CN117800655A - A one-step 3D printing method for high-precision interconnected porous hydroxyapatite/chitosan composite scaffold at room temperature - Google Patents

Abstract

The invention belongs to the field of material science engineering, and discloses a high-precision 3D printing forming method of a hydroxyapatite/chitosan composite bracket with an interconnected porous structure by a room temperature one-step method. The method takes potassium-doped hydroxyapatite and chitosan as raw materials and comprises the following steps: preparing potassium-doped hydroxyapatite slurry; mixing potassium-doped hydroxyapatite slurry with chitosan solution; and extruding the 3D printing and forming at room temperature to obtain the one-step formed 3D printing interconnection porous structure composite material. The hydroxyapatite powder is prepared by potassium doping modification, does not need to be printed in a curing solution, does not need to be subjected to crosslinking treatment such as spraying curing solution and the like, and avoids the processes such as high-temperature treatment, sintering and the like. The 3D printing interconnection porous structure of the interconnection porous structure composite material is prepared, has a high-precision structure and excellent mechanical properties, and realizes normal-temperature one-step extrusion 3D printing molding. The 3D printing forming porous material prepared by the method has potential application value in the fields of water treatment, biomedical stents and the like.

Description

A high-precision interconnected porous structure hydroxyapatite/chitosan composite scaffold at room temperature One-step 3D printing molding method

Technical field

The invention belongs to the field of materials science engineering and relates to a high-precision interconnected porous structure hydroxyapatite/chitosan composite material and a room temperature one-step 3D printing molding method. It has certain application value in the fields of water treatment, biomedical stents and other fields. .

Background technique

Hydroxyapatite is widely recognized as an excellent scaffold material. However, traditional preparation methods, such as foaming method, sintered microsphere method and sol-gel method, usually require high-temperature calcination, the preparation process is complicated, and it is not convenient to load bioactive drugs. . Unlike traditional methods, modern 3D printing technology uses selective laser sintering to mix hydroxyapatite with low-melting point substances. However, the resulting scaffolds often suffer from poor shape and require additional processing, such as isostatic pressing, to increase density. , the entire preparation process is expensive and complicated, and it is difficult to load biologically active substances.

Other 3D printing methods (light curing, inkjet, direct writing extrusion) usually mix hydroxyapatite powder with polymer materials and then perform extrusion printing. Although direct-write extrusion 3D printing has obvious advantages in biomedical fields such as good biocompatibility and the ability to achieve multi-material custom printing, currently available 3D printing direct-write extrusion deposition technologies often require in-process deposition during the printing process. Process steps such as spraying, soaking after printing or using UV light to cure. Liu Shuifeng of South China Agricultural University published a 3D printed hydroxyapatite/polymer nanocomposite bioporous scaffold using sodium alginate (SA), hydroxyapatite (HAP) and gluconolactone (GDL) as the main raw materials. , the sodium alginate is gelled in situ to form a hydrogel as a bioink, and the gel scaffold is obtained through the extrusion 3D printing method. The scaffold is then soaked in a calcium chloride solution for a second time for cross-linking to improve the performance of the scaffold. These processes can easily lead to poor structural control and low precision in the printing process, and due to the material, the mechanical properties of the stent itself are also poor, thus limiting the application and development of 3D printing materials in related fields.

Therefore, it is expected to develop a room temperature extrusion 3D printing material and a one-step molding process that is non-biotoxic, does not require post-cross-linking treatment, and has a high molding accuracy on a three-dimensional structure, with a view to its application in the fields of water treatment and biomedicine. There are certain applications.

Contents of the invention

The present invention proposes a high-precision interconnection method in view of the technical problems of current hydroxyapatite-based scaffolds in various 3D printing technologies, such as high equipment and material costs, cumbersome post-processing procedures, and the risk of potential harmful biological toxicity. One-step room temperature 3D printing method for porous structure potassium-doped hydroxyapatite/chitosan composite scaffold. By making full use of the sustained release effect of potassium ions and regulating the components and process parameters in the formula, the present invention prepares a 3D printable slurry with strong injectability and moderate curing time. This process can be extruded at room temperature without sintering or cross-linking post-processing, and ultimately results in a 3D printed scaffold material with a high-precision interconnected porous structure.

