An isobornyl acrylate modified antibacterial bone cement

Abstract

The application belongs to the field of biomedical materials, and discloses a isobornyl acrylate modified antibacterial bone cement. The application uses isobornyl acrylate (BA) as a new monomer for liquid phase modification of bone cement, finally prepares a BA modified antibacterial bone cement (BA bone cement), which is a new type of antibacterial NLBC, and has good antibacterial activity, compressive strength and biocompatibility. The excellent performance indicates that the BA bone cement has a broad prospect in clinical application.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of biomedical materials, in particular to a isobornyl acrylate modified antibacterial bone cement. BACKGROUND

[0002] As a commonly used biomedical material, polymethyl methacrylate (PMMA) bone cement is widely used in surgical procedures such as joint replacement and vertebroplasty. However, its insufficient antibacterial activity has been a major concern. Staphylococcus aureus is the most common pathogenic bacteria in orthopedics, which can lead to postoperative infection, delayed healing and even surgical failure, seriously affecting the prognosis and quality of life of patients. To address this serious challenge, the traditional improvement method is to mix antibiotics into bone cement to make antibiotic-loaded bone cement (ALBC). Since Buchholz first added antibiotics to bone cement in 1969, research on antibiotic-loaded bone cement (ALBC) has attracted widespread attention. However, this method has problems such as antibiotic burst release and bacterial resistance, limiting its further use in clinical applications. Against this background, the development of new antibacterial bone cement has become one of the hotspots in the field of orthopedics.

[0003] Non-leaching antibacterial bone cement (NLBC) fixes groups with antibacterial activity on bone cement through covalent bonding or physical adsorption, thereby preparing modified bone cement with long-term antibacterial activity and good contact-killing activity. However, there is currently no NLBC that is good in antibacterial activity, mechanical strength and biocompatibility, and usually needs to make compromises in other aspects to prioritize certain performance, limiting the further research and application of NLBC. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art and provide an isobornyl acrylate modified antibacterial bone cement. The present application uses isobornyl acrylate (BA) as a new monomer for liquid-phase modification of bone cement, ultimately preparing a BA modified antibacterial bone cement (BA bone cement), which is a new type of antibacterial NLBC with good antibacterial activity, compressive strength and biocompatibility. Its excellent performance indicates that it has broad prospects in clinical applications.

[0005] To achieve the purpose of the present application, the isobornyl acrylate modified antibacterial bone cement of the present application is obtained by adding isobornyl acrylate to bone cement.

[0006] Further, in some embodiments of the present application, the bone cement is polymethyl methacrylate (PMMA) bone cement.

[0007] Further, in some embodiments of the present application, the mass ratio of the solid phase and the liquid phase in the polymethyl methacrylate bone cement is 1.5-2.5:1.

[0008] Further, in some embodiments of the present application, the mass ratio of the solid phase and the liquid phase in the polymethyl methacrylate bone cement is 1.6-2.2:1.

[0009] Further, in some embodiments of the present application, the mass ratio of the solid phase and the liquid phase in the polymethyl methacrylate bone cement is 1.65-2.05:1.

[0010] Further, in some embodiments of the present application, the concentration of isobornyl acrylate in the bone cement is greater than or equal to 10.0%, for example, greater than or equal to 15.0%, for example, greater than or equal to 20.0%, preferably greater than or equal to 25.0%, more preferably greater than or equal to 30.0%, wherein the concentration of isobornyl acrylate in the bone cement is calculated as the mass proportion of isobornyl acrylate in the liquid phase of the bone cement.

[0011] Further, in some embodiments of the present application, the specific steps of adding isobornyl acrylate to the bone cement are as follows: isobornyl acrylate is added to the liquid phase of the bone cement, and then mixed uniformly with the solid phase of the bone cement to prepare a bone cement sample.

[0012] Isobornyl acrylate (BA) is a liquid that is easily soluble in MMA, and the present application first reports a non-leaching type of antibacterial bone cement (BA bone cement) modified by isobornyl acrylate (BA). This bone cement has excellent antibacterial activity and mechanical strength, the compressive strength meets the ISO5833 standard, and it has no hemolytic activity, low in vitro cytotoxicity, and good application potential. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is the mechanical strength test result of the BA bone cement of the present application, wherein A is a stress-strain graph, wherein the slope represents the elastic modulus and the parallel lines represent the compressive strength; B is a statistical histogram of the compressive strength data; and C is a histogram of the elastic modulus data. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. Additional aspects and advantages of the present application will be given in the following description, some will become apparent from the following description, or will be understood by those skilled in the art through the practice of the present application. It should be understood that the following description is only intended to explain the present application and is not intended to limit the present application.

