An antibacterial degradable calcium phosphate bone cement and a preparation method thereof

Abstract

The application belongs to the technical field of biological medical material production and preparation, and discloses an antibacterial degradable calcium phosphate bone cement and a preparation method thereof. The raw material of the bone cement comprises a solid-phase powder component and a curing liquid, 330-360 muL of the curing liquid is required for every 0.7 g of the solid-phase powder component; the solid-phase powder component comprises tetracalcium phosphate powder, anhydrous dicalcium phosphate powder and strontium-copper-doped beta-tricalcium phosphate powder, the molar ratio of the tetracalcium phosphate powder to the anhydrous dicalcium phosphate powder is 1:1, and the mass ratio of the sum of the mass of the tetracalcium phosphate powder and the mass of the anhydrous dicalcium phosphate powder to the mass of the strontium-copper-doped beta-tricalcium phosphate powder is (7-9):(1-3). The degradation rate of the bone cement is well matched with human bone, and the bone cement has the characteristics of good antibacterial property, good biocompatibility and good mechanical property, and the bone cement product will have good application prospect in the field of orthopedics.

Description

Technical Field

[0001] This invention belongs to the field of biomedical material production and preparation technology, specifically relating to an antibacterial and biodegradable calcium phosphate bone cement and its preparation method. Background Technology

[0002] Osteoporosis is one of the most common bone diseases, characterized by bone loss and destruction of bone microstructure, leading to increased bone fragility and fracture risk. Clinically, there is a huge demand for bone repair materials. Calcium phosphate cement (CPC) is one of the most promising injectable bone repair materials. The solid phase of CPC is composed of a mixture of one or more calcium phosphate salt powders, while the liquid phase is usually water or an aqueous solution. The CPC solid and liquid phases are mixed in a certain proportion to form a paste. This paste can be arbitrarily shaped and has certain mechanical properties, and it can undergo a curing reaction after implantation. It can be used to repair bone defects, but it has significant drawbacks in practical use, mainly including a degradation rate mismatch with human bone and a lack of antibacterial properties. Therefore, developing calcium phosphate cement with antibacterial properties and a controllable degradation rate is very important.

[0003] Chinese patent (application number: 202310966230.2, publication number: CN116870250A) discloses an antibacterial bone cement composed of three parts: powder, antibiotic, and liquid, and its preparation method. Antibiotics are incorporated into non-leaching furanyl bone cement through physical doping, developing a bifunctional antibacterial bone cement that combines both non-release and release antibacterial properties. However, bone cement with added antibiotics suffers from antibiotic toxicity, bacterial resistance, and its mechanical properties are affected. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide an antibacterial and biodegradable calcium phosphate bone cement and its preparation method. The degradation rate of the bone cement of the present invention matches human bone well, and it also has the characteristics of antibacterial properties, good biocompatibility, and good mechanical properties. This bone cement product will have good application prospects in the field of orthopedics.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An antibacterial and biodegradable calcium phosphate bone cement, the raw materials of which include a solid powder component and a curing liquid, wherein the solid-liquid ratio of the solid powder component to the curing liquid is 0.7 g:(330 μL~360 μL);

[0007] The solid-phase powder composition includes tetracalcium phosphate powder, anhydrous dicalcium phosphate powder, and strontium copper-doped β-tricalcium phosphate powder, wherein the molar ratio of tetracalcium phosphate powder to anhydrous dicalcium phosphate powder is 1:1, and the mass ratio of the sum of the mass of tetracalcium phosphate powder and anhydrous dicalcium phosphate powder to the mass of strontium copper-doped β-tricalcium phosphate powder is (7-9):(1-3).

[0008] Preferably, the particle size range of the tetracalcium phosphate powder is 0.1 μm to 100 μm.

[0009] Preferably, the particle size range of the anhydrous dicalcium phosphate powder is 0.2 μm to 10 μm.

[0010] Preferably, the particle size range of the strontium copper-doped β-tricalcium phosphate powder is 0.2 μm to 10 μm.

[0011] Preferably, the curing solution is an aqueous solution of phosphoric acid with a concentration of 0.5 to 1 mol / L.

