A chitosan-protein biomimetic composite based on hot melt processing and a preparation method and application thereof

Abstract

The application belongs to the technical field of natural polymer materials, and discloses a chitosan-protein biomimetic composite material based on hot melt processing, and a preparation method and application thereof.The preparation method comprises the following steps: mixing chitosan, protein, tannic acid, metal oxide and a protonating agent to obtain a mixed system; and sequentially performing hot melt processing and hot press forming on the mixed system to obtain the chitosan-protein biomimetic composite material; and the hot melt processing is performed under a closed condition.The application utilizes the coordination action of the metal oxide and the tannic acid in combination with the electrostatic interaction of the chitosan-protein, maximizes the reaction between the components through the high temperature and high shear action of the hot melt processing process, thereby forming a functional metal-phenolic network, and enhancing the performance of the chitosan-protein biomimetic composite material, so that the chitosan-based composite material has excellent mechanical properties and ultraviolet resistance and antibacterial properties.

Description

Technical Field

[0001] This invention relates to the field of natural polymer materials technology, and in particular to a chitosan-protein biomimetic composite material based on thermal melting processing, its preparation method and application. Background Technology

[0002] Currently, the main methods for preparing chitosan-based composite materials include direct blending, directional freeze-thaw, layer-by-layer lamination, and self-assembly. Reference 1 (Song F, Kong Y, Shao C, et al. Chitosan-based multifunctional flexible hemostatic bio-hydrogel[J]. Acta biomaterialia, 2021, 136: 170-183.) discloses a direct blending method for preparation; Reference 2 (Gao H, Zhu Y, Mao L, et al. Super-elastic and fatigue-resistant carbon material with lamellar multi-arch microstructure[J]. Nature communications, 2016, 7(1): 12920.) discloses a directional freeze-thaw method for preparation; Reference 3 (Fang Y, Liu X, Zheng H, et al. Bio-inspired fabrication of nacre-mimetic hybrid nanocoating for eco-friendly fire-resistant precious cellulosic Chinese Xuan paper[J]. Carbohydrate Polymers, 2020, 235: 115782.) discloses a layer-by-layer lamination method for preparation; Reference 4 (Xie H, Lai X, Wang Y, et al. Agreen An approach to fabricating nacre-inspired nanocoating for super-efficiently fire-safe polymers via one-step self-assembly [J]. Journal of Hazardous Materials, 2019, 365: 125-136) discloses a self-assembly method for preparing such polymers.

[0003] However, most of the methods mentioned above for preparing chitosan-based composites are solution-based. Solution methods not only consume large amounts of solvent, but most schemes remain at the experimental stage and cannot be used for large-scale industrial production. More importantly, solution methods require a high level of interaction between reactants; incomplete contact or incomplete reaction can lead to non-uniform structures in the composite material, thus affecting its mechanical properties. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing chitosan-protein biomimetic composite materials based on thermal melting processing, which solves the problem that solution-based preparation of chitosan-based composite materials easily leads to structural inhomogeneity and thus affects mechanical properties.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing a chitosan-protein biomimetic composite material based on thermal melt processing, comprising the following steps:

[0007] (1) Chitosan, protein, tannic acid, metal oxide and protonating agent are mixed to obtain a mixed system;

[0008] (2) The mixture system in step (1) is subjected to hot melt processing and hot pressing molding in sequence to obtain chitosan-protein biomimetic composite material;

[0009] The hot melt process is carried out under closed conditions.

[0010] Preferably, in step (1), the protein is a plant protein, hydrolyzed plant protein, animal protein, or hydrolyzed animal protein.

[0011] Preferably, in step (1), the protein is soy protein, soy protein peptide, silk fibroin or silk peptide.

[0012] Preferably, in step (1), the metal oxide is iron oxide, copper oxide, zinc oxide, zirconium oxide, aluminum oxide, nano iron oxide, nano copper oxide, nano zinc oxide, nano zirconium oxide, or nano aluminum oxide; the protonating agent includes formic acid.

