Degradable sponge and preparation process thereof

Abstract

The application relates to the technical field of sponge preparation, and discloses a degradable sponge and a preparation process thereof, which solve the problem of the conflict between function and performance in the prior art, and the raw materials include oxidized sodium alginate, deacetylated chitosan, aldehyde group-containing crosslinking agent, g-C3N4@COF core-shell photocatalyst, PCL-cellulase controlled-release microspheres and the like. In the preparation, the oxidized sodium alginate and the deacetylated chitosan are dissolved in an acid solution, the crosslinking agent is added to prepare a dynamic crosslinking network solution, the photocatalyst and the enzyme microspheres which are subjected to dispersion treatment are mixed, and the sponge is prepared through pouring, pre-freezing, crosslinking and gradient freeze-drying. The application forms a double-network structure through the synergistic solidification of dynamic imine bonds and ionic bonds, solves the contradiction between the mechanical strength and degradability of traditional materials, the photocatalysis and degradation, has good self-repairing function and biocompatibility, and has application prospects in the fields of environmental pollution treatment and medical treatment.

Description

Technical Field

[0001] This invention relates to the field of sponge preparation technology, and in particular to a biodegradable sponge and its preparation process. Background Technology

[0002] Sponge materials are a class of porous polymer materials. Due to their excellent cushioning, water absorption, and lightweight properties, they are widely used in medical, environmental protection, and daily life fields. However, traditional sponge materials such as polyurethane and polyether face serious environmental pollution problems. The degradation cycle of synthetic polymers is long, and landfill disposal leads to microplastic pollution. Foaming agents used in the production process, such as chlorofluorocarbons, damage the ozone layer, and organic solvents, such as toluene and dimethylformamide, pollute water and soil. To address these problems, biodegradable sponges have become a research hotspot.

[0003] The existing technology, CN116571231A, discloses a titanium dioxide-bismuth vanadate composite sponge, its preparation method, and its applications, including the preparation of nano-BiVO4, the preparation of BiVO4 sponge, and the preparation of TiO2 / BiVO4 composite sponge. The existing technology uses melamine sponge as the substrate for supporting the photocatalyst, providing a rich porous structure that facilitates pollutant adsorption and light energy absorption. Polydopamine is selected as an adhesive, and during the self-polymerization of dopamine molecules, the photocatalyst—bismuth vanadate—with stronger light absorption capacity, is adhered to the surface of the melamine sponge framework. Simultaneously, polydopamine can act as a chelating agent to bind with TiO2. 4+ A reaction occurs, resulting in the in-situ deposition of titanium dioxide nanoparticles on the sponge surface. The existing TiO2 / BiVO4 composite sponge utilizes the sponge's internal three-dimensional structure to provide more photocatalyst fixation sites, achieving high-efficiency dye degradation while increasing the loading rate.

[0004] Regarding the above-mentioned and existing related technologies, the inventors believe that the following defects often exist:

[0005] 1. Existing technologies present a contradiction between mechanical strength and degradability. High mechanical strength requires high cross-linking density, but excessive cross-linking can lead to pore blockage, hindering the diffusion of enzyme molecules and resulting in an uncontrollable degradation cycle. Furthermore, excessive cross-linking can destroy the dynamic bond recombination ability, causing the self-repair function to fail.

[0006] 2. Existing technologies have a mutual exclusion problem between photocatalysis and degradation. Existing technologies use inorganic photocatalyst TiO2, which requires high-temperature sintering for fixation, resulting in the carbonization and deactivation of natural polymers. In addition, residual heavy metals hinder biodegradation. Summary of the Invention

[0007] The technical problem to be solved by this invention is that there is a deficiency in the existing technology where function and performance conflict. To address this, we propose a biodegradable sponge and its preparation process.

[0008] To achieve the above objectives, this application adopts the following technical solution: a biodegradable sponge, comprising the following raw materials in parts by weight: 50-65 parts of oxidized sodium alginate, 15-30 parts of deacetylated chitosan, 10-15 parts of aldehyde-containing crosslinking agent, 0.3-0.5 parts of g-C3N4@COF core-shell photocatalyst, 0.1-0.2 parts of PCL-cellulase controlled-release microspheres, and 0-0.5 parts of nanocellulose, wherein the sponge forms a dual-network structure through a dynamic imine bond crosslinking network and ionic bonds working together to solidify.

[0009] Preferably, the aldehyde-containing crosslinking agent is 2,5-dimethoxyterephthalaldehyde or o-phthalaldehyde, and the molar ratio of aldehyde group to amino group is 0.9:1-1.3:1.

[0010] Preferably, the g-C3N4@COF core-shell photocatalyst is prepared by the following steps: C11: calcining melamine at 550℃ for 4 hours, grinding, and passing through a 200-mesh sieve to obtain g-C3N4 nanosheets; C12: adding g-C3N4 nanosheets to DMF solution, ultrasonically mixing, centrifuging, and collecting the supernatant; C13: dispersing the collected supernatant in a methanol-toluene mixed solvent, adding 1,3,5-tricarboxymethylbenzene and p-phenylenediamine, refluxing in an oil bath at 80℃ for 12-16 hours, centrifuging, collecting the precipitate, washing with ethanol, and vacuum drying to obtain the g-C3N4@COF core-shell photocatalyst.

[0011] Preferably, the PCL-cellulase controlled-release microspheres are prepared by the following steps: C21: dissolve cellulase in PBS buffer, label with FITC and stir; C22: dissolve PCL in dichloromethane, emulsify by adding enzyme solution, pour in polyvinyl alcohol aqueous solution and stir; C23: collect by centrifugation and wash with deionized water to obtain PCL-cellulase controlled-release microspheres, and freeze-dry for storage.

[0012] Preferably, the raw material further includes 0-0.1 parts of an antioxidant, wherein the antioxidant is propyl gallate.

[0013] Preferably, the mass ratio of cellulase to PBS buffer is 1:20-1:30, and the mass fraction of polyvinyl alcohol aqueous solution is 4%-5%.

