Microwave assisted synthesis & properties of nano HA-TCP biphasic calcium phosphate

Biphasic calcium phosphate （BCP） nanopowders were synthesized by using microwave and non-microwave irradiation assisted processes. The synthesized powders were pressed under a pressure of 90 MPa, and then were sintered at 1000-1200℃ for 1 h. The mechanical properties of the samples were investigated. The formed phases and microstructures were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results showed that the synthesis time was shorter, along with a more homogeneous microstructure, when the microwave irradiation assisted method was applied. The compression strength and the Young＇s modulus of the samples synthesized with microwave irradiation were about 60 MPa and 3 GPa, but those of the samples synthesized without microwave irradiation were about 30 MPa and 2 GPa, respectively. XRD patterns of the microwave irradiation assisted and non-microwave irradiation assisted nanopowders showed the coexistence of hydroxyapatite （HA） and lricalcium phosphate （TCP） phases in the system.

Osteogenesis and Degradation Behavior of rhBMP-27/β-Tricalcium Phosphate Porous Composite Materials

Ultrafine-tricalcium phosphate(β-TCP)powders with good crystalline structure were produced by a new process through bone tissue engineering approach rorous β-TCPcermic was combined with recombined human bone morphogenetic proteins-2(rhBMP-2)to develop a novel composite material ,osteogenesis capacity of the composite was investigated intramuscularly in rat with histological analyses and SEM examination pureβ-TCP porous carmic wsa investigated as the control results show that the compostie materials possess good bilcompatibility biodegradation and strong osteogenesis capacity through inductive process after implantation material degradation began from 2 weeks post-implantation accompanying with the changing o pore structure with the enwrapping and separation fo materials by hyperplatic mesenchymal cells and fibroblast and with the phagocytose reaction of multinucleated giant cells early in 72h immature cartilage could be found within novel composite mature lamellar bone was induced to generate after 3 weeks with strong osteoinduction capacity and controlable bildegradation the novel rhBMP-2\β-TCP porous ceramic is expected to be a promising bone grafting substitute for bone tissue engineering

Hydroxyapatite/β-tricalcium Phosphate Composite for Guiding Bone Tissue Growth into a Titanium Tube in 8 mm Dog Tibia Cavity Defects

We developed a fixation method and evaluate bone regrowth in the cavities of a Ф4 mm× 8 mm titanium（Ti）tube through porous hydroxyapatite（HAP）/β-tricalcium phosphate（β-TCP）composite filling（group A）,chitosan/calcium phosphate composite filling（group B）,and HAP particle modification（group C）.After 2 and 5 months of implantation in dog tibia defects,new bone formation in the three groups was studied by histology and histomorphometry.Group A displayed the most bone regenerated area in both 2 and 5 months post-operation.The chitosan/calcium phosphate composite in group B mostly degraded 2 months after implantation,leading to fibrous tissue invasion after 5 months.By contrast,less bone formation was observed in group C.These results indicated that filling the cavities of metalprostheses with a porous HAP/β-TCP composite can be used for stable long-term fixation in clinicalsettings.

Three-dimensional printing of β-tricalcium phosphate/calcium silicate composite scaffolds for bone tissue engineering

Bioactive scaffolds with interconnected porous structures are essential for guiding cell growth and new bone formation. In this work, we successfully fabricated three-dimensional （3D） porous β-tricalcium phosphate （β-TCP）/calcium silicate （CS） composite scaffolds with different ratios by 3D printing technique and further investigated the physiochemical properties, in vitro apatite mineralization properties and degradability of porous β-TCP/CS scaffolds. Moreover, a series of in vitro cell experiments including the attachment, proliferation and osteogenic differentiation of mouse bone marrow stromal cells were conducted to testify their biological performances. The results showed that 3D printed β-TCP/CS scaffolds possessed of controllable internal porous structures and external shape. Furthermore, the introduction of CS decreased the shrinkage of scaffolds and improved the in vitro apatite formation activity and degradation rate. Meanwhile, compared with pure β- TCP scaffold, the β-TCP/CS composite scaffolds were more conducive to promote cell adhesion, spread and osteogenesis differentiation. However, when the content of CS was increased to 45%, the ions dissolution rate of the composite scaffolds was so high that leaded to the increase in pH value, which inhibited the proliferation of cells. Our results suggested that the introduction of appropriate CS into β-TCP bioceramic is an effective strategy to prepare bioactive 3D printed bioceramic scaffolds for hard tissue regeneration.

