An injectable bone cement and a method for its preparation

Abstract

The application discloses an injectable bone cement and a preparation method thereof, and relates to the technical field of bone cement. The injectable bone cement comprises a powder and a liquid, the powder comprises the following components in parts by weight: 50-60 parts of composite calcium phosphate salt, 8-10 parts of chitosan, 5-10 parts of hydroxyapatite, 1-3 parts of antibacterial agent, 8-10 parts of modified reinforcing agent, and 3-7 parts of coagulation reaction regulator; and the liquid comprises the following components in parts by weight: 20-30 parts of phosphate buffer, 3-8 parts of sodium citrate solution, and 1-5 parts of hyaluronic acid solution. The injectable bone cement prepared by the application has excellent injectability, compressive strength, self-repairing performance and antibacterial performance.

Description

Technical Field

[0001] This invention relates to the field of bone cement technology, specifically to an injectable bone cement and its preparation method. Background Technology

[0002] With the accelerating aging of the global population and the increasing number of trauma cases such as traffic accidents, sports injuries, and osteoporosis-related fractures, the demand for bone defect repair is showing a significant upward trend. Injectable bone cement, as a minimally invasive treatment material, has the advantages of simple operation, immediate support, and filling of irregular bone defects. It has been widely used in vertebroplasty, kyphoplasty, internal fixation assistance for fractures, and filling and repairing various bone defects.

[0003] Currently, clinically used bone cements are mainly divided into two categories: polymethyl methacrylate (PMMA) bone cement and calcium phosphate (CMP) bone cement. While PMMA bone cement offers rapid curing, high compressive strength, and good injectability, its polymerization process generates a large amount of heat, easily leading to thermal necrosis of surrounding tissues. Furthermore, PMMA is non-biodegradable, and long-term retention in the body may cause foreign body reactions. It also lacks biological activity and cannot promote new bone growth, often requiring secondary surgery for removal. Calcium phosphate (CMP) bone cement, on the other hand, has good biocompatibility and osteoconductivity, and its final degradation products closely resemble the composition of natural bone minerals (hydroxyapatite). However, it has a longer curing time, lower early compressive strength, and lacks antibacterial properties, resulting in a higher risk of postoperative infection.

[0004] Chinese invention patent CN107303397A discloses a bioactive injectable composite bone cement, its preparation method, and its uses. The bone cement consists of two parts: a solid powder and a curing liquid. The solid powder is a mixture of phosphosilicate bioactive glass and calcium sulfate, and the curing liquid contains chitosan and sodium β-glycerophosphate. This bone cement exhibits good injectability, anti-collapse properties, and mechanical properties, but its antibacterial properties are still insufficient. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide an injectable bone cement and its preparation method.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The powder comprises the following components in parts by weight: 50-60 parts of complex calcium phosphate, 8-10 parts of chitosan, 5-10 parts of hydroxyapatite, 1-3 parts of antibacterial agent, 8-10 parts of modifier and reinforcing agent, and 3-7 parts of coagulation reaction regulator.

[0008] The liquid comprises the following components in parts by weight: 20-30 parts phosphate buffer, 3-8 parts sodium citrate solution, and 1-5 parts hyaluronic acid solution.

[0009] The antibacterial agent is prepared by the following method:

[0010] S1: 2-(4-(dimethylamino)phenyl)ethane-1-thiol reacts with 10-bromo-1-decyl alcohol to form a quaternary ammonium salt compound.

[0011] S2: Quaternary ammonium salt compounds react with methyl linoleate to form bisquaternary ammonium salt compounds.

[0012] S3: A bisquaternary ammonium salt compound reacts with (3-propanoyl)triphenylphosphine bromide to form an antibacterial agent.

[0013] In step S1, the molar ratio of 2-(4-(dimethylamino)phenyl)ethane-1-thiol to 10-bromo-1-decanol is 1:(1.05-1.1).

[0014] In step S2, the molar ratio of the quaternary ammonium salt compound to methyl linoleate is (2.02-2.08):1.

[0015] In step S3, the molar ratio of the bisquaternary ammonium salt compound to (3-propanoyl)triphenylphosphine bromide is 1:(2.05-2.1).

[0016] The modified reinforcing agent is prepared by the following method:

[0017] A1: 2',5'-Dimethoxy-[1,1':4',1''-terphenyl]-3,3'',5,5''-tetracarboxaldehyde reacts with 12-amino-1-dodecanool to form a four-armed compound.

[0018] A2: The four-armed compound reacts with α-lipoic acid to generate a modified reinforcing agent.

[0019] In step A1, the molar ratio of 2',5'-dimethoxy-[1,1':4',1''-terphenyl]-3,3'',5,5''-tetracarboxaldehyde to 12-amino-1-dodecanool is 1:4.05.

[0020] In step A2, the molar ratio of the four-armed compound to α-lipoic acid is 1:4.08.

[0021] The composite calcium phosphate salt is a mixture of α-tricalcium phosphate and tetracalcium phosphate, with a mixing weight ratio of α-tricalcium phosphate to tetracalcium phosphate of 1:(0.2-0.5).

[0022] The coagulation reaction regulator is one of calcium hydrogen phosphate or calcium carbonate.