[0012] More preferably, the concentration of the phosphoric acid aqueous solution is 0.75 mol / L.

[0013] Preferably, in the strontium-copper doped β-tricalcium phosphate powder, the molar amount of strontium (i.e., n(Sr)) accounts for 2% to 8% of the total molar amount of calcium, strontium and copper (i.e., n(Ca+Sr+Cu)).

[0014] Preferably, the molar amount of copper (i.e., n(Cu)) accounts for 2% to 8% of the total molar amount of calcium, strontium and copper (i.e., n(Ca+Sr+Cu)).

[0015] Preferably, the total molar amount of strontium and copper (i.e., n(Sr+Cu)) accounts for no more than 10% of the total molar amount of calcium, strontium and copper (i.e., n(Ca+Sr+Cu)).

[0016] The present invention provides a method for preparing antibacterial and biodegradable calcium phosphate bone cement as described above, comprising:

[0017] Solid powder components and curing liquid are mixed to form bone cement slurry;

[0018] The bone cement slurry is solidified to form the antibacterial and biodegradable calcium phosphate bone cement.

[0019] Preferably, when the bone cement slurry is cured:

[0020] The bone cement slurry is pre-cured in an environment of 36-37°C and 75%-100% relative humidity for 30 minutes to 2 hours to obtain a pre-cured molded body;

[0021] The pre-cured molded body is then subjected to final curing in the application environment of the antibacterial and biodegradable calcium phosphate bone cement.

[0022] The present invention has the following beneficial effects:

[0023] This invention relates to an antibacterial and biodegradable calcium phosphate bone cement, a strontium-copper ion-doped biphasic calcium phosphate bioactive bone cement. The invention utilizes strontium-copper-doped β-tricalcium phosphate powder, in which the strontium can stimulate bone formation and reduce bone resorption. For osteoblasts, strontium (Sr) promotes gene expression, thereby promoting the proliferation and differentiation of mesenchymal stem cells into osteoblasts, which in turn promote bone formation. For osteoclasts, strontium (Sr) promotes the expression of the osteoprotegerin (OPG) gene, increasing OPG content. OPG not only inhibits osteoclast differentiation and maturation but also accelerates osteoclast apoptosis, thus reducing bone resorption. The copper ions contained in the strontium-copper-doped β-tricalcium phosphate powder used in this invention can act as an angiogenic agent and an antibacterial agent. The antibacterial mechanism of copper ions mainly involves the following four aspects: ① Positively charged copper ions adsorb onto the negatively charged bacterial outer membrane through electrostatic interaction, disrupting the normal metabolism of bacteria and leading to metabolic disorders and death; ② Copper ions penetrate the cell membrane and enter the bacterial cavity, causing cytoplasmic extravasation and death; ③ Copper ions disrupt the respiratory chain, reducing energy production and thus affecting bacterial gene replication, leading to bacterial death; ④ Copper ions can generate reactive oxygen species (ROS), which kill bacteria through oxidative stress. Appropriate concentrations of copper ions can stimulate endothelial cell proliferation and differentiation, and by simulating hypoxia, stabilize the structure of hypoxia-inducible factors, upregulate the expression of angiogenesis-related factors such as vascular endothelial growth factor, promote angiogenesis, and thus promote osteogenic processes. Its biodegradation rate can be controlled not only by parameters such as the relative content of the two phases in the solidified product, the strontium / copper doping amount, and the strontium-copper / phosphorus molar ratio, but also by a higher rate than that of single-phase apatite bone cement, thus endowing bone cement with antibacterial and angiogenesis-inducing abilities while maintaining high mechanical properties. It can be seen that the antibacterial and biodegradable calcium phosphate bone cement of this invention has the characteristics of antibacterial properties and good biocompatibility. Experiments have shown that the antibacterial and biodegradable calcium phosphate bone cement of this invention has high and long-term stable mechanical properties, a suitable setting time, adjustable strontium / copper content and calcium-strontium-copper / phosphorus ratio, a controllable degradation rate, and the ability to slowly release strontium-copper ions that promote bone tissue regeneration, induce angiogenesis, and have antibacterial properties. Compared with traditional single-phase calcium phosphate bone cement containing antibiotics, it has significant advantages and is expected to achieve wider clinical application. Attached Figure Description

