Surface-modified Biphasic Calcium Phosphate/Poly (L-lactide) Biocomposite

Biphasic calcium phosphate （BCP） powders were prepared by hydrolyzation proc-ess and surface-modified by directly grafted L-lactide （LLA） onto the surface of BCP through a chemical linkage. The grafting ratio of organic groups was 9 wt%. After surface modification, the surface of BCP powders was covered by the lamella-shaped crystal. Poly （L-lactide） was mixed with BCP to form the BCP/PLLA biocomposite. Modified BCP （mBCP） particles could be uniformly dis-persed in PLLA matrix. The compressive strength of the mBCP/PLLA composite is 115 MPa, 28% higher than that of unmodified-BCP/PLLA composite. The improved mechanical strength is attributed to the enhanced adhesion between the inorganic BCP filler and the organic PLLA matrix.

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.

Effect of Magnesium on the Mechanical and Bioactive Properties of Biphasic Calcium Phosphate

Incorporation of trace elements into calcium phosphate structure is of great interest for the development of artificial bone implants. Biphasic calcium phosphate (BCP) composed of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) have been synthesized in the presence of magnesium (5 M% - 20 M%) by gel method under physiological conditions. Crystallization of Mg-BCP in the gel medium mimics the Mg intake in the human body. Powder X-ray dif- fraction and Fourier transform infrared analyses confirmed that the Mg doping leads to the enrichment of β-TCP phase and suppresses the HA content in BCP. Nanoindentation studies indicate a significant decrease in hardness and elastic modulus values of BCP due to Mg doping. In vitro bioactivity study has confirmed the formation of apatite layer on the Mg doped samples making it suitable for bone replacement. The results suggest that the optimum Mg doping promotes the bioactivity which is perquisite for biomedical applications.

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.

Graphene oxide coated three-dimensional printed biphasic calcium phosphate scaffold for angiogenic and osteogenic synergy in repairing critical-size bone defect

The custom-tailored medicine requires a developmental strategy that integrates excellent osteogene-sis with mechanical stability to enhance the reconstruction of the critical-size bone defect(CSBD)and the healing process in weight-bearing bone.We prepared three-dimensional(3D)printed biphasic cal-cium phosphate(BCP)scaffolds composited with nano-graphene oxide(GO).The biological effects of the GO/BCP composite scaffolds could induce the differentiation of rat bone marrow stem cells(BM-SCs)and the migration of human umbilical vein endothelial cells(HUVECs)for bone repair.The proper ratio of GO in the composite scaffold regulated the composites’surface roughness and hydrophilicity to a suitable range for the adhesion and proliferation of BMSCs and HUVECs.Besides,the GO/BCP composite scaffold increased osteogenesis and angiogenesis by activating BMP-2,RUNX-2,Smad1/4,and VEGF.The customized intramedullary nail combined with GO/BCP scaffold was applied to repair CSBD(2.0 cm in length)in a beagle femur model.This fixation strategy was confirmed by finite element analysis.In vivo,the results indicated that the custom-made internal fixation provided sufficient stability in the early stage,ensuring bone healing in a considerable mechanical environment.At 9 months postoperatively,longitudi-nal bony union and blood vessels in osteon were observed in the CSBD area with partial degradation in the 0.3%GO/BCP group.In the three-point bending test,the ultimate load of 0.3%GO/BCP group reached over 50%of the normal femur at 9 months after repair.These results showed a promising application of osteogenic GO/BCP scaffold and custom-made intramedullary nails in repairing CSBD of the beagle femur.This effective strategy could provide an option to treat the clinical CSBD in weight-bearing bones.

Biocompatibility of Surface-Modified Biphasic Calcium Phosphate/Poly-L-Lactide Biocomposite in vitro and in vivo

The biocompatibility of surface-modified biphasic calcium phosphate （mBCP）/poly-L-Lactide （PLLA） biocomposite was investigated through a series of experiments in vitro and in vivo. Acute toxicity and short term systemic toxicity experiments revealed no toxicity of the materials. Hemolysis assay indicated the good blood compatibility of the composite. In cytotoxicity assay, L929 mouse fibroblasts could well differentiate and proliferate. Animal experiments in vivo were.performed by implanting the materials into rabbits muscle for 8 weeks. The decreasing of inflammatory cells, the building of fibrous tissue layer as well as the growing of blood cells into materials indicated the nontoxicity of the composite. Based on the experiment results, surfacemodified BCP/PLLA biocomposite is proven to have superior biocompatibility, which would be a promising bone repairing material.

