A double network gradient gel for 3D printing and a preparation method and application thereof

Abstract

The application discloses a double-network gradient gel for 3D printing and a preparation method and application thereof. The method comprises the following steps: adding sodium alginate into deionized water to swell to form a sol to obtain solution 1; adding 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride, N-hydroxy-succinimide and N-(3-aminopropyl) methacrylamide into the solution 1; the above solution is cleaned with ethanol and acetone respectively, and the obtained solid is placed into a vacuum drying oven for drying after filtration; sodium alginate with a double bond after grafting is obtained; N-isopropyl acrylamide and NN methylene bisacrylamide and alpha-ketoglutaric acid are added into deionized water to configure a precursor solution; the sodium alginate with the double bond and carbomer are added into the precursor solution to adjust rheology to obtain a slurry; a sample piece is swelled in deionized water, placed on an anode plate, powered to form an electric field, and a sodium alginate gel is formed by metal ions and modified sodium alginate.

Description

Technical Field

[0001] This invention relates to the field of 3D printing hydrogels, specifically to a dual-network gradient gel for 3D printing, its preparation method, and its applications. Background Technology

[0002] Hydrogels are three-dimensional network structures composed of covalent bonds and hydrophilic groups. Due to their biocompatibility and biodegradability, they have been widely used in biomedicine and tissue engineering. Examples include scaffolds for tissue repair and regeneration, filling irregular lesions, slow-release drug reservoirs, and drug delivery carriers. One major application of hydrogels as delivery carriers is the fabrication of hydrogel actuators. Existing actuators are mainly divided into two categories: bilayer hydrogels and gradient hydrogels. Current methods for preparing gradient hydrogels include electrodeposition and in-situ polymerization. These methods involve adding an unpolymerized hydrogel precursor solution to a mold. The shape of the gradient hydrogels produced by these methods largely depends on the mold shape or subsequent cutting and bonding, making it difficult to form complex models. 3D printing technology can solve the molding problem, but existing 3D-printed hydrogels form a bilayer structure with two materials. Since there are no chemical bonds between the two hydrogels, the interlayers are bonded by glue. This structure results in two layers of hydrogel lacking consistent chemical stability compared to gradient hydrogels, affecting the actuator's lifespan. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention proposes a dual-network gradient gel for 3D printing, its preparation method, and its applications.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] A method for preparing a dual-network gradient gel for 3D printing, comprising:

[0006] Sodium alginate was added to deionized water and heated to allow it to swell fully and form a sol. After cooling, it was diluted with deionized water to obtain solution 1.

[0007] Add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxy-succinimide and N-(3-aminopropyl)methacrylamide to solution 1; stir magnetically under a protective gas atmosphere;

[0008] The above solution was washed with ethanol and acetone respectively, filtered, and the resulting solid was dried in a vacuum drying oven.

[0009] The obtained solid was ground into powder in a vertical planetary ball mill to obtain sodium alginate with double bonds after grafting.

[0010] A hydrogel precursor solution was prepared by adding N-isopropylacrylamide, NN-methylenebisacrylamide, and α-ketoglutaric acid particles to deionized water.

[0011] Sodium alginate and carbomer with double bonds were added to the precursor solution to adjust the rheology and obtain a slurry that can be directly written for 3D printing.

[0012] After the printed sample is cured under a UV lamp, it is placed in deionized water to swell.

[0013] The swollen sample is placed on the anode plate in the electric field of pure aqueous solution. An electric field is formed by passing an electric current to promote the movement of metal ions on the anode plate, thereby obtaining metal ions and modified sodium alginate to form an alginate gel.

[0014] Optionally, the anode is made of copper, iron, zinc, or aluminum.

[0015] In this process, as copper on the anode continuously loses electrons to become copper ions and distributes them in a gradient along the potential direction under the presence of an electric field, the copper ions and the modified sodium alginate form a copper alginate gel. This gel interpenetrates with the original hydrogel network, and the gel network density decreases in gradient along the potential direction. Thus, a gradient hydrogel is formed.

[0016] Optionally, the step of preparing the hydrogel precursor solution further includes adding acrylamide.

[0017] Optionally, the step of preparing the hydrogel precursor solution may further include adding iron oxide nanoparticles.

[0018] Optionally, by controlling the voltage magnitude, the electron loss rate of the anode plate can be adjusted, thereby adjusting the content of metal ions generated on the anode plate, and thus controlling the number of cross-linked ionic bonds to form gradient cross-links.

[0019] Optionally, the voltage applied is set to 10V.

[0020] A dual-network gradient gel for 3D printing, with the following structural formula:

[0021]

[0022] Optionally, the copper ions can be replaced with iron ions, zinc ions, or aluminum ions.

[0023] The above-mentioned application of sodium alginate with double bonds in the preparation of 3D printing materials.

[0024] The beneficial effects of this invention are:

[0025] 1. The hydrogel material of the present invention can be used as a material for slurry-to-write 3D printing, and can be processed into more and more complex shapes.

