Graphene oxide-containing collagen corona composite hydrogel, and preparation method and application thereof

Abstract

The application discloses a collagen crown-containing graphene oxide composite hydrogel as well as a preparation method and application thereof, and belongs to the technical field of functional polymer materials. The graphene oxide is added into a polyvinyl alcohol / glycerol solution by taking the collagen crown as a medium, the uniformity of graphene oxide dispersion is enhanced, the mechanical strength and the responsiveness to a small strain of the hydrogel are improved, and the hydrogel is suitable for preparing a flexible stress and strain sensor. The collagen crown / polyvinyl alcohol composite hydrogel is prepared by a one-pot method. The water / glycerol mixed solvent is used to replace a pure water system, the freezing resistance of the hydrogel is greatly improved, the hydrogel has good tensile property, viscoelasticity, transparency and sensitivity, and the current hydrogel sensor can be effectively improved in the aspects of low sensitivity and poor adaptability in a special environment. The collagen crown / polyvinyl alcohol composite hydrogel can be applied to monitoring human motion as a sensitive sensor.

Description

Technical Field

[0001] This invention belongs to the field of functional polymer materials technology, specifically relating to a composite hydrogel containing graphene oxide and collagen crown, its preparation method, and its application. Background Technology

[0002] With rapid societal development and a general improvement in people's quality of life, health has become a focal point of public attention. One requirement for maintaining good health is consistent physical exercise. Consequently, in recent years, the number of people participating in various sports has been increasing. However, due to a lack of professional training and guidance, many people experience physical injuries during exercise due to improper technique, failing to achieve the desired fitness benefits. Therefore, the design of flexible wearable sensors capable of detecting human movement has garnered significant attention. Currently, while some wearable sensors have been designed for monitoring minute activities such as heart rate and pulse during exercise, the diversification of sports activities and the increasing complexity of sports environments mean that traditionally designed hydrogel sensors can no longer meet people's exercise needs, exhibiting problems such as reduced sensitivity and decreased adaptability in extreme environments.

[0003] Currently, hydrogel substrates commonly used for flexible sensors include natural and synthetic polymers. While hydrogels made from natural polymers such as starch and chitosan exhibit good biocompatibility, they suffer from poor mechanical properties. Hydrogels made from synthetic polymers such as acrylic acid and polyacrylamide overcome the problem of low mechanical strength but fail to meet the requirement of good biocompatibility and possess a certain degree of toxicity, significantly limiting their application range. In contrast, polyvinyl alcohol (PVA) possesses low toxicity and high biocompatibility, making it an ideal choice for flexible sensor substrate materials.

[0004] In the field of sensors, pure polyvinyl alcohol (PVA) hydrogel sensors suffer from poor freeze resistance, resulting in unsatisfactory sensing performance. PVA hydrogel sensors prepared by modification with functional groups and inorganic additives show only minor performance improvements and are time-consuming and labor-intensive. Nanocomposite hydrogels prepared by modifying with nanofillers such as nanodots, nanoparticles, nanowires, nanotubes, and nanosheets exhibit mutual repulsion when these nanofillers aggregate within a hydrophilic hydrogel network due to their hydrophobicity. This not only affects the basic properties of the hydrogel but also weakens the functionality of the nanofillers themselves. Furthermore, attempting to improve the nanofiller's performance through chemical modification presents challenges such as difficulty in successful modification and increased process complexity. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a method for preparing and applying a composite hydrogel containing graphene oxide collagen crown, so as to solve the problems of easy aggregation of nanoparticles, difficulty in introducing them into the hydrogel system, and low sensitivity and poor adaptability of traditional hydrogel sensors in complex external environments.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses a method for preparing a composite hydrogel containing graphene oxide collagen crown, comprising the following steps:

[0008] 1) Add collagen to a glycerol solution and stir until homogeneous to obtain a collagen solution; add graphene oxide to a glycerol solution and stir until homogeneous, then disperse by ultrasonication to obtain a graphene oxide dispersion;