[0015] When equivalent, concentration, or other value or parameter is expressed in a range or a preferred range or a series of upper preferred values and lower preferred values, it is to be understood that the full range of equivalents, concentrations, or other values or parameters, whether or not within the ranges stated, are contemplated unless otherwise indicated. For example, where the range of "1 to 5" is disclosed, the disclosure is to be interpreted to include ranges of "1 to 4," "1 to 3," "1 to 2," "1 to 2 and 4 to 5," "1 to 3 and 5," etc. Where a range of values is stated in this document, unless otherwise stated, the range is intended to include both the end values and all integers and fractions within the range.

[0016] The indefinite articles "a" and "an" preceding an element, installation, or component of the application are intended to be construed to cover both the singular and the plural of the element, installation, or component unless otherwise indicated by the context. Thus, the use of the singular will include the plural unless it would contradict the context and terminology.

[0017] In addition, the terms "one embodiment," "some embodiments," "an example," "specific example," or "some examples," and so forth, as can be used herein, mean that a particular implementation described in connection with the embodiment or example is included in at least one embodiment or example of the present application. The use of these terms does not imply that all embodiments or examples of the present application include the discussed feature, advantage or mode of implementation unless otherwise expressly set forth in a claim. Moreover, the described features, advantages and specific modes of implementation are for illustrative purposes only and are not intended to limit the scope of the application since additional features and modes of implementation will become apparent to the skilled person.

[0018] The isobornyl acrylate (BA) used in the present application is a commercially available reagent, and its structure is shown as follows:

[0019]

[0020] Example 1

[0021] The preparation method of the BA bone cement is as follows: the formula and grouping of the bone cement are shown in Table 1. 10wt% and 30wt% represent the mass ratio of the antibacterial monomer BA added into the liquid phase. The commercially available PMMA bone cement without any antibacterial monomer is used as a blank control group. The polymethyl methacrylate (PMMA) bone cement involved in the present application can be selected from the commercially available Eurofix brand, which includes a solid phase and a liquid phase, and the solid-liquid ratio is about 2:1.

[0022] Table 1 Antibacterial bone cement modified by isobornyl acrylate with different proportions

[0023]

[0024] Preparation of bone cement standard samples: According to Table 1, the antibacterial monomer BA was mixed into the liquid phase in the corresponding proportion. The solid phase agent was uniformly mixed with the liquid phase agent at room temperature to make a cylindrical bone cement sample. The sample length was 12.0±0.1 mm, and the diameter was 6.0±0.1 mm. A woodworking clamp was used to fix the mold, and after the bone cement was completely cured, it was removed and sanded with sandpaper to control the total mass to be 0.40±0.01 g to ensure that the top and bottom surfaces of the bone cement were flat. Finally, all samples were sterilized by ethylene oxide.

[0025] Example 2

[0026] BA bone cement antibacterial activity test: BA bone cement samples were immersed in physiological saline at a ratio of 0.1 g / mL at room temperature for 24 hours to remove monomers on the surface that did not participate in polymerization. Then the sample was taken out, sterilized, and placed aside for use. First, S. aureus was resuscitated and subcultured to obtain a concentration of 0.5×10 8 CFU / mL. Subsequently, each group of bone cement samples was placed in a test tube containing 1 mL of the bacterial solution at this concentration. The CO2 incubator was set to 37°C and incubated for 6 hours. After incubation, the samples were slowly rinsed with pure water to remove S. aureus that did not adhere or adhered poorly to the surface of the bone cement. Then, the samples were placed in a test tube containing 5 mL of physiological saline and washed with an ultrasonic oscillator cleaner for a controlled time of 2 minutes to remove S. aureus that was tightly adhered to the surface of the bone cement. After washing, the bone cement samples were removed and the sample solution was shaken well. Take 40 μL of the sample solution, dilute it with a 0.9% NaCl solution at a ratio of 1:100 for plate coating. Incubate in a 37°C CO2 incubator for 24 hours, count the number of colonies, and calculate the surface antibacterial rate. Each group of bone cement samples was repeated five times. The antibacterial rate of PMMA bone cement was set to 0.