[0026] 2. The grafting rate of the modified sodium alginate of the present invention is less than 10%, which will not affect the crosslinking of carboxyl groups and metal ions. At the same time, sodium alginate can be used as a rheology modifier to enhance the printability of the hydrogel precursor solution.

[0027] 3. The present invention adjusts the electron loss rate of the anode plate (copper plate) by controlling the voltage, thereby adjusting the content of generated metal ions and controlling the number of cross-linked ionic bonds to form gradient cross-linking. Attached Figure Description

[0028] The invention will now be further described with reference to the accompanying drawings.

[0029] Figure 1 This is a schematic diagram of the copper alginate gel of the present invention;

[0030] Figure 2 This is a schematic diagram of the grafting of sodium alginate with N-(3-aminopropyl)methacrylamide according to the present invention;

[0031] Figure 3 This is a schematic diagram of the modified sodium alginate of the present invention forming an ionized gel;

[0032] Figure 4 This is a schematic diagram of the DC electric field of the present invention;

[0033] Figure 5 This is a schematic diagram of the gradient crosslinking of the hydrogel of the present invention;

[0034] Figure 6 This is a schematic diagram of the hydrogel brake prepared in Embodiment 1 of the present invention;

[0035] Figure 7 This is the bending effect of adding iron oxide to Fe2O3 in hot water in Example 2 of the present invention;

[0036] Figure 8 This is a schematic diagram of bending under alternating magnetic field heating according to Embodiment 2 of the present invention.

[0037] The components or ingredients corresponding to the icon labels are as follows:

[0038] 1. Sodium alginate structure; 2. Gel network formed by sodium alginate; 3. Copper ions; 4. Grafted alginate hydrogel structure; 5. DC electric field cathode plate; 6. Cured single-network hydrogel; 7. DC electric field anode plate; 8. Deionization; 9. DC power supply. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0040] Example 1

[0041] Step 1: Add 2.22g of sodium alginate to deionized water and heat it to allow it to swell fully and form a sol. After cooling, add deionized water to dilute it and obtain solution 1.

[0042] Step 2: Add 0.179g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), 0.17g of N-hydroxy-succinimide (NHS) and 0.28g of N-(3-aminopropyl)methacrylamide to solution 1, and add 12M hydrochloric acid solution dropwise to adjust the pH of solution 1 to 4.

[0043] Step 3: Transfer the solution from Step 2 to a three-necked flask and magnetically stir the resulting solution at room temperature under a nitrogen atmosphere for 20 hours.

[0044] Step 4: Wash the above solution three times with ethanol and acetone respectively, filter it using a vacuum filtration device, and then dry the resulting solid in a vacuum drying oven for 24 hours.

[0045] Step 5: Grind the obtained solid into powder in a vertical planetary ball mill.

[0046] Step 6: Add 2.25g of N-isopropylacrylamide, 0.07g of N-methylenebisacrylamide, 0.03g of photoinitiator α-ketoglutarate, and 0.11g of acrylamide monomer to 20ml of deionized water to prepare a hydrogel precursor solution.

[0047] Step 7: Weigh 0.22g of the prepared modified sodium alginate with double bonds, add 0.45g of carbomer, adjust the solution rheology, and then adjust the pH to 7 to obtain a slurry suitable for direct 3D printing.

[0048] Step 8: After printing, cure the printed sample under ultraviolet light and then swell it in deionized water.

[0049] Step 9: Place the swollen hydrogel sample onto the anode plate in the electric field.

[0050] Step 10: Adjust the voltage to 10V and keep it powered on for 30 minutes.

[0051] like Figure 6As shown, the method of this embodiment can be used to fabricate a gradient hydrogel actuator that is subject to thermal braking.

[0052] Example 2

[0053] Step 1: Add 2.22g of sodium alginate to deionized water and heat it to allow it to swell fully and form a sol. After cooling, add deionized water to dilute it and obtain solution 1.

[0054] Step 2: Add 0.179g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC), 0.17g of N-hydroxy-succinimide (NHS) and 0.28g of N-(3-aminopropyl)methacrylamide to solution 1, and add 12M hydrochloric acid solution dropwise to adjust the pH of solution 1 to 4.

[0055] Step 3: Transfer the solution from Step 2 to a three-necked flask and magnetically stir the resulting solution at room temperature under a nitrogen atmosphere for 20 hours.

[0056] Step 4: Wash the above solution three times with ethanol and acetone respectively, filter it using a vacuum filtration device, and then dry the resulting solid in a vacuum drying oven for 24 hours.

[0057] Step 5: Grind the obtained solid into powder in a vertical planetary ball mill.

[0058] Step 6: Add 1.13g N-isopropylacrylamide, 0.035g N-N-methylenebisacrylamide, 0.025g thermal initiator ammonium persulfate, 0.11g acrylamide monomer, and 1.5g iron oxide nanoparticles to 20ml of deionized water to prepare a hydrogel precursor solution.

