A photocrosslinked organic piezoelectric heterojunction hydrogel and its preparation method and application

Abstract

The present invention discloses a photocrosslinked organic piezoelectric heterojunction hydrogel and its preparation method and application, belonging to the field of biomedical materials technology. The photocrosslinked organic piezoelectric heterojunction hydrogel includes the following component raw materials: 5 to 20 parts of double-bonded protein, 0.2 to 0.3 parts of photoinitiator and 0.5 to 4 parts of skeleton material; the double-bonded protein is double-bonded gelatin or double-bonded silk fibroin; the skeleton material is at least one of a composite material of a double-bonded cobalt porphyrin covalent organic skeleton and a hafnium-based metal organic skeleton, a composite material of double-bonded hyaluronic acid and a hafnium-based metal organic skeleton-polypyrrole grafted, and double-bonded silk fibroin-polypyrrole. The present invention also discloses a preparation method and application of the photocrosslinked organic piezoelectric heterojunction hydrogel. The hydrogel of the present invention has both good piezoelectric-conductive properties, and the obtained electrical signal is strong and stable. At the same time, it has good mechanical properties and broad application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedical materials, and in particular relates to a photocrosslinked organic piezoelectric heterojunction hydrogel and a preparation method and application thereof. Background Art

[0002] Hydrogels, due to their unique three-dimensional network structure and high water content, play an important role in the biomedical field, especially in tissue engineering, drug delivery systems, cell culture matrices, and biosensors. Since the last century, hydrogels have been widely used in various biomedical applications due to their biocompatibility, plasticity, and structural adjustability. However, traditional hydrogel materials often exhibit insufficient mechanical properties in applications with high mechanical loads, such as bone and cartilage repair.

[0003] On the other hand, piezoelectric materials such as barium titanate (BaTiO3), polyvinylidene fluoride (PVDF), and polyurethane (PU) can generate an electric charge under mechanical stress and, vice versa, produce mechanical deformation under an electric field. This property has led to a wide range of applications for piezoelectric materials in sensors, actuators, and energy harvesting devices. In tissue engineering, piezoelectric materials promote cell proliferation, differentiation, and tissue remodeling by providing additional electrical stimulation signals. In particular, in bone and cartilage repair, the electrical stimulation generated by the piezoelectric effect is believed to effectively promote bone cell maturation and mineralization, accelerate cartilage cell growth, and tissue repair. Furthermore, the electrical conductivity of the material is equally important, especially for muscle and neural tissue, which require electrophysiological signal support. Conductive materials can mimic the electrical properties of native tissue and provide cells with the necessary electrophysiological environment. In muscle tissue engineering, conductive materials facilitate cell alignment and restore contractile function, and promote muscle cell proliferation and differentiation through continuous electrical stimulation. For neural tissue, conductive materials can serve as an effective medium for signal transmission, guiding axonal growth, promoting neural network reconstruction, and accelerating neural tissue regeneration.

[0004] Considering the respective advantages of hydrogels and piezoelectric materials, combining the two to form piezoelectric hydrogels has become an attractive research direction. These hydrogels not only inherit the biocompatibility and plasticity of traditional hydrogels, but also incorporate the electroactivity of piezoelectric materials, capable of withstanding and converting mechanical energy into electrical energy, offering a new solution for repairing tissues subjected to mechanical loads.

[0005] However, existing piezoelectric materials often lack effective bioactive signals when promoting muscle and nerve tissue regeneration, and are unable to accurately guide cell differentiation and tissue reconstruction. In particular, in nerve regeneration, there is a lack of precise electrophysiological signals to promote axonal growth and neural network reconstruction. At the same time, in existing piezoelectric conductive hydrogels and heterogeneous materials, functional materials such as piezoelectric components are unevenly dispersed and unstable in their binding to the hydrogel matrix, which may lead to performance degradation during in vivo application and affect the repair effect. At the same time, traditional hydrogel materials often lack mechanical strength when dealing with the mechanical challenges brought by muscle contraction and neural activity, making it difficult to achieve the stability required for muscle and nerve tissue repair. Summary of the Invention

[0006] In response to the above-mentioned deficiencies in the prior art, the present invention provides a photocrosslinked organic piezoelectric heterojunction hydrogel, a preparation method, and an application thereof. The photocrosslinked organic piezoelectric heterojunction hydrogel has good piezoelectric-conductive properties, and the resulting electrical signal is strong and stable. At the same time, it has good mechanical properties itself and has broad application prospects.

[0007] The technical solution adopted to solve the technical problem is to provide a photo-crosslinked organic piezoelectric heterojunction hydrogel, comprising the following raw materials in parts by weight: 5 to 20 parts of double-bonded protein, 0.2 to 0.3 parts of photoinitiator and 0.5 to 4 parts of skeleton material;

[0008] The double-bonded protein is double-bonded gelatin or double-bonded silk fibroin; the skeleton material is at least one of a composite material of a double-bonded cobalt porphyrin covalent organic skeleton and a hafnium-based metal organic skeleton, a composite material of a double-bonded hyaluronic acid and a hafnium-based metal organic skeleton-polypyrrole grafted thereon, and double-bonded silk fibroin-polypyrrole.

[0009] Preferably, the photo-crosslinked organic piezoelectric heterojunction hydrogel comprises the following raw materials in parts by weight: 10 to 18 parts of double-bonded protein, 0.25 parts of photoinitiator and 1 part of skeleton material.

[0010] Preferably, the photo-crosslinked organic piezoelectric heterojunction hydrogel further comprises 100 parts by weight of water.

[0011] Preferably, the photoinitiator is a LAP photoinitiator.