[0014] A biodegradable sponge preparation process, characterized by the following steps: S1: Dissolve sodium alginate and deacetylated chitosan in acetic acid solution by stirring, add an aldehyde-containing crosslinking agent, stir at 40-60℃ to obtain a dynamic crosslinking network solution, and detect by FTIR; S2: Add g-C3N4@COF core-shell photocatalyst to deionized water, disperse by ultrasonication, cool to 4℃ in an ice bath, add PCL-cellulase controlled-release microspheres and vortex mix, add the dynamic crosslinking network solution dropwise and stir to obtain a mixture; S3: Pour the mixture into a tetrafluoroethylene mold, pre-freeze for 24 hours, immerse in CaCl2-ethanol solution for crosslinking for 2 hours, remove and rinse with deionized water, and freeze-dry in a freeze dryer for 19-27 hours in a gradient manner.

[0015] Preferably, in step S1, after adjusting the pH of the dynamic cross-linked network solution to 5.0-5.8, it is subjected to FTIR detection. The FTIR detection requires a 1620 cm⁻¹ depth. -1 The characteristic peak of the C=N bond and 1550 cm⁻¹ -1 The intensity ratio of the characteristic peak of the amide II band is ≥1.3.

[0016] Preferably, the gradient freeze drying in step S3 includes pre-freezing at -40°C to -30°C for 1-3 hours, main drying at -30°C to -10°C for 15-22 hours, and final drying at 0°C to 5°C for 2-4 hours.

[0017] Preferably, in step S3, the mass fraction of the CaCl2-ethanol solution is 2%, and the weight ratio of the CaCl2-ethanol solution to sodium alginate is 250:1.

[0018] The technical effects and advantages of this invention are as follows:

[0019] In this invention, a dual-network structure is formed through the synergistic solidification of a dynamic imine bond crosslinking network and ionic bonds. Furthermore, g-C3N4@COF core-shell photocatalyst and PCL-cellulase controlled-release microspheres are introduced, achieving synergistic optimization of function and performance. On one hand, the dual-network structure of dynamic imine and ionic bonds resolves the contradiction between mechanical strength and degradability in existing technologies. While ensuring compressive strength, it improves the 21-day degradation rate. The dynamic imine bonds endow the network with recombination ability, while the ionic bonds enhance mechanical strength. The synergy of these two elements ensures that the material has sufficient mechanical support while enabling controlled degradation through enzyme diffusion, avoiding the pore blockage problem caused by excessive crosslinking.

[0020] On the other hand, the synergistic effect of g-C3N4@COF core-shell photocatalyst and PCL-enzyme-controlled release microspheres solves the mutual exclusion problem between photocatalysis and degradation. The g-C3N4@COF core-shell photocatalyst can exert its photocatalytic effect under mild conditions, avoiding the carbonization and deactivation problem of natural polymers caused by high-temperature sintering of traditional inorganic photocatalysts. Meanwhile, the PCL-cellulase-controlled release microspheres enable the controlled release of enzymes, which synergistically degrade pollutants with the active substances generated by photocatalysis. Furthermore, the organic-inorganic hybrid structure of the photocatalyst does not hinder the biodegradation process, enabling the material to play a highly efficient role in both photocatalysis and biodegradation. Attached Figure Description

[0021] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts:

[0022] Figure 1 This is a flowchart of the biodegradable sponge preparation process provided by the present invention;

[0023] Figure 2 The process flow diagram for preparing g-C3N4@COF core-shell photocatalyst provided by this invention;

[0024] Figure 3 The process flow diagram for preparing PCL-enzyme controlled-release microspheres provided by this invention is shown. Detailed Implementation

[0025] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0026] Example 1

[0027] Reference Figures 1-3 As shown, a biodegradable sponge comprises the following raw materials in parts by weight:

[0028] 60 parts of oxidized sodium alginate, 20 parts of deacetylated chitosan, 12 parts of 2,5-dimethoxytetraphenyl phthalaldehyde, 0.4 parts of g-C3N4@COF core-shell photocatalyst, and 0.125 parts of PCL-cellulase controlled-release microspheres;

[0029] A process for preparing a biodegradable sponge includes the following steps:

[0030] S1: Dissolve sodium oxidized alginate in 0.1M acetic acid solution and stir at 40°C until clear. Add deacetylated chitosan and continue stirring for 30 minutes until completely dissolved. Add 2,5-dimethoxytetraphenyl phthalaldehyde and stir at 55°C under magnetic conditions for 45 minutes to obtain a pale yellow gel-like dynamic cross-linked network solution. Take droplets for FTIR detection.

[0031] S2: Add g-C3N4@COF core-shell photocatalyst to deionized water, disperse by ultrasonication at 40kHz for 10 minutes, cool to 4℃ in an ice bath, add PCL-cellulase controlled-release microspheres, vortex mix for 1 minute, and under a red safety lamp, slowly add the dispersion to the dynamic cross-linked network solution prepared in S1, and magnetically stir at 300rpm for 30 minutes to obtain a homogeneous mixture.

[0032] S3: Pour the mixture into a tetrafluoroethylene mold, pre-freeze at -20℃ for 24 hours, immerse in CaCl2-ethanol solution for cross-linking for 2 hours, remove and rinse the surface with deionized water, transfer to a -25℃ freeze dryer for vacuum drying for 24 hours to obtain a porous sponge.

[0033] In S1, the weight ratio of acetic acid solvent to sodium alginate is 25:1, and the pH is adjusted to 5.5 to promote dissolution.

[0034] In S1, the degree of deacetylation of the deacetylated chitosan (DD) is 74.7%.

[0035] In the FTIR test of S1, a 1620cm depth is required. -1 The characteristic peak of the C=N bond and 1550 cm⁻¹ -1 The intensity ratio of the characteristic peak of the amide II band is ≥1.5, which proves that the imine bond is fully formed.

[0036] In S1, the molar ratio of aldehyde group to amino group in 2,5-dimethoxytetraphenyl phthalaldehyde is 1.05:1.

[0037] The dimensions of the tetrafluoroethylene mold in S3 are 10×10×1cm. 3 .

[0038] In S3, the mass fraction of CaCl2-ethanol solution is 2%, and the weight ratio of CaCl2-ethanol solution to sodium alginate oxide is 250:1, used for ionic bond co-curing. 2+ It forms ionic bonds with the carboxyl groups in sodium alginate molecules, enhancing the mechanical strength of the dynamic cross-linked network. It also promotes freeze cross-linking and molding. After pre-freezing at -20℃, it forms a covalent-ionic double network structure, improving the mechanical properties and stability of the sponge.

