骨碎补载入对磷酸钙骨水泥性能的影响及体外生物学评价

通过在湿法合成的二水磷酸氢钙膏体中加入中药骨碎补的提取物, 作为磷酸钙骨水泥(Calcium Phosphate Cement,CPC)原料之一, 分别制备0、5wt%、10wt%和15wt%的载骨碎补磷酸钙骨水泥. 采用Gilmore针、X射线衍射仪、红外光谱仪、万能材料试验机、扫描电子显微镜和紫外分光光度计研究载骨碎补CPC的理化性能和药物释放; 体外培养MC-3T3成骨细胞, 进行Alamar Blue和碱性磷酸酶检测, 研究载骨碎补CPC对成骨细胞增殖和分化的影响, 扫描电子显微镜观察细胞形貌. 结果表明: 随骨碎补浓度的增加, CPC凝结时间明显延长, 其抗压强度显著提高; 骨碎补促进初期CPC的水化, 却阻碍了α-磷酸三钙的转化, 且随骨碎补浓度增大作用愈明显, 骨碎补不影响CPC水化后的相成分; 含骨碎补CPC的微观形貌中出现片状和针状晶体, 结构较空白CPC更加致密; 药物释放分为突释和缓释两个阶段, 符合Higuchi基质扩散释放模型; 载骨碎补CPC对成骨细胞的作用呈剂量和时间依赖关系, 培养5d时浓度为5wt%和10wt%的CPC较明显地促进细胞增殖, 7d时载骨碎补CPC的细胞增殖较稳定, 细胞分化能力无显著性差异; 成骨细胞在载骨碎补CPC表面生长形态良好, 表明该材料具有较好的生物相容性.     

载香丹磷酸氢钙的研究

研究了湿法合成对香丹和磷酸氢钙的影响,以及温度和香丹添加量对磷酸氢钙载药量的影响.结果表明,湿法合成对香丹和磷酸钙氢钙均无明显影响,温度对香丹载入量影响较小,香丹载入量与合成体系中香丹添加量成正比.通过湿法合成制备载不同浓度香丹磷酸氢钙具有可行性.     

药物对磷酸钙骨水泥性能的影响综述

药物载入磷酸钙骨水泥(CPC)可能会导致CPC凝结时间、力学性能等发生变化.难溶于水的药物与CPC接触形成的固-固界面相互间作用较弱,在载入量不太高时对CPC凝结时间、力学性能影响较小.而易溶于水的药物则可能导致CPC界面性质、酸碱性、转化过程等发生变化,从而时CPC凝结时间、力学性能等产生影响.CPC凝结时间和力学性能分别是衡量手术可操作性的重要指标和决定CPC应用范围的重要参数,就药物载入后对CPC凝结时间、力学性能的影响进行了综述.     

纳米晶体纤维素增强磷酸钙骨水泥的研究

本研究探索具有良好力学性能的纳米晶体纤维素(NCC)对磷酸钙骨水泥(CPC)抗压强度的影响。采用万能力学试验机、Gilmore双针、X射线衍射仪(XRD)和X射线光电子能谱仪(XPS)表征含不同NCC的CPC理化性能; 利用扫描电子显微镜(SEM)和荧光显微镜观察CPC断面形貌和荧光标记的NCC在CPC中的分散。抗压强度结果表明: NCC能显著提高CPC的抗压强度, 且2% NCC-CPC的抗压强度最高, 约为27 MPa; CPC的凝固时间随NCC含量的增加而延长, 含量为2%时基本符合临床要求; XRD和XPS结果显示NCC与Ca²⁺形成不稳定的配合物, 促进了CPC中二水磷酸氢钙(DCPD)和CaCO₃的溶解和转化; SEM观察结果显示加入NCC使CPC内部结构更致密, 孔隙和裂纹减少; 荧光显微观察结果表明NCC在CPC中均匀分散。     

磷酸钙骨水泥负载庆大霉素的制备与性能

制备了庆大霉素、磷酸钙骨水泥药物缓释体系,研究了药物缓释效果及载入庆大霉素对骨水泥组成、结构与性能的影响.结果表明,庆大霉素、磷酸钙骨水泥体系具有良好的药物缓释效果;随着庆大霉素的载入,骨水泥的凝结时间延长,但当载入量达到5%时,骨水泥的凝结时间又缩短至15 min,继续增大药物含量,凝结时间又略有延长.低载药量(1%)时骨水泥的抗压强度有所提高,但再继续增大载药量,体系的抗压强度又逐渐下降.庆大霉素的加入对骨水泥的最终水化产物没有明显影响,水化产物都是弱结晶的羟基磷灰石.庆大霉素的载入量为3%～5%时,庆大霉素/磷酸钙骨水泥缓释体系具有最佳的综合性能.     