[0023] A method for preparing injectable bone cement includes the following steps:

[0024] (1) Weigh out the following by weight: 50-60 parts of compound calcium phosphate, 8-10 parts of chitosan, 5-10 parts of hydroxyapatite, 1-3 parts of antibacterial agent, 8-10 parts of modifier and reinforcing agent, 3-7 parts of coagulation reaction regulator; 20-30 parts of phosphate buffer, 3-8 parts of sodium citrate solution, and 1-5 parts of hyaluronic acid solution;

[0025] (2) The composite calcium phosphate salt, chitosan, hydroxyapatite, antibacterial agent, modifier and coagulation reaction regulator are mixed in a three-dimensional mixer to obtain a powder;

[0026] (3) Mix the phosphate buffer solution, sodium citrate solution and hyaluronic acid solution, and degas by sonication to obtain a liquid;

[0027] (4) When using, mix the powder and liquid at a mass ratio of 1:0.8 and stir to obtain injectable bone cement.

[0028] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include:

[0029] The bone cement prepared by this invention has excellent injectability, compressive strength, self-healing properties, and antibacterial properties. The added antibacterial agent, through quaternary ammonium salt, bisphosphonate salt, long alkyl chain, and ester bond, synergistically provides high positive charge and lipophilicity, effectively destroying bacterial cell membranes and achieving broad-spectrum and long-lasting antibacterial activity. The added modifier and reinforcing agent, through the synergistic effect of rigid aromatic core, dynamic covalent bond, and flexible chain, significantly improves the compressive strength and self-healing ability of the bone cement. Attached Figure Description

[0030] Figure 1 The 1H NMR spectrum of the quaternary ammonium salt compound prepared in step S1 of Example 1;

[0031] Figure 2 The 1H NMR spectrum of the bisquaternary ammonium salt compound prepared in step S2 of Example 1;

[0032] Figure 3 The 1H NMR spectrum of the antibacterial agent prepared in step S3 of Example 1;

[0033] Figure 4 This is a high-resolution mass spectrum of the antibacterial agent prepared in step S3 of Example 1;

[0034] Figure 5 The 1H NMR spectrum of the four-armed compound prepared in step A1 of Example 4;

[0035] Figure 6 The 1H NMR spectrum of the modified reinforcing agent prepared in step A2 of Example 4;

[0036] Figure 7 This is a high-resolution mass spectrum of the modified reinforcing agent prepared in step A2 of Example 4. Detailed Implementation

[0037] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments.

[0038] Example 1: Preparation of antibacterial agent:

[0039] S1: Under nitrogen protection, add 300 mL of anhydrous DMF (N,N-dimethylformamide) and 0.1 mol of 2-(4-(dimethylamino)phenyl)ethane-1-thiol to the reactor and stir at room temperature until completely dissolved; then add 0.15 mol of triethylamine and 0.01 mol of... DMAP (4-dimethylaminopyridine) was stirred and mixed thoroughly. 50 mL of anhydrous DMF solution containing 0.11 mol of triphenylmethyl chloride was slowly added dropwise over 20 min. After the addition was complete, the reaction was allowed to proceed at room temperature for 6 h. Then, 300 mL of deionized water was slowly added to quench the reaction, and the mixture was stirred for 10 min. The mixture was extracted three times with 200 mL of ethyl acetate each time. The organic phases were combined and washed successively with deionized water (2 × 50 mL) and 50 mL of saturated sodium chloride solution. The mixture was dried over 40 g of anhydrous sodium sulfate, filtered, and distilled under reduced pressure at 60 °C for 2 h. The mixture was then purified by silica gel column chromatography (petroleum ether / ethyl acetate gradient elution, volume ratio 10:1 → 5:1), and dried under vacuum at 50 °C for 12 h to obtain a triphenylmethyl-protected thiol compound.

[0040] Under nitrogen protection, 300 ml of acetonitrile and 0.1 mol of triphenylmethyl-protected thiol compound were added to the reactor. The mixture was stirred at room temperature for 5 min, and then 0.105 mol of 10-bromo-1-decyl alcohol was slowly added dropwise over 20 min. After the addition was complete, the temperature was raised to 40 °C and the reaction was carried out for 8 h. The mixture was then distilled under reduced pressure at 50 °C for 1.5 h. The solid was then slowly added to 500 ml of diethyl ether, stirred, and filtered. The solid was washed three times with diethyl ether (50 ml of diethyl ether each time) and dried under vacuum at 50 °C for 12 h to obtain the triphenylmethyl-protected quaternary ammonium salt compound.

[0041] Under nitrogen protection, 300 mL of anhydrous dichloromethane and 0.1 mol of a triphenylmethyl-protected quaternary ammonium salt compound were added to a reactor and stirred at room temperature until completely dissolved. Then, 58 mL of triethylsilane and 154 mL of trifluoroacetic acid were added, and the mixture was stirred at room temperature for 2 h. The mixture was then distilled under reduced pressure at 35 °C for 1 h to obtain the crude product. 300 mL of anhydrous diethyl ether was added to the crude product, and the mixture was stirred to precipitate a solid. The solid was filtered, washed three times with cold diethyl ether (50 mL each time), and dried under vacuum at 50 °C for 12 h to obtain the quaternary ammonium salt compound. The reaction equation is shown below:

[0042]

[0043] Its proton nuclear magnetic resonance spectrum is as follows Figure 1 As shown, its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, DMSO- d 6 )δ 7.40 – 7.32 (m, 2H), 7.31 – 7.23 (m, 2H), 3.87 (t, J = 8.5 Hz, 2H), 3.75(s, 6H), 3.54 (t, J = 5.8 Hz, 2H), 2.92 – 2.85 (m, 4H), 2.80 (t, J = 5.9 Hz,1H), 2.69 – 2.63 (m, 1H), 1.93 (tt, J = 8.5, 6.1 Hz, 2H), 1.62 – 1.24 (m,14H); HRMS (m / z):338.2515[M-Br] + .