[0027]

[0028] The antibacterial activity of the BA bone cement disclosed in the present application is positively correlated with the content of BA, wherein the antibacterial rate of 10wt% BA bone cement against S. aureus is 41.0±10.8%, and the antibacterial rate of 30wt% BA bone cement is 81.0±3.1%. As shown in Table 2 below.

[0029] Table 2 Antibacterial rate of BA bone cement against S. aureus

[0030] Bone cement Antibacterial rate PMMA bone cement 0％ 10% BA bone cement 41.0±10.8％ 30% BA bone cement 81.0±3.1％

[0031] Example 3

[0032] Mechanical strength test was as follows: the bone cement samples (5 for each group) were incubated at 37℃ and 100% humidity for 24 hours. At room temperature, the deformation-load curve of the bone cement sample was plotted using a material testing machine (MTS809, Bose Company, USA) at a loading rate of 20 mm / min. The compressive strength and elastic modulus of each bone cement sample were calculated from these curves. All operations were carried out in accordance with the requirements and standards of ISO 5833. The test results are shown in the following table. Figure 1 .

[0033] Example 4

[0034] Preparation of bone cement leaching solution: The bone cement standard samples were respectively placed in cell culture medium (DMEM / F12 medium) and normal saline (0.9% NaCl solution) according to GB / T 16886 standard, and the ratio of sample to liquid was set to 0.2 g / mL. The cell culture medium group was incubated at 37℃ in a 5% CO2 incubator for 24 hours, and the normal saline group was incubated under the same conditions for 30 minutes. The obtained cell culture medium extract was used for in vitro cytotoxicity test, and the normal saline extract was used for hemolysis test.

[0035] Hemolysis rate determination: According to GB / T 16886 standard, the bone cement leaching solution was placed in a sterile centrifuge tube, and 200 μL of 2% rabbit red blood cell suspension was added. In addition, 200 μL of 2% rabbit red blood cell suspension was added to 1.8 mL of normal saline and pure water as negative and positive controls, respectively. After incubation at 37℃ in a 5% CO2 incubator for 1 hour, centrifugation was performed at a speed of 3000 rpm for 5 minutes. The optical density (OD) of the supernatant was measured at 545 nm using a spectrophotometer. Hemolysis was evaluated by visual inspection of the clarity of the supernatant. Each group of bone cement samples was tested three times. The hemolysis rate (HR) was calculated using the following formula:

[0036]

[0037] where OD T1 is the optical density of the experimental group solution, OD N1 is the optical density of the negative control, and OD P is the optical density of the positive control. As shown in the following table, a hemolysis rate of less than 5% is considered to be no hemolysis. It is shown that the BA bone cement obtained by the present application is similar to the commercially available bone cement, and no hemolysis occurs.

[0038] Table 3 Hemolysis rate determination results of BA bone cement

[0039] Bone cement Hemolysis rate PMMA bone cement 2.35±1.22％ 10% BA bone cement 2.37±1.24％ 30% BA bone cement 3.13±1.37％

[0040] Those skilled in the art can understand that the above description is only an embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An antibacterial bone cement modified with isoborneol acrylate, characterized in that, The isoborneol-modified antibacterial bone cement is obtained by adding isoborneol acrylate to bone cement; the bone cement is polymethyl methacrylate bone cement; the polymethyl methacrylate bone cement comprises a solid phase and a liquid phase, the mass ratio of the solid phase to the liquid phase being 1.5-2.5:1; the concentration of isoborneol acrylate in the bone cement is greater than or equal to 25.0%, wherein the concentration of isoborneol acrylate in the bone cement is calculated based on the mass ratio of isoborneol acrylate in the liquid phase of the bone cement; the specific steps for adding isoborneol acrylate to the bone cement are as follows: adding isoborneol acrylate to the liquid phase of the bone cement, and then mixing it evenly with the solid phase of the bone cement to prepare a bone cement sample.

2. The isoborneol-modified antibacterial bone cement according to claim 1, characterized in that, The mass ratio of solid phase to liquid phase in the polymethyl methacrylate bone cement is 1.6-2.2:

1.

3. The isoborneol-modified antibacterial bone cement according to claim 1, characterized in that, The mass ratio of solid to liquid phase in the polymethyl methacrylate bone cement is 1.65-2.05:

1.

4. The isoborneol-modified antibacterial bone cement according to claim 1, characterized in that, The concentration of isoborneol acrylate in the bone cement is greater than or equal to 30.0%, wherein the concentration of isoborneol acrylate in the bone cement is calculated based on the mass ratio of isoborneol acrylate in the liquid phase of the bone cement.

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