Drug-loaded bone implant and preparation method thereof

Abstract

The invention belongs to the field of bone implants, and relates to a drug-loaded bone implant and a preparation method thereof. The bone implant disclosed by the invention is composed of a porous scaffold and medicine-containing hydrogel, wherein the porous scaffold is formed by 3D printing of polylactic acid; the medicine-containing hydrogel is prepared from diclofenac sodium, sodium alginate, calcium carbonate, gluconolactone and water. The porous scaffold provided by the invention not only provides mechanical support for a bone defect part, but also can fix the medicine-containing hydrogel so that the medicine-containing hydrogel plays a role; and the mechanical strength, the drug loading capacity and the drug release behavior can be adjusted by changing the column spacing. Meanwhile, the water-containing hydrogel disclosed by the invention can be uniformly injected into the porous scaffold and can be quickly solidified, and additional physical and chemical crosslinking is not needed. According to the drug-loaded bone implant and the preparation method thereof provided by the invention, in the whole diagnosis, design, preparation and use processes, the requirements of personalized implantation and medication in the orthopedics department are met, on-demand anti-inflammatory analgesia after operation can be realized, and the drug-loaded bone implant has a wide market application prospect.

Description

Technical Field

[0001] The invention belongs to the field of bone implants, and in particular relates to a drug-loaded bone implant and a preparation method thereof. Technical Background

[0002] Bone implants are important supporting materials for repairing bone defects. Combining injectable hydrogels with bone implants to prepare drug-containing bone implants can slowly release drugs at the implant site to achieve local therapeutic effects. Existing research mainly focuses on tissue engineering scaffolds of universal form or bone implants of personalized form. Their mechanical strength cannot be adjusted individually, and their biomechanical performance after implantation is difficult to fully match the surrounding tissues of the defect site; their drug release behavior cannot be adjusted individually, and their drug release behavior after implantation is difficult to meet the personalized needs of local treatment (for example: anti-inflammatory and analgesic on demand after surgery).

[0003] Comparative Literature 1 (Polyethylene glycol diacrylate scaffold filled with cell-laden methacrylamide gelatin / alginate hydrogels used for cartilage repair) adds cells to the GelMA / Alginate hydrogel solution and drips it into the 3D printed mesh scaffold. Through UV light curing cross-linking and CaCl2 solution ion cross-linking, a stable double-cross-linked mesh hydrogel is formed for implantation. However, the 3D printed mesh scaffold in the literature is a general regular shape (cylinder). After the hydrogel solution is dripped into the mesh scaffold, it cannot be formed immediately. Additional physical / chemical cross-linking (UV light curing cross-linking and CaCl2 solution ion cross-linking) is required. The process is complicated and difficult to operate clinically. Moreover, the scaffold is not drug-loaded and does not have the function of personalized regulation of drug release.

[0004] Reference 2 (3D printed calcium phosphate scaffolds with controlled release of osteogenic drugs for bone regeneration) uses a mixture of hydroxyapatite, sodium alginate and icariin, extrudes a 3D printed scaffold, and soaks it in a calcium solution for ion cross-linking. The 3D extrusion-printed scaffold can slowly release icariin, and the drug release behavior can be regulated by adjusting the internal pore structure of the scaffold. However, the scaffold is based on sodium alginate cross-linking, and the overall mechanical strength is low. The scaffold completely swells and dissolves within 1 week, which cannot meet the biomechanical requirements of implantation in bone defects.

[0005] In contrast, Patent 1 (CN1586621A injectable gel-type bone repair bioactive material and its preparation method) uses sodium alginate as the main component, carries bone morphogenetic protein and gluconolactone, and the release behavior of the active ingredients is adjustable. However, the patent discloses an injectable hydrogel with low mechanical strength and cannot be used for bone defect implantation; and the formula disclosed in the patent does not contain specific drugs, and there is no technical inspiration for the development of drug-loaded implants, the regulation of drug release behavior, and the use of postoperative anti-inflammatory analgesia.