Microemulsion Synthesis of Mesoporous β-tricalcium Phosphate Powder with a Novel System

The synthesis of mesoporous β-tricalcium phosphate(β-TCP)powder was performed by using the microemulsion approach,with hexadecyltrimethyl ammonium bromide(CTAB)/cyclohexane/n-octyl alcohol microemulsion system.The influences of different pH values and calcination temperatures on the phase composition of the β-TCP powder were studied.The in vitro proliferation of bone marrow mesenchymal stem cells(BMSCs)in the suspensions of β-TCP powders with meso-structure was studied.The phase composition,mesoporous structure,powder morphology,cell morphology and the optical density(OD)were characterized through X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),Fourier transform infrared(FTIR)spectroscopy,Nadsorption-desorption isotherms,inverted phase contrast microscopy and Multiskan spectrum,respectively.The mesoporous β-TCP powder with specific surface area of 12.85 m^(2)/g and the average pore size 7.11 nm was obtained through the microemulsion approach(100 g/L CTAB/250 mL/L cyclohexane/250 mL/L n-octyl alcohol)with a controlled pH of 7.0,after calcinating the powder at 800℃.It was confirmed that mesoporous β-TCP powder benefits the activity of BMSCs more than the non-mesoporous β-TCP powder.

Local Application of Alendronate on <i>β</i>-Tricalcium Phosphate Accelerated Induction of Osteogenesis with Formation of Giant Osteoclast-Like Cell

Intrinsic osteoinductivity—the ability to induce bone formation in ectopic sites without addition of osteogenic factors has been reported in various porous materials. Tartrate-resistant acid phosphatase (TRAP)-positive osteoclast-like cells are thought to play an important role in material-induced osteoinduction. To investigate the influence of osteoclastic activity on intrinsic osteoinduction, we loaded alendronate (10–2 , 10–4 , and 10–6 M) onto porous β-tricalcium phosphate (β-TCP) blocks to inhibit osteoclastic activity, and evaluated osteoinductivity by implantation of the blocks into the dorsal muscles of adult beagle dogs. Alendronate-loaded porous β-TCP blocks increased both speed and amount of osteoinduction, as measured 4 weeks after implantation, with the 10–4 M alendronate-loaded β-TCP being especially active. This finding indicates that β-TCP loaded with 10–4 M alendronate might prove crucial in providing the desirable balance between the degradation rate of bone scaffolds and their osteoinductive replacement. Thus, material-induced osteoinduction may be controlled by local application of alendronate, establishing alendronate loading as a promising therapeutic approach.

Microstructure and mechanical properties analysis of β-tricalcium phosphate/carbon nanotubes scaffold based on rapid prototyping

β-TCP ceramic scaffolds were fabricated with selective laser sintering (SLS) in this work. Carbon nanotubes (CNTs) were mixed with porous β-TCP matrix to enhance the mechanical performance of the bone tissue engineering scaffolds. Scaffold reconstruction and microstructure analysis were fulfilled based on micro-computed tomography (Micro-CT) scanning data. Results show that the strength of scaffold mixed with 0.2% CNTs reaches 0.819 MPa which has been improved by 85.7% compared with that without CNTs. Micro-CT analysis shows that the scaffold has a good interconnectivity, and pore size mainly distributes in the two regions of 60-340 μm and 500-620 μm.