[0059] Step 7: Weigh 0.22g of the prepared modified sodium alginate with double bonds, add 0.45g of carbomer, adjust the solution rheology, and then adjust the pH to 7 to obtain a slurry suitable for direct 3D printing.

[0060] Step 8: After printing, cure the printed sample under ultraviolet light and then swell it in deionized water.

[0061] Step 9: Place the swollen hydrogel sample onto the anode plate in the electric field.

[0062] Step 10: Adjust the voltage to 10V and keep it powered on for 30 minutes.

[0063] like Figure 7 As shown, iron oxide nanoparticles are added in this embodiment without affecting the bending phenomenon.

[0064] In actual tests, it was found that under alternating magnetic field, the temperature rose to 34.7℃ in 54s, 37.9℃ in 80s, and 53.8℃ in 500s.

[0065] like Figure 8 As shown, after incorporating iron oxide nanoparticles, remote alternating magnetic field heating can be achieved.

[0066] In other embodiments of the present invention, the metal ions are not limited to copper ions. Furthermore, the copper ions in the above embodiments can be replaced with iron, aluminum, or zinc, and the desired effects of the present invention can be achieved by performing the same preparation and verification steps as in the above embodiments.

[0067] In summary, the preparation method of the present invention involves adding modified sodium alginate to a hydrogel precursor solution to initiate crosslinking, which copolymerizes the alginate onto a hydrogel network. At this point, the hydrogel is a single-network hydrogel. By controlling the directional movement of metal ions, a second gradient gel can be formed with the sodium alginate on the network through ionic bonds. Thus, the preparation of a dual-network gradient hydrogel is complete. This method utilizes the ability of sodium alginate to form an ionic gel with metal ions (see attached schematic diagram). Figure 1 However, sodium alginate has weak bonding with the hydrogel network, so grafting modification is being considered (grafting principle attached). Figure 2 Modified sodium alginate can be copolymerized onto the hydrogel network via grafted carbon-carbon double bonds, and gradient cross-linking can be achieved by controlling the concentration difference of ions through an electric field (see attached diagram). Figure 3 , 4 Copper on the anode plate continuously loses electrons to become copper ions, which are distributed along the potential direction under the presence of an electric field. The copper ions and sodium alginate on the first layer of hydrogel network form copper alginate gel. This gel interpenetrates with the first layer of hydrogel network, and the density of the gel network decreases along the potential direction, forming a gradient hydrogel (see attached schematic diagram). Figure 5 ).

[0068] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0069] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for the preparation of a double network gradient gel for 3D printing, characterized in that, include: Sodium alginate was added to deionized water and heated to allow it to swell fully and form a sol. After cooling, it was diluted with deionized water to obtain solution 1. Add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxy-succinimide and N-(3-aminopropyl)methacrylamide to solution 1; stir magnetically under a protective gas atmosphere; The above solution was washed with ethanol and acetone respectively, filtered, and the resulting solid was dried in a vacuum drying oven. The obtained solid was ground into powder in a vertical planetary ball mill to obtain sodium alginate with double bonds after grafting. A hydrogel precursor solution was prepared by adding N-isopropylacrylamide, N,N-methylenebisacrylamide, and α-ketoglutaric acid particles to deionized water. Sodium alginate and carbomer with double bonds were added to the precursor solution to adjust the rheology and obtain a slurry that can be directly written for 3D printing. After the printed sample is cured under a UV lamp, it is placed in deionized water to swell. The swollen sample is placed on the anode plate in the electric field of pure aqueous solution. A DC electric field is formed by passing an electric current to promote the movement of metal ions on the anode plate, so that the metal ions and modified sodium alginate form alginate gel. Gradient crosslinking is achieved by controlling the concentration difference of metal ions through the electric field.

2. The method for the preparation of a dual-network gradient gel for 3D printing according to claim 1, characterized in that, The anode is made of copper, iron, zinc, or aluminum.

3. The method for preparing a dual-network gradient gel for 3D printing according to claim 1, characterized in that, The step of preparing the hydrogel precursor solution also includes adding acrylamide.

4. The method for preparing a dual-network gradient gel for 3D printing according to claim 1, characterized in that, The step of preparing the hydrogel precursor solution also includes adding iron oxide nanoparticles.

5. The method for preparing a dual-network gradient gel for 3D printing according to claim 1, characterized in that, By controlling the voltage, the rate of electron loss of the anode plate is adjusted, thereby adjusting the content of metal ions generated on the anode plate, and thus controlling the number of cross-linked ionic bonds to form gradient cross-links.

6. The method for preparing a dual-network gradient gel for 3D printing according to claim 1, characterized in that, The voltage for power supply is set to 10V.

7. A dual-network gradient gel for 3D printing, characterized in that, It is prepared by the preparation method of the dual-network gradient gel for 3D printing according to any one of claims 1 to 6.

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