[0044] S2: Under nitrogen protection, add 800 ml of tetrahydrofuran, 0.1 mol of methyl linoleate, 0.202 mol of quaternary ammonium salt compound, and 1.0 g of photoinitiator 184 to the reactor, stir and mix thoroughly, and at room temperature, with an intensity of 8.4 mW / cm². 2 After irradiation under a 365nm UV LED lamp for 12 hours, 800 mL of ethyl acetate was added to the reaction mixture for dilution. The mixture was then washed successively with 5wt% sodium bicarbonate solution (2 × 300 mL), deionized water (2 × 300 mL), and 300 mL of saturated sodium chloride solution. The organic phase was dried over 50 g of anhydrous sodium sulfate, filtered, and distilled under reduced pressure at 45°C for 1.5 hours. 1000 mL of n-hexane was added, and the mixture was stirred at room temperature for 30 minutes to precipitate. The precipitate was filtered, washed with cold n-hexane (3 × 100 mL), and dried under vacuum at 45°C for 12 hours to obtain the bisquaternary ammonium salt compound. The reaction equation is shown below:

[0045]

[0046] Its proton nuclear magnetic resonance spectrum is as follows Figure 2 As shown, its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, DMSO- d 6)δ 7.46 – 7.26 (m, 8H), 3.98 (t, J = 5.8 Hz, 2H), 3.88 (t, J = 8.5 Hz, 4H), 3.74 (s, 12H), 3.62 (s, 3H), 3.53 (t, J = 5.8 Hz, 4H), HRMS (m / z):485.3790[M-2Br] 2+ .

[0047] S3: Under nitrogen protection, 1000 ml of tetrahydrofuran, 0.205 mol of (3-propanoyl)triphenylphosphine bromide, 0.21 mol of DCC (N,N'-dicyclohexylcarbodiimide), and 0.01 mol of DMAP (4-dimethylaminopyridine) were added to the reactor. The mixture was stirred for 10 min, and then 0.1 mol of a quaternary ammonium salt compound was added. The reaction was carried out at room temperature for 12 h. The mixture was filtered, and the filtrate was washed successively with 150 ml of 1 wt% dilute hydrochloric acid, 150 ml of saturated sodium bicarbonate solution, and 150 ml of saturated brine. The filtrate was dried over 40 g of anhydrous sodium sulfate, filtered, and distilled under reduced pressure at 50 °C for 1 h. The filtrate was purified by silica gel column chromatography (using a petroleum ether / ethyl acetate mixture as the eluent, with a petroleum ether / ethyl acetate volume ratio of 5:1 to 10:1 gradient elution). The filtrate was then distilled under reduced pressure at 50 °C for 1.5 h and dried under vacuum at 50 °C for 12 h to obtain the antibacterial agent. The reaction equation is shown below.

[0048]

[0049] Its proton nuclear magnetic resonance spectrum is as follows Figure 3 As shown, its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, DMSO- d 6)δ 7.86 – 7.75 (m, 12H), 7.71 – 7.65 (m, 18H), 7.42 – 7.38 (m, 4H), 7.34 –7.29 (m, 4H), 4.11 – 4.02 (m, 8H), 3.88 (t, J = 8.5 Hz, 4H), 3.74 (s, 12H), 3.62 (s, 3H), 2.93 – 2.71 (m, 10H), 2.61 (td, J = 9.5, 0.4 Hz, 4H), 2.27 (t,J = 8.5 Hz, 2H), 2.06 – 1.84 (m, 8H), 1.71 – 1.22 (m, 54H), 0.91 – 0.86 (m, 3H); its high-resolution mass spectrum is shown below. Figure 4 As shown, HRMS (m / z): 408.5032 [M-4Br] 4+ .

[0050] Example 2: Preparation of antibacterial agent:

[0051] S1: Under nitrogen protection, 300 mL of anhydrous DMF and 0.1 mol of 2-(4-(dimethylamino)phenyl)ethane-1-thiol were added to the reactor and stirred at room temperature until completely dissolved. Then, 0.15 mol of triethylamine and 0.01 mol of DMAP were added and stirred until well mixed. 50 mL of anhydrous DMF solution containing 0.11 mol of triphenylmethyl chloride was slowly added dropwise over 20 min. After the addition was complete, the reaction was allowed to proceed at room temperature for 6 h. Then, 300 mL of deionized water was slowly added to quench the reaction, and the mixture was stirred for 10 min. The mixture was extracted three times with ethyl acetate (200 mL each time). The organic phases were combined and washed successively with deionized water (2 × 50 mL) and 50 mL of saturated sodium chloride solution. The mixture was dried over 40 g of anhydrous sodium sulfate, filtered, and distilled under reduced pressure at 60 °C for 2 h. The mixture was then purified by silica gel column chromatography (petroleum ether / ethyl acetate gradient elution, volume ratio 10:1 → 5:1), and dried under vacuum at 50 °C for 12 h to obtain the triphenylmethyl-protected thiol compound.

[0052] Under nitrogen protection, 300 ml of acetonitrile and 0.1 mol of triphenylmethyl-protected thiol compound were added to the reactor. The mixture was stirred at room temperature for 5 min, and then 0.108 mol of 10-bromo-1-decyl alcohol was slowly added dropwise over 20 min. After the addition was complete, the temperature was raised to 45 °C and the reaction was carried out for 7 h. The mixture was then distilled under reduced pressure at 50 °C for 1.5 h. The solid was then slowly added to 500 ml of diethyl ether, stirred, and filtered. The solid was washed three times with diethyl ether (50 ml of diethyl ether each time) and dried under vacuum at 50 °C for 12 h to obtain the triphenylmethyl-protected quaternary ammonium salt compound.