[0006] The present invention adds diclofenac sodium to an injectable hydrogel and fills it in the pores of a 3D-printed personalized bone implant to prepare a drug-loaded bone implant with adjustable surface morphology, biomechanical behavior and drug release behavior. Combined with ultrasound, drug release can be controlled to achieve the effects of bone defect implantation and postoperative anti-inflammatory and analgesic effects. Summary of the invention

[0007] Based on the above technical problems, the present invention provides a bone implant loaded with diclofenac sodium and a preparation method thereof, which has the advantages of adjustable surface morphology, mechanical strength, drug loading and drug release behavior, and is used for bone defect implantation and postoperative anti-inflammatory analgesia.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] Provided is a drug-loaded bone implant, the bone implant is composed of a porous scaffold and a drug-containing hydrogel, the porous scaffold is 3D printed from polylactic acid, the printed model is composed of a cross-section of 1.0×1.0mm rectangular long columns, and the column spacing of each layer is 0.50-1.25mm; the drug-containing hydrogel is composed of diclofenac sodium, sodium alginate, calcium carbonate, gluconolactone and water. By adopting the above-mentioned technical scheme, the porous scaffold of the present invention forms a porous internal structure by adjusting the column spacing, which not only provides mechanical support for the bone defect site, but also can fix the drug-containing hydrogel to make it work; and the mechanical strength, drug loading and drug release behavior can be adjusted by changing the column spacing. At the same time, the drug-containing hydrogel formula disclosed in the present invention can delay solidification into gel, so it can be evenly injected into the porous scaffold, and there is no need to solidify through physical and chemical cross-linking after injection, and it has excellent mechanical properties, which is convenient for clinical use.

[0010] Preferably, the drug-containing hydrogel is made of 0.5-5 parts of diclofenac sodium, 1.5-2.5 parts of sodium alginate, 0.2-1 parts of calcium carbonate, 1-3 parts of gluconolactone, and 100 parts of water in parts by weight.

[0011] Preferably, the drug-containing hydrogel is made of 1-2 parts of diclofenac sodium, 2 parts of sodium alginate, 0.5 parts of calcium carbonate, 1.8 parts of gluconolactone, and 100 parts of water in parts by weight.

[0012] The present invention also provides a method for preparing a drug-loaded bone implant, which specifically comprises the following steps:

[0013] S1: Printing porous scaffolds based on 3D printing technology: Design a three-dimensional model of a porous scaffold with a general shape or a bionic surface shape. The interior of the model is constructed by cross-sections of 1.0×1.0mm rectangular long columns, and the column spacing of each layer of the model is 0.50-1.50mm; use polylactic acid as the printing material to 3D print the porous scaffold;

[0014] S2: Sodium alginate is added into water to swell, and then diclofenac sodium is added and mixed evenly; before use, calcium carbonate and gluconolactone are added, and the mixture is quickly mixed to prepare a drug-containing hydrogel, and the prepared drug-containing hydrogel is quickly injected into a porous scaffold to prepare a drug-loaded bone implant.

[0015] Preferably, in step S1, a three-dimensional model of a porous scaffold is designed based on the morphology and strength of defective bone tissue.

[0016] Preferably, in step S1, the column spacing is 0.10-1.25 mm.

[0017] Preferably, the 3D printing method in step S1 is fused deposition modeling, and the 3D printing parameters are layer height 0.10-0.20 mm, printing temperature 190-210° C., and printing speed 40-60 mm / s. More preferably, the layer height is 0.15 mm, which can further ensure printing accuracy at a faster printing speed.

[0018] Preferably, the total time for the rapid mixing preparation and rapid injection of the drug-containing hydrogel in step S2 should be controlled within 7.5 minutes, more preferably within 5 minutes. When the total time is 7.5 minutes, the fluidity of the gel begins to decrease, and the injection speed and pore distribution ability also begin to decrease. When the time exceeds 7.5 minutes, for example, 10 minutes, the extrudate is difficult to extrude continuously, indicating that the gel has begun to solidify and the solidified gel begins to block the syringe needle. Accordingly, the gel is also difficult to flow between the internal pores and cannot be evenly and quickly distributed.

[0019] Preferably, the drug-loaded bone implant is filled into the bone defect site for use. When it is necessary to increase the anti-inflammatory and analgesic effect, the drug release rate is increased by applying ultrasound. More preferably, the ultrasound intensity is 0.5-1.0 W / cm 2 , time 30s-60s, 3-5 times, interval 60s.

[0020] Compared with the prior art, the drug-loaded bone implant and the preparation method thereof provided by the present invention have the following beneficial effects:

[0021] 1) Based on the morphology and strength of defective bone tissue, a porous scaffold with bionic surface morphology and suitable internal structure is prepared for loading injectable hydrogel, which can achieve the bionic surface morphology and mechanical strength of drug-loaded bone implants.

[0022] The structure of the present invention is constructed by cross-building rectangular long columns (6 layers of 3D printing are required for a height of 1 mm), and has the following advantages: 1) The axial solid volume is large and has strong axial compressive resistance. 2) The internal channels are connected and of appropriate size, and the drug-loaded hydrogel can be solidified after injection filling to obtain a gel with an appropriate specific surface area, preventing the drug from being released too quickly or too slowly.