[0013] Preferably, in step (1), based on a total mass fraction of 100% for chitosan and protein, the mass fraction of chitosan is 40-80%, and the mass fraction of protein is 20-60%; the tannic acid is 1-10% of the total mass of chitosan and protein, and the metal oxide is 1-5% of the total mass of chitosan and protein; the mass of the protonating agent is 80-120% of the sum of the masses of chitosan, protein, tannic acid, and metal oxide.

[0014] Preferably, in step (2), the temperature of the hot melt processing is 60 to 100°C, and the rotation speed of the hot melt processing is 80 to 200 rpm.

[0015] Preferably, after the hot pressing molding described in step (2), the process further includes recrystallization and pH adjustment.

[0016] Preferably, the pH adjustment is to adjust the pH value to 6-12.

[0017] The present invention also provides a chitosan-protein biomimetic composite material prepared by the above preparation method based on thermal melting processing.

[0018] This invention also provides an application of chitosan-protein biomimetic composite material based on hot melt processing in food packaging, environmental or medical fields.

[0019] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) During the molting process of insect cuticles, catecholamine derivatives are secreted into the cuticle and then converted into reactive quinone-containing intermediates by diphenol oxidase. These intermediates bind chitin and structural proteins through their amino groups, leading to the hardening of the new cuticle and the re-formation of a hard exoskeleton. This invention mimics the hardening process of insect cuticles by combining chitosan (a deacetylated product of chitin) with proteins to simulate the formation of polysaccharide-protein in insect cuticles. Under hot-melt processing conditions, chitosan-protein forms a continuous network through electrostatic interactions. The phenolic hydroxyl groups of tannic acid (TA) are oxidized to orthoquinone structures, which then undergo quinone cross-linking reactions with proteins and chitosan. Furthermore, tannic acid and metal oxides form a metal-phenol-quinone network. Therefore, the prepared material has a biomimetic concept and possesses excellent mechanical strength and hardness similar to that of insect cuticles.

[0021] (2) This invention maximizes the contact area and interaction between reactants through hot melt processing. That is, in a closed system, the high temperature and high shear of hot melt processing maximize the reaction between components, effectively avoiding the volatilization of formic acid during processing, improving the compatibility between reactants, thereby forming a functional metal-phenol quinone network, enhancing the performance of chitosan-protein biomimetic composite material. The resulting chitosan-based composite material has excellent mechanical properties as well as UV resistance, antibacterial and other properties, solving the problem of structural inhomogeneity and reduced material mechanical properties in solution preparation of chitosan-based composite materials;

[0022] (3) The present invention prepares chitosan-based composite materials by hot melt processing, which has the advantages of low solvent consumption, short time, no secondary pollution and high efficiency, and can be directly connected to large-scale industrial production. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0024] Figure 1 The image shows a cross-sectional SEM image (magnified 500x) of the chitosan-protein biomimetic composite material obtained in Example 1.

[0025] Figure 2 The image shows a cross-sectional SEM image (magnified 5000 times) of the chitosan-protein biomimetic composite material obtained in Example 1.

[0026] Figure 3 The C1s diagram of the chitosan-protein biomimetic composite material obtained in Example 1 is shown.

[0027] Figure 4 The N1s plot of the chitosan-protein biomimetic composite material obtained in Example 1;

[0028] Figure 5 The infrared spectra of the chitosan-protein biomimetic composite materials obtained in Example 1, Comparative Example 1, and Comparative Examples 3-4 are shown. Detailed Implementation

[0029] This invention provides a method for preparing a chitosan-protein biomimetic composite material based on thermal melt processing, comprising the following steps:

[0030] (1) Chitosan, protein, tannic acid, metal oxide and protonating agent are mixed to obtain a mixed system;

[0031] (2) The mixture system in step (1) is subjected to hot melt processing and hot pressing molding in sequence to obtain chitosan-protein biomimetic composite material;

[0032] The hot melt process is carried out under closed conditions.