[0053] Under nitrogen protection, 300 mL of anhydrous dichloromethane and 0.1 mol of a triphenylmethyl-protected quaternary ammonium salt compound were added to the reactor and stirred at room temperature until completely dissolved. Then, 58 mL of triethylsilane and 154 mL of trifluoroacetic acid were added and stirred at room temperature for 2 h. The mixture was then distilled under reduced pressure at 35 °C for 1 h to obtain the crude product. 500 mL of anhydrous diethyl ether was added to the crude product and stirred to precipitate the solid. The solid was filtered, washed three times with cold diethyl ether (50 mL each time), and dried under vacuum at 50 °C for 12 h to obtain the quaternary ammonium salt compound.

[0054] S2: Under nitrogen protection, add 800 ml of tetrahydrofuran, 0.1 mol of methyl linoleate, 0.205 mol of quaternary ammonium salt compound, and 1.0 g of photoinitiator 184 to the reactor, stir and mix thoroughly, and at room temperature, at an intensity of 8.4 mW / cm². 2 After irradiation under a 365nm UV LED lamp for 14 hours, 800mL of ethyl acetate was added to the reaction mixture for dilution. The mixture was then washed successively with 5wt% sodium bicarbonate solution (2×300mL), deionized water (2×300mL), and 300mL of saturated sodium chloride solution. The organic phase was dried with 50g of anhydrous sodium sulfate, filtered, and distilled under reduced pressure at 45℃ for 1.5 hours. 1000mL of n-hexane was added, and the mixture was stirred at room temperature for 30 minutes to precipitate the precipitate. The precipitate was filtered, washed with cold n-hexane (3×100mL), and dried under vacuum at 45℃ for 12 hours to obtain the bisquaternary ammonium salt compound.

[0055] S3: Under nitrogen protection, 1000 ml of tetrahydrofuran, 0.208 mol of (3-propanoyl)triphenylphosphine bromide, 0.21 mol of DCC, and 0.01 mol of DMAP were added to the reactor and stirred for 10 min. Then, 0.1 mol of the bisquaternary ammonium salt compound was added, and the reaction was carried out at room temperature for 11 h. The mixture was filtered, and the filtrate was washed successively with 150 ml of 1 wt% dilute hydrochloric acid, 150 ml of saturated sodium bicarbonate solution, and 150 ml of saturated brine. The filtrate was dried over 40 g of anhydrous sodium sulfate, filtered, and distilled under reduced pressure at 50 °C for 1 h. The filtrate was purified by silica gel column chromatography (using a petroleum ether / ethyl acetate mixed solution as the eluent, with a petroleum ether / ethyl acetate volume ratio of 5:1 to 10:1 gradient elution), distilled under reduced pressure at 50 °C for 1.5 h, and dried under vacuum at 50 °C for 12 h to obtain the antibacterial agent.

[0056] Example 3: Preparation of antibacterial agent:

[0057] S1: Under nitrogen protection, 300 mL of anhydrous DMF and 0.1 mol of 2-(4-(dimethylamino)phenyl)ethane-1-thiol were added to the reactor and stirred at room temperature until completely dissolved. Then, 0.15 mol of triethylamine and 0.01 mol of DMAP were added and stirred until well mixed. 50 mL of anhydrous DMF solution containing 0.11 mol of triphenylmethyl chloride was slowly added dropwise over 20 min. After the addition was complete, the reaction was allowed to proceed at room temperature for 6 h. Then, 300 mL of deionized water was slowly added to quench the reaction, and the mixture was stirred for 10 min. The mixture was extracted three times with ethyl acetate (200 mL each time). The organic phases were combined and washed successively with deionized water (2 × 50 mL) and 50 mL of saturated sodium chloride solution. The mixture was dried over 40 g of anhydrous sodium sulfate, filtered, and distilled under reduced pressure at 60 °C for 2 h. The mixture was then purified by silica gel column chromatography (petroleum ether / ethyl acetate gradient elution, volume ratio 10:1 → 5:1), and dried under vacuum at 50 °C for 12 h to obtain the triphenylmethyl-protected thiol compound.

[0058] Under nitrogen protection, 300 ml of acetonitrile and 0.1 mol of triphenylmethyl-protected thiol compound were added to the reactor. The mixture was stirred at room temperature for 5 min, and then 0.11 mol of 10-bromo-1-decyl alcohol was slowly added dropwise over 20 min. After the addition was complete, the temperature was raised to 50 °C and the reaction was carried out for 6 h. The mixture was then distilled under reduced pressure at 50 °C for 1.5 h. The solid was then slowly added to 500 ml of diethyl ether, stirred, and filtered. The solid was washed three times with diethyl ether (50 ml of diethyl ether each time) and dried under vacuum at 50 °C for 12 h to obtain the triphenylmethyl-protected quaternary ammonium salt compound.

[0059] Under nitrogen protection, 300 mL of anhydrous dichloromethane and 0.1 mol of a triphenylmethyl-protected quaternary ammonium salt compound were added to the reactor and stirred at room temperature until completely dissolved. Then, 58 mL of triethylsilane and 154 mL of trifluoroacetic acid were added and stirred at room temperature for 2 h. The mixture was then distilled under reduced pressure at 35 °C for 1 h to obtain the crude product. 500 mL of anhydrous diethyl ether was added to the crude product and stirred to precipitate the solid. The solid was filtered, washed three times with cold diethyl ether (50 mL each time), and dried under vacuum at 50 °C for 12 h to obtain the quaternary ammonium salt compound.

