A high-performance, tough, oxidized chitosan hybrid gelatin hydrogel with excellent photothermal conversion properties and its preparation.

Abstract

This invention belongs to the field of polymer materials technology and discloses a high-performance, tough, photothermal conversion hybrid gelatin made from oxidized chitosan and its preparation. The oxidized chitosan hybrid gelatin hydrogel of this invention comprises the following components by weight: 80-100 parts water, 20-40 parts gelatin, 1-5 parts oxidized chitosan, and 0.5-2 parts soluble metal salt. The hydrogel of this invention is obtained by combining oxidized chitosan and gelatin, fully integrating the advantages of both. The oxidized chitosan is rich in amino and carboxyl groups, which form enhanced hydrogen bonds and electrostatic forces with the hydroxyl / amino groups of gelatin, promoting the formation of gelatin crystal domains and generating strong physical cross-linking, thus forming a hybrid hydrogel material with high strength, high photothermal conversion efficiency, and good biocompatibility, achieving over 98% full-spectrum solar energy absorption. The hydrogel of this invention exhibits photothermal-driven self-healing properties, maintaining a 92% photothermal-driven self-healing efficiency even after five damage / self-healing cycles.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and specifically relates to a high-performance, tough, oxidized chitosan hybrid gelatin hydrogel with high photothermal conversion properties and its preparation. Background Technology

[0002] In recent years, hydrogels have gained widespread attention in various fields such as biomedicine, flexible electronics, environmental remediation, and energy conversion due to their unique three-dimensional network structure, tunable mechanical properties, and good biocompatibility. Hydrogels can absorb large amounts of water while maintaining structural stability, thus showing great potential in applications such as flexible sensors, tissue engineering, drug delivery, and wound healing. However, traditional hydrogels suffer from insufficient mechanical properties, poor durability, and limited functionality, restricting their application in environments requiring high strength and durability.

[0003] Photothermal conversion hydrogels are an emerging class of materials that, by embedding photothermal conversion substances (such as carbon-based materials, metal nanoparticles, or organic dyes) into a hydrogel matrix, can efficiently convert absorbed light energy into heat energy. These materials have broad application prospects in areas such as solar energy capture, photocatalytic sterilization, temperature-controlled release, and intelligent response. However, the photothermal materials commonly used in traditional photothermal hydrogels are costly and pose risks of toxicity and environmental pollution. Therefore, developing hydrogel materials with high photothermal conversion performance, low cost, environmental friendliness, and excellent mechanical properties has become an urgent technical challenge.

[0004] Against this backdrop, natural polymer materials have gradually gained attention as low-cost, sustainable, and environmentally friendly photothermal conversion materials. Chitosan, a natural polysaccharide widely found in the exoskeletons of crustaceans, possesses excellent biocompatibility, biodegradability, and chemical modification capabilities. On the other hand, gelatin, a natural protein polymer extracted from animal collagen, exhibits good biocompatibility, biodegradability, and processability, and is widely used in the preparation of hydrogels.

[0005] Currently, although some hydrogels have been applied in the field of photothermal conversion, most of them face problems such as insufficient photothermal conversion efficiency, poor mechanical properties, and lack of antibacterial properties. Therefore, developing hydrogels with high photothermal conversion efficiency and excellent mechanical properties will provide new application prospects and technical solutions for fields such as biomedicine, energy conversion, and environmental remediation. Summary of the Invention

[0006] In order to overcome the shortcomings and deficiencies of the prior art, the primary objective of this invention is to provide a high-performance, tough, oxidized chitosan hybrid gelatin hydrogel with high photothermal conversion properties.

[0007] This invention prepares a hydrogel by combining oxidized chitosan and gelatin, fully leveraging the advantages of both to form a hybrid hydrogel material with high strength, high photothermal conversion efficiency, and good biocompatibility. The photothermal conversion efficiency of the oxidized chitosan / gelatin hybrid hydrogel of this invention is significantly improved, making it demonstrate great potential in photothermal therapy, wound healing, temperature control sensors, and solar energy capture applications.