[0009] 2) Add the graphene oxide dispersion to the collagen solution and let it stand to obtain the collagen crown solution;

[0010] 3) First, add polyvinyl alcohol to a glycerol solution to prepare a polyvinyl alcohol / glycerol solution. Then, add konjac gum and the collagen crown solution prepared in step 2) to the polyvinyl alcohol / glycerol solution. Stir at 50-60°C for 1-3 hours, pour into a mold, freeze and thaw at room temperature, and cycle 2-4 times. Then, transfer to a lithium chloride solution for soaking to obtain a collagen crown / polyvinyl alcohol / konjac gum composite hydrogel.

[0011] Optimally, the mass ratio of collagen:graphene oxide:konjac gum:polyvinyl alcohol is (0.0025~0.025):(0.005~0.015):(0.5~1):(2.4~4.8).

[0012] Ideally, the glycerol solution is prepared by mixing water and glycerol with a mass fraction of 99.5% in a mass ratio of (0.8:1.2) to (1.2:0.8).

[0013] Optimally, in step 2), the graphene oxide dispersion is added to the collagen solution without stirring and allowed to stand for 5-10 minutes to obtain a collagen crown solution.

[0014] Optimally, in step 3), the molecular weight of the polyvinyl alcohol is 30,000 to 40,000, and the average molecular weight of the konjac gum is 200,000 to 2,000,000; in the polyvinyl alcohol / glycerol solution, the mass ratio of polyvinyl alcohol to glycerol solution is (2.4 to 4.8):(20 to 40), and the reaction conditions are stirring at 95 to 100°C for 4 to 5 hours.

[0015] Optimally, in step 3), the freezing conditions are -20 to -15°C for 8 to 12 hours, the thawing time is 2 to 4 hours, the mass fraction of the lithium chloride solution is 5% to 10%, and the soaking time is 2 to 4 hours.

[0016] Optimally, in step 1), the mass ratio of graphene oxide to glycerol solution in the graphene oxide dispersion is (0.005–0.015):(0.1–2.5), and the stirring conditions are stirring at 25–30°C for 5–10 minutes and ultrasonic dispersion for 20–30 minutes; the mass ratio of collagen to glycerol solution in the collagen solution is (0.0025–0.025):(2.5–5); the stirring conditions are stirring at 25–30°C for 15–20 minutes; the collagen is bovine collagen with a molecular weight of 8,000–12,000, a protein mass fraction greater than 90%, a moisture content less than 5%, and a pH value of 5.0–7.5.

[0017] Optimally, in step 1), the graphene oxide dispersion contains 0.3%–0.5% graphene oxide by mass; the graphene oxide nanosheets have a thickness of 1.3–2.2 nm and a diameter of 280–970 nm; the graphene oxide contains 25.3%–28.6% oxygen by mass, of which the epoxy groups contain 22.3%–25.7%, the carboxyl groups contain 31.6%–33.2%, and the hydroxyl groups contain 21.4%–23.8% by mass; and the graphene oxide dispersion has a pH of 4–6.

[0018] The present invention also discloses a composite hydrogel containing graphene oxide collagen crown prepared by the above preparation method.