[0060] S2: Under nitrogen protection, add 800 ml of tetrahydrofuran, 0.1 mol of methyl linoleate, 0.208 mol of quaternary ammonium salt compound, and 1.0 g of photoinitiator 184 to the reactor, stir and mix thoroughly, and at room temperature, with an intensity of 8.4 mW / cm². 2After irradiation under a 365nm UV LED lamp for 16 hours, 800mL of ethyl acetate was added to the reaction mixture for dilution. The mixture was then washed successively with 5wt% sodium bicarbonate solution (2×300mL), deionized water (2×300mL), and 300mL of saturated sodium chloride solution. The organic phase was dried with 50g of anhydrous sodium sulfate, filtered, and distilled under reduced pressure at 45℃ for 1.5 hours. 1000mL of n-hexane was added, and the mixture was stirred at room temperature for 30 minutes to precipitate the precipitate. The precipitate was filtered, washed with cold n-hexane (3×100mL), and dried under vacuum at 45℃ for 12 hours to obtain the bisquaternary ammonium salt compound.

[0061] S3: Under nitrogen protection, 1000 ml of tetrahydrofuran, 0.21 mol of (3-propanoyl)triphenylphosphine bromide, 0.21 mol of DCC, and 0.01 mol of DMAP were added to the reactor and stirred for 10 min. Then, 0.1 mol of the bisquaternary ammonium salt compound was added, and the reaction was carried out at room temperature for 10 h. The mixture was filtered, and the filtrate was washed successively with 150 ml of 1 wt% dilute hydrochloric acid, 150 ml of saturated sodium bicarbonate solution, and 150 ml of saturated brine. The filtrate was dried over 40 g of anhydrous sodium sulfate, filtered, and distilled under reduced pressure at 50 °C for 1 h. The filtrate was purified by silica gel column chromatography (using a petroleum ether / ethyl acetate mixed solution as the eluent, with a petroleum ether / ethyl acetate volume ratio of 5:1 to 10:1 gradient elution), distilled under reduced pressure at 50 °C for 1.5 h, and dried under vacuum at 50 °C for 12 h to obtain the antibacterial agent.

[0062] Example 4: Preparation of the modified reinforcing agent:

[0063] A1: Add 400 ml of tetrahydrofuran, 0.405 mol of 12-amino-1-dodecaneol, and 40 g of 4A molecular sieve (sodium-A type molecular sieve) to the reactor, stir and mix well, then slowly add 600 ml of tetrahydrofuran solution containing 0.1 mol of 2',5'-dimethoxy-[1,1':4',1''-terphenyl]-3,3'',5,5''-tetracarboxaldehyde over 1 hour. After the addition is complete, heat to reflux for 6 hours, cool to room temperature, filter, and distill the filtrate under reduced pressure at 40°C for 1 hour. Then add 800 ml of cold n-hexane, stir to precipitate, filter, wash three times with petroleum ether (100 ml each time), and dry under vacuum at 60°C for 12 hours to obtain the four-armed compound; the reaction equation is shown below:

[0064]

[0065] Its proton nuclear magnetic resonance spectrum is as follows Figure 5 As shown, its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, DMSO- d 6)δ 8.44 (m, 4H), 7.88 – 7.80 (m, 6H), 7.26 (s, 2H), 3.98 (t, J = 5.8 Hz, 4H), 3.84 (s, 6H), 3.57 – 3.37 (m, 16H), 1.76 – 1.20 (m, 80H); HRMS (m / z):1135.9067[M+H] + .

[0066] A2: Under nitrogen protection, 1500 ml of toluene, 0.408 mol of α-lipoic acid, 0.41 mol of DCC, and 0.01 mol of DMAP were added to the reactor and stirred for 10 min. Then, 0.1 mol of the four-arm compound was added, and the reaction was carried out at room temperature for 12 h. The mixture was filtered, and the filtrate was washed successively with 150 ml of 1 wt% dilute hydrochloric acid, 150 ml of saturated sodium bicarbonate solution, and 150 ml of saturated brine. The filtrate was dried over 40 g of anhydrous sodium sulfate, filtered, and distilled under reduced pressure at 60 °C for 1 h. The filtrate was purified by silica gel column chromatography using a mixed solution of petroleum ether and ethyl acetate (petroleum ether / ethyl acetate volume ratio of 5:1 → 10:1 gradient elution). The mixture was distilled under reduced pressure at 50 °C for 1 h and dried under vacuum at 50 °C for 12 h to obtain the modified reinforcing agent. The reaction equation is shown below.

[0067]

[0068] Its proton nuclear magnetic resonance spectrum is as follows Figure 6 As shown, its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, DMSO- d 6 δ 8.44 (m, 4H), 7.94 – 7.75 (m, 6H), 7.26 (s, 2H), 4.07 (t, J = 6.2 Hz, 8H), 3.84 (s, 6H), 3.53 – 3.39 (m, 12H), 3.11 (dddd, J = 18.5, 12.4, 4.4, 2.6 Hz, 8H), 2.35 – 2.24 (m, 12H), 2.03 (m, 4H), 1.75 – 1.21 (m, 104H); its high-resolution mass spectrum is as follows: Figure 7 As shown, HRMS (m / z): 1889.0408 [M+H] + .

[0069] Example 5: Preparation of injectable bone cement:

[0070] (1) Weigh the following by weight: 500g of compound calcium phosphate (417g of α-tricalcium phosphate and 83g of tetracalcium phosphate), 80g of chitosan, 50g of hydroxyapatite, 10g of antibacterial agent (prepared in Example 1), 80g of modifier and reinforcing agent (prepared in Example 4), 30g of coagulation reaction regulator (dicalcium phosphate), 200g of phosphate buffer, 30g of sodium citrate solution, and 10g of hyaluronic acid solution;

[0071] (2) The composite calcium phosphate, chitosan, hydroxyapatite, antibacterial agent, modifier and coagulation reaction regulator are mixed in a three-dimensional mixer at 60 rpm for 2 hours to obtain a powder.