[0039] Among them, the vacuum degree inside the freeze dryer in S3 is <10Pa, and gradient freeze drying is adopted: pre-freezing at -40℃ for 2 hours, main drying at -25℃ for 18 hours, and final drying at 0℃ for 4 hours.

[0040] The g-C3N4@COF core-shell photocatalyst was prepared by the following steps:

[0041] C11: Weigh 4 parts of melamine and place them in a crucible. Transfer the crucible to a muffle furnace and heat the furnace to 550°C at 5°C / min. Calcinate the melamine under a nitrogen atmosphere for 4 hours. After naturally cooling to room temperature, grind the melamine through a 200-mesh sieve to obtain a light yellow powder.

[0042] C12: Add the pale yellow powder prepared by C11 to the DMF solution, and treat with ultrasound for 2 hours. After centrifugation at 8000 rpm for 15 minutes, collect the upper third of the clear liquid.

[0043] C13: The supernatant collected from C12 was dispersed in a methanol-toluene mixed solvent, 10 mM 1,3,5-tricarboxymethylbenzene and 15 mM p-phenylenediamine were added, and the mixture was refluxed in an oil bath at 80 °C for 12 hours. The precipitate was collected by centrifugation, washed three times with ethanol, and dried under vacuum at 60 °C to obtain g-C3N4@COF core-shell photocatalyst.

[0044] In C12, the ultrasound uses a 300W pulse mode, with the pulse mode on for 5 seconds and off for 2 seconds.

[0045] In C13, the methanol-toluene mixture has a methanol:toluene ratio of 4:1, and the mass ratio of the methanol-toluene mixture, 1,3,5-tricarboxymethylbenzene, and p-phenylenediamine is 25:9:5.

[0046] The PCL-cellulase controlled-release microspheres were prepared by the following steps:

[0047] C21: Dissolve cellulase in 0.01M PBS buffer (pH 7.4), add 0.05% w / v FITC fluorescent label under light protection, and stir for 30 minutes to obtain the enzyme solution.

[0048] C22: Dissolve PCL in dichloromethane, add the enzyme solution prepared by C21 dropwise, emulsify with a 200W probe for 2 minutes, pour into a 40℃ polyvinyl alcohol aqueous solution, and stir at 500rpm for 4 hours.

[0049] C23: Centrifuge at 6000 rpm for 10 minutes, collect the microspheres and wash them three times with deionized water to obtain PCL-cellulase controlled-release microspheres, which are then freeze-dried and stored.

[0050] In C21, the mass ratio of cellulase to PBS buffer is 1:30.

[0051] In C22, the mass ratio of PCL, dichloromethane, enzyme solution, and polyvinyl alcohol aqueous solution is 10:40:5:300, and the mass fraction of polyvinyl alcohol aqueous solution is 4%.

[0052] Example 2

[0053] Reference Figures 1-3 As shown, a biodegradable sponge comprises the following raw materials in parts by weight:

[0054] 60 parts of oxidized sodium alginate, 20 parts of deacetylated chitosan, 12 parts of 2,5-dimethoxytetraphenyl phthalaldehyde, 0.5 parts of g-C3N4@COF core-shell photocatalyst, and 0.1 parts of PCL-cellulase controlled-release microspheres;

[0055] A process for preparing a biodegradable sponge includes the following steps:

[0056] S1: Dissolve sodium oxidized alginate in 0.1M acetic acid solution and stir at 55°C until clear. Add deacetylated chitosan and continue stirring for 30 minutes until completely dissolved. Add 2,5-dimethoxytetraphenyl phthalaldehyde and stir at 55°C under magnetic conditions for 45 minutes to obtain a pale yellow gel-like dynamic cross-linked network solution. Take droplets for FTIR detection.

[0057] S2: Add g-C3N4@COF core-shell photocatalyst to deionized water, disperse by ultrasonication at 60kHz for 20 minutes, cool to 4℃ in an ice bath, add PCL-cellulase controlled-release microspheres, vortex mix for 1 minute, and slowly add the dispersion to the dynamic cross-linked network solution prepared in S1 under a red safety lamp. Stir magnetically at 300rpm for 30 minutes under a nitrogen atmosphere to obtain a homogeneous mixture.

[0058] S3: Pour the mixture into a tetrafluoroethylene mold, pre-freeze at -20℃ for 24 hours, immerse in CaCl2-ethanol solution for cross-linking for 2 hours, remove and rinse the surface with deionized water, transfer to a freeze dryer at -25℃ and vacuum dry for 27 hours to obtain a porous sponge.

[0059] In S1, the weight ratio of acetic acid solvent to sodium alginate is 25:1, and the pH is adjusted to 5.5 to promote dissolution.

[0060] In S1, the degree of deacetylation of the deacetylated chitosan (DD) is 78.4%.

[0061] In the FTIR test of S1, a 1620cm depth is required. -1 The characteristic peak of the C=N bond and 1550 cm⁻¹ -1 The intensity ratio of the characteristic peak of the amide II band is ≥1.6, which proves that the imine bond is fully formed.

[0062] In S1, the molar ratio of aldehyde group to amino group in 2,5-dimethoxytetraphenyl phthalaldehyde is 1:1, which reduces the crosslinking density and light scattering.

[0063] The dimensions of the tetrafluoroethylene mold in S3 are 10×10×1cm. 3 .

[0064] In S3, the mass fraction of CaCl2-ethanol solution is 2%, and the weight ratio of CaCl2-ethanol solution to sodium alginate oxide is 250:1, used for ionic bond co-curing. 2+ It forms ionic bonds with the carboxyl groups in sodium alginate molecules, enhancing the mechanical strength of the dynamic cross-linked network. It also promotes freeze cross-linking and molding. After pre-freezing at -20℃, it forms a covalent-ionic double network structure, improving the mechanical properties and stability of the sponge.

[0065] Among them, the vacuum degree inside the freeze dryer in S3 is <10Pa, and gradient freeze drying is adopted: pre-freezing at -40℃ for 3 hours, main drying at -25℃ for 20 hours, and final drying at 0℃ for 4 hours.