载黄芪多糖羟基磷灰石的制备及生物学性能评价

室温湿法合成载不同浓度黄芪多糖(APS)的羟基磷灰石(HA/APS), 通过X射线衍射(XRD)表征APS对HA晶体结构、结晶度及晶粒尺寸的影响; 用透射电子显微镜(TEM)表征HA和HA/APS的晶体形貌, 用激光粒度仪和比表面积仪分别检测HA的粒度及比表面积;体外培养MC3T3-E1成骨细胞, 进行Alamar Blue、噻唑蓝(MTT)及碱性磷酸酶(ALP)检测, 光镜观察细胞形貌, 研究APS对成骨细胞作用的有效浓度范围及HA/APS对成骨细胞活性及分化的影响. 结果表明: 所载APS对HA晶体结构、结晶度和晶粒尺寸没有明显影响, 晶体形貌没有变化, HA平均粒径为1.17 μm, 比表面积为132.194 m²/g;APS对成骨细胞的作用呈剂量和时间依赖关系, 80~200 μg/mL促进细胞活性及ALP表达, HA/APS增强细胞活性, 细胞形貌完整. 因此, 0.5 g HA载入100~250 μg APS时明显促进成骨细胞活性, HA/APS具有作为临床骨缺损填充材料的潜能.     

提高磷酸钙骨水泥抗压强度的方法及相关机理

抗压强度是评价骨填充材料性能优劣的主要因素之一。作为骨填充材料的磷酸钙骨水泥(CPC),较低的抗压强度限制了其应用。为拓展CPC的应用范围,研究者们采用多种方法提高其抗压强度,如增强CPC颗粒之间的键接,改变晶体微观形貌、结晶度、孔隙率、孔隙特征等。就各种提高CPC抗压强度的方法及相关机理进行综述。     

柠檬酸浓度对硼酸盐玻璃骨水泥性能的影响

以壳聚糖-甘油磷酸钠-柠檬酸溶液为液相, 制备了一种新型可注射的硼酸盐玻璃骨水泥, 通过维卡仪、万能试验机、XRD、FTIR、SEM-EDS等探究了液相中柠檬酸浓度(0.1, 0.2和0.4 g/mL)对硼酸盐玻璃骨水泥性能的影响。结果表明: 柠檬酸浓度显著影响骨水泥的凝结时间和可注射性。柠檬酸浓度为0.2 g/mL时获得的骨水泥的凝结时间最短, 为(16±0.5) min; 可注射性最好, 接近100%。骨水泥压缩强度随柠檬酸浓度增大而增强, 最大可达(26.7±1.9) MPa。SEM照片显示骨水泥中生成了许多纳米微粒。XRD、FTIR和EDS等结果证明, 这些纳米微粒主要是硼酸盐、磷酸盐和柠檬酸盐等物质, 而且柠檬酸浓度能够影响骨水泥中硼酸盐晶体的形成。此外, 柠檬酸能够加速玻璃颗粒在磷酸钠盐缓冲液中的降解速率。     

含锶磷酸钙骨水泥的制备及性能研究

通过混合磷酸四钙、磷酸氢钙、磷酸氢锶及稀磷酸制备了一种含锶磷酸钙骨水泥(Sr-CPC),研究了水泥固/液比、含锶量及仿生浸泡时间对其结构组态及抗压强度的影响.结果表明,不同组分的CPC在调和浆体时均存在最佳固/液比,且对应的凝结时间适合临床手术要求;Sr-CPC试样在模拟体液(SBF)中浸泡24h后固化产物为含锶缺钙羟基磷灰石;适量锶的加入及较短时间仿生浸泡均可显著改善Sr-CPC固化体的抗压强度,并且浸泡过程对固化体抗压强度的影响主要体现在其微观结构的变化.     