[0008] Another object of the present invention is to provide a method for preparing the above-mentioned oxidized chitosan hybrid gelatin hydrogel.

[0009] Another object of the present invention is to provide applications of the above-mentioned oxidized chitosan hybrid gelatin hydrogel, particularly in the fields of photothermal therapy, wound healing, temperature control sensors, and solar energy capture.

[0010] The purpose of the present invention is achieved through the following solutions:

[0011] A high-performance, high-thermal-conversion-performance, tough oxidized chitosan hybrid gelatin hydrogel comprises the following components in parts by weight: 80-100 parts water, 20-40 parts gelatin, 1-5 parts oxidized chitosan, and 0.5-2 parts soluble metal salt.

[0012] Furthermore, the gelatin mentioned can be any gelatin commonly used in the art, including at least one of fish skin gelatin and chicken skin gelatin.

[0013] Furthermore, the carboxyl content of the oxidized chitosan can be 5-30%, more preferably 10-25%.

[0014] Furthermore, the oxidized chitosan can be chitosan obtained by oxidation treatment known in the art, such as at least one of hydrogen peroxide / divalent metal ion oxidized chitosan, potassium permanganate oxidized chitosan, and TEMPO oxidized chitosan, preferably hydrogen peroxide / divalent metal ion oxidized chitosan.

[0015] Furthermore, the soluble metal salt includes at least one of potassium citrate, sodium citrate, calcium citrate, etc.

[0016] The hydrogel of this invention is obtained by combining oxidized chitosan and gelatin, fully leveraging the advantages of both. Oxidized chitosan, rich in amino and carboxyl groups, forms enhanced hydrogen bonds and electrostatic interactions with the hydroxyl / amino groups of gelatin, promoting gelatin domain formation and generating strong physical cross-linking. This results in a hybrid hydrogel material with high strength, high photothermal conversion efficiency, and good biocompatibility, achieving over 98% full-spectrum solar energy absorption. Furthermore, the hydrogel of this invention possesses photothermal-driven self-healing properties, maintaining a 92% photothermal-driven self-healing efficiency even after five damage / self-healing cycles.

[0017] The present invention also provides a method for preparing the above-mentioned oxidized chitosan hybrid gelatin hydrogel, comprising the following steps: mixing each component in proportion and dissolving it by heating, and then preparing the oxidized chitosan hybrid gelatin hydrogel by low-temperature gelation.

[0018] Furthermore, the temperature can be raised to 60-100℃, and the dissolution time can be 0.5-5h.

[0019] Furthermore, the low temperature can be 5-15℃, and the gelation time can be 12-48h.

[0020] In this invention, the oxidized chitosan hybrid gelatin hydrogel possesses excellent mechanical properties and photothermal self-healing properties due to the photothermal conversion ability and macromolecular cross-linking characteristics formed by the special structure of gelatin and oxidized chitosan, overcoming the shortcomings of traditional hydrogel materials. The oxidized chitosan hybrid gelatin hydrogel in this invention also has excellent antibacterial and water-retention properties, making it suitable for various applications, such as flexible sensors, photothermal therapy, photothermal power generation, and energy storage.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) The oxidized chitosan hybrid gelatin hydrogel of the present invention has excellent mechanical properties, with tensile strength and toughness reaching 5.53 MPa and 9.81 MJ·m, respectively. -3 .

[0023] (2) The oxidized chitosan hybrid gelatin hydrogel based on the present invention has high photothermal conversion performance, achieving more than 98% full-spectrum solar energy absorption, and can still maintain 92% photothermal driven self-healing efficiency after five damage / self-healing cycles.

[0024] (3) In the oxidized chitosan hybrid gelatin hydrogel of the present invention, the oxidized chitosan, as a molecularly dispersed macromolecular crosslinking agent, can form abundant crosslinking points between gelatin molecular chains through electrostatic interactions and hydrogen bonding, promoting the aggregation of gelatin chains into more triple helix structures. These crosslinking points and crystalline regions serve as energy dissipation points, preventing the macromolecular chains from slipping rapidly under stress, thereby simultaneously strengthening and toughening the hydrogel.