[0024] Figure 1 This is a sample image of the antibacterial biodegradable calcium phosphate bone cement obtained in Example 1 of the present invention after curing;

[0025] Figure 2 These are the XRD patterns of the samples obtained in Examples 1 to 3 of this invention after curing for 3 days;

[0026] Figure 3(a) is a microscopic morphology of the sample obtained in Example 1 of the present invention after curing for 3 days; Figure 3(b) is a microscopic morphology of the sample obtained in Example 2 of the present invention after curing for 3 days; Figure 3(c) is a microscopic morphology of the sample obtained in Example 3 of the present invention after curing for 3 days.

[0027] Figure 4 This is a schematic diagram of the in vitro degradation rate of the solidified samples obtained in Examples 1 to 3 and the comparative examples of the present invention;

[0028] Figure 5 This is a schematic diagram showing the release of strontium ions from samples obtained in Examples 1 to 3 of the present invention after soaking in phosphate buffer solution for different numbers of days;

[0029] Figure 6 This is a schematic diagram showing the amount of copper ions released from the samples obtained in Examples 1 to 3 of this invention after soaking in phosphate buffer solution for different numbers of days;

[0030] Figure 7 It is the compressive strength of the samples obtained in Examples 1 to 3 of this invention after curing for 3 days.

[0031] Figure 8 It is the compressive strength of the samples obtained in Examples 4 to 6 of this invention after curing for 3 days.

[0032] Figure 9 It is the compressive strength of the samples obtained in Examples 7 to 9 of this invention after curing for 3 days. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] This invention adds strontium- and copper-doped tricalcium phosphate to bone cement solid powder. By adjusting the amount of tricalcium phosphate added and the amount of ion doping, the degradation rate is controlled, ensuring that the bone cement has good biocompatibility while also having good antibacterial and osteoinductive properties.

[0035] The specific solution of this invention is as follows:

[0036] The raw materials of the antibacterial and biodegradable calcium phosphate bone cement of the present invention include solid powder components and curing liquid. The solid powder components include tetracalcium phosphate (TTCP) powder, anhydrous calcium hydrogen phosphate powder (DCPA) powder, and strontium copper doped β-tricalcium phosphate powder (denoted as (Sr / Cu)-β-TCP). The curing liquid is a dilute phosphoric acid aqueous solution with a concentration w of 0.5 to 1 mol / L.

[0037] In the above-described scheme of the present invention, the amount of dilute phosphoric acid aqueous solution required for curing each 0.7g solid powder component ranges from 330μL to 360μL. The particle size range of TTCP powder is 0.1μm to 100μm. The particle size range of DCPA powder is 0.2μm to 10μm. The particle size range of (Sr / Cu)-β-TCP powder is 0.2μm to 10μm. The molar ratio of TTCP to DCPA is 1:1. The mass ratio of the total mass of TTCP and DCPA powder to the mass of (Sr / Cu)-β-TCP powder is (7-9):(1-3). In the strontium-copper doped β-tricalcium phosphate powder, the strontium doping n(Sr) / n(Ca+Sr+Cu) is 2% to 8%, the copper doping n(Cu) / n(Ca+Sr+Cu) is 2% to 8%, and the total strontium and copper doping n(Sr+Cu) / n(Ca+Sr+Cu) does not exceed 10%. The raw material formulations of tricalcium phosphate with different strontium-copper contents are shown in Table 1.

[0038] Table 1

[0039]

[0040] The present invention provides a method for preparing antibacterial and biodegradable calcium phosphate bone cement as described above, comprising:

[0041] Solid powder components and curing liquid are mixed to form bone cement slurry;

[0042] The bone cement slurry is pre-cured in an environment of 36-37°C and 75%-100% relative humidity for 30 minutes to 2 hours to obtain a pre-cured molded body, which is then finally cured in the use environment to form the antibacterial and biodegradable calcium phosphate bone cement of the present invention.