[0023] The porous scaffold of the present invention forms a porous internal structure by adjusting the column spacing, which not only provides mechanical support for the bone defect site, but also fixes the drug-containing hydrogel. The mechanical strength, drug loading and drug release behavior can be adjusted by changing the column spacing.

[0024] 2) Calcium carbonate and gluconolactone are added to the drug-containing hydrogel solution before use to prepare an injectable drug-loaded hydrogel with delayed solidification properties, which can be directly injected into the porous scaffold before clinical use and automatically solidified. Therefore, the formula disclosed in the present invention does not need to be solidified by physical and chemical cross-linking after injection, which is convenient for clinical use.

[0025] 3) The drug-loaded bone implant has an appropriate drug release rate to prevent excessive drug release, which may result in a short-lasting anti-inflammatory and analgesic effect; to prevent excessive drug release, which may result in a lack of obvious anti-inflammatory and analgesic effect; at the same time, ultrasound can be further applied according to the requirements of postoperative anti-inflammatory and analgesic, which can accelerate drug release and achieve on-demand drug delivery.

[0026] In summary, the drug-loaded bone implant and preparation method thereof provided by the present invention realize the needs of personalized orthopedic implantation and medication throughout the entire diagnosis, design, preparation and use process, can achieve on-demand anti-inflammatory and analgesic effects after surgery, and have broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of (a) preparation process, (b) model and (c) in vitro release of diclofenac sodium bone implant in generic form;

[0028] Figure 2 The figure shows the effect of ultrasound on the in vitro drug release behavior of generic diclofenac sodium bone implants;

[0029] Figure 3 Schematic diagram of the design of the bionic surface morphology porous scaffold (a) appearance and (b) internal column spacing;

[0030] Figure 4 (a) Extrudability and (b) time-extrusion amount curves of injectable blank hydrogel at different times;

[0031] Figure 5 Effect of scaffold column spacing on the (a) appearance, (b) maximum filling content, and (c) mechanical properties of a general morphological porous scaffold.

[0032] Figure 6 This figure shows the effect of the spacing between stent columns on the drug release behavior of diclofenac sodium bone implants with bionic surface morphology. DETAILED DESCRIPTION

[0033] In order to better clarify and understand the purpose, process scheme and advantages of the present invention, the technical scheme and implementation method of the present invention are further described clearly, completely and in detail through specific examples and in combination with the accompanying drawings. It should be noted that the embodiments described in the present invention are implemented on the premise of the technical scheme of the present invention, and detailed implementation methods and specific operating processes are given, but they are only part of the embodiments of the present invention, not all of the embodiments. The specific implementation methods described are limited to explaining and interpreting the present invention, and do not limit the present invention. Based on the embodiments in the present invention, all other implementation methods obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] The experimental methods and conditions used in the embodiments of the present invention are conventional methods and conventional conditions unless otherwise specified. The materials, reagents or instruments used in the embodiments, unless otherwise specified, can be obtained from commercial sources or prepared by conventional methods. The reaction conditions embodied in the content of the invention of the present invention can achieve the reaction and obtain the product of the expected effect. Due to space limitations, some embodiments are listed below to further illustrate the advantages of the technical solution of the present invention.

[0035] Example 1: General form of diclofenac sodium bone implant and preparation method thereof

[0036] The preparation process of diclofenac sodium bone implant in generic form is as follows Figure 1 The general porous scaffold is constructed by cross-sectioning rectangular columns with a cross section of 1.0×1.0 mm. The column spacing of each layer of rectangular columns is 1.00 mm. The cylindrical space with a diameter of 10 mm and a height of 6 mm is further cut to form a three-dimensional model of the porous scaffold (the top view and side view of the model are shown in FIG. Figure 1 b). Set the layer height to 0.15 mm and generate a slice model. Use polylactic acid printing filament as the material, print at 200 °C, and print at 50.0 mm / s to prepare a porous scaffold.

[0037] 1g of diclofenac sodium, 2g of sodium alginate and 100g of water were mixed evenly to prepare a diclofenac sodium hydrogel solution containing 1% of the drug. Before use, 10mL of the drug-loaded hydrogel solution was taken, 0.05g of calcium carbonate and 0.18g of gluconolactone were added, and the solution was stirred for 1min to make the system uniform, and then injected and filled into the general-shaped porous scaffold within 4min (the filling volume was controlled to be 0.15mL / piece) to prepare a general-shaped diclofenac sodium bone implant.