[0025] (4) When the oxidized chitosan hybrid gelatin hydrogel of the present invention is exposed to sunlight, it effectively absorbs solar energy and converts it into heat. This heat generation occurs at the molecular level due to the strong intermolecular interactions between the water-soluble oxidized chitosan and gelatin chains within the hydrogel matrix. When the absorbed light energy is converted into heat, the temperature within the hydrogel rises, resulting in a localized heating effect. This temperature increase triggers a gel-sol transition in the organic hydrogel, temporarily softening the gelatin matrix. In this softened state, the molecular network can rapidly reorganize, effectively healing cracks or damage, thus enabling the oxidized chitosan hybrid gelatin hydrogel of the present invention to exhibit excellent photothermal-driven self-healing properties. Attached Figure Description

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 The mechanical properties of the oxidized chitosan hybrid gelatin hydrogel of the present invention are described.

[0028] Figure 2 This invention relates to the self-healing process of the oxidized chitosan hybrid gelatin hydrogel. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, all materials involved in the following embodiments are commercially available. Unless otherwise specified, all methods are conventional methods. The amounts of each component are expressed in parts by mass (g, mL).

[0030] The gelatin (chemically pure) used in the following examples was purchased from Sinopharm Chemical Reagent Co., Ltd.; chitosan and potassium citrate and other metal salts were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0031] The oxidized chitosan used in this invention is commercially available, including at least one of hydrogen peroxide / divalent metal ion oxidized chitosan, potassium permanganate oxidized chitosan, and TEMPO oxidized chitosan. For better comparison, the following examples all use hydrogen peroxide / divalent metal ion oxidized chitosan, which can be prepared by the following steps: dispersing chitosan in water, adding a certain amount of 30 wt.% hydrogen peroxide solution and anhydrous copper sulfate catalyst, and continuing the reaction with mechanical stirring at 600 rpm for 48 hours. After the reaction is complete, the resulting product is repeatedly centrifuged and washed until the washing liquid is neutral, and then freeze-dried to constant weight to obtain oxidized chitosan. By controlling the amount of hydrogen peroxide and copper sulfate used, oxidized chitosan with different carboxyl content can be prepared. The following examples all use oxidized chitosan with a carboxyl content of 20%.

[0032] Example 1

[0033] 30 parts by weight of gelatin, 1 part by weight of oxidized chitosan, and 1.5 parts by weight of potassium citrate were added to 100 parts by weight of deionized water and mixed thoroughly. The mixture was mechanically stirred at 80°C for 1 hour to form a homogeneous viscous solution. A flask equipped with a spherical condenser was sealed with silicone grease to prevent water vapor diffusion at high temperatures. The mixture was then stirred continuously under vacuum for 5 minutes to remove air bubbles. Subsequently, the mixture was transferred to a 3 mm thick rectangular polytetrafluoroethylene mold and gelatinized at 5°C for 1 hour to obtain an oxidized chitosan hybrid gelatin hydrogel.

[0034] Example 2

[0035] 30 parts by weight of gelatin, 2 parts by weight of oxidized chitosan, and 1.5 parts by weight of potassium citrate were added to 100 parts by weight of deionized water and mixed thoroughly. The mixture was mechanically stirred at 80°C for 1 hour to form a homogeneous viscous solution. A flask equipped with a spherical condenser was sealed with silicone grease to prevent water vapor diffusion at high temperatures. The mixture was then stirred continuously under vacuum for 5 minutes to remove air bubbles. Subsequently, the mixture was transferred to a 3 mm thick rectangular polytetrafluoroethylene mold and gelatinized at 5°C for 1 hour to obtain an oxidized chitosan hybrid gelatin hydrogel.