Preparation and properties of β-tricalcium phosphate porous bioceramic

Porous β-tricalcium phosphate bioceramic （PTCP） has important roles in surgical implants because of good biocompatibility. But the low compressive strength of the ceramic limits its application. The preparation of PTCP was improved with the adjustment of the constituents and the sintering-process. A new type of PTCP material with high compressive strength was made. The compositions, microstructure and properties of PTCP were analyzed by TG-DSC, XRD, TEM, SEM and so on. The result indicates that stearic acid burns sufficiently and gives out carbon dioxide and water vapor when slowly heated between 200 ℃ and 400 ℃ so that the porous structure like coral in β-TCP bioceramic is formed. Through crystallization at 470 ℃ and 570 ℃, more CaO-P2O5 glass-cement is converted into crystallite-glass, which is beneficial for improving the compressive strength of β-TCP bioceramic. PTCP can form a support action in bone imperfect section with good solubility.

Characterization of tricalcium phosphate solubilization by Stenotrophomonas maltophilia YC isolated from phosphate mines

The phosphate solubilizing characteristics of a strain YC, which was isolated from phosphate mines (Hubei, China), were studied in National Botanical Research Institute’s phosphate (NBRIP) growth medium containing tricalcium phosphate (TCP) as sole phosphorus (P) source. The strain YC is identified as Stenotrophomonas maltophilia (S. maltophilia) based upon the results of morphologic, physiological and biochemical characteristics and 16S rRNA sequences analysis. The results show that the strain S. maltophilia YC can solubilize TCP and release soluble P in NBRIP growth medium. A positive correlation between concentration of soluble P and population of the isolate and a negative correlation between concentration of soluble P and pH in the culture medium are observed from statistical analysis results. Moreover, gluconic acid is detected in the culture medium by HPLC analysis. It indicates that the isolate can release gluconic acid during the solubilizing experiment, which causes acidification of the culture medium and then TCP solubilization. S. maltophilia YC has a maximal TCP solubilizing capability when using maltose as carbon source and ammonium nitrate as nitrogen source, respectively, in NBRIP growth medium.

Synthesis of Biphasic Calcium Phosphate by Hydrothermal Route and Conversion to Porous Sintered Scaffold

Biphasic calcium phosphate (BCP) consisting of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) was successfully synthesized by new hydrothermal route using β-TCP as precursor. The X-ray diffraction analysis of as-synthesized powder indicated that β-TCP had been transformed into HA phase and amount of HA formed gradually increased with prolonged time. The results revealed that the recent technique may be able to control the composition of the obtained BCP which would influence the bioresorbability. Porous body of BCP was prepared by impregnation of polymeric sponge template with the slurry of the powder followed by sintering. The X-ray diffraction of porous product revealed that the composition of β-TCP increased after sintering indicating that HA had been decomposed. Porous BCP obtained from the recent technique possessed both macro and micropores structure which are useful for rapid tissue formation. Besides, the recent porous fabrication technique yielded porous BCP which preserved the sponge template morphology, enabling it to fabricate porous material with controlled pores structure.

Calcium Phosphate Biomaterials: An Update

Current calcium phosphate （ CaP ） biomaterials for bone repair, substitution, augmentation and regeneration include hydroxyapatite （ HA ） from synthetic or biologic origin, beta-tricaicium phosphate （ β- TCP ）, biphasic calcium phosphate （BCP）, and are available as granules, porous blocks, components of compashes （CaP/pollymer） cements, and as coatings on orthopedic and dental implants. Experimental calcium phosphate biomaterials include CO3^- and F-substituted apatites, Mg-and Zn-substituted β-TCP, calcium phosphate glasses, This paper is a brief review of the different types of CaP biomaterials and their properties such as bioactivity , osteoconductivity , osteoinductivity.