[0038] The diclofenac sodium bone implant was placed in a release mold of a six-well plate, and 4 mL of pH 7.4 PBS was added to the upper surface to conduct in vitro release evaluation ( Figure 1 c). All release media were taken out at regular intervals and the solution was replenished. The absorbance of the filtrate was measured at 278 nm. According to the standard curve (y = 0.035x + 0.0077, R 2 =0.9997) to calculate the drug concentration and draw a time-drug cumulative release percentage curve. Apply ultrasound at regular intervals (each time with an intensity of 0.5-1.0 W / cm 2 , time 60s, 3 times, interval 60s), to study the effect of ultrasound on drug release behavior. Figure 2 As shown in the figure, diclofenac sodium bone implants release drugs uniformly and slowly, with a release percentage of 26% in 8 hours. Ultrasound was applied to diclofenac sodium bone implants, and each ultrasound could significantly promote drug release, with a release percentage of 42.2% in 8 hours.

[0039] Example 2: Bionic surface morphology of diclofenac sodium bone implant and preparation method thereof

[0040] Design of bionic surface morphology porous scaffold appearance ( Figure 3 a), the interior of the model is constructed by cross-section 1.0×1.0mm rectangular columns, and the column spacing of each layer of rectangular columns is designed to be 0.50mm, 0.75mm, 1.00mm and 1.25mm respectively ( Figure 3 b). Further cut out the part of the volume of the specific bone defect cavity as a three-dimensional model of the porous scaffold. Set the layer height to 0.15mm to generate a slice model. Using polylactic acid printing filament as the material, the printing temperature is 200℃, and the printing speed is 50.0mm / s to prepare a porous scaffold with a bionic surface morphology. Add 2g of diclofenac sodium to 100mL of 2% sodium alginate aqueous solution, mix well, and prepare a diclofenac sodium hydrogel solution with a drug content of 2%. When used, take 10mL of the drug-loaded hydrogel solution, add 0.05g of calcium carbonate and 0.20g of gluconolactone, stir for 0.5min to make the system uniform, and then inject and fill it into the porous scaffold with different column spacing within 3.5min (to the maximum filling amount) to obtain a diclofenac sodium bone implant with a bionic surface morphology.

[0041] Weigh accurately and record the weight change of bone implants to obtain the maximum filling amount of porous scaffolds with different column spacings; calculate the corresponding maximum drug loading according to the drug content of 2%. The results show that the maximum drug loading of diclofenac sodium bone implants is affected by the column spacing inside the porous scaffold. When the column spacing increases from 0.5mm to 1.75mm, the maximum drug loading increases from 160mg to 210mg.

[0042] Comparative study:

[0043] (1) Effects of cross-linking agent and operation time on the extrudability of injectable hydrogels

[0044] Before use, take 10 mL of 2% sodium alginate aqueous solution, add 0.05 g of calcium carbonate and 0.18 g of gluconolactone to prepare an injectable blank hydrogel (drug content is 0%). Use a 0.8 mm inner diameter needle and 20 N force to extrude. The time-extruded performance of the injectable blank hydrogel and the time-extrusion amount curve are shown in Figure 2. Figure 4 As shown in the figure, the hydrogel has good extrudability within 7.5 minutes, and the extrudability deteriorates significantly after 7.5 minutes. The results show that the injectable hydrogel has delayed curing characteristics and needs to be prepared before use and injected quickly. To ensure stable injectability, the optimized operation time should be controlled within 7.5 minutes, preferably within 5 minutes.

[0045] Take 10mL of 2% sodium alginate aqueous solution before use, add different crosslinking agents and mix quickly. Use a needle with an inner diameter of 0.8mm and extrude with a force of 20N. Study the effects of the type and amount of crosslinking agent on delayed coagulation and gel quality. The results are shown in Table 1: The type and amount of crosslinking agent not only affect the extrusion operation, but also the quality of the formed gel. When using Rx1 crosslinker, the operating time is the longest and the gel quality is good.

[0046] Table 1 Effect of crosslinking agent type and dosage on delayed coagulation of gel

[0047]

[0048]

[0049] (2) Effect of column spacing on the appearance, maximum filling volume and mechanical strength of porous scaffolds

[0050] The diclofenac sodium hydrogel solution containing 1% of the drug content in Example 1 was directly filled into a cylindrical female mold with a diameter of 10 mm and a height of 6 mm, and was allowed to stand in a 2% calcium chloride solution for 60 minutes to solidify, thereby obtaining a cylindrical drug-loaded gel block without a porous scaffold. The axial compressive resistance was determined using a universal testing machine, and the flat probe was pressed down at a speed of 0.5 mm / s to record the compression force-displacement data. The stress-strain was calculated, and the stress-strain curve was drawn. The inflection point on the curve was recorded as the compressive strength. The experiment showed that the cylindrical drug-loaded gel block without a porous scaffold was easily broken by axial force and had poor axial compressive resistance (compressive strength <0.5Mpa).