Technical solution of the present invention:

A one-step 3D printing method for a high-precision interconnected porous structure hydroxyapatite/chitosan composite scaffold at room temperature is disclosed. Potassium-doped hydroxyapatite powder and chitosan are prepared into a hydroxyapatite-chitosan mixed slurry, and the hydroxyapatite-chitosan mixed slurry is extruded at room temperature for 3D printing and self-consolidation to obtain a hydroxyapatite/chitosan scaffold material.

The molar ratio of calcium + potassium to phosphorus in the potassium-doped hydroxyapatite powder is 5:3; the mass proportion of potassium in the potassium-doped hydroxyapatite powder is 10 to 25 wt% calculated as potassium oxide.

Among them, the potassium salt is potassium carbonate, potassium sulfate or potassium hydroxide.

The microscopic morphology of the potassium-doped hydroxyapatite powder is nanoscale, with a length of 20 to 100 nm and a width of 5 to 10 nm.

A hydroxyapatite-chitosan mixed slurry is prepared from potassium-doped hydroxyapatite powder and chitosan. The specific steps are: first, add potassium-doped hydroxyapatite powder to deionized water and disperse it ultrasonically to form potassium-doped hydroxyapatite. Apatite slurry; then dissolve chitosan in an acetic acid solution to obtain a chitosan solution; add the potassium-doped hydroxyapatite slurry to the chitosan solution drop by drop at a temperature of 30 to 75°C and a rotational speed of Stir in a magnetic stirrer at 600 to 1000 rpm to obtain a hydroxyapatite-chitosan mixed slurry.

In the hydroxyapatite-chitosan mixed slurry, the mass ratio of chitosan and potassium-doped hydroxyapatite is 1:1 to 1:2.

The deacetylation degree of the chitosan is 80-95%; the mass concentration of chitosan in the chitosan solution is 1-8%, and the mass concentration of acetic acid is 2-6%.

The stirring time is 2.5~4.5h.

The diameter of the 3D printing extrusion head is 0.2~1.2mm, the printing layer height is 0.1~0.6mm, the printing speed is 0.1mm/s~50mm/s, and the printing air pressure is 30~800kPa.

The potassium-doped hydroxyapatite is uniformly distributed inside and on the surface of the interconnected porous structure.

There is no need to print in a curing solution, cross-linking treatment such as spraying the curing solution, or high-temperature treatment such as sintering. Among them, the temperature of the printing environment should be kept at room temperature, and it should be placed on the printing substrate for 5 to 15 minutes after printing.

Beneficial effects of the present invention: The present invention provides a high-precision continuous porous structure potassium-doped hydroxyapatite/chitosan composite material room temperature one-step 3D printing molding method. Starting from the modification of hydroxyapatite, hydroxyapatite is obtained The injectability and adjustable setting time of the stone/chitosan composite slurry allow the slurry to be used for direct-write 3D printing, thereby obtaining well-formed and high-precision engineering scaffolds.

Specifically including the following aspects:

(1) The introduction of potassium-doped hydroxyapatite into the composite system significantly improves the injectability (more than 90%) and uniformity of the slurry. By regulating the concentration of potassium ion release in potassium-doped hydroxyapatite and regulating the composition ratio and process of chitosan, a processing window suitable for 3D printing is provided. The preparation method of the present invention adopts one-step extrusion printing and self-curing molding at room temperature, without the need for high-energy beam-assisted sintering (such as laser, electron beam), nor does it require ultraviolet light-assisted curing, and does not require subsequent debinding, high-temperature sintering and other complex post-processing steps, which provides a new and convenient way for 3D printing of hydroxyapatite in bone tissue engineering scaffolds and water treatment.