Comparison between Two Different Manufactured Forms of β-Tricalcium Phosphate Bone Graft in Immediate Implant Placement

Objectives: The aim of this study was to compare the efficacy of using the synthetic β-TCP bone grafting material in two different manufacturing forms (putty and granular) in grafting the jumping zone around immediate implant. Patients and Method: A randomized controlled clinical and radiographic trial was conducted on 24 male patients aged from 45 - 55 with badly decayed non-restorable teeth in the posterior mandibular area and seeking for receiving immediate dental implant directly after extraction. Vertical bone height and bone density were taken at time of implant placement and 6 months postoperatively. Results: The Putty form group and the Granular form group did not differ statistically in terms of age, post-operative complications, or implant outcome six months postoperatively. Additionally, there was a statistically significant increase in Putty form group compared to the Granular form group regarding Marginal bone loss 6 months postoperatively, but there was no statistically significant difference between the Putty form group and the Granular form group regarding Bone density by CBCT. Conclusion: The β-TCP Putty material, compared to β-TCP granular, displayed better surgical handling properties, and both forms had no adverse effect on bone formation, bone tissue maturation or graft volume stability, The β-TCP granular material, compared to β-TCP putty, displayed less marginal bone loss 6 months post-operatively.

α-TCP水化生成羟基磷灰石机理及其应用研究进展

介绍了α-TCP水化反应热力学基础及动力学模型,总结了原料粒度、水化温度、水化初始pH值等因素对α-TCP水化反应的影响;综述了α-TCP在制备骨水泥、羟基磷灰石晶须等方面的应用;提出了利用α-TCP水化反应,通过控制水化初始pH值等因素,制备羟基磷灰石晶须原位增强的磷酸钙基生物材料的设想。

HA/β-TCP双相磷酸钙陶瓷材料的生物学性能研究

研究了双相磷酸钙陶瓷在SBF中类骨磷灰石的形成,采用小鼠骨骼肌母细胞C2C12细胞系和HA/β-TCP复合培养,通过细胞增殖实验,电镜和荧光染色法观察并实施动物肌肉内植入实验,得出:材料在SBF中浸泡后有利于类骨磷灰石的沉积。细胞在HA/β-TCP支架材料上生长良好。对HA/β-TCP进行细胞毒性评价,与阴性对照组比较,样品不抑制细胞增殖,表现出良好的生物相容性。HA/β-TCP支架材料能促进细胞的增殖。动物实验表明,在体内HA/β-TCP有很好的骨形成能力。因此,实验制备的HA/β-TCP支架材料有良好的生物学性能。

煅烧牛松质骨制备β-TCP/HAP/Ca_2P_2O_7多孔陶瓷反应机制研究

以牛松质骨(CBB)为原料,经过系列脱脂处理,采用低温煅烧工艺,通过调整浸泡溶液NH4H2PO4浓度及煅烧温度等工艺参数,制备出具有天然骨多孔结构的β-TCP/HAP/Ca2P2O7多相生物陶瓷材料。利用X射线衍射分析对煅烧产物的相组成进行表征,采用FTIR、TG对反应机制进行探讨。结果表明:浸泡溶液NH4H2PO4浓度对制备的样品相组成具有重要影响,通过合理控制NH4H2PO4浸泡溶液浓度,可以获得不同相组成的多孔生物陶瓷材料。煅烧产物的相组成主要受到HAP分解的OH-量(x)和与NH4H2PO4反应的OH-的量(3m)影响,当x>3m时,煅烧产物含有β-TCP与HAP两相;当x=3m时,煅烧产物为纯相β-TCP;x<3m时,煅烧产物含有β-TCP、Ca2P2O7和HAP或β-TCP和Ca2P2O7。

新型聚乳酸/β-磷酸三钙(PLLA/β-TCP)多孔支架材料的性能研究

选择含有70%β-磷酸三钙加入聚乳酸中,致孔剂含量为70%(质量分数),制作成孔径为200～400μm的复合多孔支架材料,将其压成直径为5 mm、高为5 mm的圆柱体形状。将大鼠的骨髓间充质干细胞(BMSCs,Bone Mesenchymal Stem Cells)经过体外分离培养、传代诱导后,与多孔聚乳酸/β-磷酸三钙支架材料在培养板内共同培养1、3、5、7、10、14 d。采用扫描电镜观察、MTT法及ALP检测试剂盒等方法检测BMSCs在材料表面的粘附、增殖和分化能力。检测结果显示:BMSCs能在该支架材料表面早期粘附和增殖,在体外共同培养时BMSCs大量增殖后维持其碱性磷酸酶活性。此种方法制造的多孔聚乳酸/β-磷酸三钙复合支架材料有望成为组织工程骨支架材料。