[0033] In this invention, the preferred method for mixing chitosan, protein, tannic acid, metal oxide and protonating agent in step (1) is as follows: chitosan and protein are premixed to obtain a premix; tannic acid, metal oxide and protonating agent are ultrasonically dispersed and stirred to obtain a mixture; the premix is ​​added to the mixture for preliminary mixing, sealed and left to stand.

[0034] The present invention does not limit the frequency of ultrasonic dispersion, and any scheme known to those skilled in the art can be used; the ultrasonic dispersion time is preferably 10 to 20 minutes, more preferably 15 to 20 minutes, and more preferably 20 minutes.

[0035] In this invention, the stirring rate is preferably 200-600 rpm, more preferably 300-500 rpm, and even more preferably 400 rpm; the stirring time is preferably 10-30 min, more preferably 15-25 min, and even more preferably 15 min.

[0036] In this invention, the settling time is preferably 0.5 to 2 days, more preferably 1 to 2 days, and even more preferably 2 days.

[0037] In this invention, in step (1), the molecular weight of the chitosan is preferably (1.5-5) × 10⁻⁶. 5 g·mol -1 A further preferred option is (3~5)×10 5 g·mol -1 More preferably 4×10 5 g·mol -1 .

[0038] In this invention, in step (1), the protein is preferably plant protein, hydrolyzed plant protein, animal protein or hydrolyzed animal protein, more preferably plant protein, hydrolyzed plant protein or hydrolyzed animal protein, and more preferably plant protein.

[0039] The present invention does not limit the source of the plant protein, the hydrolyzed plant protein, the animal protein and the hydrolyzed animal protein, and may select commercially available products or obtain them using methods known to those skilled in the art.

[0040] In specific embodiments of the present invention, the protein in step (1) is preferably soy protein, soy protein peptide, silk fibroin or silk peptide, more preferably soy protein or silk peptide, and even more preferably soy protein.

[0041] In this invention, in step (1), the metal oxide is preferably iron oxide, copper oxide, zinc oxide, zirconium oxide, aluminum oxide, nano iron oxide, nano copper oxide, nano zinc oxide, nano zirconium oxide or nano aluminum oxide, more preferably zinc oxide, aluminum oxide, nano zinc oxide or nano aluminum oxide, and more preferably nano zinc oxide.

[0042] In this invention, the particle sizes of the iron oxide, copper oxide, zinc oxide, zirconium oxide, and aluminum oxide are independently determined, preferably 1-45 μm, more preferably 1-20 μm, and even more preferably 1-10 μm.

[0043] In this invention, the nano-iron oxide, nano-copper oxide, nano-zinc oxide, nano-zirconia, and nano-alumina have independently independent particle sizes, preferably 20-200 nm, more preferably 20-80 nm, and even more preferably 20-40 nm.

[0044] In this invention, the protonating agent preferably includes formic acid.

[0045] This invention utilizes a metal-phenol-quinone network formed by TA and metal oxides to crosslink with chitosan-protein macromolecules. TA contains a large number of pyrogallol and catechol groups, and the presence of multiple phenolic hydroxyl groups endows it with the ability to complex or crosslink macromolecules through various interactions such as hydrogen bonds, coordination bonds, and hydrophobic bonds. The numerous active groups in TA can combine with amino and carboxyl groups in the chitosan and protein backbone to form strong hydrogen bonds; furthermore, TA is readily oxidized, with two adjacent hydroxyl groups being oxidized to form quinone bonds. These quinone bonds can further react with amino groups, enabling covalent modification of biomolecules through Michael addition or Schiff base reactions, thereby improving material properties. In addition, two adjacent hydroxyl groups facilitate the formation of coordination bonds between TA and metal ions such as iron and copper.

[0046] In this invention, in step (1), based on the total mass fraction of chitosan and protein being 100%, the mass fraction of chitosan is preferably 40-80%, more preferably 50-80%, and even more preferably 50%; the mass fraction of protein is preferably 20-60%, more preferably 20-50%, and even more preferably 50%.

[0047] In this invention, in step (1), the tannic acid is preferably 1 to 10% of the total mass of the chitosan and the protein, more preferably 3 to 5%, and even more preferably 3%.