[0072] (3) Mix the phosphate buffer, sodium citrate solution and hyaluronic acid solution, stir at 500 rpm for 20 min, and degas at 20 kHz for 10 min to obtain the liquid.

[0073] (4) When using, mix the powder and liquid at a mass ratio of 1:0.8 and stir for 5 minutes to obtain injectable bone cement.

[0074] Example 6: Preparation of injectable bone cement:

[0075] (1) Weigh the following by weight: 550g of compound calcium phosphate (423g of α-tricalcium phosphate and 127g of tetracalcium phosphate), 90g of chitosan, 80g of hydroxyapatite, 20g of antibacterial agent (prepared in Example 2), 90g of modifier and reinforcing agent (prepared in Example 4), 50g of coagulation reaction regulator (calcium carbonate), 250g of phosphate buffer, 50g of sodium citrate solution, and 30g of hyaluronic acid solution;

[0076] (2) The composite calcium phosphate, chitosan, hydroxyapatite, antibacterial agent, modifier and coagulation reaction regulator are mixed in a three-dimensional mixer at 60 rpm for 2 hours to obtain a powder.

[0077] (3) Mix the phosphate buffer, sodium citrate solution and hyaluronic acid solution, stir at 500 rpm for 20 min, and degas at 20 kHz for 10 min to obtain the liquid.

[0078] (4) When using, mix the powder and liquid at a mass ratio of 1:0.8 and stir for 5 minutes to obtain injectable bone cement.

[0079] Example 7: Preparation of injectable bone cement:

[0080] (1) Weigh the following by weight: 600g of compound calcium phosphate (400g of α-tricalcium phosphate and 200g of tetracalcium phosphate), 100g of chitosan, 100g of hydroxyapatite, 30g of antibacterial agent (prepared in Example 3), 100g of modifier and reinforcing agent (prepared in Example 4), 70g of coagulation reaction regulator (dicalcium phosphate), 300g of phosphate buffer, 80g of sodium citrate solution, and 50g of hyaluronic acid solution;

[0081] (2) The composite calcium phosphate, chitosan, hydroxyapatite, antibacterial agent, modifier and coagulation reaction regulator are mixed in a three-dimensional mixer at 60 rpm for 2 hours to obtain a powder.

[0082] (3) Mix the phosphate buffer, sodium citrate solution and hyaluronic acid solution, stir at 500 rpm for 20 min, and degas at 20 kHz for 10 min to obtain the liquid.

[0083] (4) When using, mix the powder and liquid at a mass ratio of 1:0.8 and stir for 5 minutes to obtain injectable bone cement.

[0084] Comparative Example 1

[0085] The raw material composition and preparation method of injectable bone cement are basically the same as in Example 6, except that the antibacterial agent is replaced with an equal weight of an antibacterial agent prepared by the following method:

[0086] The preparation method of the antibacterial agent is basically the same as that in Example 2, except that 10-bromo-1-decyl alcohol in step S1 is replaced with an equimolar amount of 6-bromohexanol.

[0087] Comparative Example 2

[0088] The raw material composition and preparation method of injectable bone cement are basically the same as in Example 6, except that the antibacterial agent is replaced with an equal weight of an antibacterial agent prepared by the following method:

[0089] The preparation method of the antibacterial agent is basically the same as that in Example 2, except that 2-(4-(dimethylamino)phenyl)ethane-1-thiol in step S1 is replaced with an equimolar amount of 2-diethylaminoethanethiol.

[0090] Comparative Example 3

[0091] The raw material composition and preparation method of injectable bone cement are basically the same as in Example 6, except that the antibacterial agent is replaced with an equal weight of an antibacterial agent prepared by the following method:

[0092] The preparation method of the antibacterial agent is basically the same as that in Example 2, except that methyl linoleate in step S2 is replaced with an equimolar amount of methyl trans-palmitoyl ester; and the amount of (3-propanoyl)triphenylphosphine bromide in step S3 is 1.08 mol.

[0093] Comparative Example 4

[0094] The raw material composition and preparation method of the injectable bone cement are basically the same as in Example 6, except that the modifier is replaced with an equal weight of a modifier prepared by the following method:

[0095] The preparation method of the modified reinforcing agent is basically the same as that in Example 4, except that 2',5'-dimethoxy-[1,1':4',1''-terphenyl]-3,3'',5,5''-tetracarboxaldehyde in step A1 is replaced with 5'-(3,5-dicarboxyphenyl)-[1,1':3',1''-terphenyl]-3,3'',5,5''-tetracarboxaldehyde; and the amount of α-lipoic acid added in step A2 is 0.608 mol.

[0096] Comparative Example 5

[0097] The raw material composition and preparation method of the injectable bone cement are basically the same as in Example 6, except that the modifier is replaced with an equal weight of a modifier prepared by the following method:

[0098] The preparation method of the modified reinforcing agent is basically the same as that in Example 4, except that 12-amino-1-dodecanool in step A1 is replaced with an equimolar amount of 6-amino-1-hexanol.

[0099] Comparative Example 6

[0100] The raw material composition and preparation method of the injectable bone cement are basically the same as in Example 6, except that the modifier is replaced with an equal weight of a modifier prepared by the following method:

[0101] The preparation method of the modified reinforcing agent is basically the same as that in Example 4, except that the α-lipoic acid in step A2 is replaced with an equimolar amount of 4-(methyldithioalkyl)butyric acid.