[0012] Preferably, the double-bonded gelatin is prepared by the following steps:

[0013] Gelatin is dissolved in phosphate buffer at 60°C and methacrylic anhydride is added for reaction, followed by dialysis and freeze-drying to obtain the product; the mass ratio of gelatin to methacrylic anhydride is 5:6; the reaction temperature is 50°C and the time is 3 hours; the dialysis temperature is 40°C and the time is 7 days, and the water is changed 2 to 3 times a day during the dialysis process.

[0014] Preferably, the double-bonded silk fibroin is prepared by the following steps:

[0015] The degummed silk fibroin is added into the LiBr solution and stirred, and then glycidyl methacrylate is added to react. After the reaction is completed, the silk fibroin is dialyzed, centrifuged, and the supernatant is freeze-dried to obtain the product.

[0016] The molar concentration of the LiBr solution is 9.3 M; the mass ratio of glycidyl methacrylate to silk fibroin is 1:1-4; the reaction temperature is 60°C and the time is 4 hours; the dialysis temperature is 4°C and the time is 7 days, and the water is changed 2-3 times a day during the dialysis process.

[0017] Preferably, the double-bonded silk fibroin-polypyrrole is prepared by the following steps:

[0018] The double-bonded silk fibroin is dissolved in a buffer solution, pyrrole is added and stirred, an oxidant is added and stirred for reaction, and then dialyzed and freeze-dried to obtain the product.

[0019] More preferably, the oxidant is ammonium persulfate; the stirring mixing temperature is 45-50°C and the time is 1.5-2.5h; the stirring reaction temperature is 35-45°C and the time is 8-12h; the dialysis time is 2-3d; the material-liquid ratio of double-bonded silk fibroin, pyrrole and oxidant is 1g:(300-500)μL:(0.05-0.2)g.

[0020] More preferably, the material-liquid ratio of double-bonded silk fibroin, pyrrole and oxidant is 1 g:400 μL:0.1 g.

[0021] More preferably, the size of the hafnium-based metal-organic framework is 50 nm.

[0022] More preferably, the hafnium-based metal-organic framework is prepared by the following steps:

[0023] (1) HfCl4 and 2-aminoterephthalic acid are dissolved in N,N-dimethylformamide, water is added, ultrasonication is performed, and heating reaction is performed to obtain a suspension;

[0024] (2) The suspension is centrifuged to obtain a precipitate, which is then immersed in N,N-dimethylformamide. The precipitate is taken out, washed, dried, and heated under an inert gas atmosphere to obtain the product.

[0025] More preferably, the molar ratio of HfCl4 to 2-aminoterephthalic acid is 1:2; the heating reaction temperature is 120°C and the time is 24h; the heating treatment temperature is 100°C and the time is 48h.

[0026] Preferably, the composite material of the double-bonded cobalt porphyrin covalent organic framework and the hafnium-based metal organic framework is prepared by the following steps:

[0027] (1) adding cobalt porphyrin, hafnium-based metal organic framework and p-phenylenediamine to polyphosphoric acid in sequence, performing a freeze-thaw cycle, activating the precursor under sealed conditions, and then heating the mixture to obtain a reactant;

[0028] (2) adjusting the pH of the reactants to 8-9, and then centrifuging, extracting, washing, and drying in sequence to obtain composite material particles of the cobalt porphyrin covalent organic framework and the hafnium-based metal organic framework;

[0029] (3) The composite material particles of the cobalt porphyrin covalent organic framework and the hafnium-based metal organic framework are dispersed in a solvent, ultrasonically treated, and glycidyl methacrylate is added for heating reaction, and then centrifuged, washed and vacuum dried in sequence to obtain the product.

[0030] More preferably, in step (1), the precursor activation temperature is 60-70°C, and the time is 10-14 h; the heating reaction temperature is 140-160°C, and the time is 55-65 h; the material-liquid ratio of cobalt porphyrin, hafnium-based metal organic framework, p-phenylenediamine and polyphosphoric acid is (20-25) mg: (10-20) mg: (6-9) mg: (2-4) mL.

[0031] More preferably, in step (1), the precursor activation temperature is 66°C and the time is 12h; the heating reaction temperature is 150°C and the time is 60h; the material-liquid ratio of cobalt porphyrin, hafnium-based metal organic framework, p-phenylenediamine and polyphosphoric acid is 23.7mg:15mg:7.5mg:3mL.

[0032] More preferably, the pH in step (2) is adjusted using a saturated sodium bicarbonate solution; the extraction comprises the following steps: Soxhlet extraction with water, tetrahydrofuran and methanol in sequence; washing time is 24 hours; and drying temperature is 90° C. for 12 hours.

[0033] More preferably, the solvent in step (3) is tetrahydrofuran; the material-liquid ratio of the composite material of cobalt porphyrin covalent organic framework and hafnium-based metal organic framework to glycidyl methacrylate is (50-70) mg: (200-230) μL; the heating reaction is carried out under stirring conditions at a temperature of 50-60° C. for 34-38 h.

[0034] More preferably, the material-liquid ratio of the composite material of cobalt porphyrin covalent organic framework and hafnium-based metal organic framework to glycidyl methacrylate is 60 mg:215 μL; the heating reaction is carried out under stirring conditions at a temperature of 55° C. for 36 hours.

[0035] More preferably, in step (3), the washing is performed with tetrahydrofuran for 3 times, and then with chloroform for 3 times under ultrasonic conditions; the vacuum drying temperature is 50° C. and the time is 24 h.