(2) The hydroxyapatite and chitosan used in the present invention have high safety and good biocompatibility. The printed bone scaffold has appropriate porosity and pore size structure, which is conducive to the growth of bone tissue, making the scaffold have excellent biocompatibility and osteoconductivity. The interconnected porous structure is conducive to the transportation of nutrients, the growth of blood vessels, and can promote cell attachment, proliferation, and differentiation.

(3) The potassium-doped hydroxyapatite/chitosan composite scaffold material prepared by the present invention is 3D printed at about room temperature. This low-temperature 3D printing technology is helpful for the maintenance and component affinity of the scaffold. , to avoid pollution. Compared with products that require high-temperature sintering or high-temperature printing after printing, it has a higher activity advantage.

(4) The one-step forming process at room temperature used in the present invention is beneficial to the loading of drugs, highly active factors, and even the affinity addition of active cells, enabling the scaffold to have higher biological activity.

Description of drawings

Figure 1 is a sample obtained in Example 1. It is basically impossible to form, it is easy to collapse and fuse, and it is basically impossible to print. It fuses and collapses quickly after printing, making it impossible to obtain a practical scaffold material.

Figure 2 shows the sample obtained in Example 2; where (a) shows that the sample obtained has higher precision, and (b) shows that after (a) is placed for a period of time, the layers are clear and still maintain high precision.

Figure 3 is a sample obtained in Example 3.

Figure 4 is the sample obtained in Example 6; among them, (a) some nodes of the printed sample will produce a certain degree of fusion, and the overall molding quality is acceptable; (b) the sample collapses and fuses quickly after molding, and the accuracy is poor. .

Detailed ways

The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings and technical solutions.

Example 1

2g chitosan was dissolved in 3wt% (concentration of acetic acid) acetic acid aqueous solution, and a magnetic stirrer was used to stir at 60°C and 800rpm to prepare a chitosan acetic acid solution with a concentration of 5w%. 3.0g of undoped potassium hydroxyapatite was mixed with deionized water and ultrasonicated for 10-20 minutes using an ultrasonic cell disruptor to make it evenly dispersed. The potassium-doped hydroxyapatite suspension was added dropwise to the chitosan acetic acid solution, with a chitosan and undoped potassium hydroxyapatite mass ratio of 2:3, and continued to stir for 3h to obtain a uniformly mixed potassium-doped hydroxyapatite chitosan suspension. The composite gel ink was printed using a DIW printer, and the printing process conditions were that the diameter of the 3D printing extruder was 0.3mm, the printing layer height was 0.3mm, the printing speed was 30mm/s, and the printing pressure was 400kPa. The obtained sample was basically unable to be formed, was very easy to collapse and fuse, and was basically unable to be printed (as shown in Figure 1). It quickly fused and collapsed after printing, and no practical scaffold material could be obtained.

Example 2

Dissolve 2g of chitosan in an acetic acid aqueous solution of 3wt% (concentration of acetic acid), and stir vigorously until it is clear and transparent, to prepare a chitosan gel ink with a concentration of 5wt%. Mix 3 g of potassium-doped hydroxyapatite with deionized water, and use an ultrasonic cell disrupter to sonicate for 10-20 minutes to disperse evenly. Add the potassium-doped hydroxyapatite suspension droplets into the chitosan ink. The mass ratio of chitosan and potassium-doped hydroxyapatite is 2:3. Continue stirring for 3 hours to obtain the potassium-doped hydroxyapatite chitosan composite. ink. Use a DIW printer to print the composite gel ink. The printing process conditions are as follows: the diameter of the 3D printing extrusion head is 0.3mm, the printing layer height is 0.3mm, the printing speed is 30mm/s, and the printing air pressure is 400kPa. The obtained sample has high precision, as shown in Figure 2(a). After being placed for a period of time, the layers are clearly separated and still maintains high precision, as shown in Figure 2(b). Then freeze-drying is performed to obtain the potassium-doped hydroxyapatite/chitosan composite scaffold.