[0102] The hydroxyapatite used in the embodiments and comparative examples of this application is model HAP03-20, produced by Nanjing Junzhuo Biotechnology Co., Ltd.; the number average molecular weight of hyaluronic acid is 10 kDa; the number average molecular weight of chitosan is 800 kDa, and the degree of deacetylation is 80%; the concentration of phosphate buffer is 0.2 M, and the pH is 7.2; the concentration of sodium citrate solution is 0.1 M; and the concentration of hyaluronic acid solution is 0.2 w / v.

[0103] Preparation of phosphate buffer (0.2 M, pH 7.2): Weigh 35.814 g of disodium hydrogen phosphate dodecahydrate and 13.609 g of potassium dihydrogen phosphate, dissolve them separately in 400 ml of deionized water, combine them after complete dissolution, and transfer them to a 1000 ml volumetric flask. Dilute to 1-2 cm below the mark with deionized water, shake well, and adjust the pH to 7.20 ± 0.02 with 1 M NaOH or HCl. Finally, dilute to 1000 ml to obtain a 0.2 M, pH 7.2 phosphate buffer.

[0104] The injectable bone cements prepared in Examples 5-7 and Comparative Examples 1-6 were tested for injectability, compressive strength, self-healing properties, and antibacterial properties. The test results are shown in Table 1.

[0105] Injectability Test: The prepared bone cement was transferred to a 1m syringe, which was then vertically fixed to the base of the universal testing machine. A force of 1mm / min was applied to the syringe plunger, and the test ended when the force reached 100N. Each group of samples was tested 5 times, and the average value was taken. The injectability formula for the sample is as follows:

[0106]

[0107] M0 is the weight of the syringe itself, M1 is the weight of the syringe after the slurry is injected, and M2 is the weight of the remaining slurry and syringe after the test.

[0108] Preparation of compressive strength test specimens: The bone cement prepared in the comparative example and the example were poured into a polytetrafluoroethylene cylindrical mold, cured at 37°C for 1 hour, and demolded to obtain specimens (the specimens are 6 mm in diameter and 12 mm in length).

[0109] Compressive strength test: The compressive strength of the bone cement was tested using a universal testing machine at a loading speed of 20 mm / min. Before the test, the sample was kept at 23℃ for 24 hours.

[0110] Self-repair test: A 0.5 mm deep and 10 mm long incision was made at the center of the gauge length of the specimen using a blade. The specimen was then immersed in 50 ml of 0.1 M PBS buffer (pH 7.4) at 37°C for 24 hours to obtain the repaired bone cement. The compressive strength was then tested. The self-repair rate was calculated using the following formula:

[0111] .

[0112] Antibacterial performance test: Bone cement samples with a diameter of 10 mm and a thickness of 1 mm were placed in capped glass bottles containing PBS buffer (0.1 M, pH=7.4) and autoclaved at 120°C for 15 min. After aeration and cooling, the samples were further sterilized by UV irradiation in a clean bench for 1 h. The tested bacterial species was Staphylococcus aureus. Individual colonies were picked from the test strain and diluted with 0.9 wt% physiological saline to a bacterial concentration of 10. 8 CFU / ml. Add 100 μl of bacterial suspension to LB solid medium, spread the bacterial suspension evenly with a spreader, place the sample in the medium, seal it, and place the culture dish in a 37℃ biochemical incubator for 24 h. After removing the culture plate, take an optical photograph to observe whether a clear inhibition zone appears around the bone cement sample, and measure the diameter of the inhibition zone by measurement method.

[0113] Table 1 Performance Indicators of Bone Cement

[0114]

[0115] As can be seen from Table 1, the injectable bone cement prepared in Examples 5-7 of this application has excellent injectability, compressive strength, self-healing properties and antibacterial properties.

[0116] The antibacterial agent prepared in this invention uses a long-chain alkyl group derived from methyl linoleate as its hydrophobic backbone, with quaternary ammonium salt cations and phosphine salt cations connected to its two ends via thioether bonds. The bisquaternary ammonium salt and bistriphenylphosphine cations provide a high density of positive charge centers, strongly adsorbing negatively charged bacterial cell membranes through electrostatic interactions and disrupting membrane potential balance, leading to leakage of bacterial contents. The ester bond, as a polar bonding point, stabilizes the hydrophobic chain conformation while its weak hydrophilicity and hydrolytic properties enhance the interaction between the long-chain alkyl group and the cell membrane interface. The long-chain alkyl group, as the hydrophobic host, binds to the nonpolar tails of membrane phospholipids through hydrophobic interactions, disrupting their arrangement. The terminal ester bond, under hydrophobic conditions, undergoes dipole-dipole interactions with the membrane lipid heads or membrane-water interface regions, helping to anchor the long-chain alkyl group to the membrane bilayer, thereby more effectively interfering with the membrane's order and stability. These functional groups work synergistically to give the antibacterial agent broad-spectrum and long-lasting antibacterial properties, especially showing significant antibacterial effects against Staphylococcus aureus.

[0117] In Comparative Example 2, after replacing 2-(4-(dimethylamino)phenyl)ethane-1-thiol in step S1 with an equimolar amount of 2-diethylaminoethanethiol, the antibacterial properties of the bone cement decreased significantly. The main reason is that the aromatic ring (benzene ring) in the original structure forms a strong π-electron conjugation system with the dimethylamino group, which can enhance the electron cloud density and positive electrical stability of the quaternary ammonium salt group, thereby strengthening its electrostatic interaction with the bacterial cell membrane (which is negatively charged). After replacing it with 2-diethylaminoethanethiol, the aromatic ring structure is missing in the molecule, leaving only the tertiary amine group on the aliphatic chain. Its conjugation effect disappears, the positive charge and affinity with the bacterial membrane are weakened, and the antibacterial efficiency decreases.