[0036] Preferably, the composite material of double-bonded hyaluronic acid and hafnium-based metal organic framework-polypyrrole grafted thereon is prepared by the following steps:

[0037] (1) dissolving carbodiimide and N-hydroxysuccinimide in water respectively and adding a hyaluronic acid aqueous solution to stir and activate, then adding a hafnium-based metal organic framework aqueous solution, adjusting the pH to 8-9 and stirring to react, and after the reaction is completed, centrifuging, washing and freeze-drying are performed in sequence to obtain a hyaluronic acid-grafted hafnium-based metal organic framework;

[0038] (2) dispersing the hafnium-based metal organic framework grafted with hyaluronic acid in a buffer solution, adding a solvent and methacrylic anhydride to react, then adding anhydrous ethanol to precipitate, wash, dialyze and freeze-dry to obtain a double-bonded hyaluronic acid grafted hafnium-based metal organic framework;

[0039] (3) The hafnium-based metal organic framework grafted with double-bonded hyaluronic acid and pyrrole are dispersed in a hydrochloric acid solution, and then a hydrochloric acid solution containing FeCl3 is added dropwise and stirred for reaction, followed by dialysis, centrifugation and freeze-drying to obtain the product.

[0040] More preferably, in step (1), the stirring activation temperature is room temperature and the time is 22 to 26 hours; the stirring reaction temperature is 35 to 39° C. and the time is 22 to 26 hours; the mass ratio of carbodiimide, N-hydroxysuccinimide, hyaluronic acid and hafnium-based metal organic framework is (50 to 55): (95 to 99): (25 to 35): (25 to 35); in step (2), the mass ratio of methacrylic anhydride to hafnium-based metal organic framework grafted with hyaluronic acid is 1 to 2: 1 to 2; the solvent is N, N-dimethylformamide; the reaction temperature is 35 to 39° C. and the time is 22 to 26 hours. The temperature is 2-4° C. and the time is 22-26 h; the dialysis temperature is 35-45° C. and the time is 2-4 d; the solid-liquid ratio of the double-bonded hyaluronic acid-grafted hafnium-based metal organic framework, pyrrole and hydrochloric acid solution in step (3) is (80-100) mg:(0.03-0.04) mL:(30-60) mL; the molar concentration of the hydrochloric acid solution is 0.05-1 M; the solid-liquid ratio of FeCl 3 to hydrochloric acid in the hydrochloric acid solution containing FeCl 3 is (0.1-0.3) g:30 mL; and the stirring reaction time is 2-6 h.

[0041] More preferably, in step (1), the stirring activation temperature is room temperature and the time is 24 hours; the stirring reaction temperature is 38° C. and the time is 24 hours; and the mass ratio of carbodiimide, N-hydroxysuccinimide, hyaluronic acid and hafnium-based metal organic framework is 52.8:97.8:30:30.

[0042] More preferably, the buffer solution in step (2) is a mixed solution of sodium carbonate and sodium bicarbonate with a pH of 9; the mass ratio of methacrylic anhydride to the hafnium-based metal organic framework grafted with hyaluronic acid is 1:1; the reaction temperature is 4°C and the time is 24 hours; the dialysis temperature is 40°C and the time is 3 days.

[0043] More preferably, in step (3), the material-liquid ratio of the double-bonded hyaluronic acid-grafted hafnium-based metal-organic framework, pyrrole and hydrochloric acid solution is 100 mg:0.037 mL:30 mL; the molar concentration of the hydrochloric acid solution is 0.1 M; the material-liquid ratio of FeCl3 to hydrochloric acid in the hydrochloric acid solution containing FeCl3 is 0.2 g:30 mL; and the stirring reaction time is 4 h.

[0044] The present invention also provides a method for preparing the above-mentioned photocrosslinked organic piezoelectric heterojunction hydrogel, comprising the following steps:

[0045] The double-bonded protein, photoinitiator and skeleton material are dissolved in water at 35-38° C. and then irradiated under ultraviolet light for 10-60 seconds to obtain a photocrosslinked organic piezoelectric heterojunction hydrogel.

[0046] Preferably, the wavelength of ultraviolet light is 360-480 nm, and the irradiance is 1-10 mW / cm 2 .

[0047] The present invention also provides the use of the photo-crosslinked organic piezoelectric heterojunction hydrogel in the preparation of biological tissue engineering repair materials.

[0048] The present invention has the following beneficial effects:

[0049] (1) The photocrosslinked organic piezoelectric heterojunction hydrogel of the present invention can provide accurate electrophysiological signals through the combination of a metal-organic framework and a conductive material. The metal-organic framework and the conductive material not only participate in the formation of the piezoelectric heterojunction, but their own conductivity can also increase the overall conductivity of the hydrogel, so that the hydrogel prepared by the present invention can better simulate the conductive properties of natural tissues, further improving the compatibility with biological tissues.

[0050] (2) In the preparation method of the present invention, the organic piezoelectric heterojunction is tightly combined with the gel matrix through covalent cross-linking technology to form a more solid network structure with better mechanical properties. At the same time, the organic piezoelectric heterojunction in the present invention is evenly distributed in the gel matrix, avoiding the problems of uneven dispersion and easy loss of functional materials in the prior art. When used as a biological tissue engineering repair material, it can provide the mechanical stability, piezoelectric properties and sustained effectiveness of electrical stimulation signals required for muscle contraction and neural activity.

