A graphene gel and a method for preparing the same

Abstract

The application relates to the technical field of composite gel preparation, and discloses a graphene gel and a preparation method thereof, which comprises the following steps: adding graphene material into deionized water, adding a carboxyl-containing functional compound, and then performing ultrasonic stirring to obtain a graphene dispersion liquid with a surface carboxyl group; adding polyvinyl alcohol into the graphene dispersion liquid to form a composite solution; adding the composite solution into a forming mold; performing cyclic freezing and thawing on the composite solution and the forming mold, wherein the number of thawing is at least one time; performing annealing treatment after the final thawing; and soaking the graphene gel obtained after the annealing treatment in a metal salt aqueous solution; wherein the forming mold is provided with a forming protrusion, the forming protrusion is used for forming a connecting channel in the formed graphene gel, and the bottom cross section of the connecting channel is smaller than the top cross section. The application solves the problem that the graphene gel is poor in bone base combining property when being applied to artificial cartilage in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite gel preparation, in particular to a graphene gel and a preparation method thereof. BACKGROUND

[0002] Joints are an important part of the human skeletal muscle system and are the basis for maintaining normal life and movement. Articular cartilage is a tissue located between bones and plays an important role in load transmission and absorption. Articular cartilage damage can cause direct friction between bone ends, which in turn can cause bone damage. Currently, artificial joint replacement materials used to treat osteoarthritis are mostly metals (such as titanium alloy), ceramics, ultra-high molecular weight polyethylene, and polyurethane. These materials have problems such as easy wear and tear, stress shielding, accumulation of metal positive ions in the body, easy aging, and residual carcinogenic substances.

[0003] In order to overcome the problems of artificial joint materials in the prior art, porous polyvinyl alcohol with similar natural cartilage tissue is considered an ideal material for cartilage replacement. Although polyvinyl alcohol has many excellent characteristics such as non-toxicity, good biocompatibility, chemical stability, good flexibility, high elasticity, and small stress shielding, there are still many problems when using polyvinyl alcohol as a cartilage replacement material. For example, as a structural material in the body, the function of articular cartilage is highly dependent on its mechanical properties, and it lacks sufficient compression and shear resistance to withstand severe load conditions on the surface of the human joint. Self-lubricating properties also need to be improved.

[0004] In view of the problems of polyvinyl alcohol currently used, an invention with publication number CN 111333865A discloses a preparation method of high-strength and wear-resistant polyvinyl alcohol hydrogel. By adding carbon nanomaterials such as graphene into the gel and introducing hydroxyl groups, the mechanical strength and wear resistance and self-lubricating properties of the polyvinyl alcohol gel are effectively improved, making it more suitable for artificial cartilage materials. However, when the gel prepared using the material of the above-mentioned patent is applied to artificial cartilage, the combination of the gel surface, which is smooth and has no biological activity, with the bone substrate is poor, which affects the fixation and repair function of the cartilage. SUMMARY

[0005] The present application aims to provide a graphene gel and a preparation method thereof to solve the problem of poor combination of graphene gel with bone substrate when applied to artificial cartilage in the prior art.

[0006] To solve the problems in the prior art, the present application adopts the following technical solution: a graphene gel preparation method, comprising the following steps:

[0007] (1) adding graphene material into deionized water, adding carboxyl-containing functional compound, and then performing ultrasonic stirring to obtain a graphene dispersion liquid with surface carboxylation;

[0008] (2) adding polyvinyl alcohol into the graphene dispersion liquid to form a composite solution, and adding the composite solution into a forming mold;

[0009] (3) performing cyclic freezing and thawing on the composite solution and the forming mold, wherein the number of times of thawing is at least one;

[0010] (4) performing annealing treatment after final thawing, and then performing soaking in a metal salt aqueous solution to obtain a graphene gel;

[0011] The forming mold is provided with a forming protrusion, and the forming protrusion is used to form a connecting channel penetrating from the bottom to the top of the formed graphene gel, and the bottom cross section of the connecting channel is smaller than the top cross section.