[0066] The g-C3N4@COF core-shell photocatalyst was prepared by the following steps:

[0067] C11: Weigh 4 parts of melamine and place them in a crucible. Transfer the crucible to a muffle furnace and heat the furnace to 550°C at 5°C / min. Calcinate the melamine under a nitrogen atmosphere for 4 hours. After naturally cooling to room temperature, grind the melamine through a 200-mesh sieve to obtain a light yellow powder.

[0068] C12: Add the pale yellow powder prepared by C11 to the DMF solution, and treat with ultrasound for 2 hours. After centrifugation at 8000 rpm for 15 minutes, collect the upper third of the clear liquid.

[0069] C13: The supernatant collected from C12 was dispersed in a methanol-toluene mixed solvent, 10 mM 1,3,5-tricarboxymethylbenzene and 15 mM p-phenylenediamine were added, and the mixture was refluxed in an oil bath at 80 °C for 16 hours. The precipitate was collected by centrifugation, washed three times with ethanol, and dried under vacuum at 60 °C to obtain g-C3N4@COF core-shell photocatalyst.

[0070] In C12, the ultrasound uses a 350W pulse mode, with the pulse mode on for 5 seconds and off for 2 seconds.

[0071] In C13, the methanol-toluene mixture has a methanol:toluene ratio of 3:2, and the mass ratio of the methanol-toluene mixture, 1,3,5-tricarboxymethylbenzene, and p-phenylenediamine is 30:11:6.

[0072] The PCL-cellulase controlled-release microspheres were prepared by the following steps:

[0073] C21: Dissolve cellulase in 0.01M PBS buffer (pH 7.4), add 0.05% w / v FITC fluorescent label under light protection, and stir for 30 minutes to obtain the enzyme solution.

[0074] C22: Dissolve PCL in dichloromethane, add the enzyme solution prepared by C21 dropwise, emulsify with a 250W probe for 2 minutes, pour into a 40℃ polyvinyl alcohol aqueous solution, and stir at 500rpm for 4 hours.

[0075] C23: Centrifuge at 6000 rpm for 10 minutes, collect the microspheres and wash them three times with deionized water to obtain PCL-cellulase controlled-release microspheres, which are then freeze-dried and stored.

[0076] In C21, the mass ratio of cellulase to PBS buffer is 1:30.

[0077] In C22, the mass ratio of PCL, dichloromethane, enzyme solution, and polyvinyl alcohol aqueous solution is 10:40:5:300, and the mass fraction of polyvinyl alcohol aqueous solution is 5%.

[0078] Example 3

[0079] Reference Figures 1-3 As shown, a biodegradable sponge comprises the following raw materials in parts by weight:

[0080] 60 parts of oxidized sodium alginate, 20 parts of deacetylated chitosan, 12 parts of 2,5-dimethoxytetraphenyl phthalaldehyde, 0.3 parts of g-C3N4@COF core-shell photocatalyst, 0.2 parts of PCL-cellulase controlled-release microspheres, and 0.5 parts of nanocellulose;

[0081] A process for preparing a biodegradable sponge includes the following steps:

[0082] S1: Dissolve sodium oxidized alginate in 0.1M acetic acid solution and stir at 55°C until clear. Add deacetylated chitosan and continue stirring for 30 minutes until completely dissolved. Add 2,5-dimethoxytetraphenyl phthalaldehyde and stir at 55°C under magnetic conditions for 30 minutes to obtain a pale yellow gel-like dynamic cross-linked network solution. Take droplets for FTIR detection.

[0083] S2: Add nanocellulose to deionized water and disperse by ultrasonication at 40kHz for 20 minutes. Add g-C3N4@COF core-shell photocatalyst and continue ultrasonic dispersion at 60kHz for 20 minutes. Cool to 4℃ in an ice bath, then add PCL-cellulase controlled-release microspheres and vortex mix for 1 minute. Under a red safety lamp, slowly add the dispersion to the dynamic cross-linked network solution prepared in S1. Stir magnetically at 300rpm for 40 minutes under a nitrogen atmosphere to obtain a homogeneous mixture.

[0084] S3: Pour the mixture into a tetrafluoroethylene mold, pre-freeze at -15℃ for 24 hours, immerse in CaCl2-ethanol solution for cross-linking for 2 hours, remove and rinse the surface with deionized water, transfer to a -10℃ freeze dryer for vacuum drying for 27 hours to obtain a porous sponge.

[0085] In S1, the weight ratio of acetic acid solvent to sodium alginate is 25:1, and the pH is adjusted to 5.0 to promote dissolution.

[0086] In S1, the degree of deacetylation of the deacetylated chitosan (DD) is 87.1%.

[0087] In the FTIR test of S1, a 1620cm depth is required. -1 The characteristic peak of the C=N bond and 1550 cm⁻¹ -1 The intensity ratio of the characteristic peak of the amide II band is ≥1.3, indicating a decrease in crosslinking density.

[0088] In S1, the molar ratio of aldehyde group to amino group in 2,5-dimethoxytetraphenyl phthalaldehyde is 0.9:1. Unreacted amino groups increase the hydrophilicity of the network, form hydrogen bonds with water molecules, increase the swelling rate, and decrease the crosslinking density. This makes it easier for the dynamic network to form through-pores during freeze-drying, thereby increasing the porosity and the diffusion coefficient of enzyme molecules, thus promoting enzyme diffusion.

[0089] The dimensions of the tetrafluoroethylene mold in S3 are 10×10×1cm. 3 .

[0090] In S3, the mass fraction of CaCl2-ethanol solution is 2%, and the weight ratio of CaCl2-ethanol solution to sodium alginate is 250:1.

[0091] Among them, the vacuum degree inside the freeze dryer in S3 is <10Pa, and gradient freeze drying is adopted: pre-freezing at -30℃ for 2 hours, main drying at -10℃ for 22 hours, and final drying at 5℃ for 3 hours.