[0051] (3) The photocrosslinked organic piezoelectric heterojunction hydrogel of the present invention can be customized according to different tissue repair needs, such as muscle repair, nerve repair, bone repair, cartilage regeneration, skin repair, etc., promoting personalized treatment plans for tissue engineering and regenerative medicine, and has wide adaptability;

[0052] (4) The silk fibroin or gelatin matrix selected in the present invention has good biocompatibility, ensuring that the implanted material will not cause an immune rejection reaction; at the same time, the degradability of the photocrosslinked organic piezoelectric heterojunction hydrogel allows it to be gradually absorbed by the body after tissue repair is completed, making it more convenient to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is the H NMR spectrum of double-bonded silk fibroin;

[0054] Figure 2 is the H NMR spectrum of double-bonded gelatin;

[0055] Figure 3 This is the electrochemical test result of hafnium-based metal-organic framework;

[0056] Figure 4 The figure shows the electrochemical test results of the composite material of double-bonded cobalt porphyrin covalent organic framework and hafnium-based metal organic framework;

[0057] Figure 5 Graphs showing the gelling properties of hydrogels; wherein (a) is a graph showing the gelling properties of 5 parts by weight of double-bonded gelatin; (b) is a graph showing the gelling properties of 10 parts by weight of double-bonded gelatin; (c) is a graph showing the gelling properties of 15 parts by weight of double-bonded gelatin; and (d) is a graph showing the gelling properties of the photo-crosslinked organic piezoelectric heterojunction hydrogel prepared in Example 2.

[0058] Figure 6 Figures 2 and 3 are graphs showing the gelation performance of hydrogels; (a) shows the gelation performance of 15 parts by weight of double-bonded silk fibroin; (b) shows the gelation performance of the photo-crosslinked organic piezoelectric heterojunction hydrogel prepared in Example 4; (c) shows the gelation performance of the photo-crosslinked organic piezoelectric heterojunction hydrogel prepared in Example 3;

[0059] Figure 7 This is a graph showing the piezoelectric output test results of the photo-crosslinked organic piezoelectric heterojunction hydrogel prepared in Example 1;

[0060] Figure 8 Graph showing the piezoelectric output test results of the photo-crosslinked organic piezoelectric heterojunction hydrogels prepared in Example 2 and Comparative Example 2;

[0061] Figure 9 The graph shows the mechanical properties test results of the double-bonded silk fibroin gel and the photo-crosslinked organic piezoelectric heterojunction hydrogels prepared in Example 3 and Example 4;

[0062] Figure 10 The figure shows the mechanical property test results of the double-bonded gelatin and the photo-crosslinked organic piezoelectric heterojunction hydrogel prepared in Example 2. DETAILED DESCRIPTION

[0063] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with Examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. That is, the embodiments described are only part of the present invention, rather than all of the embodiments. In the embodiments, if specific conditions are not specified, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the reagents or instruments are not specified by the manufacturer, they are all conventional products that can be purchased commercially.

[0064] Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the invention as claimed, but is merely intended to represent selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0065] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0066] Example 1

[0067] A photocrosslinked organic piezoelectric heterojunction hydrogel comprises the following raw materials in parts by weight: 15 parts of double-bonded silk fibroin, 0.25 parts of LAP photoinitiator, and 1 part of a composite material of double-bonded hyaluronic acid and hafnium-based metal organic framework-polypyrrole grafted thereon;

[0068] Wherein, the double-bonded silk fibroin is prepared by the following steps:

[0069] Prepare a 9.3M LiBr solution and add 10 wt% degummed silk fibroin to it. Stir at 60°C until the silk fibroin is completely dissolved. Then, add glycidyl methacrylate in an equal mass ratio to the silk fibroin. Stir and react at 60°C for 4 hours. After the reaction, place the solution in a 14 kDa dialysis bag and dialyze at 4°C for 7 days, changing the water three times a day. After the dialysis, centrifuge and collect the supernatant, which is then freeze-dried.

[0070] The composite material of double-bonded hyaluronic acid and hafnium-based metal organic framework-polypyrrole grafted therein is prepared by the following steps:

[0071] (1) 0.3 mmol of HfCl4 and 0.6 mmol of 2-aminoterephthalic acid were dissolved in 15 mL of N,N-dimethylformamide, deionized water was added and ultrasonicated until the solution was clarified, and then heated at 120°C for 24 hours to obtain a suspension; the suspension was centrifuged to obtain a precipitate and immersed in N,N-dimethylformamide for 72 hours, with the N,N-dimethylformamide being replaced once a day during the immersion process. After being taken out, the precipitate was washed with methanol and dried under flowing nitrogen, and then placed in a gas adsorption tube and heated at 100°C for 48 hours under a flowing nitrogen atmosphere to obtain a hafnium-based metal organic framework;

[0072] (2) Ultrasonic dispersion of 30 mg of hafnium-based metal organic framework in 10 mL of deionized water to obtain a hafnium-based metal organic framework aqueous solution; dissolving 30 mg of hyaluronic acid in 10 mL of deionized water to obtain a hyaluronic acid aqueous solution; taking another container, dissolving 52.8 mg of carbodiimide and 97.8 mg of N-hydroxysuccinimide in 1.5 mL of deionized water, adding the hyaluronic acid aqueous solution, stirring and activating at room temperature for 24 h, then adding the hafnium-based metal organic framework aqueous solution, adjusting the pH to 9 with triethanolamine, stirring and reacting at 38°C for 24 h, and after the reaction, centrifuging at 21000 rpm in sequence, taking the precipitate and washing it with deionized water three times, and then freeze-drying it to obtain a hyaluronic acid-grafted hafnium-based metal organic framework;

[0073] (3) A mixed solution of sodium carbonate and sodium bicarbonate with a pH of 9 was prepared as a buffer solution, and the hyaluronic acid-grafted hafnium-based metal organic framework was dispersed in 50 mL of the buffer solution and stirred for 30 minutes. Then, 25 mL of N,N-dimethylformamide and methacrylic anhydride with an equal mass ratio to the hyaluronic acid-grafted hafnium-based metal organic framework were added under ice bath conditions at 4°C for 24 hours. Then, 5 times the volume of anhydrous ethanol was added for precipitation and washing. The mixture was dialyzed at 40°C for 3 days and freeze-dried to obtain a double-bonded hyaluronic acid-grafted hafnium-based metal organic framework.