[0019] The present invention also discloses the application of the above-mentioned graphene oxide-containing collagen crown composite hydrogel as a sensor in detecting human movement. The human movement is monitored by the change in the internal resistance of the hydrogel, and the sensitivity factor is 1.38 to 1.88.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention discloses a method for preparing a graphene oxide-containing collagen crown composite hydrogel. Using graphene oxide, collagen, and polyvinyl alcohol (PVA) as raw materials, a graphene oxide dispersion is added to a collagen solution to obtain a collagen crown solution. Using this collagen crown solution as a medium, graphene oxide nanoparticles are introduced into a PVA / glycerol copolymer solution, and then konjac gum is added. The collagen crown / PVA / konjac gum composite hydrogel is prepared in a one-pot process. Introducing nanoscale graphene oxide into the hydrogel system via a protein crown enhances the uniformity of graphene oxide dispersion, improves the mechanical strength of the hydrogel, and increases its responsiveness to small strains, making it suitable for fabricating flexible stress-strain sensors. The collagen crown allows for a simpler introduction of graphene oxide into the hydrogel system while significantly reducing the toxicity of the nanoparticles. The combination of collagen and graphene oxide improves the biocompatibility and sensing performance of the hydrogel sensor. Furthermore, freeze-thaw cycles are used to strengthen the hydrogen bonding between PVA and glycerol, thereby improving the mechanical strength and freeze resistance of the hydrogel. During the dissolution process, polyvinyl alcohol (PVA) forms hydrogen bonds with the hydroxyl groups in glycerol and interacts with konjac gum, which gels at high temperatures, to construct a dual three-dimensional network structure. Collagen corona is added during the construction of the first network structure, allowing it to interweave within it. Finally, freeze-thaw cycles enhance the hydrogen bonding between PVA and glycerol, ultimately forming a dual-network hydrogel structure system. Compared to traditional hydrogel sensors, this method solves the problems of nanoparticle aggregation during preparation, difficulty in integrating them into the hydrogel network, and low sensitivity and poor adaptability in harsh environments.

[0022] Furthermore, the protein crown is introduced by using a glycerol solution prepared by mixing water and glycerol, which avoids the influence of adding other solvents on the formation and performance of the three-dimensional network structure. Moreover, using glycerol solution instead of pure water greatly improves the freeze resistance of the hydrogel, while giving it good stretchability, viscoelasticity, transparency and sensitivity. This can effectively improve the shortcomings of current hydrogel sensors, such as low sensitivity and poor adaptability in special environments.

[0023] Furthermore, the collagen is bovine collagen, which fully utilizes collagen, reducing resource waste and alleviating environmental pollution from the leather industry.

[0024] This invention also discloses a graphene oxide-containing collagen crown composite hydrogel prepared by the above-mentioned preparation method. The graphene oxide-containing collagen crown composite hydrogel uses polyvinyl alcohol / glycerol as the first network structure and konjac gum as the second network structure. It makes full use of collagen extracted from leather solid waste to prepare a collagen crown, and uses this as a medium to introduce graphene oxide into the system to prepare a hydrogel sensor. By using the collagen crown to regulate the sensing performance of the hydrogel, the problem of easy aggregation of nanoparticles and difficulty in introducing them into the hydrogel system is effectively solved. At the same time, it also solves the problem of low sensitivity and poor adaptability of traditional hydrogel sensors in more severe external environments.

[0025] This invention also discloses the application of the above-mentioned graphene oxide-containing collagen crown composite hydrogel as a sensor in detecting human movement. By recording the changes in internal resistance of the hydrogel sensor in real time during human movement, some unnecessary physical injuries can be reduced. At the same time, in some special sports, such as skydiving, skiing, and winter swimming, the hydrogel can still maintain ultra-sensitive detection performance in low-pressure, low-temperature, and high-concentration water environments, providing an effective means for correcting movements and responding to emergencies. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the internal structure of the graphene oxide-containing collagen crown composite hydrogel prepared according to the present invention.

[0027] Figure 2 The resistivity change rate-time graph of the graphene oxide-containing collagen crown composite hydrogel prepared in Example 1 of the present invention during finger movement;

[0028] Figure 3 The resistivity change rate-time graph of the graphene oxide-containing collagen crown composite hydrogel prepared in Example 2 of this invention during arm bending;

[0029] Figure 4 The resistivity change rate-time graph of the graphene oxide-containing collagen crown composite hydrogel prepared in Example 3 of the present invention during knee flexion;

[0030] Figure 5 The resistivity change rate-time graph of the graphene oxide-containing collagen crown composite hydrogel prepared in Example 4 of the present invention during finger movement at -20℃;

[0031] Figure 6 The resistivity change rate-time graph of the graphene oxide-containing collagen crown composite hydrogel prepared in Example 5 of the present invention during knee flexion in water;