[0012] The principle and beneficial effects of the scheme are as follows: graphene dispersion liquid is prepared before the preparation of the composite solution, so that the graphene material with excellent mechanical properties can reinforce the performance of the gel, and the graphene has the characteristics of easy functional modification, can be combined with the carboxyl-containing functional compound and polyvinyl alcohol to prepare a composite hydrogel, and then the cyclic freezing and thawing method is adopted to form microcrystals through hydrogen bonding between molecules, so as to form physical crosslinking points and a three-dimensional network structure; subsequent annealing treatment is performed to enhance the hydrogen bonding between molecules and the crosslinking degree, and finally the graphene gel is soaked in a salt solution, so that not only the hydroxyl groups on the polyvinyl alcohol molecules can form complex bonding with metal ions, but also the carboxyl groups on the surface of the carbon nanometer particles can enhance the complex bonding of the composite gel with metal ions, so as to construct multiple intermolecular interactions and multiple network structures, effectively play the excellent performance of graphene, and greatly improve the mechanical strength and wear resistance and self-lubricating property of the polyvinyl alcohol gel.

[0013] In addition, in the step (2) of the present application, when the composite solution is added into the forming mold, the forming protrusion arranged in the forming mold forms a connecting channel in the finally formed graphene gel. The connecting channel can not only be used as an active connecting channel for the graphene gel to be applied to the preparation of artificial cartilage and combined with the human bone basement, but also can form a storage space for water and body fluid to infiltrate or extrude, so as to form a lubricating layer on the contact surface, greatly reducing the friction resistance of the friction surface. In addition, in the present application, when the connecting channel is formed, the bottom cross section of the connecting channel is smaller than the top cross section, so that the cross section of the connecting channel decreases from the bottom to the top of the graphene gel. When the graphene gel is used as an artificial cartilage material, the bottom of the graphene gel is arranged as a surface combined with the bone basement. Since the larger end of the cross section of the connecting channel is combined with the bone basement, it is more conducive to the formation of a firm active connection between the graphene gel and the bone basement. In addition, the graphene gel prepared by the preparation method of the present application can promote the adhesion and growth of surrounding stem cells and chondrocytes and produce new cartilage tissue, thereby prolonging the service life of the implanted material.

[0014] At the same time, the cross section of the connecting channel near the top position is small, which is conducive to the infiltration and storage of water and body fluid, and is extruded when subjected to a load to play a good lubricating effect. In addition, the connecting channel provides a deformation space for the graphene gel to deform when subjected to a load, thereby improving the flexibility of the graphene gel. On the other hand, the cross section of the connecting channel near the top position of the graphene gel is arranged to be small, which is conducive to the graphene gel to maintain good flexibility, and can avoid secondary damage to the surrounding tissue caused by stress shielding after being implanted into the body, thereby reducing postoperative complications.

[0015] Preferably, as an improvement, the connecting channel comprises a bottom hole and a top hole in communication with each other. Along the thickness direction of the graphene gel, the longitudinal section of the bottom hole is trapezoidal, the pore size of the top hole is equal to the minimum pore size of the bottom hole, and the top end of the bottom hole is a small end.

[0016] In the present application, along the thickness direction of the graphene gel, the longitudinal section of the bottom hole is trapezoidal, so that the bottom hole is conical with the small end upward and the large end downward. The connecting channel near the bottom position has a large cross section, so that the connecting channel and the bone basement form an active connection. In addition, the pore size of the top hole is equal to or smaller than the minimum pore size of the top end of the bottom hole, so that the top hole can effectively form a storage space and a deformable space, and the structure is simple and convenient to form. In addition, since the longitudinal section of the bottom hole is trapezoidal and forms a certain chamfer, when the graphene gel is taken out from the base after forming, the bottom hole with a larger contact surface can be more easily and conveniently separated from the forming mold, thereby reducing the difficulty of demolding.

[0017] Preferably, as an improvement, the forming mold is further provided with a liquid storage protrusion, which is used to form a liquid storage channel in the graphene gel and communicate with the top of the graphene gel.

[0018] In this scheme, the liquid storage protrusion is added to the forming mold, and the liquid storage channel extending downward is formed on the top surface of the graphene gel by the liquid storage protrusion, which further increases the liquid storage space of the graphene gel and the deformation space of the graphene gel, and is beneficial to improve the flexibility of the graphene gel.

[0019] Preferably, as an improvement, the number of forming protrusions is multiple, and the liquid storage protrusion is located between adjacent forming protrusions, and the length of the liquid storage protrusion is less than or equal to the length of the forming protrusion.

[0020] In this scheme, the number of forming protrusions is multiple, which improves the strength of the active connection between the graphene gel prepared artificial cartilage and the bone basement after the preparation of the artificial cartilage.

[0021] Preferably, as an improvement, the diameter of the bottom end of the bottom hole ranges from 260 to 390 μm, and the pore size of the liquid storage channel ranges from 50 to 100 μm.