聚乳酸/杆菌肽静电纺丝纤维的体外释药研究

为探讨聚乳酸纤维结构形貌对杆菌肽药物的缓慢释放行为及作用机理,通过静电纺丝法制备了聚乳酸/杆菌肽单轴纤维、聚乳酸/杆菌肽串珠和(聚乳酸/杆菌肽)-聚乳酸同轴核-壳纤维等聚乳酸/杆菌肽药物缓释体系,并采用红外光谱法和差热分析法对其化学结构和热性能进行了表征.利用紫外分光光度计法研究了不同载药体系的体外药物释放行为,并探索了不同降解时期载药纤维的质量和形貌变化规律.研究表明:杆菌肽与聚乳酸主要为物理结合;聚乳酸单轴纤维和串珠对杆菌肽的扩散释放机理,属于纯Fick扩散;采用单轴和同轴静电纺丝技术可以获得两种不同释药特性的载药纤维.单轴纤维和串珠能够将药物快速释放,适合抗生素的治疗;同轴纤维中药物受控释放,更适合长期、小剂量的药物释放.     

Addition of sodium hyaluronate and the effect on performance of the injectable calcium phosphate cement

An injectable calcium phosphate cement (CPC) with porous structure and excellent anti-washout ability was developed in the study. Citric acid and sodium bicarbonate were added into the CPC powder consisting of tetracalcium phosphate (TTCP) and dicalcium phosphate dihydrate (DCPD) to form macro-pores, then different concentrations of sodium hyaluronate (NaHA) solution, as liquid phase, was added into the cement to investigate its effect on CPC’s performance. The prepared CPCs were tested on workability (injectable time and setting time), mechanical strength, as well as anti-washout ability. The experimental results showed that addition of NaHA not only enhanced the anti-washout ability of the CPC dramatically but also improve its other properties. When NaHA concentration was 0.6 wt%, the injectable time elongated to 15.7 ± 0.6 min, the initial and final setting times were respectively shorten to 18.3 ± 1.2 and 58.7 ± 2.1 min, and the compressive strength were increased to 18.78 ± 1.83 MPa. On the other hand, Addition of NaHA showed little effect on porous structure of the CPC and enhanced its bioactivity obviously, which was confirmed by the apatite formation on its surface after immersion in simulated body fluid (SBF). In conclusion, as an in situ shaped injectable biomaterials, the CPC with appropriate addition of NaHA would notably improve its performance and might be used in minimal invasive surgery for bone repair or reconstruction.     

Porous calcium phosphate ceramics prepared by coating polyurethane foams with calcium phosphate cements

Porous calcium phosphates have important biomedical applications such as bone defect fillers, tissue engineering scaffolds and drug delivery systems. While a number of methods to produce the porous calcium phosphate ceramics have been reported, this study aimed to develop a new fabrication method. The new method involved the use of polyurethane foams to produce highly porous calcium phosphate cements (CPCs). By firing the porous CPCs at 1200 °C, the polyurethane foams were burnt off and the CPCs prepared at room temperature were converted into sintered porous hydroxyapatite (HA)-based calcium phosphate ceramics. The sintered porous calcium phosphate ceramics could then be coated with a layer of the CPC at room temperature, resulting in high porosity, high pore interconnectivity and controlled pore size.     

机械活化增强多孔磷酸钙骨水泥支架的研究

本研究采用球磨对磷酸钙骨水泥(CPC)起始粉末进行机械活化处理, 以期改善CPC力学性能, 并探讨了其影响机理。采用激光粒度仪、比表面积测量仪和X射线衍射仪(XRD)表征球磨后的CPC粉末(Ball milling CPC, BCPC)。利用发泡法制备多孔BCPC支架, 采用万能力学试验机、XRD和扫描电子显微镜(SEM)表征多孔BCPC支架。结果显示, 球磨后的BCPC粉末平均粒径减小, 比表面积增大, 表观密度、堆积密度及紧密密度减小。BCPC支架孔隙率为(77.98 ± 0.58)%, 抗压强度为(4.11 ± 0.46) MPa, 相比CPC支架的(64.23 ± 2.32)%和(1.99 ± 0.43) MPa有显著提高。SEM结果显示BCPC支架具有数微米和数百微米的两种孔隙结构。XRD结果表明机械活化作用降低了DCPD、α-TCP、CaCO₃和HA的晶粒尺寸和结晶度, 促使DCPD向DCPA转化, 促进了各相磷酸钙盐的水化和HA的沉积, 提高了BCPC支架的力学性能, 为增强CaP基多孔材料的力学性能和扩展其临床应用提供了新途径。     

Calcium phosphate bone cements

The principles of developing calcium phosphate cements (CPCs) for replacement and regeneration of bone tissue are considered. The basic classification of CPCs is given according to the phase composition of the reaction products in the setting systems. Processes of phase composition and development of microstructure and properties are discussed. Injectable CPC compositions are considered, and the factors affecting the injectability, as well as the ways to modify the cement pastes to improve their properties, are discussed. The results of research and development in the field of composite CPCs, including those reinforced by disperse phases, are described. In the final part of the review, some data on commercial CPCs and their biological behavior are presented.     