[0036] Example 3

[0037] 30 parts by weight of gelatin, 3 parts by weight of oxidized chitosan, and 1.5 parts by weight of potassium citrate were added to 100 parts by weight of deionized water and mixed thoroughly. The mixture was mechanically stirred at 80°C for 1 hour to form a homogeneous viscous solution. A flask equipped with a spherical condenser was sealed with silicone grease to prevent water vapor diffusion at high temperatures. The mixture was then stirred continuously under vacuum for 5 minutes to remove air bubbles. Subsequently, the mixture was transferred to a 3 mm thick rectangular polytetrafluoroethylene mold and gelatinized at 5°C for 1 hour to obtain an oxidized chitosan hybrid gelatin hydrogel.

[0038] Example 4

[0039] 30 parts by weight of gelatin, 4 parts by weight of oxidized chitosan, and 1.5 parts by weight of potassium citrate were added to 100 parts by weight of deionized water and mixed thoroughly. The mixture was mechanically stirred at 80°C for 1 hour to form a homogeneous viscous solution. A flask equipped with a spherical condenser was sealed with silicone grease to prevent water vapor diffusion at high temperatures. The mixture was then stirred continuously under vacuum for 5 minutes to remove air bubbles. Subsequently, the mixture was transferred to a 3 mm thick rectangular polytetrafluoroethylene mold and gelatinized at 5°C for 1 hour to obtain an oxidized chitosan hybrid gelatin hydrogel.

[0040] Example 5

[0041] 30 parts by weight of gelatin, 5 parts by weight of oxidized chitosan, and 1.5 parts by weight of potassium citrate were added to 100 parts by weight of deionized water and mixed thoroughly. The mixture was mechanically stirred at 80°C for 1 hour to form a homogeneous viscous solution. A flask equipped with a spherical condenser was sealed with silicone grease to prevent water vapor diffusion at high temperatures. The mixture was then stirred continuously under vacuum for 5 minutes to remove air bubbles. Subsequently, the mixture was transferred to a 3 mm thick rectangular polytetrafluoroethylene mold and gelatinized at 5°C for 1 hour to obtain an oxidized chitosan hybrid gelatin hydrogel.

[0042] Example 6

[0043] 30 parts by weight of gelatin, 5 parts by weight of oxidized chitosan, and 1 part by weight of potassium citrate were added to 100 parts by weight of deionized water and mixed thoroughly. The mixture was mechanically stirred at 80°C for 1 hour to form a homogeneous viscous solution. A flask equipped with a spherical condenser was sealed with silicone grease to prevent water vapor diffusion at high temperatures. The mixture was then stirred continuously under vacuum for 5 minutes to remove air bubbles. Subsequently, the mixture was transferred to a 3 mm thick rectangular polytetrafluoroethylene mold and gelatinized at 5°C for 1 hour to obtain an oxidized chitosan hybrid gelatin hydrogel.

[0044] Example 7

[0045] 30 parts by weight of gelatin, 5 parts by weight of oxidized chitosan, and 2 parts by weight of potassium citrate were added to 100 parts by weight of deionized water and mixed thoroughly. The mixture was mechanically stirred at 80°C for 1 hour to form a homogeneous viscous solution. A flask equipped with a spherical condenser was sealed with silicone grease to prevent water vapor diffusion at high temperatures. The mixture was then stirred continuously under vacuum for 5 minutes to remove air bubbles. Subsequently, the mixture was transferred to a 3 mm thick rectangular polytetrafluoroethylene mold and gelatinized at 5°C for 1 hour to obtain an oxidized chitosan hybrid gelatin hydrogel.

[0046] Example 8

[0047] 30 parts by weight of gelatin, 5 parts by weight of oxidized chitosan, and 1.5 parts by weight of sodium citrate were added to 100 parts by weight of deionized water and mixed thoroughly. The mixture was mechanically stirred at 80°C for 1 hour to form a homogeneous viscous solution. A flask equipped with a spherical condenser was sealed with silicone grease to prevent water vapor diffusion at high temperatures. The mixture was then stirred continuously under vacuum for 5 minutes to remove air bubbles. Subsequently, the mixture was transferred to a 3 mm thick rectangular polytetrafluoroethylene mold and gelatinized at 5°C for 1 hour to obtain an oxidized chitosan hybrid gelatin hydrogel.