[0074] (4) 100 mg of double-bonded hyaluronic acid-grafted hafnium-based metal-organic framework and 37 μL of pyrrole were dispersed in 30 mL of 0.1 M hydrochloric acid solution and ultrasonically treated for 30 min. Then, 30 mL of 0.1 M hydrochloric acid solution containing 0.2 g of FeCl3 was added dropwise in an ice bath at 4°C and stirred for 4 h. The mixture was then dialyzed for 3 days, centrifuged, and freeze-dried to obtain the product.

[0075] The H NMR spectrum of double bonded silk fibroin (SilMA) is as follows Figure 1 As shown, from Figure 1 It can be seen that the double-bonded silk fibroin was successfully synthesized.

[0076] This embodiment also provides a method for preparing the above-mentioned photocrosslinked organic piezoelectric heterojunction hydrogel, comprising the following steps:

[0077] The double-bonded silk fibroin, LAP photoinitiator, double-bonded hyaluronic acid and hafnium-based metal organic framework-polypyrrole grafted composite material were dissolved in 100 parts by weight of water at 37°C, and then irradiated with light at a wavelength of 360-480nm and an irradiance of 1-10mW / cm 2 The photocrosslinked organic piezoelectric heterojunction hydrogel was obtained by irradiating the sample under ultraviolet light for 60 seconds.

[0078] Example 2

[0079] A photocrosslinked organic piezoelectric heterojunction hydrogel comprises the following raw materials in parts by weight: 10 parts of double-bonded gelatin, 0.25 parts of LAP photoinitiator, and 1 part of a composite material of a double-bonded cobalt porphyrin covalent organic framework and a hafnium-based metal organic framework;

[0080] Wherein, double-bonded gelatin is prepared by the following steps:

[0081] 20 g of gelatin was dissolved in 200 mL of phosphate buffer at 60 ° C and 24 g of methacrylic anhydride was added to react at 50 ° C for 3 hours, and then dialyzed at 40 ° C for 7 days. The water was changed twice a day during the dialysis process, and then freeze-dried to obtain the product;

[0082] The composite material of the double-bonded cobalt porphyrin covalent organic framework and the hafnium-based metal organic framework is prepared by the following steps:

[0083] (1) 0.3 mmol of HfCl4 and 0.6 mmol of 2-aminoterephthalic acid were dissolved in 15 mL of N,N-dimethylformamide, deionized water was added and ultrasonicated until the solution was clarified, and then heated at 120°C for 24 hours to obtain a suspension; the suspension was centrifuged to obtain a precipitate and immersed in N,N-dimethylformamide for 72 hours, with the N,N-dimethylformamide being replaced once a day during the immersion process. After being taken out, the precipitate was washed with methanol and dried under flowing nitrogen, and then placed in a gas adsorption tube and heated at 100°C for 48 hours under a flowing nitrogen atmosphere to obtain a hafnium-based metal organic framework;

[0084] (2) 23.7 mg of cobalt porphyrin, 15 mg of hafnium-based metal organic framework and 7.5 mg of p-phenylenediamine were added to a 10 mL Pyrex glass tube, and then added to 3 mL of polyphosphoric acid. After three cycles of freeze pump-thaw, an N2 protective tube was sealed with a flame spray gun, and the precursor was activated at 66 ° C for 12 h, and then heated at 150 ° C for 60 h. After the reaction was completed, it was naturally cooled to room temperature and then transferred to a beaker to obtain the reactant;

[0085] (3) adjusting the pH of the reactants to 8-9 with a saturated sodium bicarbonate solution, and then centrifuging to obtain a precipitate, performing Soxhlet extraction with water, tetrahydrofuran, and methanol, respectively, and washing for 24 hours. After drying at 90° C. for 12 hours, composite particles of the cobalt porphyrin covalent organic framework and the hafnium-based metal organic framework were obtained;

[0086] (4) 60 mg of the composite material particles of cobalt porphyrin covalent organic framework and hafnium-based metal organic framework were dispersed in 5 mL of tetrahydrofuran and ultrasonicated for 20 min, and 215 μL of glycidyl methacrylate was added and stirred at 55°C for heating reaction for 36 h. The mixture was then centrifuged, washed with tetrahydrofuran three times, washed with chloroform under ultrasonic conditions three times, and dried in vacuum at 50°C for 24 h.

[0087] The H NMR spectrum of double bonded gelatin (GelMA) is as follows Figure 2 As shown, from Figure 2 It can be seen that the double-bonded gelatin was successfully synthesized.

[0088] This embodiment also provides a method for preparing the above-mentioned photocrosslinked organic piezoelectric heterojunction hydrogel, comprising the following steps:

[0089] The composite material of double-bonded gelatin, LAP photoinitiator, double-bonded cobalt porphyrin covalent organic framework and hafnium-based metal organic framework was dissolved in 100 parts by weight of water at 37°C, and then irradiated with light of wavelength of 360-480nm and irradiance of 1-10mW / cm 2 The photocrosslinked organic piezoelectric heterojunction hydrogel was obtained by irradiating the sample under ultraviolet light for 60 seconds.