Physicochemical properties and release characteristics of growth factor‐modified calcium phosphate bone cement

The addition of growth factors, such as recombinant human transforming growth factor‐β1 (rhTGF‐β1) to calcium phosphate cements (CPCs) may improve bone regeneration. Previously we have shown that the differentiation of pre‐osteoblastic cells from adult rat long bones was stimulated by rhTGF‐β1 in CPC. CPC that was intermixed with rhTGF‐β1 and then applied in rat calvarial defects enhanced bone growth around the cement and increased the degradation of the cement. It is still unknown however whether the addition of rhTGF‐β1 changes the material properties of the CPC, and what the release characteristics are of rhTGF‐β1 from the CPC. We therefore determined here the release of rhTGF‐β1 in vitro from the cement pellets as implanted in the rat calvariae. The possible intervening effects of rhTGF‐β1‐intermixing on clinical compliance of CPC were studied by assessing its compressive strength and setting time, as well as crystallinity, calcium to phosphorus ratio, porosity and microscopic structure. CPC was prepared by mixing calcium phosphate powder (58% α‐tricalcium‐phosphate, 25% dicalcium‐phosphate anhydrous, 8.5% calcium‐carbonate and 8.5% hydroxyapatite), with liquid (3 g/ml). The liquid for standard CPC consisted of water with 4% sodium hydrogen phosphate, while the liquid for modified CPC, was mixed with an equal amount of 4 mM hydrochloride with 0.2% bovine serum albumin. The hydrochloride liquid contained the rhTGF‐β1 in different concentrations for the release experiments. Most of the incorporated rhTGF‐β1 in the cement pellets was released within the first 48 hr. Approximately 0.5% rhTGF‐β1 (intermixed at 100 ng to 2.5 mg/g CPC) was released within the first 4 hr increasing to 1% after 48 hr. rhTGF‐β1 release continued at 0.1% up to at least 8 weeks. Modification of CPC slightly increased the initial setting time at 20°C from 2.6 to 5 min, but did not affect the final setting time of the CPC at 20°C, nor the initial and final setting time at 37°C. The compressive strength was increased from 18 MPa (standard CPC) to 28 MPa (modified CPC) only at 4 hr after mixing. The compressive strength diminished in the modified CPC between 24 hr and 8 weeks from 55 to 25 MPa. X‐ray diffraction revealed that both standard and modified CPC changed similarly from the basic components, alpha‐tri‐calcium phosphate and dicalcium phosphate anhydrous, into an apatite cement. The calcium to phosphorus ratio as determined by an electron microprobe did not differ for standard CPC and modified CPC. Standard and modified CPC became a dense and homogeneous structure after 24 hr, but the modified CPC contained more crystal plaques compared to the standard CPC, as observed by scanning electron microscopy (SEM). SEM and back scattered electron images revealed that after 8 weeks both cements showed an equally and uniform dense structure with microscopic pores (less than 1 μm). Both CPCs showed fewer crystal plaques at 8 weeks than at 24 hr. This study shows that the calcium phosphate cement was not severely changed by modification of the CPC for rhTGF‐β1. Clinical handling may be affected by the prolonged setting time of modified cement, but it is still within preferable limits. Compressive strength was for both standard and modified cements within the range of thin trabecular bone, and therefore both CPCs can withstand equal mechanical loading. The faster diminishing compressive strength of modified cement (from 24 hr to 8 weeks) likely results in early breakdown, and therefore might be favourable for bone regeneration. Together with our previous studies showing the beneficial effects of adding rhTGF‐β1 to CPC on bone regeneration, we conclude that the envisaged applications for CPC in bone defects are upgraded by intermixing of rhTGF‐β1. Therefore the combination of CPC with rhTGF‐β1 forms a promising synthetic bone graft.     