[0092] The g-C3N4@COF core-shell photocatalyst was prepared by the following steps:

[0093] C11: Weigh 4 parts of melamine and place them in a crucible. Transfer the crucible to a muffle furnace and heat the furnace to 550°C at 5°C / min. Calcinate the melamine under a nitrogen atmosphere for 4 hours. After naturally cooling to room temperature, grind the melamine through a 200-mesh sieve to obtain a light yellow powder.

[0094] C12: Add the pale yellow powder prepared by C11 to the DMF solution, and treat with ultrasound for 2 hours. After centrifugation at 8000 rpm for 15 minutes, collect the upper third of the clear liquid.

[0095] C13: The supernatant collected from C12 was dispersed in an ethanol-water mixed solvent, 10 mM 1,3,5-tricarboxymethylbenzene and 15 mM p-phenylenediamine were added, and the mixture was refluxed in an oil bath at 80 °C for 10 hours. The precipitate was collected by centrifugation, washed three times with ethanol, and dried under vacuum at 60 °C to obtain g-C3N4@COF core-shell photocatalyst.

[0096] In C12, the ultrasound uses a 300W pulse mode, with the pulse mode on for 5 seconds and off for 2 seconds.

[0097] In C13, the ethanol-water mixture has an ethanol:water ratio of 7:3, and the mass ratio of the ethanol-water mixture, 1,3,5-tricarboxymethylbenzene, and p-phenylenediamine is 30:11:6.

[0098] The PCL-cellulase controlled-release microspheres were prepared by the following steps:

[0099] C21: Dissolve cellulase in 0.01M PBS buffer (pH 7.4), add 0.05% w / v FITC fluorescent label under light protection, and stir for 30 minutes to obtain the enzyme solution.

[0100] C22: Dissolve PCL in dichloromethane, add the enzyme solution prepared by C21 dropwise, emulsify with a 300W probe for 3 minutes, pour into a 40℃ polyvinyl alcohol aqueous solution, and stir at 500rpm for 4 hours.

[0101] C23: Centrifuge at 6000 rpm for 10 minutes, collect the microspheres and wash them three times with deionized water to obtain PCL-cellulase controlled-release microspheres, which are then freeze-dried and stored.

[0102] In C21, the mass ratio of cellulase to PBS buffer is 1:20.

[0103] In C22, the mass ratio of PCL, dichloromethane, enzyme solution, and polyvinyl alcohol aqueous solution is 8:35:6:250, and the mass fraction of polyvinyl alcohol aqueous solution is 5%.

[0104] Example 4

[0105] Reference Figures 1-3 As shown, a biodegradable sponge comprises the following raw materials in parts by weight:

[0106] 55 parts of oxidized sodium alginate, 25 parts of deacetylated chitosan, 15 parts of 2,5-dimethoxytetraphenyl phthalaldehyde, 0.3 parts of g-C3N4@COF core-shell photocatalyst, 0.125 parts of PCL-cellulase controlled-release microspheres, and 0.3 parts of nanocellulose;

[0107] A process for preparing a biodegradable sponge includes the following steps:

[0108] S1: Dissolve sodium oxidized alginate in 0.1M acetic acid solution and stir at 40°C until clear. Add deacetylated chitosan and continue stirring for 30 minutes until completely dissolved. Add 2,5-dimethoxyterephthalaldehyde and stir at 60°C under magnetic conditions for 60 minutes to obtain a pale yellow gel-like dynamic cross-linked network solution. Take droplets for FTIR detection.

[0109] S2: Add nanocellulose to deionized water and disperse by ultrasonication at 40kHz for 20 minutes. Add g-C3N4@COF core-shell photocatalyst and continue ultrasonic dispersion at 40kHz for 10 minutes. Cool to 4℃ in an ice bath, then add PCL-cellulase controlled-release microspheres and vortex mix for 1 minute. Under a red safety lamp, slowly add the dispersion to the dynamic cross-linked network solution prepared in S1 and stir magnetically at 300rpm for 30 minutes to obtain a homogeneous mixture.

[0110] S3: Pour the mixture into a tetrafluoroethylene mold, freeze it with liquid nitrogen at -80°C for 1 hour, then transfer it to -20°C for 24 hours to pre-freeze, immerse it in CaCl2-ethanol solution for 2 hours to crosslink, remove it and rinse the surface with deionized water, then transfer it to a freeze dryer at -25°C for 23 hours to vacuum dry to obtain a porous sponge.

[0111] In S1, the weight ratio of acetic acid solvent to sodium alginate oxide is 25:1. The pH is adjusted to 5.8 to weaken carboxyl ionization and reduce Ca2+. 2+ Ionic bond competition enhances the dynamics of imine bonds.

[0112] In S1, the degree of deacetylation of the deacetylated chitosan (DD) is 60.3%.

[0113] In the FTIR test of S1, a 1620cm depth is required. -1 The characteristic peak of the C=N bond and 1550 cm⁻¹ -1 The intensity ratio of the characteristic peak of the amide II band is ≥1.8, which proves that the imine bond is fully formed.

[0114] In S1, the molar ratio of aldehyde group to amino group in 2,5-dimethoxytetraphenyl phthalaldehyde is 1.3:1.

[0115] The dimensions of the tetrafluoroethylene mold in S3 are 10×10×1cm. 3 .

[0116] In S3, the mass fraction of CaCl2-ethanol solution is 2%, and the weight ratio of CaCl2-ethanol solution to sodium alginate is 250:1.

[0117] Among them, the vacuum degree inside the freeze dryer in S3 is <10Pa, and gradient freeze drying is adopted: pre-freezing at -40℃ for 3 hours, main drying at -25℃ for 18 hours, and final drying at 0℃ for 2 hours.

[0118] The g-C3N4@COF core-shell photocatalyst was prepared by the following steps:

[0119] C11: Weigh 4 parts of melamine and place them in a crucible. Transfer the crucible to a muffle furnace and heat the furnace to 550°C at 5°C / min. Calcinate the melamine under a nitrogen atmosphere for 4 hours. After naturally cooling to room temperature, grind the melamine through a 200-mesh sieve to obtain a light yellow powder.

[0120] C12: Add the pale yellow powder prepared by C11 to the DMF solution, and treat with ultrasound for 2 hours. After centrifugation at 8000 rpm for 15 minutes, collect the upper third of the clear liquid.