[0118] The modified reinforcing agent prepared in this invention uses terphenyl as a rigid central core, extending outward through Schiff base bonds to form a four-armed star structure. Each arm chain is connected to a terminal α-thiooctyl ester group by a long-chain methylene flexible segment. The rigid aromatic core and benzene ring provide high modulus and π-π stacking, significantly improving the compressive strength and overall rigidity of bone cement. The Schiff base bonds and cyclic disulfide bonds, as reversible dynamic covalent bonds, can achieve self-repair through bond exchange when damaged, improving the material's fatigue resistance and long-term mechanical stability, while also enhancing its redox response under physiological conditions. The long alkyl chain imparts flexibility and energy dissipation capacity, improving the material's toughness and preventing brittle fracture. The ester group promotes hydrogen bonding interactions between the reinforcing agent and the calcium phosphate matrix, enhancing interfacial bonding strength. This synergistic structure of "rigid core-dynamic bond-flexible chain" formed by these functional groups significantly improves the compressive strength, self-repair ability, and comprehensive mechanical properties of bone cement.

[0119] In Comparative Example 6, replacing α-lipoic acid in step A2 with an equimolar amount of 4-(methyldithioalkyl)butyric acid significantly reduced the compressive strength and self-healing properties of the bone cement. This is because 4-(methyldithioalkyl)butyric acid introduces open-chain asymmetric disulfide bonds. These open-chain disulfide bonds lack ring strain, and while the steric hindrance around the SS bonds is small, their exchange activity is significantly lower than that of cyclic disulfides. Consequently, the network cannot be rapidly reconstructed after material damage, resulting in a significant reduction in self-healing efficiency. Furthermore, open-chain asymmetric disulfide bonds exhibit higher thermal and chemical stability, but weakened dynamic reversibility, making it difficult to effectively dissipate stress concentration and increasing the material's susceptibility to brittle fracture.

[0120] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. An injectable bone cement, characterized in that, Including powders and liquids; The powder comprises the following components in parts by weight: 50-60 parts of complex calcium phosphate, 8-10 parts of chitosan, 5-10 parts of hydroxyapatite, 1-3 parts of antibacterial agent, 8-10 parts of modifier and reinforcing agent, and 3-7 parts of coagulation reaction regulator. The liquid comprises the following components in parts by weight: 20-30 parts phosphate buffer, 3-8 parts sodium citrate solution, and 1-5 parts hyaluronic acid solution; The antibacterial agent is prepared by the following method: S1: 2-(4-(dimethylamino)phenyl)ethane-1-thiol reacts with 10-bromo-1-decyl alcohol to form a quaternary ammonium salt compound. S2: Quaternary ammonium salt compounds react with methyl linoleate to form bisquaternary ammonium salt compounds. S3: A bisquaternary ammonium salt compound reacts with (3-propanoyl)triphenylphosphine bromide to form an antibacterial agent; The modified reinforcing agent is prepared by the following method: A1: 2',5'-Dimethoxy-[1,1':4',1''-terphenyl]-3,3'',5,5''-tetracarboxaldehyde reacts with 12-amino-1-dodecanool to form a four-armed compound. A2: The four-armed compound reacts with α-lipoic acid to generate a modified reinforcing agent.

2. The injectable bone cement according to claim 1, characterized in that, In step S1, the molar ratio of 2-(4-(dimethylamino)phenyl)ethane-1-thiol to 10-bromo-1-decanol is 1:(1.05-1.1).

3. The injectable bone cement according to claim 1, characterized in that, In step S2, the molar ratio of the quaternary ammonium salt compound to methyl linoleate is (2.02-2.08):

1.

4. The injectable bone cement according to claim 1, characterized in that, In step S3, the molar ratio of the bisquaternary ammonium salt compound to (3-propanoyl)triphenylphosphine bromide is 1:(2.05-2.1).

5. An injectable bone cement according to claim 1, characterized in that, In step A1, the molar ratio of 2',5'-dimethoxy-[1,1':4',1''-terphenyl]-3,3'',5,5''-tetracarboxaldehyde to 12-amino-1-dodecanool is 1:4.

05.

6. The injectable bone cement according to claim 1, characterized in that, In step A2, the molar ratio of the four-armed compound to α-lipoic acid is 1:4.

08.

7. The injectable bone cement according to claim 1, characterized in that, The composite calcium phosphate salt is a mixture of α-tricalcium phosphate and tetracalcium phosphate, with a mixing weight ratio of α-tricalcium phosphate to tetracalcium phosphate of 1:(0.2-0.5).

8. The injectable bone cement according to claim 1, characterized in that, The coagulation reaction regulator is one of calcium hydrogen phosphate or calcium carbonate.

9. A method for preparing injectable bone cement according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Weigh out the following by weight: 50-60 parts of compound calcium phosphate, 8-10 parts of chitosan, 5-10 parts of hydroxyapatite, 1-3 parts of antibacterial agent, 8-10 parts of modifier and reinforcing agent, 3-7 parts of coagulation reaction regulator; 20-30 parts of phosphate buffer, 3-8 parts of sodium citrate solution, and 1-5 parts of hyaluronic acid solution; (2) The composite calcium phosphate salt, chitosan, hydroxyapatite, antibacterial agent, modifier and coagulation reaction regulator are mixed in a three-dimensional mixer to obtain a powder; (3) Mix the phosphate buffer solution, sodium citrate solution and hyaluronic acid solution, and degas by sonication to obtain a liquid; (4) When using, mix the powder and liquid at a mass ratio of 1:0.8 and stir to obtain injectable bone cement.

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