[0022] In this scheme, the diameter of the bottom end of the bottom hole is limited to a range of 260 to 390 μm, so that the graphene gel and the bone basement can form an active connection conveniently and stably, and the pore size of the liquid storage channel is set to a range of 50 to 100 μm, which can effectively play a liquid storage role.

[0023] Preferably, as an improvement, the carboxyl-containing functional compound is any one of glutamic acid, hyaluronic acid, sodium alginate, chondroitin sulfate, lysine, sodium carboxymethyl cellulose, and glycine; and the aqueous metal salt solution is any one of a calcium chloride aqueous solution, a magnesium chloride aqueous solution, a ferric chloride aqueous solution, a copper chloride aqueous solution, an aluminum chloride aqueous solution, and a zinc chloride aqueous solution with a mass concentration of 5 to 20%.

[0024] Preferably, as an improvement, in step (1), the ultrasonic stirring time is 20 to 60 min, the ultrasonic power is 500 to 2000 w, and the ultrasonic temperature is 60 to 80℃; in step (3), the freezing temperature is -50 to -10℃, the freezing time is 10 to 15 h, and the thawing time is 2 to 5 h; in step (4), the annealing temperature is 60 to 90℃, the annealing time is 5 to 10 h, and the soaking time is 5 to 10 h.

[0025] Preferably, as an improvement, the mass fraction of the graphene material is 1 to 20 parts, the mass fraction of the polyvinyl alcohol is 100 to 120 parts, the mass fraction of the carboxyl-containing functional compound is 0.1 to 10 parts, and the mass fraction of the aqueous metal salt solution is 100 to 1000 parts.

[0026] Preferably, as an improvement, the molding die includes a base and a top cover that interlock with each other, and the molding protrusion includes a bottom conical section and a top cylindrical section. The bottom conical section is fixedly connected to the base and is used to mold a bottom hole, and the top cylindrical section is fixedly connected to the top cover and is used to mold a top hole.

[0027] In this design, the molding die includes a base and a top cover that interlock. The base and top cover form a molding space for molding graphene gel. A bottom conical segment is placed on the base, and a top cylindrical segment is placed on the top cover. During molding, the top cover is snapped onto the base, with the top cylindrical segment and the bottom conical segment corresponding to and abutting each other. After molding, when separating the top cover and the base, regardless of whether the graphene gel remains on the base or the top cover, it can be demolded more easily and effortlessly, which helps to reduce damage to the graphene gel during removal. At the same time, because the aperture of the connecting channel is small, the molding protrusion is also small. Dividing the molding protrusion into relatively independent bottom conical segment and top cylindrical segment can avoid the molding protrusion being too large.

[0028] The second objective of this invention is to provide a graphene gel prepared by the aforementioned graphene gel preparation method. Attached Figure Description

[0029] Figure 1 This is a longitudinal sectional view of the graphene gel in Embodiment 1 of the present invention when it is located inside the molding die.

[0030] Figure 2 for Figure 1 Longitudinal cross-section of the graphene gel, substrate, and top cover in their separated state.

[0031] Figure 3 for Figure 2 A magnified view of a portion of point A in the middle.

[0032] Figure 4 The same as in Embodiment 2 of the present invention Figure 2 A magnified view of a portion of point A in the middle. Detailed Implementation

[0033] The following detailed description illustrates the specific implementation method:

[0034] The reference numerals in the accompanying drawings include: graphene gel 1, bottom hole 101, top hole 102, liquid storage channel 103, base 2, top cover 3, feed port 301, overflow port 302, bottom conical section 4, top cylindrical section 5, liquid storage protrusion 6.

[0035] Example 1

[0036] A method for preparing graphene gel, comprising the following steps:

[0037] (1) Take 1 g of graphene and 100 g of deionized water to mix, then add 0.2 g of sodium alginate and stir evenly, then use ultrasonic dispersion for 20-60 min, ultrasonic power is 500-2000 w, ultrasonic temperature is 60-80℃, in this embodiment, the ultrasonic dispersion time is preferably 40 min, the ultrasonic power is 1000 w, and the ultrasonic temperature is 60℃, to obtain a carboxylated graphene dispersion.

[0038] (2) Take 100 g of polyvinyl alcohol and heat the graphene dispersion in step (1) at 80℃ for 2 h to form a composite solution, and then pour the composite solution into a forming mold, wherein the forming mold is as shown in Figure 1 The forming mold includes a base 2 and an upper cover 3 arranged above and below and can be buckled with each other, the upper cover 3 is buckled on the top of the base 2, and the top surface of the base 2 is provided with a groove, so that the upper cover 3 and the base 2 can form a forming space for forming graphene gel 1 after buckling.