[0048] In this invention, in step (1), the metal oxide is preferably 1 to 5% of the total mass of the chitosan and the protein, more preferably 1 to 3%, and even more preferably 1%.

[0049] In this invention, in step (1), the mass of the protonating agent is preferably 80-120% of the sum of the masses of the chitosan, the protein, the tannic acid and the metal oxide, more preferably 100-120%, and even more preferably 117%.

[0050] In this invention, in step (2), the temperature of the hot melt processing is preferably 60-100°C, more preferably 80-100°C, and even more preferably 80°C; the time of the hot melt processing is preferably 10-25 min, more preferably 15-20 min, and even more preferably 15 min.

[0051] In this invention, in step (2), the rotation speed of the hot melt processing is preferably 80 to 200 rpm, more preferably 80 to 100 rpm, and even more preferably 80 rpm.

[0052] In this invention, in step (2), the hot melt processing is preferably carried out in a mixer.

[0053] This invention replaces the existing solution synthesis method with a hot melt processing method. Under the high temperature and high shear of hot melt processing, the oxidation of TA can be accelerated. On the other hand, the addition of metal oxides can better release metal ions. Furthermore, the catalytic effect of metal oxides under high temperature conditions can further oxidize TA. The complexation of metal ions with TA can be further enhanced by subsequent pH adjustment.

[0054] In this invention, in step (2), the temperature of the hot pressing is preferably 80-100°C, more preferably 80-90°C, and even more preferably 80°C; the pressure of the hot pressing is preferably 10000-15000 psi, more preferably 11000-13000 psi, and even more preferably 12000 psi; the time of the hot pressing is preferably 3-5 min, more preferably 3-4 min, and even more preferably 3 min.

[0055] In this invention, in step (2), the hot pressing is preferably performed in a hot press.

[0056] In this invention, after the hot pressing molding described in step (2), the process further includes recrystallization and pH adjustment.

[0057] In this invention, the recrystallization is preferably performed by immersing the product obtained from hot pressing in an aqueous methanol solution; the immersion time in the aqueous methanol solution is 1 to 2 days, more preferably 1 to 1.4 days, and even more preferably 1 day; the concentration of the aqueous methanol solution is preferably 99.5 wt%.

[0058] In this invention, the pH adjustment is preferably adjusted to a pH value of 6 to 12, more preferably 10 to 12, and even more preferably 12.

[0059] In this invention, the reagent used to adjust the pH is preferably a sodium hydroxide solution; the mass concentration of the sodium hydroxide solution is preferably 4-8%, more preferably 4-6%, and even more preferably 4%.

[0060] In this invention, after pH adjustment, washing, drying and conditioning are preferably performed sequentially.

[0061] In this invention, the drying temperature is preferably 40-60°C, more preferably 40-46°C, and even more preferably 40°C; the drying time is preferably 1-2 days, more preferably 1-1.5 days, and even more preferably 1 day.

[0062] In this invention, the curing temperature is preferably 20-30°C, more preferably 24-28°C, and even more preferably 25°C; the curing humidity is preferably 50-60%, more preferably 55-58%, and even more preferably 57%; and the curing time is preferably 4-10 days, more preferably 6-9 days, and even more preferably 7 days.

[0063] The present invention also provides a method for preparing a chitosan-protein biomimetic composite material based on thermal melt processing, resulting in a chitosan-protein biomimetic composite material based on thermal melt processing.

[0064] This invention also provides an application of a chitosan-protein biomimetic composite material based on thermal melting processing in food packaging, environmental applications, or the medical field. This invention does not limit the methods for these applications; any solution well-known to those skilled in the art can be used.