[0032] Figure 7 This is a schematic diagram illustrating the preparation process of the graphene oxide-containing collagen crown composite hydrogel obtained by the present invention. Detailed Implementation

[0033] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0034] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0035] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings:

[0036] This invention discloses a method for preparing a composite hydrogel containing graphene oxide-based collagen crowns, specifically including the following steps:

[0037] 1) By mass, add 0.0025 to 0.025 parts of collagen to 2.5 to 5 parts of a glycerol solution prepared by mixing water and 99.5% glycerol in a mass ratio of (0.8:1.2) to (1.2:0.8), and stir at 25 to 30°C for 15 to 20 minutes to obtain a collagen solution;

[0038] 2) By mass, add 0.005 to 0.015 parts of graphene oxide to 0.1 to 2.5 parts of the same glycerol solution as in step 1), stir magnetically at 25 to 30°C for 5 to 10 minutes, and then sonicate for 20 to 30 minutes to obtain a graphene oxide dispersion. Then, without stirring, slowly add it to the collagen solution prepared in step 1), and let it stand for 5 to 10 minutes to obtain a collagen crown solution.

[0039] 3) By mass, add 2.4–4.8 parts of polyvinyl alcohol to 20–40 parts of the same glycerol solution as in step 1), heat to 95–100°C, and stir for 4–5 hours to obtain a polyvinyl alcohol / glycerol solution. Add 0.5–1 parts of konjac gum and the collagen crown solution prepared in step 2) to the polyvinyl alcohol / glycerol solution, and stir at 50–60°C for 1–3 hours to obtain a collagen crown / polyvinyl alcohol / konjac gum hydrogel precursor solution. Pour the solution into a glass mold, freeze at -20–-15°C for 8–12 hours, thaw at room temperature for 2–4 hours, and repeat 2–4 times. Then transfer the solution to 10–20 parts of a 5%–10% lithium chloride solution and soak for 2–4 hours to obtain a collagen crown / polyvinyl alcohol / konjac gum composite hydrogel.

[0040] Example 1

[0041] A method for preparing a composite hydrogel containing graphene oxide-based collagen crowns specifically includes the following steps:

[0042] 1) By mass, add 0.0025 parts of collagen to 2.5 parts of a glycerol solution prepared by mixing water and 99.5% glycerol at a mass ratio of 0.8:1.2, and stir at 25°C for 20 minutes to obtain a collagen solution.

[0043] 2) By mass, add 0.005 parts of graphene oxide to 0.1 parts of the same glycerol solution as in step 1), stir magnetically for 5 minutes at 25°C, and then sonicate for 20 minutes to obtain a graphene oxide dispersion. Then, without stirring, slowly add it to the collagen solution prepared in step 1), and let it stand for 5 minutes to obtain a collagen crown solution.

[0044] 3) By mass fraction, add 2.4 parts of polyvinyl alcohol to 20 parts of the same glycerol solution as in step 1), heat to 95°C, and stir for 4 hours to obtain a polyvinyl alcohol / glycerol solution. Add 0.5 parts of konjac gum and the collagen crown solution prepared in step 2) to the polyvinyl alcohol / glycerol solution, stir at 50°C for 1 hour to obtain a collagen crown / polyvinyl alcohol / konjac gum hydrogel precursor solution. Pour into a glass mold, freeze at -20°C for 8 hours, thaw at room temperature for 2 hours, repeat twice, and then transfer to 10 parts of a 5% lithium chloride solution for 2-4 hours to obtain a collagen crown / polyvinyl alcohol / konjac gum composite hydrogel.

[0045] The collagen crown / polyvinyl alcohol composite hydrogel was made into a rectangle and connected to both ends of the hydrogel with two separate copper wires. The hydrogel served as an ion conductor and the copper wires served as electrodes to prepare a resistive strain sensor. The hydrogel was fixed at the finger joint and the copper wires were connected to a digital source meter to record the resistance change during finger movement. The sensitivity factor GF was calculated to be 1.88.