[0039] At the same time, the forming mold is provided with a forming protrusion for forming a connecting channel penetrating from the bottom to the top of the graphene gel 1, specifically, combining Figure 2 and Figure 3 , the connecting channel includes a bottom hole 101 and a top hole 102 which are connected to each other, along the thickness direction of the graphene gel 1, the longitudinal section of the bottom hole 101 is isosceles trapezoidal, so that the bottom hole 101 is conical as a whole, the hole diameter of the bottom hole 101 gradually decreases from the right bottom to the top, and the hole diameter of the top hole 102 is equal to the minimum hole diameter of the top end position of the bottom hole 101, so that the top end of the bottom hole 101 and the bottom end of the top hole 102 are smoothly connected. In addition, in this embodiment, the diameter of the bottom end of the bottom hole 101 is 260-390 μm, preferably 300 μm, and the diameter of the top hole 102 is 200-250 μm, preferably 220 μm.

[0040] Correspondingly, the forming protrusion includes a bottom conical section 4 and a top cylindrical section 5, the bottom conical section 4 is integrally formed on the bottom wall of the groove on the top of the base 2, and the top cylindrical section 5 is integrally formed on the bottom surface of the upper cover 3, the bottom conical section 4 is used to form the bottom hole 101, and the top cylindrical section 5 is used to form the top hole 102, the bottom conical section 4 and the top cylindrical section are equal in number and arranged one by one. Corresponding; at the same time, in order to facilitate feeding and forming, a feeding port 301 penetrating through the upper cover 3 is integrally formed on the top surface of the upper cover 3 near the left side, and an overflow port 302 penetrating through the upper cover 3 is integrally formed on the top surface of the upper cover 3 near the right side, the composite solution is added into the forming space through the feeding port 301, and the excess composite solution can overflow from the overflow port 302.

[0041] (3) After the composite solution is added into the molding mold and the molding space is filled, the molding mold is cycled with the composite solution for freezing and thawing, and the number of times of thawing is at least one. In this embodiment, the number of times of freezing and thawing is three, the freezing temperature is -50 to -10°C, the freezing time is 10 to 15 hours, the thawing temperature is normal temperature, and the thawing time is 2 to 5 hours. In this embodiment, the freezing temperature is preferably -25°C, the freezing time is 10 hours, and the thawing time is 3 hours. After the first freezing, the upper cover 3 can be removed, so that the product formed is left in the base 2. Since the top hole 102 in the graphene gel 1 is in an empty state at this time, it is beneficial to rapid freezing and thawing.

[0042] (4) After the final thawing, the product is taken out of the base 2, and then annealing treatment is performed. The annealing temperature is 60 to 90°C, and the annealing time is 5 to 10 hours. In this embodiment, the annealing temperature is preferably 80°C, and the annealing time is 6 hours. After annealing, the product is placed in a calcium chloride aqueous solution with a mass concentration of 20%, the mass of the calcium chloride aqueous solution is 800g, and the soaking time is 5 to 10 hours, preferably 6 hours. Finally, the graphene gel 1 is obtained.

[0043] The graphene gel 1 prepared by the preparation method in this embodiment effectively improves the comprehensive mechanical properties of the graphene gel 1 due to the use of graphene materials. Combined with the excellent properties of polyvinyl alcohol, the overall performance of the graphene gel 1 is excellent. The graphene has a nucleation and pore-forming effect on the mesh hole, has little effect on the water content of the formed gel, and can increase the pore size of the composite gel, so that it can be used as an ideal material for making artificial cartilage. In addition, the graphene gel 1 formed in this embodiment has a large mesh diameter at the bottom, so that the graphene gel 1 can form a firm active connection with the bone base. The top hole 102 near the top not only has a liquid storage function, but also allows water and body fluids to penetrate into the top hole 102. When the liquid is squeezed out, it can lubricate the contact surface. The top hole 102 provides a deformation space for the material under compression, so that the material has good flexibility and is suitable for the production of artificial cartilage.