[0090] Example 3

[0091] A photocrosslinked organic piezoelectric heterojunction hydrogel comprises the following raw materials in parts by weight: 15 parts of double-bonded silk fibroin, 3 parts of double-bonded silk fibroin-polypyrrole, 0.25 parts of LAP photoinitiator, and 1 part of a composite material of double-bonded hyaluronic acid and hafnium-based metal organic framework-polypyrrole grafted thereon;

[0092] The preparation of the composite material of double-bonded silk fibroin, double-bonded hyaluronic acid and hafnium-based metal organic framework-polypyrrole grafted is the same as in Example 1;

[0093] Wherein, the double-bonded silk fibroin-polypyrrole is prepared by the following steps:

[0094] (1) Prepare a 9.3M LiBr solution and add 10 wt% degummed silk fibroin to it, stir at 60°C until the silk fibroin is completely dissolved, then add glycidyl methacrylate in an equal mass ratio to the silk fibroin, stir and react at 60°C for 4 h, after which the solution is placed in a 14 kDa dialysis bag and dialyzed at 4°C for 7 days, changing the water three times a day. After the dialysis is completed, the supernatant is centrifuged and freeze-dried to obtain double-bonded silk fibroin;

[0095] (2) 1 g of double-bonded silk fibroin was dissolved in phosphate buffer at 45°C and 400 μL of pyrrole was added and magnetically stirred for 2 h. Then 0.1 g of ammonium persulfate was added and stirred at 40°C for 12 h. The mixture was dialyzed for 3 days and freeze-dried to obtain the product.

[0096] This embodiment also provides a method for preparing the above-mentioned photocrosslinked organic piezoelectric heterojunction hydrogel, comprising the following steps:

[0097] The double-bonded silk fibroin, double-bonded silk fibroin-polypyrrole, LAP photoinitiator, double-bonded hyaluronic acid and hafnium-based metal organic framework-polypyrrole grafted composite material were dissolved in 100 parts by weight of water at 37°C, and then irradiated with light at a wavelength of 360-480nm and an irradiance of 1-10mW / cm 2 The photocrosslinked organic piezoelectric heterojunction hydrogel was obtained by irradiating the sample under ultraviolet light for 60 seconds.

[0098] Example 4

[0099] A photo-crosslinked organic piezoelectric heterojunction hydrogel comprises the following raw materials in parts by weight: 15 parts of double-bonded silk fibroin, 0.25 parts of LAP photoinitiator, and 3 parts of double-bonded silk fibroin-polypyrrole;

[0100] The preparation of double-bonded silk fibroin is the same as that in Example 1; the preparation of double-bonded silk fibroin-polypyrrole is the same as that in Example 3.

[0101] This embodiment also provides a method for preparing the above-mentioned photocrosslinked organic piezoelectric heterojunction hydrogel, comprising the following steps:

[0102] The double-bonded silk fibroin, double-bonded silk fibroin-polypyrrole and LAP photoinitiator were dissolved in 100 parts by weight of water at 37°C, and then the mixture was irradiated with light at a wavelength of 360-480 nm and an irradiance of 1-10 mW / cm 2 The photocrosslinked organic piezoelectric heterojunction hydrogel was obtained by irradiating the sample under ultraviolet light for 60 seconds.

[0103] Comparative Example 1

[0104] A photo-crosslinked organic piezoelectric heterojunction hydrogel comprises the following raw materials in parts by weight: 15 parts of double-bonded silk fibroin, 0.25 parts of LAP photoinitiator and 1 part of hafnium-based metal organic framework;

[0105] Wherein, the preparation of double-bonded silk fibroin is the same as that in Example 1;

[0106] The hafnium-based metal-organic framework is prepared by the following steps:

[0107] 0.3 mmol of HfCl4 and 0.6 mmol of 2-aminoterephthalic acid were dissolved in 15 mL of N,N-dimethylformamide, deionized water was added and ultrasonicated until the solution was clarified, and then heated at 120°C for 24 hours to obtain a suspension; the suspension was centrifuged to obtain a precipitate and immersed in N,N-dimethylformamide for 72 hours, with the N,N-dimethylformamide replaced once a day during the soaking process. After taking out, the precipitate was washed with methanol and dried under flowing nitrogen, then placed in a gas adsorption tube and heated at 100°C for 48 hours under a flowing nitrogen atmosphere to obtain the product.

[0108] This comparative example also provides a method for preparing the above-mentioned photocrosslinked organic piezoelectric heterojunction hydrogel, comprising the following steps:

[0109] The double-bonded silk fibroin, LAP photoinitiator and hafnium-based metal organic framework were dissolved in 100 parts by weight of water at 37°C, and then irradiated with light at a wavelength of 360-480 nm and an irradiance of 1-10 mW / cm 2 The photocrosslinked organic piezoelectric heterojunction hydrogel was obtained by irradiating the sample under ultraviolet light for 60 seconds.

[0110] Comparative Example 2

[0111] A photocrosslinked organic piezoelectric heterojunction hydrogel comprises the following raw materials in parts by weight: 10 parts of double-bonded gelatin, 0.25 parts of LAP photoinitiator and 1 part of hafnium-based metal organic framework;

[0112] The preparation of double-bonded silk fibroin was the same as in Example 2; and the preparation of hafnium-based metal organic framework was the same as in Comparative Example 1.

[0113] This comparative example also provides a method for preparing the above-mentioned photocrosslinked organic piezoelectric heterojunction hydrogel, comprising the following steps:

[0114] Double-bonded gelatin, LAP photoinitiator and hafnium-based metal organic framework were dissolved in 100 parts by weight of water at 37°C, and then irradiated with light at a wavelength of 360-480 nm and an irradiance of 1-10 mW / cm 2 The photocrosslinked organic piezoelectric heterojunction hydrogel was obtained by irradiating the sample under ultraviolet light for 60 seconds.