[0043] Example 1:

[0044] The preparation method of antibacterial and biodegradable calcium phosphate bone cement in this embodiment includes the following steps:

[0045] (1) Mix the original solid powder, weigh TTCP and DCPA powder with a molar ratio of 1:1, mix them evenly and record it as TD, weigh TD powder with a mass ratio of 8:2 and 8Sr2Cu-TCP powder, mix them evenly as solid powder components.

[0046] (2) Weigh 0.7g of solid powder component and measure 340μL of 0.75M dilute phosphoric acid aqueous solution. Mix with a spatula for 30s to form a uniform bone cement slurry.

[0047] Example 2:

[0048] The preparation method of antibacterial and biodegradable calcium phosphate bone cement in this embodiment includes the following steps:

[0049] (1) Mix the original solid phase powder, weigh TTCP and DCPA powder with a molar ratio of 1:1, mix them evenly and record it as TD, weigh TD powder with a mass ratio of 8:2 and 5Sr5Cu-TCP powder, mix them evenly as solid phase powder components.

[0050] (2) Weigh 0.7g of solid powder component and measure 340μL of 0.75M dilute phosphoric acid aqueous solution. Mix with a spatula for 30s to form a uniform bone cement slurry.

[0051] Example 3:

[0052] The preparation method of antibacterial and biodegradable calcium phosphate bone cement in this embodiment includes the following steps:

[0053] (1) Mix the original solid phase powder, weigh TTCP and DCPA powder with a molar ratio of 1:1, mix them evenly and record it as TD, weigh TD powder with a mass ratio of 8:2 and 5Sr5Cu-TCP powder, mix them evenly as solid phase powder components.

[0054] (2) Weigh 0.7g of solid powder component and measure 350μL of 0.75M dilute phosphoric acid aqueous solution. Mix with a spatula for 30s to form a uniform bone cement slurry.

[0055] Example 4:

[0056] The preparation method of antibacterial and biodegradable calcium phosphate bone cement in this embodiment includes the following steps:

[0057] (1) Mix the original solid phase powder, weigh TTCP and DCPA powder with a molar ratio of 1:1, mix them evenly and record it as TD, weigh TD powder with a mass ratio of 9:1 and 8Sr2Cu-TCP powder, mix them evenly as solid phase powder components.

[0058] (2) Weigh 0.7g of solid powder component and measure 330μL of 1M dilute phosphoric acid aqueous solution. Mix with a spatula for 30s to form a uniform bone cement slurry.

[0059] Example 5:

[0060] The preparation method of antibacterial and biodegradable calcium phosphate bone cement in this embodiment includes the following steps:

[0061] (1) Mix the original solid phase powder, weigh TTCP and DCPA powder with a molar ratio of 1:1, mix them evenly and record it as TD, weigh TD powder with a mass ratio of 9:1 and 5Sr5Cu-TCP powder, mix them evenly as solid phase powder components.

[0062] (2) Weigh 0.7g of solid powder component and measure 330μL of 1M dilute phosphoric acid aqueous solution. Mix with a spatula for 30s to form a uniform bone cement slurry.

[0063] Example 6:

[0064] The preparation method of antibacterial and biodegradable calcium phosphate bone cement in this embodiment includes the following steps:

[0065] (1) Mix the original solid phase powder, weigh TTCP and DCPA powder with a molar ratio of 1:1, mix them evenly and record it as TD, weigh TD powder with a mass ratio of 9:1 and 2Sr8Cu-TCP powder, mix them evenly as solid phase powder components.

[0066] (1) Weigh 0.7g of solid powder component and measure 330μL of 1M dilute phosphoric acid aqueous solution. Mix with a spatula for 30s to form a uniform bone cement slurry.

[0067] Example 7:

[0068] The preparation method of antibacterial and biodegradable calcium phosphate bone cement in this embodiment includes the following steps:

[0069] (1) Mix the original solid phase powder, weigh TTCP and DCPA powder with a molar ratio of 1:1, mix them evenly and record them as TD, weigh TD powder with a mass ratio of 7:3 and 8Sr2Cu-TCP powder, mix them evenly as solid phase powder components.