[0065] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0066] Example 1

[0067] This embodiment provides a method for preparing a chitosan-protein biomimetic composite material based on thermal melt processing, including the following steps:

[0068] (1) Take 50g of chitosan (the molecular weight of chitosan is 4×10) 5 g·mol -1 ) and 50g of silk peptides (the molecular weight of silk peptides is approximately 1.5 × 10⁻⁶). 3 g·mol -1 The manufacturer is Huzhou Xintiansi Biotechnology Co., Ltd. (Huzhou)) premixed to obtain a premix;

[0069] Add 3g of tannic acid and 1g of zinc oxide (zinc oxide particle size 1-10μm) to 100mL of formic acid and disperse by ultrasonication for 20min. Then place it in a magnetic stirrer and stir at 300rpm for 15min at room temperature. Then add it to the premix to obtain a viscous solid. Seal it and let it stand for 2 days to obtain a mixed system.

[0070] (2) The mixture from step (1) is placed in a closed internal mixer for hot melting and mixing. The temperature of the front, rear and middle sections of the internal mixer is 80°C, the rotor speed is 80 rpm, and the processing time is set to 15 min. After the internal mixer is finished, the composite is taken out and cooled to room temperature.

[0071] The composite was hot-pressed into a film using a hot press. The temperature of the hot press was set to 80°C, the pressure to 12000 psi, and the hot pressing time to 3 min. After hot pressing, it was soaked in a 99.5 wt% methanol aqueous solution for 1 day, then the pH was adjusted to 12 with sodium hydroxide solution and soaked for 1 day. The surface chemical residues were repeatedly washed with pure water.

[0072] Finally, the sample was placed in a 40℃ oven to dry for 1 day. During drying, it was fixed with a porous air-permeable plate. After drying, the sample was placed in a constant temperature and humidity chamber at 25℃ and 57% for equilibration for 7 days to obtain a phenol-quinone crosslinked chitosan-protein biomimetic composite material, denoted as CS-SP-3%TA-ZnO (CS-chitosan, SP-silk peptide, TA-tannic acid, ZnO-zinc oxide).

[0073] The chitosan-protein composite material obtained in Example 1 was characterized by XPS, and the results are as follows: Figure 3 , 4 As shown. Figure 3 The C1s curve of the composite material obtained in Example 1 shows that 284.8, 286.1, and 289.2 eV correspond to C-C bonds, CN / CO bonds, and C=O bonds, respectively. The composite material with added zinc oxide in Example 1 shows a significant increase in peak area at 289.2 eV and a significant decrease in peak area at 286.1 eV. This indicates that a large number of phenolic hydroxyl groups are oxidized to C=O bonds under the action of metal oxides, and that the C=O bonds undergo quinone cross-linking reactions with the amino groups in chitosan and silk peptides to form C=N bonds. Figure 4 The N1s plot of the composite material obtained in Example 1 shows that a C=N peak appears at 402.3 eV, which further confirms the occurrence of the quinone crosslinking reaction.

[0074] The tensile strength of the composite material prepared in Comparative Example 1 was determined using a Sansi universal tensile tester with a load unit of 10 kN (accuracy less than ±1% of the indicated value) and a constant horizontal axis speed of 3 mm / min. The hardness of the composite material was measured using a Shore hardness tester.

[0075] The method for testing the inhibition zone is as follows: (1) Activation of the bacterial strains: The strains used are Escherichia coli (E. coli, ATCC 25922) and Staphylococcus aureus (S. aureus, ATCC 25923). After activation in LB nutrient broth for 24 hours, the bacterial suspension is diluted sequentially in a 10-fold gradient to obtain a bacterial suspension with a final concentration of 10⁸ CFU / mL; (2) First, the single strains of Escherichia coli and Staphylococcus aureus are diluted to 10⁶ CFU / mL. 15 mL of NA agar is poured into each petri dish, cooled and solidified, and then 100 μL of bacterial suspension diluted to 10⁶ CFU / mL is spread on it. The membrane prepared by the punch is placed in the dish, diffused in a refrigerator at 4℃ for 24 h, and then incubated at 37℃ for 24 h. The diameter of the inhibition zone is measured, and the experiment is repeated 3 times.

[0076] The rectangular film was placed directly into a cuvette, and the transmittance was measured at 200–800 nm using a UV-Vis spectrophotometer.