[0044] Embodiment Two

[0045] The difference between Embodiment Two and Embodiment One is that, as shown in FIG. 2, the bottom surface of the upper cover 3 is also integrally formed with a liquid storage protrusion 6. The liquid storage protrusion 6 is used to form a liquid storage channel 103 in the graphene gel 1 that communicates with the top of the graphene gel 1. The length of the liquid storage channel 103 is less than or equal to the thickness of the graphene gel 1, and the pore size of the liquid storage channel 103 is in the range of 50 to 100 μm. In this embodiment, the length of the liquid storage channel 103 is equal to half the length of the top hole 102, and the pore size of the liquid storage channel 103 is 100 μm. Figure 4 ​

[0046] In the embodiment, by arranging the liquid storage channel 103 on the top of the graphene gel 1, the liquid storage effect of the graphene gel 1 is improved, so that the self-lubricating performance is enhanced, and the internal gap space of the graphene gel 1 is increased, so that the flexibility of the graphene gel 1 is further enhanced.

[0047] The above is only an embodiment of the present application, and the specific technical solutions and / or common knowledge of the scheme are not described in detail. It should be pointed out that for those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, which will not affect the effect and practicality of the patent. The protection scope of the present application should be subject to the content of its claims, and the specific embodiments in the specification can be used to explain the content of the claims.

Claims

1. A method of preparing a graphene gel, the method comprising: The method comprises the following steps: ​ (1) adding graphene material into deionized water, and performing ultrasonic stirring after adding a carboxyl-containing functional compound to obtain a graphene dispersion liquid with surface carboxylation; (2) adding polyvinyl alcohol into the graphene dispersion liquid to form a composite solution, and adding the composite solution into a forming mold; (3) performing cyclic freezing and thawing on the composite solution and the forming mold, wherein the number of thawing is at least one time; (4) performing annealing treatment after final thawing, and performing soaking by using a metal salt aqueous solution to obtain a graphene gel; The forming mold is provided with a forming protrusion, and the forming protrusion is used for forming a connecting channel penetrating through the graphene gel from the bottom to the top in the formed graphene gel, and the bottom cross section of the connecting channel is larger than the top cross section.

2. The method of claim 1, wherein: The connecting channel comprises a bottom hole and a top hole which are in communication with each other, and the longitudinal section of the bottom hole is trapezoidal along the thickness direction of the graphene gel, and the aperture of the top hole is equal to the minimum aperture of the bottom hole.

3. The method for preparing graphene gel according to claim 2, characterized in that: The forming mold is further provided with a liquid storage protrusion, and the liquid storage protrusion is used for forming a liquid storage channel in communication with the top of the graphene gel.

4. The method for preparing graphene gel according to claim 3, characterized in that: The number of the forming protrusions is multiple, the liquid storage protrusion is located between adjacent forming protrusions, and the length of the liquid storage protrusion is less than or equal to the length of the forming protrusion.

5. The method for preparing graphene gel according to claim 3, characterized in that: The diameter of the bottom end of the bottom hole ranges from 260 to 390 μm, and the aperture of the liquid storage channel ranges from 50 to 100 μm.

6. The method of claim 1, wherein: The carboxyl-containing functional compound is any one of glutamic acid, hyaluronic acid, sodium alginate, chondroitin sulfate, lysine, sodium carboxymethyl cellulose, and glycine; and the metal salt aqueous solution is any one of calcium chloride aqueous solution, magnesium chloride aqueous solution, iron chloride aqueous solution, copper chloride aqueous solution, aluminum chloride aqueous solution, and zinc chloride aqueous solution with a mass concentration of 5 to 20%.

7. The method of claim 1, wherein: In step (1), the ultrasonic stirring time is 20 to 60 min, the ultrasonic power is 500 to 2000 w, and the ultrasonic temperature is 60 to 80℃; in step (3), the freezing temperature is-50 to-10℃, the freezing time is 10 to 15 h, and the thawing time is 2 to 5 h; in step (4), the annealing temperature is 60 to 90℃, the annealing time is 5 to 10 h, and the soaking time is 5 to 10 h.

8. The method of claim 1, wherein: The mass fraction of the graphene material is 1 to 20 parts, the mass fraction of the polyvinyl alcohol is 100 to 120 parts, the mass fraction of the carboxyl-containing functional compound is 0.1 to 10 parts, and the mass fraction of the metal salt aqueous solution is 100 to 1000 parts.

9. The method of claim 2, wherein the method is characterized by: The forming mold comprises a base and an upper cover which are buckled with each other, the forming protrusion comprises a bottom tapered section and a top cylindrical section, the bottom tapered section is fixedly connected to the base and used for forming the bottom hole, and the top cylindrical section is fixedly connected to the upper cover and used for forming the top hole.

10. A graphene gel prepared by the method of any one of claims 1 to 9.

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