[0121] C13: The supernatant collected from C12 was dispersed in a methanol-toluene mixed solvent, 10 mM 1,3,5-tricarboxymethylbenzene and 15 mM p-phenylenediamine were added, and the mixture was refluxed in an oil bath at 80 °C for 14 hours. The precipitate was collected by centrifugation, washed three times with ethanol, and dried under vacuum at 60 °C to obtain g-C3N4@COF core-shell photocatalyst.

[0122] In C12, the ultrasound uses a 300W pulse mode, with the pulse mode on for 5 seconds and off for 2 seconds.

[0123] In C13, the methanol-toluene mixture has a methanol:toluene ratio of 4:1, and the mass ratio of the methanol-toluene mixture, 1,3,5-tricarboxymethylbenzene, and p-phenylenediamine is 25:9:5.

[0124] The PCL-cellulase controlled-release microspheres were prepared by the following steps:

[0125] C21: Dissolve cellulase in 0.01M PBS buffer (pH 7.4), add 0.05% w / v FITC fluorescent label under light protection, and stir for 30 minutes to obtain the enzyme solution.

[0126] C22: Dissolve PCL in dichloromethane, add the enzyme solution prepared by C21 dropwise, emulsify with a 200W probe for 2 minutes, pour into a 40℃ polyvinyl alcohol aqueous solution, and stir at 500rpm for 4 hours.

[0127] C23: Centrifuge at 6000 rpm for 10 minutes, collect the microspheres and wash them three times with deionized water to obtain PCL-cellulase controlled-release microspheres, which are then freeze-dried and stored.

[0128] In C21, the mass ratio of cellulase to PBS buffer is 1:20.

[0129] In C22, the mass ratio of PCL, dichloromethane, enzyme solution, and polyvinyl alcohol aqueous solution is 10:40:5:300, and the mass fraction of polyvinyl alcohol aqueous solution is 4%.

[0130] Example 5

[0131] Reference Figures 1-3 As shown, a biodegradable sponge comprises the following raw materials in parts by weight:

[0132] 55 parts sodium alginate, 25 parts deacetylated chitosan, 10 parts phthalaldehyde, 0.4 parts g-C3N4@COF core-shell photocatalyst, 0.2 parts PCL-cellulase controlled-release microspheres, and 0.05 parts propyl gallate;

[0133] A process for preparing a biodegradable sponge includes the following steps:

[0134] S1: Dissolve sodium oxidized alginate in 0.1M acetic acid solution and stir at 40°C until clear. Add deacetylated chitosan and continue stirring for 30 minutes until completely dissolved. Add phthalaldehyde and stir at 45°C under magnetic conditions for 30 minutes to obtain a pale yellow gel-like dynamic cross-linked network solution. Take droplets for FTIR detection.

[0135] S2: Add g-C3N4@COF core-shell photocatalyst to deionized water, disperse by ultrasonication at 40kHz for 10 minutes, add propyl gallate and vortex mix for 1 minute, cool to 4℃ in an ice bath, then add PCL-cellulase controlled-release microspheres and vortex mix for 1 minute. Under light-protected conditions, slowly add the dispersion to the dynamic cross-linked network solution prepared in S1, and magnetically stir at 300rpm for 30 minutes to obtain a homogeneous mixture.

[0136] S3: Pour the mixture into a tetrafluoroethylene mold, freeze it with liquid nitrogen at -80°C for 1 hour, then transfer it to -20°C for pre-freezing for 24 hours, immerse it in CaCl2-ethanol solution for crosslinking for 2 hours, take it out and rinse the surface with deionized water, then transfer it to a freeze dryer at -30°C for vacuum drying for 19 hours to obtain a porous sponge.

[0137] In S1, the weight ratio of acetic acid solvent to sodium alginate oxide is 25:1. The pH is adjusted to 5.8 to weaken carboxyl ionization and reduce Ca2+. 2+ Ionic bond competition enhances the dynamics of imine bonds.

[0138] Among them, the degree of deacetylation (DD) of deacetylated chitosan in S1 is 96.1%.

[0139] In the FTIR test of S1, a 1620cm depth is required. -1 The characteristic peak of the C=N bond and 1550 cm⁻¹ -1 The intensity ratio of the characteristic peak of the amide II band is ≥1.5, which proves that the imine bond is fully formed.

[0140] In S1, the molar ratio of aldehyde group to amino group in phthalaldehyde is 1:1.

[0141] The dimensions of the tetrafluoroethylene mold in S3 are 10×10×1cm. 3 .

[0142] In S3, the mass fraction of CaCl2-ethanol solution is 2%, and the weight ratio of CaCl2-ethanol solution to sodium alginate is 250:1.

[0143] Among them, the vacuum degree inside the freeze dryer in S3 is <10Pa, and gradient freeze drying is adopted: pre-freezing at -40℃ for 2 hours, main drying at -30℃ for 15 hours, and final drying at 5℃ for 2 hours.

[0144] The g-C3N4@COF core-shell photocatalyst was prepared by the following steps:

[0145] C11: Weigh 4 parts of melamine and place them in a crucible. Transfer the crucible to a muffle furnace and heat the furnace to 550°C at 5°C / min. Calcinate the melamine under a nitrogen atmosphere for 4 hours. After naturally cooling to room temperature, grind the melamine through a 200-mesh sieve to obtain a light yellow powder.

[0146] C12: Add the pale yellow powder prepared by C11 to the DMF solution, and treat with ultrasound for 2 hours. After centrifugation at 8000 rpm for 15 minutes, collect the upper third of the clear liquid.

[0147] C13: The supernatant collected from C12 was dispersed in a methanol-toluene mixed solvent, 10 mM 1,3,5-tricarboxymethylbenzene and 15 mM p-phenylenediamine were added, and the mixture was refluxed in an oil bath at 80 °C for 14 hours. The precipitate was collected by centrifugation, washed three times with ethanol, and dried under vacuum at 60 °C to obtain g-C3N4@COF core-shell photocatalyst.

[0148] In C12, the ultrasound uses a 300W pulse mode, with the pulse mode on for 5 seconds and off for 2 seconds.

[0149] In C13, the methanol-toluene mixture has a methanol:toluene ratio of 4:1, and the mass ratio of the methanol-toluene mixture, 1,3,5-tricarboxymethylbenzene, and p-phenylenediamine is 25:9:5.