[0077] The results showed that the chitosan-protein biomimetic composite material obtained in Example 1 had a tensile strength of 57.7 MPa, an elongation at break of 52%, a hardness of 58 HD, and inhibition zone diameters of 11.2 mm and 10.2 mm for Escherichia coli and Staphylococcus aureus, respectively. It also had 100% UV blocking capability.

[0078] Example 2

[0079] This embodiment provides a method for preparing a chitosan-protein biomimetic composite material based on thermal melt processing, including the following steps:

[0080] (1) Take 50g of chitosan (the molecular weight of chitosan is 4×10) 5 g·mol -1 ) and 50g of soy protein (soy protein purity of 88%, manufactured by Shanghai Jiaoyuan Industrial Co., Ltd.) are premixed to obtain a premix;

[0081] Add 3g of tannic acid and 1g of nano zinc oxide (particle size 50nm) to 100mL of formic acid and disperse by ultrasonication for 20min. Then place it in a magnetic stirrer and stir at 600rpm for 15min at room temperature. Then add it to the premix to obtain a viscous solid. Seal it and let it stand for 2 days to obtain a mixed system.

[0082] (2) The mixture from step (1) is placed in a closed internal mixer for hot melting and mixing. The temperature of the front, rear and middle sections of the internal mixer is 80°C, the rotor speed is 80 rpm, and the processing time is set to 15 min. After the internal mixer is finished, the composite is taken out and cooled to room temperature.

[0083] The composite was hot-pressed into a film using a hot press. The temperature of the hot press was set to 80°C, the pressure to 12000 psi, and the hot pressing time to 3 min. After hot pressing, it was soaked in a 99.5 wt% methanol aqueous solution for 1 day, then the pH was adjusted to 12 with sodium hydroxide solution and soaked for 1 day. The surface chemical residues were repeatedly washed with pure water.

[0084] Finally, the sample was placed in a 40℃ oven to dry for 1 day, and a porous air-permeable plate was used to fix it during drying. After drying, the sample was placed in a constant temperature and humidity chamber at 25℃ and 57% for equilibration for 7 days to obtain a phenol-quinone crosslinked chitosan-protein biomimetic composite material.

[0085] The properties of the composite material were determined using the method described in Example 1. The results showed that the chitosan-protein biomimetic composite material obtained in Example 2 had a tensile strength of 69.7 MPa, an elongation at break of 43.6%, a hardness of 69HD, inhibition zone diameters of 13.2 mm for Escherichia coli and 11.7 mm for Staphylococcus aureus, and 100% UV blocking capability.

[0086] Comparative Example 1

[0087] This comparative example provides a method for preparing a chitosan-protein composite material based on thermal melt processing, including the following steps:

[0088] (1) Take 50g of chitosan (the molecular weight of chitosan is 4×10) 5 g·mol -1 The mixture was premixed with 50g of silk fibroin (the relative molecular weight of silk fibroin is approximately 250,000, manufactured by Huzhou Xintiansi Biotechnology Co., Ltd. (Huzhou)) to obtain a premix.

[0089] Add 5g of tannic acid to 100mL of formic acid and disperse by ultrasonication for 15min. Then, stir at 400rpm for 15min at room temperature in a magnetic stirrer. Add the mixture to the premix to obtain a viscous solid. Seal and let stand for 2 days to obtain a mixed system.

[0090] (2) The mixture from step (1) is placed in a closed internal mixer for hot melting and mixing. The temperature of the front, middle and rear plates of the internal mixer is 80°C, the rotor speed is 100 rpm, and the processing time is set to 20 min. After the internal mixer is finished, the composite is taken out and cooled to room temperature.

[0091] The composite was hot-pressed into a film using a hot press. The temperature of the hot press was set to 80°C, the pressure to 12000 psi, and the hot pressing time to 3 min. After hot pressing, it was soaked in a 99.5 wt% methanol aqueous solution for 1 day, then the pH was adjusted to 12 with sodium hydroxide solution and soaked for 1 day. The surface chemical residues were repeatedly washed with pure water.