[0070] (2) Weigh 0.7g of solid powder component and measure 360μL of 0.5M dilute phosphoric acid aqueous solution. Mix with a spatula for 30s to form a uniform bone cement slurry.

[0071] Example 8:

[0072] The preparation method of antibacterial and biodegradable calcium phosphate bone cement in this embodiment includes the following steps:

[0073] (1) Mix the original solid phase powder, weigh TTCP and DCPA powder with a molar ratio of 1:1, mix them evenly and record them as TD, weigh TD powder with a mass ratio of 7:3 and 5Sr5Cu-TCP powder, mix them evenly as solid phase powder components.

[0074] (2) Weigh 0.7g of solid powder component and measure 360μL of 0.5M dilute phosphoric acid aqueous solution. Mix with a spatula for 30s to form a uniform bone cement slurry.

[0075] Example 9:

[0076] The preparation method of antibacterial and biodegradable calcium phosphate bone cement in this embodiment includes the following steps:

[0077] (1) Mix the original solid phase powder, weigh TTCP and DCPA powder with a molar ratio of 1:1, mix them evenly and record it as TD, weigh TD powder with a mass ratio of 7:3 and 2Sr8Cu-TCP powder, mix them evenly as solid phase powder components.

[0078] (2) Weigh 0.7g of solid powder component and measure 360μL of 0.5M dilute phosphoric acid aqueous solution. Mix with a spatula for 30s to form a uniform bone cement slurry.

[0079] Comparative Example

[0080] The comparative method for preparing bone cement includes the following steps:

[0081] (1) Mix the original solid phase powder, weigh TTCP and DCPA powder with a molar ratio of 1:1, mix them evenly and record it as TD, weigh TD powder with a mass ratio of 8:2 and β-TCP powder, mix them evenly as solid phase powder components.

[0082] (2) Weigh 0.7g of solid powder and measure 330μL of 0.75M dilute phosphoric acid aqueous solution. Mix with a spatula for 30s to form a uniform bone cement slurry.

[0083] The bone cement slurries from Examples 1 to 9 and the comparative example were filled into stainless steel cylindrical molds with a diameter of 6 mm and a height of 12 mm, respectively, and compacted under a pressure of 2 kg. The resulting cylindrical samples were then inserted into glass tubes with a diameter of 6.5 mm and a height of 13 mm, and placed in an environment with a temperature of 36–37 °C and a relative humidity of 100% for curing. After pre-curing for 30 min, the samples were removed and quickly immersed in SBF simulated body fluid for further curing. The physicochemical properties and in vitro degradation experiments of these four types of bone cement were then performed.

[0084] According to the present invention and specific embodiments, the effects are illustrated in the figures:

[0085] Figure 1 The diagram shows the sample obtained after curing in Example 1. It can be seen that the cured sample is intact, with a smooth surface and no damage, indicating that the bone cement of the present invention has good mechanical strength. Figure 2 The X-ray diffraction pattern after curing for 3 days was obtained from... Figure 2 It can be seen that the solidified products are mainly two phases: tricalcium phosphate and hydroxyapatite. Figures 3(a) to 3(c) The SEM image of the solidified product shows the formation of hydroxyapatite.

[0086] To evaluate the in vitro degradation of composite bone cement, cured cylindrical samples were dried, weighed, and the initial weight was recorded as m0. These samples were then immersed in phosphate buffered saline (PBS, pH = 7.40), with the surface area of ​​the sample to the volume of the degradation solution being 0.2 g / mL. Centrifuge tubes containing the sample and degradation solution were placed in an oven at 37°C. Samples were removed weekly for a total of four weeks. Samples were thoroughly washed with deionized water and ethanol and dried before collection. The PBS solution was replaced weekly. The degradation rate was assessed by measuring the mass change at different immersion times. Specifically, samples were removed from the solution and dried to constant weight in a vacuum oven at 65°C. The formula for calculating the weight loss rate of the material in PBS is as follows: where m0 is the original weight of the sample, m... t This refers to the mass after degradation. Each sample group should be tested at least 3 times.