[0046] See Figure 1 This is a schematic diagram of the internal structure of the graphene oxide-containing collagen crown composite hydrogel prepared according to the present invention. As can be seen from the figure, polyvinyl alcohol and glycerol form the first network structure of the hydrogel through hydrogen bonding, and konjac gum forms the second network structure of the hydrogel through hydrogen bonding and hydrophobic interaction. The protein crown is interspersed in the double network structure. The collagen on its surface is physically cross-linked with polyvinyl alcohol and konjac gum through electrostatic interaction and hydrophobic interaction. Lithium ions are uniformly dispersed in the hydrogel system.

[0047] See Figure 2 The graph shows the resistance change rate-time of the graphene oxide-containing collagen crown composite hydrogel prepared in Example 1 of this invention during finger movement; it can be seen from the graph that the resistance change rate of the hydrogel can reach about 45% over time.

[0048] Example 2

[0049] A method for preparing a composite hydrogel containing graphene oxide-based collagen crowns specifically includes the following steps:

[0050] 1) By weight, add 0.025 parts of collagen to 5 parts of a glycerol solution prepared by mixing water and 99.5% glycerol in a mass ratio of 1.2:0.8, and stir at 30°C for 20 minutes to obtain a collagen solution.

[0051] 2) By mass, add 0.015 parts of graphene oxide to 2.5 parts of the same glycerol solution as in step 1), stir magnetically for 10 minutes at 30°C, and then sonicate for 30 minutes to obtain a graphene oxide dispersion. Then, without stirring, slowly add it to the collagen solution prepared in step 1), and let it stand for 10 minutes to obtain a collagen crown solution.

[0052] 3) By mass fraction, add 4.8 parts of polyvinyl alcohol to 40 parts of the same glycerol solution as in step 1), heat to 100℃, and stir for 5 hours to obtain a polyvinyl alcohol / glycerol solution. Add 1 part of konjac gum and the collagen crown solution prepared in step 2) to the polyvinyl alcohol / glycerol solution, stir at 60℃ for 3 hours to obtain a collagen crown / polyvinyl alcohol / konjac gum hydrogel precursor solution. Pour into a glass mold, freeze at -15℃ for 12 hours, thaw at room temperature for 4 hours, and repeat 4 times. Then transfer to 20 parts of a 10% lithium chloride solution and soak for 4 hours to obtain a collagen crown / polyvinyl alcohol / konjac gum composite hydrogel.

[0053] The collagen crown / polyvinyl alcohol composite hydrogel was made into a rectangle and connected to both ends of the hydrogel with two separate copper wires. The hydrogel served as an ion conductor and the copper wires served as electrodes to prepare a resistive strain sensor. The hydrogel was fixed at the joint of the arm and the copper wires were connected to a digital source meter to record the resistance change when the arm was bent. The sensitivity factor GF was calculated to be 1.77.

[0054] See Figure 3 The graph shows the resistance change rate-time of the graphene oxide-containing collagen crown composite hydrogel prepared in Example 2 of this invention when the arm is bent. It can be seen from the graph that the resistance change rate of the hydrogel can reach about 60% over time.

[0055] Example 3

[0056] A method for preparing a composite hydrogel containing graphene oxide-based collagen crowns specifically includes the following steps:

[0057] 1) By weight, 0.0027 parts of collagen were added to 3.5 parts of a glycerol solution prepared by mixing water and 99.5% glycerol at a mass ratio of 0.9:1.0, and stirred at 27°C for 17 minutes to obtain a collagen solution.

[0058] 2) By mass, add 0.009 parts of graphene oxide to 0.18 parts of the same glycerol solution as in step 1), stir magnetically for 7 minutes at 27°C, and then sonicate for 25 minutes to obtain a graphene oxide dispersion. Then, without stirring, slowly add it to the collagen solution prepared in step 1), and let it stand for 7 minutes to obtain a collagen crown solution.