[0092] Finally, the sample was placed in a 40℃ oven to dry for 1 day. During drying, it was fixed with a porous air-permeable plate. After drying, the sample was placed in a constant temperature and humidity chamber at 25℃ and 57% for equilibration for 7 days to obtain a phenol-quinone crosslinked chitosan-protein biomimetic composite material, denoted as CS-SF-5%TA.

[0093] The properties of the composite material were determined using the method described in Example 1. The results showed that the chitosan-protein biomimetic composite material obtained in Comparative Example 1 had a tensile strength of 40.6 MPa, an elongation at break of 70%, a hardness of 53 HD, inhibition zone diameters of 9.1 and 9.0 mm for Escherichia coli and Staphylococcus aureus, respectively, and a 100% UV blocking ability.

[0094] Comparative Example 2

[0095] This comparative example provides a method for preparing chitosan-protein composite materials using a solution method, comprising the following steps:

[0096] (1) Take 1g of chitosan (the molecular weight of chitosan is 4×10) 5 g·mol -1 ) and 1g of silk peptide (the molecular weight of silk peptide is approximately 1.5 × 10⁻⁶) 3 g·mol -1 The manufacturer is Huzhou Xintiansi Biotechnology Co., Ltd. (Huzhou). After premixing, 100 mL of 1 wt% formic acid was added; 0.06 g of tannic acid and 0.02 g of zinc oxide (1-10 μm) were added, and after ultrasonic dispersion for 30 min, the mixture was placed in a magnetic stirrer and stirred at 400 rpm at room temperature for 12 h to obtain the composite membrane solution.

[0097] (2) After adjusting the pH of the composite membrane solution to 12 with sodium hydroxide, the composite membrane solution was poured into a petri dish; the petri dish was placed in a 40℃ oven to dry for 1 day, and after drying, it was placed in a constant temperature and humidity chamber at 25℃ and 57% for 7 days to equilibrate, thus obtaining the chitosan-protein biomimetic composite material.

[0098] The properties of the composite material were determined using the method described in Example 1. The results showed that the chitosan-protein biomimetic composite material obtained in Comparative Example 2 had a tensile strength of 15.2 MPa and a hardness of 0 HD; the inhibition zone diameters against Escherichia coli and Staphylococcus aureus were 8.2 and 7.7 mm, respectively; and the UV blocking ability was 30%.

[0099] Comparative Example 3

[0100] This comparative example provides a method for preparing a chitosan-protein composite material based on hot melt processing. The difference from Example 1 is that 3g of tannic acid and 1g of zinc oxide are removed, while other experimental conditions are the same as in Example 1. This method is denoted as CS-SP.

[0101] The properties of the composite material were determined using the method described in Example 1. The results showed that the chitosan-protein biomimetic composite material obtained in Comparative Example 3 had a tensile strength of 29.7 MPa, an elongation at break of 100.5%, a hardness of 27 HD, inhibition zone diameters of 7.8 and 7.9 mm for Escherichia coli and Staphylococcus aureus, respectively, and a 100% UV blocking capacity.

[0102] Comparative Example 4

[0103] This comparative example provides a method for preparing a chitosan-protein composite material based on hot melt processing. The difference from Example 1 is that 1g of zinc oxide is removed, while other parameters and conditions are the same as in Example 1, denoted as CS-SP-3%TA.

[0104] The properties of the composite material were determined using the method described in Example 1. The results showed that the chitosan-protein biomimetic composite material obtained in Comparative Example 4 had a tensile strength of 43.4 MPa, an elongation at break of 48.6%, a hardness of 44 HD, inhibition zone diameters of 9.4 mm and 8.7 mm for Escherichia coli and Staphylococcus aureus, respectively, and a UV blocking ability of 100%.