[0087]

[0088] like Figure 4 The diagram shows the in vitro degradation rates of the examples and comparative examples. It can be seen from the figure that ion doping can effectively improve the degradation rate of cement. To further investigate the release behavior of ions in the composite cement, inductively coupled plasma atomic emission spectrometry (ICP) was used to detect the release of strontium and copper ions from bone cement in PBS degradation solution. Figure 5 and Figure 6 The figure shows the cumulative release of strontium and copper ions. It can be seen that as the number of soaking days increases, the cumulative release of ions increases linearly and can be sustained.

[0089] Figure 7 The compressive strength of the sample after 3 days of curing was 36-45 MPa, indicating that the bone cement has good compressive strength. Figure 8 The compressive strength of the samples from Examples 4 to 6 after three days of curing is 28-35 MPa. Figure 9 The compressive strength of the samples from Examples 7 to 9 after three days of curing ranges from 26 to 33 MPa, indicating that all samples possess a certain strength.

[0090] As can be seen from the above scheme, the antibacterial and biodegradable bioactive bone cement raw material system prepared by this invention is simple, consisting only of three-phase powder. The ion content can be controlled, the degradation rate is manageable, and it can slowly release special pharmacological strontium and copper ions without toxic side effects. While maintaining the strength of cement, it possesses degradability, and the dual bioactive ion stimulation accelerates early angiogenesis and bone regeneration, giving CPC antibacterial properties and promising applications in the clinical treatment of bone defects.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An antibacterial and biodegradable calcium phosphate bone cement, characterized in that, Its raw materials include solid powder components and curing liquid, with a solid-liquid ratio of 0.7g:(330μL~360μL). The solid powder component includes tetracalcium phosphate powder, anhydrous dicalcium phosphate powder, and strontium copper-doped β-tricalcium phosphate powder, wherein the molar ratio of tetracalcium phosphate powder to anhydrous dicalcium phosphate powder is 1:1, and the mass ratio of the sum of the mass of tetracalcium phosphate powder and anhydrous dicalcium phosphate powder to the mass of strontium copper-doped β-tricalcium phosphate powder is (7-9):(1-3). In strontium-copper doped β-tricalcium phosphate powder, the molar amount of strontium accounts for 2% to 8% of the total molar amount of calcium, strontium, and copper; In strontium-copper doped β-tricalcium phosphate powder, the molar amount of copper accounts for 2% to 8% of the total molar amount of calcium, strontium, and copper. In strontium-copper doped β-tricalcium phosphate powder, the total molar amount of strontium and copper accounts for no more than 10% of the total molar amount of calcium, strontium, and copper. The curing solution is a phosphoric acid aqueous solution with a concentration of 0.5 to 1 mol / L.

2. The antibacterial and biodegradable calcium phosphate bone cement according to claim 1, characterized in that, The particle size range of the tetracalcium phosphate powder is 0.1 μm to 100 μm.

3. The antibacterial and biodegradable calcium phosphate bone cement according to claim 1, characterized in that, The particle size range of the anhydrous calcium hydrogen phosphate powder is 0.2 μm to 10 μm.

4. The antibacterial and biodegradable calcium phosphate bone cement according to claim 1, characterized in that, The particle size range of strontium copper-doped β-tricalcium phosphate powder is 0.2 μm to 10 μm.

5. The method for preparing antibacterial biodegradable calcium phosphate bone cement according to any one of claims 1-4, characterized in that, include: Solid powder components and curing liquid are mixed to form bone cement slurry; The bone cement slurry is solidified to form the antibacterial and biodegradable calcium phosphate bone cement.

6. The method for preparing antibacterial biodegradable calcium phosphate bone cement according to claim 5, characterized in that, When the bone cement slurry is cured: The bone cement slurry is pre-cured in an environment of 36-37°C and 75%-100% relative humidity for 30 minutes to 2 hours to obtain a pre-cured molded body; The pre-cured molded body is then subjected to final curing in the application environment of the antibacterial and biodegradable calcium phosphate bone cement.

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