[0115] Experimental example

[0116] 1. The hafnium-based metal-organic framework (MOF) obtained in step (1) of the preparation of the composite material of the double-bonded cobalt porphyrin covalent organic framework and the hafnium-based metal-organic framework in Example 2 is divided into three types according to their sizes: MOF-L (400 nm), MOF-M (200 nm) and MOF-S (50 nm). MOF-L, MOF-M, MOF-S and the composite material of the double-bonded cobalt porphyrin covalent organic framework and the hafnium-based metal organic framework (MOF@COF) prepared in Example 2 were subjected to electrochemical testing. The MOF treatment method was as follows: 10 mg of MOF or MOF@COF was dispersed in a mixed solution of 0.5 mL of ethanol and 20 μL of Nafion solution (5%), respectively. After ultrasonic treatment for 30 minutes, 20 μL of the mixed solution was pipetted onto a glassy carbon electrode with a diameter of 5 mm and air-dried for 12 hours. The specific test method was as follows: electrochemical impedance spectroscopy was tested on piezoelectric ceramics using an electrochemical workstation (Versa STAT3F, Ametek, USA). The working electrode was a sample-loading electrode, the auxiliary electrode was a platinum sheet (1-2×1-2 cm), and the reference electrode was a saturated Ag / AgCl electrode. In 0.5 M Na2SO4 solution and 0.1-10 5 Electrochemical impedance spectroscopy (EIS) was recorded using an alternating current with an amplitude of 5 mV in the frequency range of 1 Hz. Figures 3-4 shown.

[0117] from Figures 3-4 It can be seen that the smaller MOF-S has a lower impedance value, and the composite material of the double-bonded cobalt porphyrin covalent organic framework and the hafnium-based metal organic framework synthesized using MOF-S has better electrochemical performance.

[0118] 2. The gelling properties of double-bonded gelatin, double-bonded silk fibroin, and the photo-crosslinked organic piezoelectric heterojunction hydrogels prepared in Examples 2 to 4 were studied. The results are as follows: Figures 5-6 shown.

[0119] from Figure 5 It can be seen that the gelling performance of 5 parts by weight of double-bonded gelatin is poor, while the gelling performance of 10-15 parts by weight of double-bonded gelatin is good. The photo-crosslinked organic piezoelectric heterojunction hydrogel prepared with 10 parts by weight of double-bonded gelatin as raw material can gel well. Figure 6 It can be seen that 15 parts by weight of double-bonded silk fibroin and the photo-crosslinked organic piezoelectric heterojunction hydrogel prepared with 15 parts by weight of double-bonded silk fibroin as raw materials have good gelling properties.

[0120] 3. The MOF-L, MOF-M, and MOF-S obtained in 1 were reacted with double-bonded silk fibroin to form hydrogels under the action of LAP photoinitiator, namely SilMA+MOF-L, SilMA+MOF-M, and SilMA+MOF-S (Comparative Example 1). The above hydrogels and the photocrosslinked organic piezoelectric heterojunction hydrogels prepared in Example 1, and the photocrosslinked organic piezoelectric heterojunction hydrogels prepared in Example 2 and Comparative Example 2 were subjected to piezoelectric output tests. The specific method was as follows: a self-made electromechanical system was used to apply cyclic compression loads of various frequencies, a charge amplifier (kd5002, Baofei Vibration Instrument Co., Ltd., Jiangsu, China) was used to measure the charge signal generated by each piezoelectric hydrogel, and the charge was converted into a voltage signal for output; a data acquisition card (HK_USB6202-SDIEIE, HKTECH Co., Ltd., Zhengzhou, China) was used to obtain the signal output by the charge amplifier, and finally Labview software was used to record and display it in real time on a computer. The results are shown in FIG. Figures 7-8 shown.

[0121] from Figure 7 and Figure 8 It can be seen that the heterojunction formed in the photo-crosslinked organic piezoelectric heterojunction hydrogel prepared by the present invention can effectively increase the piezoelectric output of the hydrogel, has a good piezoelectric signal, and performs well in electrophysiological signal transmission, providing new possibilities for its application in nerve and muscle tissue repair.

[0122] 4. The mechanical properties of the gelled double-bonded silk fibroin (SilMA), the photocrosslinked organic piezoelectric heterojunction hydrogels prepared in Examples 3 and 4, the gelled double-bonded gelatin (GelMA), and the photocrosslinked organic piezoelectric heterojunction hydrogel prepared in Example 2 were tested. The specific method is as follows: the rheological behavior was measured on a rotational rheometer (TA Instruments DHR-1, USA) with a parallel plate configuration (diameter 20 mm, gap 1 mm); first, the linear viscoelastic region (LVR) of the sample was measured by amplitude (strain) scanning, and the oscillation strain was increased from 0.001% to 50% at a constant frequency of 1 Hz; then, under a fixed shear strain within the LVR, the dynamic storage modulus (G′) and loss modulus (G″) were measured in the frequency range of 0.1 to 10 Hz. Each test procedure required the addition of 500 μL of sample to the plate; the results are shown in FIG. Figures 9-10 shown.