[0105] Figure 5 The infrared spectra of the chitosan-protein biomimetic composite materials obtained in Example 1, Comparative Example 1, and Comparative Examples 3-4 are shown. The results show that with the introduction of metal ions, compared with the addition of TA alone (i.e., Comparative Example 1 or Comparative Example 4), the composite material obtained in Example 1 has a higher infrared spectrum at 3300 cm⁻¹. -1 The intensity of the broad hydroxyl peak at 1562 and 1640 cm⁻¹ decreased, which may be because the addition of metal oxide partially oxidized the phenolic hydroxyl groups in TA, and the presence of metal ions formed coordination bonds with the phenolic hydroxyl groups in TA, further consuming them. Compared with Comparative Example 3, which added chitosan-silk peptide alone, the composite material prepared in Example 1 after adding metal oxide (zinc oxide) showed higher intensity at 1562 and 1640 cm⁻¹. -1 The peak values ​​at 1640 cm⁻¹ all showed a red shift and enhancement, which may be due to the presence of C=C in TA; the carbonyl group at 1640 cm⁻¹... -1 The peaks at 1652 and 1656 cm⁻¹ shifted to 1652 and 1656 cm⁻¹. -1 This may be due to the partial oxidation of the phenolic hydroxyl groups in tannic acid into ortho-quinone structures during thermomechanical processing and subsequent alkaline treatment, which then undergoes a quinone cross-linking reaction with CS to form C=N bonds.

[0106] The above experimental results show that this invention utilizes the biomimetic concept of the hardening of the cuticle after insect molting. By constructing a metal-phenol quinone network to crosslink and enhance chitosan-protein materials under hot-melt processing conditions, the interaction between them can be maximized, and the mechanical and antibacterial properties of the chitosan-based composite material can be maximized. The tensile strength and toughness of the composite material are balanced. The resulting composite material has excellent biocompatibility and biodegradability. The manufacturing method is simple and conducive to large-scale industrial production. Furthermore, the biomimetic concept utilized has great scientific research and commercial value.

[0107] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a chitosan-protein biomimetic composite material based on thermal melt processing, characterized in that, Includes the following steps: (1) Chitosan, protein, tannic acid, metal oxide and protonating agent are mixed to obtain a mixed system; (2) The mixture system in step (1) is subjected to hot melt processing and hot pressing molding in sequence to obtain chitosan-protein biomimetic composite material; The hot melt processing is carried out under closed conditions; In step (1), the metal oxide is iron oxide, zinc oxide, or aluminum oxide; the protonating agent includes formic acid; In step (1), based on the total mass fraction of chitosan and protein being 100%, the mass fraction of chitosan is 40-80%, and the mass fraction of protein is 20-60%; the mass of tannic acid is 1-10% of the total mass of chitosan and protein, the mass of metal oxide is 1-5% of the total mass of chitosan and protein; and the mass of protonating reagent is 80-120% of the sum of the masses of chitosan, protein, tannic acid, and metal oxide.

2. The method for preparing a chitosan-protein biomimetic composite material based on thermal melting processing as described in claim 1, characterized in that, In step (1), the protein is a plant protein, hydrolyzed plant protein, animal protein, or hydrolyzed animal protein.

3. The method for preparing a chitosan-protein biomimetic composite material based on thermal melting processing as described in claim 2, characterized in that, In step (1), the protein is soy protein, soy protein peptide, silk fibroin or silk peptide.

4. The method for preparing a chitosan-protein biomimetic composite material based on thermal melting processing as described in claim 3, characterized in that, In step (1), the metal oxide is nano iron oxide, nano zinc oxide or nano aluminum oxide.

5. A method for preparing a chitosan-protein biomimetic composite material based on thermal melt processing as described in claim 1, 2, or 4, characterized in that, In step (2), the temperature of the hot melt processing is 60~100℃, and the rotation speed of the hot melt processing is 80~200rpm.

6. A method for preparing a chitosan-protein biomimetic composite material based on thermal melt processing as described in claim 1, 2, or 4, characterized in that, The process after hot pressing in step (2) also includes recrystallization and pH adjustment.

7. The method for preparing a chitosan-protein biomimetic composite material based on thermal melting processing as described in claim 6, characterized in that, The pH adjustment refers to adjusting the pH value to 6-12.

8. The chitosan-protein biomimetic composite material prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the chitosan-protein biomimetic composite material based on hot melt processing as described in claim 8 in the fields of food packaging or environment.

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