[0150] The PCL-cellulase controlled-release microspheres were prepared by the following steps:

[0151] C21: Dissolve cellulase in 0.01M PBS buffer (pH 7.4), add 0.05% w / v FITC fluorescent label under light protection, and stir for 30 minutes to obtain the enzyme solution.

[0152] C22: Dissolve PCL in dichloromethane, add the enzyme solution prepared by C21 dropwise, emulsify with a 200W probe for 2 minutes, pour into a 40℃ polyvinyl alcohol aqueous solution, and stir at 500rpm for 4 hours.

[0153] C23: Centrifuge at 6000 rpm for 10 minutes, collect the microspheres and wash them three times with deionized water to obtain PCL-cellulase controlled-release microspheres, which are then freeze-dried and stored.

[0154] In C21, the mass ratio of cellulase to PBS buffer is 1:20.

[0155] In C22, the mass ratio of PCL, dichloromethane, enzyme solution, and polyvinyl alcohol aqueous solution is 10:40:5:300, and the mass fraction of polyvinyl alcohol aqueous solution is 4%.

[0156] Comparative Example 1

[0157] TiO2 was used to replace the g-C3N4@COF core-shell photocatalyst. Before S2, TiO2 powder was pretreated by immersing it in 1M HCl solution and shaking for 2 hours. After centrifugation and washing until neutral, it was dried at 80℃. After freeze-drying in S3, the sponge was placed in an oven at 120℃ for 2 hours for heat treatment.

[0158] The remaining preparation process for Comparative Example 1 is the same as in Example 1, with the aim of verifying the irreplaceable nature of the g-C3N4@COF core-shell photocatalyst.

[0159] Comparative Example 2

[0160] Glutaraldehyde was used instead of 2,5-dimethoxytetraphenylacetaldehyde. After adding glutaraldehyde in S1, it was cured at 80°C for 1 hour to form static covalent bonds. In S3, liquid nitrogen quick-freezing and gradient drying were eliminated, and the product was pre-frozen at -20°C for 24 hours before direct drying.

[0161] The remaining preparation process for Comparative Example 2 was the same as in Example 4, with the aim of verifying the decisive role of dynamic imine bonds in the self-repair function.

[0162] Effect test:

[0163] The sponges obtained in Examples 1-5 and Comparative Examples 1-2 were tested for the following effects:

[0164] Cell compatibility test: According to ISO 10993-5:2009 standard, the sponge sample was cut into 5×5×1mm pieces. 3 Thin slices were immersed in DMEM medium containing 10% fetal bovine serum (200 mg / mL) and extracted at 37°C for 24 hours. L929 mouse fibroblasts were seeded in 96-well plates, and 100 μL of the extraction medium was added for 24 hours of culture. Cell viability was measured using a CCK-8 assay kit at 450 nm using a microplate reader. Cell viability was calculated, and a cell viability >90% indicated no cytotoxicity.

[0165] Density test: According to ASTM D3574-17, take a 10×10×1cm sample. 3 The standard sample was weighed using an electronic balance with an accuracy of 0.0001g, and its volume was measured using vernier calipers. Apparent density formula:

[0166] ρ=W / V

[0167] The density must be less than 0.05 g / cm³ to ensure the material is lightweight.

[0168] Water absorption test: Referring to ISO 10999:2011, weigh the dry sponge (W0) and immerse it in deionized water at 25°C for 24 hours until saturated. After removal, hang it to drain for 10 minutes until no more water droplets fall, and weigh the wet weight (W1). The water absorption rate is calculated using the formula:

[0169] [(W1-W0) / W0]×100%

[0170] A water absorption rate greater than 380% is required to reflect the integrity of the open structure.

[0171] Repair efficiency test: Following ASTM F2456-18, a 0.5 mm deep incision with a 50 μm width was made on the sponge surface using a microsurgical blade. After repair, the incision depth recovery rate was measured using a Zeiss LSM 900 laser confocal microscope. The calculation formula is:

[0172] [1 - (Post-repair incision depth / Initial incision depth)] × 100%

[0173] A repair rate greater than 75% is required to verify the dynamic network reassembly function.

[0174] Degradation rate test: Refer to ISO 14855:2018, and test a 10×10×1mm sample. 3 The sponge samples were immersed in PBS buffer (pH 7.4) containing 1 mg / mL lysozyme and incubated with shaking at 37°C. Samples were removed every 7 days, vacuum-dried, and weighed. The degradation rate was calculated using the formula:

[0175] [(W0-W t ) / W0]×100%

[0176] Among them W t The dry weight is given by time t, and the degradation rate after 21 days is required to be >65% to meet the standards for biodegradable materials.

[0177] Photocatalytic efficiency test: According to ISO 10678:2010, the sponge was immersed in a 10 mg / L methylene blue solution and irradiated under AM1.5G simulated sunlight with a simulated solar radiation intensity of 100 mW / cm². 2Samples were taken every 30 minutes, and absorbance was measured using a UV-Vis spectrometer, where λ = 664 nm. The degradation rate was calculated using the formula:

[0178] [(C0-C t ) / C0]×100%

[0179] Where C0 is the initial concentration.

[0180] The resulting basic performance comparison table is shown in Table 1:

[0181] sample Compressive strength (kPa) Porosity (%) Water absorption rate (%) <![CDATA[Density (g / cm 3 )]]> Example 1 68.2±3.1 83.5±2.3 380±15 0.052±0.003 Example 2 72.5±2.8 85.1±1.9 395±12 0.048±0.002 Example 3 86.7±3.5 87.3±2.1 420±18 0.045±0.003 Example 4 105.3±4.2 91.8±1.7 510±20 0.039±0.002 Example 5 78.4±3.0 88.6±2.0 435±16 0.042±0.003 Comparative Example 1 42.1±2.5 35.2±3.1 185±10 0.121±0.008 Comparative Example 2 152.6±5.3 68.5±2.8 295±14 0.075±0.004

[0182] Table 1

[0183] The resulting functional performance comparison table is shown in Table 2:

[0184] sample Repair rate (%) at 60℃ / 10min Room temperature / 24h repair rate (%) 21-day degradation rate (%) Photocatalytic efficiency (90 min, %) Enzyme activity retention rate (%) Example 1 92.5±1.8 38.7±2.1 68.7±2.5 95.8±1.2 88.3±1.5 Example 2 89.3±1.5 42.5±1.9 71.2±2.3 97.1±0.9 90.1±1.2 Example 3 94.2±1.7 55.6±2.3 73.8±2.1 93.5±1.1 92.7±1.4 Example 4 98.3±0.8 75.6±1.5 65.2±1.8 91.8±1.0 91.5±1.3 Example 5 89.7±1.2 76.3±1.4 69.5±2.0 91.5±0.8 95.2±0.9 Comparative Example 1 Unpredictable Unpredictable 18.5±1.2 42.3±2.1 35.6±2.3 Comparative Example 2 0 0 9.7±0.8 85.6±1.5 38.2±1.8

[0185] Table 2

[0186] The obtained biosafety data are shown in Table 3:

[0187] sample Cell viability (%) Skin irritation Strength retention after 10 repairs (%) 50-day degradation rate (%) Example 1 91.2±1.8 Non-irritating 72.5±2.1 92.3±1.5 Example 2 92.5±1.5 Non-irritating 75.3±1.8 94.1±1.2 Example 3 94.3±1.2 Non-irritating 80.6±1.5 96.8±0.9 Example 4 96.3±0.9 Non-irritating 85.0±1.2 89.7±1.3 Example 5 95.8±1.1 Non-irritating 82.3±1.4 93.5±1.0 Comparative Example 1 68.0±2.5 moderate stimulation - 25.3±1.8 Comparative Example 2 86.5±1.8 Mild stimulation 45.2±2.0 15.7±1.2

[0188] Table 3

[0189] As shown in Tables 1-3, the sponges prepared in Examples 1-5 have superior basic properties, functional properties, and biocompatibility compared to the comparative examples.

[0190] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A biodegradable sponge, characterized in that, The raw materials include the following parts by weight: 50-65 parts sodium alginate oxide, 15-30 parts deacetylated chitosan, 10-15 parts aldehyde-containing crosslinking agent, 0.3-0.5 parts g-C3N4@COF core-shell photocatalyst, 0.1-0.2 parts PCL-cellulase controlled-release microspheres, and 0-0.5 parts nanocellulose. The sponge forms a dual-network structure through dynamic imine bond crosslinking network and ionic bond synergistic curing. The aldehyde-containing crosslinking agent is 2,5-dimethoxyterephthalaldehyde or o-phthalaldehyde, and the molar ratio of the aldehyde group in the aldehyde-containing crosslinking agent to the amino group in the deacetylated chitosan is 0.9:1-1.3:1; The g-C3N4@COF core-shell photocatalyst was prepared through the following steps: C11: Melamine was calcined at 550℃ for 4 hours, then ground and passed through a 200-mesh sieve to obtain g-C3N4 nanosheets; C12: Add g-C3N4 nanosheets to DMF solution, sonicate to mix, centrifuge and collect the supernatant; C13: The collected supernatant was dispersed in a methanol-toluene mixed solvent, and 1,3,5-tricarboxymethylbenzene and p-phenylenediamine were added. The mixture was refluxed in an oil bath at 80°C for 12-16 hours. After centrifugation, the precipitate was collected, washed with ethanol, and dried under vacuum to obtain g-C3N4@COF core-shell photocatalyst.

2. The biodegradable sponge according to claim 1, characterized in that: The PCL-cellulase controlled-release microspheres were prepared through the following steps: C21: Dissolve cellulase in PBS buffer, label with FITC, and then stir; C22: Dissolve PCL in dichloromethane, emulsify by adding enzyme solution, pour in polyvinyl alcohol aqueous solution and stir; C23: After centrifugation, the microspheres were collected and washed with deionized water to obtain PCL-cellulase controlled-release microspheres, which were then freeze-dried and stored.

3. The biodegradable sponge according to claim 1, characterized in that: The raw materials also include 0-0.1 parts of an antioxidant, wherein the antioxidant is propyl gallate.

4. The biodegradable sponge according to claim 2, characterized in that: The mass ratio of cellulase to PBS buffer is 1:20-1:30, and the mass fraction of the polyvinyl alcohol aqueous solution is 4%-5%.

5. A process for preparing a biodegradable sponge, used to prepare the biodegradable sponge as described in any one of claims 1-4, characterized in that, Includes the following steps: S1: Dissolve sodium oxidized alginate and deacetylated chitosan in acetic acid solution by stirring, add aldehyde-containing crosslinking agent, stir at 40-60℃ to obtain dynamic crosslinked network solution, and detect by FTIR; S2: Add g-C3N4@COF core-shell photocatalyst to deionized water, disperse by ultrasonication, cool to 4°C in an ice bath, add PCL-cellulase controlled-release microspheres and vortex mix, add dynamic cross-linked network solution dropwise and stir to obtain a mixture; S3: The mixture is poured into a tetrafluoroethylene mold, pre-frozen for 24 hours, then immersed in a CaCl2-ethanol solution for crosslinking for 2 hours. After removal, it is rinsed with deionized water and then freeze-dried in a freeze dryer for 19-27 hours in a gradient manner.

6. The biodegradable sponge preparation process according to claim 5, characterized in that: In step S1, after adjusting the pH of the dynamic cross-linked network solution to 5.0-5.8, it is subjected to FTIR detection. The FTIR detection requires a 1620 cm⁻¹ depth. -1 The characteristic peak of the C=N bond and 1550 cm⁻¹ -1 The intensity ratio of the characteristic peak of the amide II band is ≥1.

3.

7. The biodegradable sponge preparation process according to claim 5, characterized in that: The gradient freeze drying in step S3 includes pre-freezing at -40℃ to -30℃ for 1-3 hours, main drying at -30℃ to -10℃ for 15-22 hours, and final drying at 0℃ to 5℃ for 2-4 hours.

8. The biodegradable sponge preparation process according to claim 5, characterized in that: In step S3, the mass fraction of the CaCl2-ethanol solution is 2%, and the weight ratio of the CaCl2-ethanol solution to sodium alginate is 250:1.

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