多孔β-TCP生物陶瓷骨内植入后的显微红外光谱

磷酸三钙（β－ＴＣＰ）生物陶瓷植入兔股骨后植入生物陶瓷、界面和兔股骨的显微红外光谱，对其红外特征频率作了指认和归属。在植入生物陶瓷和界面的红外光谱中，骨骼矿物相（或磷酸钙），胶原，蛋白质和脂类（或磷脂）的红外特征频率同时出现，它们与股骨的红外光谱非常相似，其结果与拉曼光谱相互吻合，相互补充。这些光谱数据为揭示β－ＴＣＰ生物陶瓷的生物降解和新骨生成机理提供了大量分子信息和证据，从而证明生物陶瓷骨内植入后不仅陶瓷本身已部分溶解和降解而且在植入陶瓷的表面和孔隙中以及界面处均已生成新生骨组织。

3D打印β-TCP多孔复合支架的力学和生物学特性

目的研究3D打印β磷酸三钙[β-Ca3（PO4）2,β-TCP]多孔复合支架的力学和生物学特性,为进一步动物实验中复合支架的设计提供指导。方法用新型可降解材料聚柠檬酸-1,8-辛二醇酯[poly（1,8-octanediol citrate）,POC]为粘合剂,采用熔融成型（fused deposition modeling,FDM）技术实现β-TCP支架的3D打印,并用多肽甘氨酸-精氨酸-甘氨酸-天冬氨酸-丝氨酸（Gly-Arg-Gly-Asp-Ser,GRGDS）对复合支架修饰,以改善复合支架的细胞黏附性。使用光学显微镜和扫描电镜观察复合支架的微观孔隙结构,使用材料试验机对复合支架进行压缩测试,并测量支架的水表面接触角;通过体外细胞实验检测支架的细胞黏附率和促细胞增殖能力;利用支架修复SD大鼠颅骨缺损模型,进一步研究其体内成骨能力。结果多肽在复合支架上均匀分布且不失活;复合多肽后支架的微观孔隙结构发生改变,细胞黏附率提高,但支架压缩模量、水表面接触角和体内成骨能力等特性未受明显影响。结论多肽修饰后的β-TCP多孔复合支架细胞黏附能力明显改善,而力学、亲水性和体内成骨能力等未受明显影响。研究结果为临床骨缺损修复支架的构建提供新思路,也为该支架技术的进一步临床应用提供实验室依据。

成骨诱导的大鼠骨髓间充质干细胞与不同比例的β-TCP/PLLA支架材料复合的研究

种子细胞、支架材料及二者的相互作用是骨组织工程需要解决的三大问题。骨髓间充质干细胞(Mesenchym al stem cells,MSCs)是一种很有潜力的种子细胞,但挑选什么样的MSCs作为种子细胞目前研究尚少;而材料方面,研制力学性能和生物相容性均好的可降解多孔支架材料一直是研究者努力的方向。为了挑选处于最佳时期的种子细胞以及最适比例的β- TCP/PL L A多孔支架材料,我们观察并检测了大鼠MSCs(r MSCs)成骨诱导后不同时期细胞的形态及功能,发现r MSCs成骨诱导后10 d左右开始进入增殖期,14 d左右进入基质合成期,2 0 d左右进入矿化结节期(但三者不是截然分开的) ,从而根据实验目的挑选出能作为骨组织工程用的最佳细胞。将该时期的种子细胞与不同比例的β- TCP/PL L A多孔支架材料复合后,通过荧光显微镜、扫描电镜以及MTT等方法初步比较了不同比例的材料对细胞生长状况的影响,结果显示不同比例的材料均具有一定的生物相容性,细胞生长良好。但以β- TCP/PL L A=2∶1的材料最好,对细胞的生长影响最小。