Apatite bone cement reinforced with calcium silicate fibers

Several research efforts have been made in the attempt to reinforce calcium phosphate cements (CPCs) with polymeric and carbon fibers. Due to their low compatibility with the cement matrix, results were not satisfactory. In this context, calcium silicate fibers (CaSiO₃) may be an alternative material to overcome the main drawback of reinforced CPCs since, despite of their good mechanical properties, they may interact chemically with the CPC matrix. In this work CaSiO₃ fibers, with aspect ratio of 9.6, were synthesized by a reactive molten salt synthesis and used as reinforcement in apatite cement. 5 wt.% of reinforcement addition has increased the compressive strength of the CPC by 250 % (from 14.5 to 50.4 MPa) without preventing the cement to set. Ca and Si release in samples containing fibers could be explained by CaSiO₃ partial hydrolysis which leads to a quick increase in Ca concentration and in silica gel precipitation. The latter may be responsible for apatite precipitation in needle like form during cement setting reaction. The material developed presents potential properties to be employed in bone repair treatment.     

An Octacalcium Phosphate Forming Cement

The osteoconductive and possibly osteoinductive characteristics of OCP increased the interest in preparation of bone graft materials that contain OCP in its composition. Calcium phosphate cements (CPCs) were prepared using a mixture of α-tricalcium phosphate (α-TCP) and dicalcium phosphate anhydrous (DCPA), with α-TCP / DCPA molar ratio of 1/1 and distilled water or 0.5 mol / L phosphate aqueous solution (pH = 6.1 ± 0.1) as the cement liquid. Hardening time was (30 ± 1) min for the CPC mixed with water and (5 ± 1) min for the CPC mixed with phosphate solution. Diametral tensile strength (DTS), porosity (P), and phase composition (powder x-ray diffraction) were determined after the hardened specimens had been immersed in a physiological-like solution (PLS) for 1 d, 3 d, and 7 d. In CPC specimens prepared with water, calcium hydroxyapatite (HA) was formed and DTS and P were (9.03 ± 0.48) MPa and (37.05 ± 0.20) vol % after 1 d, respectively, and (9.15 ± 0.45) MPa and (37.24 ± 0.63) vol % after 3 d, respectively. In CPC specimens prepared with phosphate solution OCP and HA were formed and DTS and P were (4.38 ± 0.49) MPa and (41.44 ± 1.25) vol % after 1 d, respectively,(4.38 ± 0.29) MPa and (42.52 ± 2.15) vol % after 3 d, respectively, and (4.30 ± 0.60) MPa and (41.38 ± 1.65) vol % after 7 d, respectively. For each group DTS and P did not change with PLS immersion time. DTS was significantly higher and P was significantly lower for CPCs prepared with water. HA formation slightly increased with immersion time from 40 mass % after 1 d to 50 mass % after 3 d in CPCs prepared with water. OCP + HA formation increased with immersion time from 30 mass % after 1 d to 35 mass % after 3 d and to 45 mass % after 7 d in CPCs prepared with 0.5 mol / L phosphate solution.     

Alginate combined calcium phosphate cements: mechanical properties and in vitro rat bone marrow stromal cell responses

Here, we prepared self-setting calcium phosphate cements (CPCs) based on α-tricalcium phosphate with the incorporation of sodium alginate, and their mechanical properties and in vitro cellular responses were investigated. The addition of alginate enhanced the hardening reaction of CPCs showing shorter setting times within a range of powder-to-liquid ratios. When immersed in a body simulating fluid the alginate-CPCs fully induced a formation of an apatite crystalline phase similar to that of bare CPCs. The compressive and tensile strengths of the CPCs were found to greatly improve during immersion in the fluid, and this improvement was more pronounced in the alginate-CPCs. As a result, the alginate-CPCs retained significantly higher strength values than the bare CPCs after 3–7 days of immersion. The rat bone marrow derived stromal cells (rBMSCs) cultured on the alginate-CPCs initially adhered to and then spread well on the cements surface, showed an on-going increase in the population with culture time, and differentiated into osteoblasts expressing bone-associated genes (collagen type I, osteopontin and bone sialoprotein) and synthesizing alkaline phosphatase. However, the stimulated level of osteogenic differentiation was not confirmative with the incorporation of alginate into the CPC composition based on the results. One merit of the use of alginate was its usefulness in forming CPCs into a variety of scaffold shapes including microspheres and fibers, which is associated with the cross-link of alginate under the calcium-containing solution.