[0048] Example 9

[0049] 30 parts by weight of gelatin, 5 parts by weight of oxidized chitosan, and 1.5 parts by weight of calcium citrate were added to 100 parts by weight of deionized water and mixed thoroughly. The mixture was mechanically stirred at 80°C for 1 hour to form a homogeneous viscous solution. A flask equipped with a spherical condenser was sealed with silicone grease to prevent water vapor diffusion at high temperatures. The mixture was then stirred continuously under vacuum for 5 minutes to remove air bubbles. Subsequently, the mixture was transferred to a 3 mm thick rectangular polytetrafluoroethylene mold and gelatinized at 5°C for 1 hour to obtain an oxidized chitosan hybrid gelatin hydrogel.

[0050] Comparative Example 1

[0051] 30 parts by weight of gelatin and 1.5 parts by weight of potassium citrate were added to 100 parts by weight of deionized water and mixed thoroughly. The mixture was mechanically stirred at 80°C for 1 hour to form a homogeneous viscous solution. A flask equipped with a spherical condenser tube was sealed with silicone grease to prevent water vapor diffusion at high temperature. The mixture was then stirred continuously under vacuum for 5 minutes to remove air bubbles. Subsequently, the mixture was transferred to a rectangular polytetrafluoroethylene mold with a thickness of 3 mm and gelled at 5°C for 1 hour to obtain gelatin hydrogel.

[0052] Comparative Example 2

[0053] 30 parts by weight of gelatin, 5 parts by weight of ordinary chitosan, and 1.5 parts by weight of potassium citrate were added to 100 parts by weight of deionized water and mixed thoroughly. The mixture was mechanically stirred at 80°C for 1 hour to form a homogeneous viscous solution. A flask equipped with a spherical condenser was sealed with silicone grease to prevent water vapor diffusion at high temperatures. The mixture was then stirred continuously under vacuum for 5 minutes to remove air bubbles. The solution was then transferred to a 3 mm thick rectangular polytetrafluoroethylene mold and gelatinized at 5°C for 1 hour to obtain a chitosan-hybridized gelatin hydrogel.

[0054] The hydrogels prepared in Examples 1-9 and Comparative Examples 1-2 were subjected to tensile strength tests (tested according to ASTM D638-2003 standard, with a tensile rate of 50 mm / min); and photothermal conversion performance tests (light intensity of 100 mW / cm²) were also performed. 2 The test results are shown in Table 1 and... Figure 1 As shown.

[0055] From Table 1 and Figure 1 It is evident that the tensile strength and toughness of the oxidized chitosan hybrid gelatin hydrogel of this invention are significantly improved compared to pure gelatin hydrogel and original chitosan hybrid gelatin hydrogel. The introduction of oxidized chitosan significantly enhances the intermolecular interactions of the hydrogel, constructing a robust three-dimensional network structure through the formation of multiple hydrogen bonds and electrostatic interactions. Oxidized chitosan can act as a macromolecular crosslinking agent for molecular dispersion, forming abundant crosslinking points between gelatin molecular chains through electrostatic interactions and hydrogen bonding, promoting the aggregation of gelatin chains into more triple helix structures. These crosslinking points and crystalline regions serve as energy dissipation points, preventing rapid slippage of macromolecular chains under stress, thereby simultaneously strengthening and toughening the hydrogel. The oxidized chitosan / gelatin hybrid hydrogel combines the advantages of oxidized chitosan and gelatin, exhibiting significantly enhanced mechanical properties. The addition of metal salts such as potassium citrate further enhances the crosslinking strength and molecular chain entanglement through the Hoffmann effect. Through the Hoffmann effect, the convergence and crystallization of gelatin and oxidized chitosan molecular chains are strengthened. This structure not only provides high strength and toughness, but also enables the hydrogel to exhibit good ductility and fatigue resistance under stress.