[0123] from Figures 9-10 It can be seen that the photocrosslinked organic piezoelectric heterojunction hydrogel in the present invention tightly combines the organic piezoelectric heterojunction with the gel matrix through covalent crosslinking technology, forming a heterojunction structure with a more solid network structure, and the mechanical properties of the hydrogel can be further improved.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A photocrosslinked organic piezoelectric heterojunction hydrogel, characterized in that: The method comprises the following raw materials in parts by weight: 10-18 parts of double-bonded protein, 0.25 parts of photoinitiator and 1 part of skeleton material; The double-bonded protein is double-bonded gelatin or double-bonded silk fibroin; the skeleton material is at least one of a composite material of a double-bonded cobalt porphyrin covalent organic skeleton and a hafnium-based metal organic skeleton and a composite material of double-bonded hyaluronic acid and a hafnium-based metal organic skeleton-polypyrrole grafted thereon; The composite material of the double-bonded cobalt porphyrin covalent organic framework and the hafnium-based metal organic framework is prepared by the following steps: (1) adding cobalt porphyrin, hafnium-based metal organic framework and p-phenylenediamine to polyphosphoric acid in sequence, performing a freeze-thaw cycle, activating the precursor under sealed conditions, and then heating the mixture to obtain a reactant; (2) adjusting the pH of the reactants to 8-9, and then centrifuging, extracting, washing, and drying in sequence to obtain composite material particles of the cobalt porphyrin covalent organic framework and the hafnium-based metal organic framework; (3) dispersing the composite material particles of the cobalt porphyrin covalent organic framework and the hafnium-based metal organic framework in a solvent, ultrasonically treating the mixture, adding glycidyl methacrylate, heating the mixture for reaction, and then centrifuging, washing, and vacuum drying the mixture in sequence; The hafnium-based metal organic framework is prepared by the following steps: (1) HfCl4 and 2-aminoterephthalic acid are dissolved in N,N-dimethylformamide, water is added, ultrasonication is performed, and heating reaction is performed to obtain a suspension; (2) centrifuging the suspension to obtain a precipitate, which is then immersed in N,N-dimethylformamide, washed, dried, and heated under an inert gas atmosphere to obtain the product; The composite material of double-bonded hyaluronic acid and hafnium-based metal organic framework-polypyrrole grafted thereon is prepared by the following steps: (1) dissolving carbodiimide and N-hydroxysuccinimide in water respectively and adding a hyaluronic acid aqueous solution to stir and activate, then adding a hafnium-based metal organic framework aqueous solution, adjusting the pH to 8-9 and stirring to react, and after the reaction is completed, centrifuging, washing and freeze-drying are performed in sequence to obtain a hyaluronic acid-grafted hafnium-based metal organic framework; (2) dispersing the hafnium-based metal organic framework grafted with hyaluronic acid in a buffer solution, adding a solvent and methacrylic anhydride to react, then adding anhydrous ethanol to precipitate, wash, dialyze and freeze-dry to obtain a double-bonded hyaluronic acid grafted hafnium-based metal organic framework; (3) The hafnium-based metal organic framework grafted with double-bonded hyaluronic acid and pyrrole are dispersed in a hydrochloric acid solution, and then a hydrochloric acid solution containing FeCl3 is added dropwise and stirred for reaction, followed by dialysis, centrifugation and freeze-drying to obtain the product.

2. The photocrosslinked organic piezoelectric heterojunction hydrogel according to claim 1, wherein: In the preparation method of the composite material of the double-bonded cobalt porphyrin covalent organic framework and the hafnium-based metal organic framework, the precursor activation temperature in step (1) is 60-70°C and the time is 10-14 h; the heating reaction temperature is 140-160°C and the time is 55-65 h; the material-liquid ratio of the cobalt porphyrin, hafnium-based metal organic framework, p-phenylenediamine and polyphosphoric acid is (20-25) mg:(10-20) mg:(6-9) mg:(2-4) mL.

3. The photoelectric heterojunction hydrogel according to claim 1, wherein: In the preparation method of the composite material of the double-bonded cobalt porphyrin covalent organic framework and the hafnium-based metal-organic framework, the solvent in step (3) is tetrahydrofuran; the material-liquid ratio of the composite material of the cobalt porphyrin covalent organic framework and the hafnium-based metal-organic framework to glycidyl methacrylate is (50-70) mg:(200-230) μL; the heating reaction is carried out under stirring conditions at a temperature of 50-60°C and a time of 34-38 hours.

4. The photocrosslinked organic piezoelectric heterojunction hydrogel according to claim 1, wherein: In the preparation method of the composite material of double-bonded hyaluronic acid and hafnium-based metal organic framework-polypyrrole grafted, the stirring activation temperature in step (1) is room temperature and the time is 22-26 h; the stirring reaction temperature is 35-39°C and the time is 22-26 h; the mass ratio of carbodiimide, N-hydroxysuccinimide, hyaluronic acid and hafnium-based metal organic framework is (50-55):(95-99):(25-35):(25-35); in the step (2), the mass ratio of methacrylic anhydride to the hafnium-based metal organic framework grafted with hyaluronic acid is 1-2:1-2; the solvent is N,N-dimethylformamide; the reaction temperature is 2-4°C and the time is 22-26 h; the dialysis temperature is 35-45°C and the time is 2-4 d; in the step (3), the material-liquid ratio of the double-bonded hyaluronic acid-grafted hafnium-based metal-organic framework, pyrrole, and hydrochloric acid solution is (80-100) mg:(0.03-0.04) mL:(30-60) mL; the molar concentration of the hydrochloric acid solution is 0.05-1 M; the material-liquid ratio of FeCl3 to hydrochloric acid in the hydrochloric acid solution containing FeCl3 is (0.1-0.3) g:30 mL; and the stirring reaction time is 2-6 h.

5. The method for preparing the photocrosslinked organic piezoelectric heterojunction hydrogel according to any one of claims 1 to 4, characterized in that: The following steps are involved: The double-bonded protein, photoinitiator, and skeleton material are dissolved in water at 35-38°C and then irradiated under ultraviolet light for 10-60s to obtain a photocrosslinked organic piezoelectric heterojunction hydrogel.

6. Use of the photocrosslinked organic piezoelectric heterojunction hydrogel according to any one of claims 1 to 4 in the preparation of biological tissue engineering repair materials.

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