Example 3

Dissolve 2 g of chitosan in an acetic acid aqueous solution of 3 wt% (concentration of acetic acid) and stir using a magnetic stirrer at 60° C. and 800 rpm to prepare a chitosan acetic acid solution with a concentration of 5 wt%. Mix 6 g of potassium-doped hydroxyapatite with deionized water, and use an ultrasonic cell disrupter to sonicate for 10-20 minutes to disperse evenly. Add the potassium-doped hydroxyapatite suspension dropwise into the chitosan acetic acid solution. The mass ratio of chitosan to potassium-doped hydroxyapatite is 1:3. Continue stirring for 3 hours to obtain a uniformly mixed potassium-doped hydroxyapatite. Chitosan suspension. Use a DIW printer to print the composite gel ink. The printing process conditions are as follows: the diameter of the 3D printing extrusion head is 0.3mm, the printing layer height is 0.3mm, the printing speed is 30mm/s, and the printing air pressure is 400kPa. As shown in Figure 3, printing and molding cannot be achieved.

Example 4

Dissolve 2.0 g of chitosan in an acetic acid aqueous solution of 2 wt% (concentration of acetic acid) and stir using a magnetic stirrer at 60° C. and 800 rpm to prepare a chitosan acetic acid solution with a concentration of 5 wt%. Mix 4.0 g of potassium-doped hydroxyapatite with deionized water, and use an ultrasonic cell disrupter to sonicate for 10-20 minutes to disperse evenly. Add the potassium-doped hydroxyapatite suspension dropwise into the chitosan acetic acid solution. The mass ratio of chitosan and potassium-doped hydroxyapatite is 1:2. Continue stirring for 3 hours to obtain a uniformly mixed potassium-doped hydroxyapatite. Chitosan suspension. Use a DIW printer to print the composite gel ink. The printing process conditions are as follows: the diameter of the 3D printing extrusion head is 0.3mm, the printing layer height is 0.3mm, the printing speed is 30mm/s, and the printing air pressure is 350kPa. The obtained specimens were formed completely. Then freeze-drying is performed to obtain the potassium-doped hydroxyapatite/chitosan composite scaffold.

Example 5

2.0g chitosan was dissolved in 2wt% (concentration of acetic acid) acetic acid aqueous solution, and a magnetic stirrer was used to stir at 60℃ and 800rpm to prepare a chitosan acetic acid solution with a concentration of 5w%. 2.0g potassium-doped hydroxyapatite was mixed with deionized water and ultrasonicated for 10-20 minutes using an ultrasonic cell disruptor to make it evenly dispersed. The potassium-doped hydroxyapatite suspension was added dropwise to the chitosan acetic acid solution, and the mass ratio of chitosan to potassium-doped hydroxyapatite was 1:1. Stirring was continued for 5h to obtain a uniformly mixed potassium-doped hydroxyapatite chitosan suspension. The composite gel ink was printed using a DIW printer. The printing process conditions were that the diameter of the 3D printing extruder was 0.3mm, the printing layer height was 0.3mm, the printing speed was 30mm/s, and the printing pressure was 800kPa. The obtained sample was completely formed, the fluency was limited during the printing process, and the printed sample had high precision. Then freeze-dried to obtain a potassium-doped hydroxyapatite/chitosan composite scaffold.

Example 6

Dissolve 2 g of chitosan in an acetic acid aqueous solution of 3 wt% (concentration of acetic acid) and stir using a magnetic stirrer at 60° C. and 800 rpm to prepare a chitosan acetic acid solution with a concentration of 5 wt%. Mix 2.0g of potassium-free hydroxyapatite with deionized water, and use an ultrasonic cell disrupter to sonicate for 10-20 minutes to disperse evenly. Add the potassium-doped hydroxyapatite suspension dropwise into the chitosan acetic acid solution. The mass ratio of chitosan to non-potassium hydroxyapatite is 1:1. Continue stirring for 3 hours to obtain a uniformly mixed potassium-doped hydroxyapatite solution. Gray stone chitosan suspension. Use a DIW printer to print the composite gel ink. The printing process conditions are as follows: the diameter of the 3D printing extrusion head is 0.3mm, the printing layer height is 0.3mm, the printing speed is 30mm/s, and the printing air pressure is 400kPa. Some nodes of the printed sample will produce a certain degree of fusion, and the overall molding quality is acceptable, as shown in Figure 4(a). After forming, the sample collapsed and fused quickly, with poor accuracy, as shown in Figure 4(b).