[0056] Table 1

[0057]

[0058] Self-healing performance test procedure: Make a clearly defined slit in the middle of the dumbbell-shaped specimen, exposing the damaged area to 100mW / cm². 2 Photothermal-driven self-healing was performed under light intensity. After different self-healing cycles, the mechanical properties of the samples were tested, and the self-healing process was observed using an optical microscope. The results are shown in [Figure number missing]. Figure 2 , Figure 2 The images are taken under a microscope of the photothermal self-healing of the hydrogel in Example 3 at 0, 2, 3, and 6 min.

[0059] As shown in the figure, the hydrogel of this invention exhibits self-healing capabilities, achieving rapid self-repair driven by photothermal conversion. The oxidized chitosan hybrid gelatin hydrogel of this invention possesses significantly enhanced light absorption capacity and further releases heat energy through intramolecular chemical bond vibrations, making it an effective photothermal converter. When exposed to sunlight, it can effectively absorb solar energy and convert it into heat. Due to the strong intermolecular interactions between water-soluble oxidized chitosan and gelatin chains within the hydrogel, this heat generation occurs at the molecular level. These interactions occur at sub-nanometer intervals, and when the absorbed light energy is converted into heat, the temperature within the hydrogel rises, leading to a localized heating effect. This temperature increase triggers a gel-sol transition in the organic hydrogel, temporarily softening the gelatin matrix. In this softened state, the molecular network can rapidly reorganize, effectively healing cracks or damage. This self-healing property is particularly suitable for applications requiring long-term reliability, such as solar-powered devices, smart sensors, and medical devices. Therefore, the oxidized chitosan hybrid gelatin hydrogel of the present invention not only has efficient photothermal conversion performance, but also significantly surpasses traditional hydrogels in mechanical properties, providing a solution with excellent reliability and durability.

[0060] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A high-performance, tough, oxidized chitosan hybrid gelatin hydrogel with excellent photothermal conversion properties, characterized in that... It includes the following components by weight: 80-100 parts water, 20-40 parts gelatin, 1-5 parts oxidized chitosan, and 0.5-2 parts soluble metal salt; The high photothermal conversion performance and tough oxidized chitosan hybrid gelatin hydrogel is prepared by the following steps: the components are mixed evenly in proportion and then heated to dissolve. After low-temperature gelation, the oxidized chitosan hybrid gelatin hydrogel is prepared; the low temperature is 5-15℃. The oxidized chitosan has a carboxyl content of 5-30%; The soluble metal salt includes at least one of potassium citrate, sodium citrate, and calcium citrate.

2. The high photothermal conversion performance and tough oxidized chitosan hybrid gelatin hydrogel according to claim 1, characterized in that: The oxidized chitosan has a carboxyl content of 10-25%.

3. The high photothermal conversion performance and tough oxidized chitosan hybrid gelatin hydrogel according to claim 1, characterized in that: The oxidized chitosan includes at least one of hydrogen peroxide / divalent metal ion oxidized chitosan, potassium permanganate oxidized chitosan, and TEMPO oxidized chitosan.

4. The high photothermal conversion performance and tough oxidized chitosan hybrid gelatin hydrogel according to claim 1, characterized in that: The oxidized chitosan includes modified Fenton reagent oxidized chitosan.

5. A method for preparing a high-photothermal-conversion-performance, tough oxidized chitosan hybrid gelatin hydrogel according to any one of claims 1-4, characterized in that... The process includes the following steps: mixing the components in proportion and heating to dissolve them, followed by low-temperature gelation to prepare oxidized chitosan hybrid gelatin hydrogel; the low-temperature process is 5-15℃.

6. The preparation method according to claim 5, characterized in that: The heating refers to heating to 60-100℃, with a dissolution time of 0.5-5 hours.

7. The preparation method according to claim 5, characterized in that: The gelation time is 12-48 hours.

8. The application of the high photothermal conversion performance and tough oxidized chitosan hybrid gelatin hydrogel according to any one of claims 1-4 in the fields of flexible sensors, photothermal therapy, photothermal power generation, and energy storage.

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