[0059] 3) By mass fraction, 4.4 parts of polyvinyl alcohol were added to 29 parts of the same glycerol solution as in step 1), heated to 97°C, and stirred for 4.5 hours to obtain a polyvinyl alcohol / glycerol solution. 0.7 parts of konjac gum and the collagen crown solution prepared in step 2) were added to the polyvinyl alcohol / glycerol solution, and stirred at 55°C for 2 hours to obtain a collagen crown / polyvinyl alcohol / konjac gum hydrogel precursor solution. The solution was injected into a glass mold, frozen at -18°C for 9 hours, thawed at room temperature for 3 hours, and repeated 3 times. Then, it was transferred to 15 parts of a 7% lithium chloride solution and soaked for 3 hours to obtain a collagen crown / polyvinyl alcohol / konjac gum composite hydrogel.

[0060] The collagen crown / polyvinyl alcohol composite hydrogel was made into a rectangle and connected to both ends of the hydrogel with two separate copper wires. The hydrogel served as an ion conductor and the copper wires served as electrodes to prepare a resistive strain sensor. The hydrogel was fixed at the joint of the arm and the copper wires were connected to a digital source meter to record the resistance change when the knee was bent. The sensitivity factor GF was calculated to be 1.60.

[0061] See Figure 4 The graph shows the resistance change rate-time of the graphene oxide-containing collagen crown composite hydrogel prepared in Example 3 of this invention during knee flexion; it can be seen from the graph that the resistance change rate of the hydrogel can reach about 77% over time.

[0062] Example 4

[0063] A method for preparing a composite hydrogel containing graphene oxide-based collagen crowns specifically includes the following steps:

[0064] 1) By mass, 0.0023 parts of collagen were added to 4.3 parts of a glycerol solution prepared by mixing water and 99.5% glycerol in a mass ratio of 1:1, and stirred at 29°C for 18 minutes to obtain a collagen solution.

[0065] 2) By mass, 0.012 parts of graphene oxide were added to 2.1 parts of the same glycerol solution as in step 1), and the mixture was magnetically stirred at 27°C for 8 minutes, and then ultrasonically dispersed for 26 minutes to obtain a graphene oxide dispersion. Then, without stirring, it was slowly added to the collagen solution prepared in step 1), and after standing for 9 minutes, a collagen crown solution was obtained.

[0066] 3) By mass fraction, 4.1 parts of polyvinyl alcohol were added to 33 parts of the same glycerol solution as in step 1), heated to 97°C, and stirred for 4.7 hours to obtain a polyvinyl alcohol / glycerol solution. 0.9 parts of konjac gum and the collagen crown solution prepared in step 2) were added to the polyvinyl alcohol / glycerol solution, and stirred at 59°C for 2.8 hours to obtain a collagen crown / polyvinyl alcohol / konjac gum hydrogel precursor solution. The solution was injected into a glass mold, frozen at -19°C for 11 hours, thawed at room temperature for 3.5 hours, and repeated 3 times. Then, it was transferred to 13 parts of a 7% lithium chloride solution and soaked for 2 hours to obtain a collagen crown / polyvinyl alcohol / konjac gum composite hydrogel.

[0067] The collagen crown / polyvinyl alcohol composite hydrogel was made into a rectangle and connected to both ends of the hydrogel with two separate copper wires. The hydrogel served as an ion conductor and the copper wires served as electrodes to prepare a resistive strain sensor. The hydrogel was fixed at the finger joint and the copper wires were connected to a digital source meter. The resistance change during finger movement was recorded at -20℃. The sensitivity factor GF was calculated to be 1.38.

[0068] See Figure 5 The graph shows the resistance change rate-time of the graphene oxide-containing collagen crown composite hydrogel prepared in Example 4 of this invention during finger movement at -20℃. As can be seen from the graph, the resistance change rate of the hydrogel can reach about 13% over time.

[0069] Example 5

[0070] A method for preparing a composite hydrogel containing graphene oxide-based collagen crowns specifically includes the following steps:

[0071] 1) By weight, add 0.020 parts of collagen to 3.7 parts of a glycerol solution prepared by mixing water and 99.5% glycerol at a mass ratio of 1.0:0.8, and stir at 26°C for 20 minutes to obtain a collagen solution.

