5:5. The collagen and cellulose are evenly mixed under mechanical stirring, and the mixed solution is placed in a low-temperature environment (6 °C) for gelation reaction for 30 h.

[0143] Exemplarily, the cellulose is an aqueous dispersion of cotton fibers with a solid content of 1%.

[0144] Exemplarily, the bio-based collagen is an acetic acid solution of porcine-derived collagen with a solid content of 1%.

[0145] (4) Place the copper stage in liquid nitrogen solution to cool it sufficiently, keep the surrounding environmental temperature stable, place the gelated sample on the copper stage to freeze it directionally for 5 h. Subsequently, place the directionally gelated sample with ice microcrystals filled in the pores in a freeze dryer, and freeze-dry the frozen gel in a low-pressure environment for 40 h to finally obtain the bio-based collagen cellulose aerogel.

[0146] As Figure 2 shown in D of Example 4, which is a display diagram of the bio-based collagen cellulose aerogel, it can be seen that the bio-based collagen cellulose aerogel presents a white porous structure without collapse and shrinkage.

[0147] Performance detection

[0148] Redisperse the bio-based collagen cellulose aerogel of Example 3 in 0.5 mol / L acetic acid solution by combining ultrasonic dispersion and mechanical grinding, and obtain a regenerated bio-based collagen cellulose aerogel through directional freezing and freeze-drying.

[0149] As Figure 3 shown, Figure 3 A in Example 3 is a display diagram of the bio-based collagen cellulose aerogel, Figure 3Figure B in it is a display diagram of the regenerated bio-based collagen cellulose aerogel of Example 3. It can be seen that the surface of the bio-based collagen cellulose aerogel is smooth and dense, without the phenomena of collapse and large pore aggregation. The surface of the regenerated bio-based collagen cellulose aerogel also presents a dense porous structure. From the surface morphology, there is no significant difference between it and the bio-based collagen cellulose aerogel, which proves that the bio-based collagen cellulose aerogel has excellent renewable performance.

[0150] As Figure 4 Figure XRD of the bio-based collagen cellulose aerogel of Example 3 and the regenerated bio-based collagen cellulose aerogel of Example 3. It can be seen that the diffraction peaks representing the (200) and (004) crystal planes of carboxymethyl cellulose (CNF) appear at 2θ = 27.7° and 31.9° for the bio-based collagen cellulose aerogel, respectively. And the large broad peak between 10° and 26° represents the semi-crystalline peak of bio-based collagen, which proves that bio-based collagen is an amorphous natural polymer. The diffraction peak positions of the regenerated bio-based collagen cellulose aerogel highly coincide with those of the bio-based collagen cellulose aerogel, and the characteristic peak intensities do not show significant attenuation, indicating that the dissolution and regeneration do not damage the crystal structure of the cellulose / collagen aerogel sample.

[0151] The compression resilience test of the bio-based collagen cellulose aerogel of Example 3 was carried out through uniaxial compression test, and the compression and resilience tests were carried out 5 times, 50 times and 100 times respectively. As Figure 5 Figure Compression and resilience curve of the bio-based collagen cellulose aerogel of Example 3 under different numbers of compressions. It can be seen that the bio-based collagen cellulose aerogel only shows linear elastic properties at low strains (less than 6%), and the yield stress cannot be detected at high strains, which is in line with the typical deformation behavior of porous materials. And the bio-based collagen cellulose aerogel shows excellent compression and resilience performance. After 100 times of compression and resilience tests under the stress of 19.85 kPa, its cyclic curve still remains basically stable.

[0152] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed in this application can easily think of changes or substitutions, which should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A bio-based collagen cellulose aerogel, characterized in that, Comprising: Bio-based collagen and cellulose connected to the bio-based collagen; carboxyl groups are connected to the cellulose, and the size of the cellulose is less than or equal to 100 nn.

2. The bio-based collagen cellulose aerogel according to claim 1, wherein The ratio range of the mass of the bio-based collagen to the mass of the cellulose is 0.1 - 0.

4.

3. The bio-based collagen cellulose aerogel according to claim 2, wherein The cellulose is connected to the bio-based collagen by at least one of hydrogen bonds, π-π stacking, and van der Waals forces.

4. The bio-based collagen cellulose aerogel according to claim 1, wherein The bio-based collagen cellulose aerogel has three-dimensional oriented pores; The range of the average pore diameter of the three-dimensional oriented pores is 20 nm - 200 nm.

5. A preparation method of a bio-based collagen cellulose aerogel, characterized in that, Comprising: Gelation reaction, mixing a bio-based collagen solution and a carboxylated cellulose solution, and performing a gelation reaction to obtain an initial gel; The size of the cellulose is less than or equal to 100 nn; Freezing, subjecting the initial gel to directional freezing; Drying, subjecting the frozen initial gel to freeze-drying to obtain the bio-based collagen cellulose aerogel.

6. The preparation method of the bio-based collagen cellulose aerogel according to claim 5, characterized in that In the gelation reaction, the solid content range of the bio-based collagen solution is 0.5% - 1.5%; the solid content range of the cellulose solution is 0.5% - 1.5%; The mass ratio range of the bio-based collagen solution to the cellulose solution is 5 - 9:1 - 5.

7. The preparation method of the bio-based collagen cellulose aerogel according to claim 5, characterized in that In the gelation reaction, the temperature range of the gelation reaction is 0 - 6°C; and / or, The time range of the gelation reaction is 20 h - 30 h.

8. The preparation method of the bio-based collagen cellulose aerogel according to claim 5, characterized in that, In the freezing process, the pH value range of the initial gel is 4.5 - 5.0, the directional freezing rate range is 0.5°C / min - 1°C / min, and the time range is 1 h - 5 h; and / or, The time range of the freeze-drying is 25 h - 40 h.

9. The preparation method of the bio-based collagen cellulose aerogel according to claim 5, wherein, In the gelation reaction, an enzymatic hydrolysis process is used to prepare the bio-based collagen solution.

10. The preparation method of the bio-based collagen cellulose aerogel according to claim 5, characterized in that, In the gelation reaction, the bio-based collagen solution includes at least one of type I collagen solution, type II collagen solution, and type III collagen solution.

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