Claims (10)

1. A high-precision interconnecting porous structure hydroxyapatite/chitosan composite scaffold room temperature one-step 3D printing forming method is characterized by comprising the following steps: preparing hydroxyapatite chitosan mixed slurry from potassium-doped hydroxyapatite powder and chitosan, extruding the hydroxyapatite chitosan mixed slurry at normal temperature, and performing 3D printing and self-solidifying forming to obtain the hydroxyapatite/chitosan scaffold material.

2. The 3D printing forming method of the high-precision interconnected porous structure hydroxyapatite/chitosan composite scaffold by a room temperature one-step method, which is characterized in that the hydroxyapatite chitosan mixed slurry is prepared from potassium-doped hydroxyapatite powder and chitosan, and specifically comprises the following steps: firstly, adding potassium-doped hydroxyapatite powder into deionized water for ultrasonic dispersion to form potassium-doped hydroxyapatite slurry; dissolving chitosan in an acetic acid solution to obtain a chitosan solution; adding the potassium-doped hydroxyapatite slurry into the chitosan solution drop by drop, and stirring in a magnetic stirrer with the temperature of 30-75 ℃ and the rotation speed of 600-1000 rpm to obtain the hydroxyapatite chitosan mixed slurry.

3. The 3D printing forming method of the high-precision interconnected porous structure hydroxyapatite/chitosan composite scaffold by a room temperature one-step method is characterized in that in the hydroxyapatite-chitosan mixed slurry, the mass ratio of chitosan to potassium-doped hydroxyapatite is 1:1 to 1:2.

4. the 3D printing forming method of the high-precision interconnected porous structure hydroxyapatite/chitosan composite scaffold by a room temperature one-step method, which is characterized in that the deacetylation degree of the chitosan is 80-95%; the mass concentration of chitosan in the chitosan solution is 1-8%, and the mass concentration of acetic acid is 2-6%.

5. The 3D printing forming method of the high-precision interconnected porous hydroxyapatite/chitosan composite scaffold according to claim 2, wherein the stirring time is 2.5-4.5 h.

6. The 3D printing forming method of the high-precision interconnected porous hydroxyapatite/chitosan composite scaffold according to any one of claims 1 to 5, wherein the diameter of an extrusion head of 3D printing is 0.2 to 1.2mm, the height of a printed layer is 0.1 to 0.6mm, the printing speed is 0.1 to 50mm/s, and the printing air pressure is 30 to 800kPa.

7. The 3D printing forming method of the high-precision interconnected porous hydroxyapatite/chitosan composite scaffold according to any one of claims 1 to 5, wherein the micro-morphology nano-scale of the potassium-doped hydroxyapatite powder is 20 to 100nm long and 5 to 10nm wide.

8. The high-precision interconnecting porous structure hydroxyapatite/chitosan composite scaffold room temperature one-step 3D printing forming method according to any one of claims 1 to 5, wherein the printing environment is room temperature, and the printing environment is placed on a printing substrate for 5 to 15 minutes after printing.

9. The 3D printing forming method of the high-precision interconnected porous hydroxyapatite/chitosan composite scaffold according to any one of claims 1 to 5, wherein the molar ratio of calcium+potassium to phosphorus in the potassium-doped hydroxyapatite powder is 5:3, a step of; the mass ratio of potassium in the potassium-doped hydroxyapatite powder is 10-25 wt% calculated by potassium oxide.

10. The 3D printing and forming method of the hydroxyapatite/chitosan composite scaffold with the high-precision interconnection porous structure according to claim 9, wherein the potassium salt is potassium carbonate or potassium sulfate or potassium hydroxide.