[0072] 2) By mass, add 0.015 parts of graphene oxide to 2.5 parts of the same glycerol solution as in step 1), stir magnetically for 9 minutes at 25°C, and then sonicate for 30 minutes to obtain a graphene oxide dispersion. Then, without stirring, slowly add it to the collagen solution prepared in step 1), and let it stand for 10 minutes to obtain a collagen crown solution.

[0073] 3) By mass fraction, add 4.8 parts of polyvinyl alcohol to 40 parts of the same glycerol solution as in step 1), heat to 95°C, and stir for 4 hours to obtain a polyvinyl alcohol / glycerol solution. Add 0.5 parts of konjac gum and the collagen crown solution prepared in step 2) to the polyvinyl alcohol / glycerol solution, stir at 50°C for 1 hour to obtain a collagen crown / polyvinyl alcohol / konjac gum hydrogel precursor solution. Pour into a glass mold, freeze at -20°C for 12 hours, thaw at room temperature for 4 hours, repeat 4 times, and then transfer to 20 parts of a 10% lithium chloride solution for 4 hours to obtain a collagen crown / polyvinyl alcohol / konjac gum composite hydrogel.

[0074] The collagen crown / polyvinyl alcohol composite hydrogel was made into a rectangle and connected to both ends of the hydrogel with two separate copper wires. The hydrogel served as an ion conductor and the copper wires served as electrodes to prepare a resistive strain sensor. The hydrogel was fixed at the knee and the copper wires were connected to a digital source meter to record the resistance change when the knee was bent in water. The sensitivity factor GF was calculated to be 1.41.

[0075] See Figure 6 The graph shows the resistance change rate-time of the graphene oxide-containing collagen crown composite hydrogel prepared in Example 5 of this invention when the knee is bent in water; it can be seen from the graph that the resistance change rate of the hydrogel can reach about 26% over time.

[0076] See Figure 7 This is a schematic diagram of the preparation process of the graphene oxide-containing collagen crown composite hydrogel obtained by the present invention. The experimental conditions and parameters of the graphene oxide-containing collagen crown composite hydrogel in the preparation process can be seen from the figure, which shows the structure of the protein crown and some structural formulas of the main forces inside the hydrogel.

[0077] Table 1 shows the sensitivity factors of hydrogels for monitoring different sites in different environments.

[0078] Table 1. Comparison of Sensitivity Factor Application Results

[0079] Example number Sensitive Factor Example 1 1.88 Example 2 1.77 Example 3 1.60 Example 4 1.38 Example 5 1.41

[0080] This invention first prepares a graphene oxide-based collagen crown using a collagen self-assembly method. Then, using polyvinyl alcohol as a raw material, a polyvinyl alcohol / glycerol copolymer solution is prepared. The collagen crown and konjac gum are added to the copolymer solution, and a collagen crown / polyvinyl alcohol composite hydrogel precursor solution is prepared by a one-pot heating method. Finally, the collagen crown / polyvinyl alcohol composite hydrogel is obtained by a freeze-thaw cycle method and an immersion method.

[0081] The method described above prepares a composite hydrogel containing graphene oxide-based collagen crowns. The synthesis principle is as follows: during the dissolution process, polyvinyl alcohol forms hydrogen bonds with the hydroxyl groups in glycerol and interacts with konjac gum that is gelled at high temperature to build a double three-dimensional network structure. Collagen crowns are added during the construction of the first network structure and interspersed within it. Finally, the hydrogen bonding between polyvinyl alcohol and glycerol is enhanced through freeze-thaw cycles, ultimately forming a double network hydrogel structure system.