[0051] Referring to the method of Example 1, a general-purpose porous scaffold with column spacing of 0.50 mm, 0.75 mm, 1.00 mm and 1.25 mm was designed. A general-purpose diclofenac sodium bone implant was prepared, and the effect of column spacing on the appearance, maximum filling amount and mechanical strength of the porous scaffold was studied. Figure 5 As shown in the figure, the column spacing of the common porous scaffold increases from 0.5mm to 1.25mm, the maximum filling amount increases from 0.11g to 0.19g, and the compressive strength decreases from 25.5MPa to 10.8MPa. The present invention fills the hydrogel into the porous scaffold, and the compressive strength is >10Mpa, which is significantly greater than the cylindrical drug-loaded gel without a porous scaffold (<0.5Mpa).

[0052] (3) Effect of column spacing on drug release behavior of porous scaffolds

[0053] The diclofenac sodium bone implant with biomimetic surface morphology was prepared according to the method of Example 2, and its in vitro release was evaluated according to the method of Example 1. Figure 6 As shown in Figure 2, as the distance between the pillars increases from 0.50 mm to 1.25 mm, the drug release is accelerated. The cumulative release amount in 7 days increases from 38.3% to 70.9%.

[0054] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment according to the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A drug-loaded bone implant, characterized in that: The bone implant consists of a porous scaffold and a drug-containing hydrogel. The porous scaffold is 3D-printed from polylactic acid. The printed model is composed of a cross-structured rectangular long column with a cross-section of 1.0×1.0 mm, and the column spacing of each layer is 0.50-1.25 mm. The drug-containing hydrogel consists of diclofenac sodium, sodium alginate, calcium carbonate, gluconolactone and water.

2. The drug-loaded bone implant according to claim 1, characterized in that: The drug-containing hydrogel is prepared from 0.5-5 parts of diclofenac sodium, 1.5-2.5 parts of sodium alginate, 0.2-1 parts of calcium carbonate, 1-3 parts of gluconolactone and 100 parts of water in parts by weight.

3. The drug-loaded bone implant according to claim 2, characterized in that: The drug-containing hydrogel is prepared from 1-2 parts of diclofenac sodium, 2 parts of sodium alginate, 0.5 parts of calcium carbonate, 1.8 parts of gluconolactone and 100 parts of water in parts by weight.

4. A method for preparing the drug-loaded bone implant according to any one of claims 1 to 3, characterized in that: The steps include: S1: Printing porous scaffolds based on 3D printing technology: Design a three-dimensional model of a porous scaffold with a general shape or a bionic surface shape. The interior of the model is constructed by cross-sections of 1.0×1.0mm rectangular long columns, and the column spacing of each layer of the model is 0.50-1.50mm; use polylactic acid as the printing material to 3D print the porous scaffold; S2: Sodium alginate is added into water to swell, and then diclofenac sodium is added and mixed evenly; before use, calcium carbonate and gluconolactone are added, and the mixture is quickly mixed to prepare a drug-containing hydrogel, and the prepared drug-containing hydrogel is quickly injected into a porous scaffold to prepare a drug-loaded bone implant.

5. The method for preparing the drug-loaded bone implant according to claim 4, characterized in that: In step S1, the column spacing is 0.10-1.25 mm.

6. The method for preparing the drug-loaded bone implant according to claim 4, characterized in that: The 3D printing method in step S1 is fused deposition modeling, and the 3D printing parameters are layer height 0.10-0.20 mm, printing temperature 190-210° C., and printing speed 40-60 mm / s.

7. The method for preparing the drug-loaded bone implant according to claim 6, characterized in that: The layer height is 0.15 mm.

8. The method for preparing the drug-loaded bone implant according to claim 4, characterized in that: The total time for the rapid mixing preparation and rapid injection of the drug-containing hydrogel in step S2 is controlled within 7.5 minutes.

9. The method for preparing the drug-loaded bone implant according to claim 8, characterized in that: The total time for the rapid mixing preparation and rapid injection of the drug-containing hydrogel in step S2 is controlled within 5 minutes.

10. The method for preparing the drug-loaded bone implant according to claim 4, characterized in that: The drug-loaded bone implant is used to fill the bone defect. When the anti-inflammatory and analgesic effect needs to be enhanced, the drug release rate is increased by applying ultrasound with an ultrasound intensity of 0.5-1.0W / cm 2 , time 30s-60s, 3-5 times, interval 60s.

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