[0082] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a composite hydrogel containing graphene oxide collagen crown, characterized in that, Includes the following steps: 1) Collagen is added to a glycerol solution and stirred until homogeneous to obtain a collagen solution; graphene oxide is added to the glycerol solution and stirred until homogeneous, then ultrasonically dispersed to obtain a graphene oxide dispersion; the collagen is bovine collagen with a molecular weight of 0.8 million to 1.2 million, a protein mass fraction greater than 90%, a water content less than 5%, and a pH value of 5.0 to 7.5; the graphene oxide dispersion contains 0.3% to 0.5% graphene oxide by mass; the graphene oxide nanosheets have a thickness of 1.3 to 2.2 nm and a diameter of 280 to 970 nm; the graphene oxide contains 25.3% to 28.6% oxygen by mass, of which the epoxy groups contain 22.3% to 25.7%, the carboxyl groups contain 31.6% to 33.2%, and the hydroxyl groups contain 21.4% to 23.8% by mass; 2) Add the graphene oxide dispersion to the collagen solution and let it stand to obtain the collagen crown solution; 3) First, polyvinyl alcohol is added to a glycerol solution to prepare a polyvinyl alcohol / glycerol solution. Then, konjac gum and the collagen crown solution prepared in step 2) are added to the polyvinyl alcohol / glycerol solution. After stirring at 50-60 °C for 1-3 hours, the solution is poured into a mold, frozen and thawed at room temperature, and circulated 2-4 times. Finally, the solution is transferred to a lithium chloride solution for soaking to obtain a collagen crown / polyvinyl alcohol / konjac gum composite hydrogel with a sensitivity factor of 1.38-1.

88. The mass ratio of collagen, graphene oxide, konjac gum, and polyvinyl alcohol is (0.0025~0.025): (0.005~0.015): (0.5~1): (2.4~4.8).

2. The preparation method of the graphene oxide-containing collagen crown composite hydrogel according to claim 1, characterized in that, The glycerol solution is prepared by mixing water and glycerol with a mass fraction of 99.5% in a mass ratio of (0.8:1.2) to (1.2:0.8).

3. The preparation method of the graphene oxide-containing collagen crown composite hydrogel according to claim 1, characterized in that, In step 2), the graphene oxide dispersion is added to the collagen solution without stirring and allowed to stand for 5-10 minutes to obtain the collagen crown solution.

4. The method for preparing the graphene oxide-containing collagen crown composite hydrogel according to claim 1, characterized in that, In step 3), the molecular weight of the polyvinyl alcohol is 30,000 to 40,000, and the average molecular weight of the konjac gum is 200,000 to 2,000,000; in the polyvinyl alcohol / glycerol solution, the mass ratio of polyvinyl alcohol to glycerol solution is (2.4 to 4.8): (20 to 40), and the reaction conditions are stirring at 95 to 100 °C for 4 to 5 hours.

5. The method for preparing the graphene oxide-containing collagen crown composite hydrogel according to claim 1, characterized in that, In step 3), the freezing conditions are -20 to -15 ℃ for 8 to 12 hours, and the thawing time is 2 to 4 hours; the mass fraction of the lithium chloride solution is 5% to 10%; and the soaking time is 2 to 4 hours.

6. The method for preparing the graphene oxide-containing collagen crown composite hydrogel according to claim 1, characterized in that, In step 1), the mass ratio of graphene oxide to glycerol solution in the graphene oxide dispersion is (0.005~0.015):(0.1~2.5), and the stirring conditions are stirring at 25~30 ℃ for 5~10 minutes and ultrasonic dispersion for 20~30 minutes; the mass ratio of collagen to glycerol solution in the collagen solution is (0.0025~0.025):(2.5~5), and the stirring conditions are stirring at 25~30 ℃ for 15~20 minutes.

7. The method for preparing the graphene oxide-containing collagen crown composite hydrogel according to claim 1, characterized in that, In step 1), the pH value of the graphene oxide dispersion is 4~6.

8. A graphene oxide-containing collagen crown composite hydrogel prepared by any one of claims 1 to 7.

9. The application of the graphene oxide-containing collagen crown composite hydrogel as a sensor in detecting human motion, as described in claim 8, is characterized in that... Human movement is monitored by measuring changes in the internal resistance of the hydrogel, with a sensitivity factor of 1.38~1.88.

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