Synergistic effects of Mg-substitution and particle size of chicken eggshells on hydrothermal synthesis of biphasic calcium phosphate nanocrystals

Magnesium(Mg^2+))ion plays important roles in biomineralization of bone,teeth and calcium carbonate skeletons.Herein,chicken eggshells mainly comprising of Mg-calcite nanocrystals(Mg/(Mg+Ca)2.0 mol.%)were used to fabricate biphasic calcium phosphate(BCP),a mixture of hydroxyapatite(HA)and p-tricalcium phosphate(p-TCP)nanocrystals,through hydrothermal reactions at 200℃for 24 h.Our results indicated thatβ-TCP nanocrystals formed through the ion-exchange reactions of Mg-calcite,while HA nanocrystals were mainly produced by dissolution-reprecipitation reactions on the surfaces of eggshell samples in the hydrothermal system.Mg substitution in calcite resulted in formation ofβ-TCP nanocrystals instead of HA crystals through ion-exchange reactions.BCP samples with different compositions(28.6-77.8 wt.%β-TCP)were produced by controlling particle sizes of eggshells for hydrothermal reactions.The larger particles lead to the larger proportion ofβ-TCP in the BCP composition.Therefore,Mg substitution and particle size had synergetic effects on the hydrothermal synthesis of BCP using chicken eggshells through balance of ion-exchange and dissolution-reprecipitation reactions.Cell culture results showed that the BCP products were non-cytotoxic to MC3 T3-E1 cells,which may be used for bone substitute materials in future.

Degradation and biological performance of porous osteomimetic biphasic calcium phosphate in vitro and in vivo

The combination between biphasic calcium phosphate(BCP)and the osteomimetic porous microstructure obtained via freeze casting is hoped to achieve excellent bone regeneration,while the effects of HA and b-TCP ratio changes on the degradation and biological performance of the BCP scaffolds with this unique microstructure need to be determined.Here,we prepared the osteomimetic BCP scaffolds with different HA/b-TCP ratios(HA30/b-TCP70,HA50/b-TCP50,HA70/b-TCP30)and the effects of different HA/b-TCPHA/b-TCP ratios on the degradation and biological performance were studied in vitro and vivo.These BCP scaffolds with different HA/b-TCP ratios exhibited similar microstructure,mechanical performance,and protein absorption capability,while HA70/b-TCP30 BCP scaffolds showed an advisable degradation rate.Study in vitro confirmed the bio-compatibility and promotion on the proliferation,differentiation of MG63 cells in the porous osteomimetic BCP scaffolds with a HA/b-TCP ratio at 30:70.Implantation experiments also showed that the porous osteomimetic BCP scaffolds with a HA/b-TCP ratio at 30:70 had excellent bone regeneration capacity and proper degradation rate compatible with bone growth.These results reveal that the porous osteomimetic BCP scaffold with a HA/b-TCP ratio at 30:70 is a potential candidate of biodegradable bone substitutes used for bone repair.

Biphasic calcium phosphate nano-composite scaffolds reinforced with bioglass provide a synthetic alternative to autografts in a canine tibiofibula defect model

Background Bone grafting is commonly used to repair bone defects.As the porosity of the graft scaffold increases,bone formation increases,but the strength decreases.Early attempts to engineer materials were not able to resolve this problem.In recent years,nanomaterials have demonstrated the unique ability to improve the material strength and toughness while stimulating new bone formation.In our previous studies,we synthesized a nano-scale material by reinforcing a porous β-tricalcium phosphate （β-TCP） ceramic scaffold with Na2O-MgO-P2O5-CaO bioglass （β-TCP/BG）.However,the in vivo effects of the β-TCP/BG scaffold on bone repair remain unknown.Methods We investigated the efficacy of β-TCP/BG scaffolds compared to autografts in a canine tibioflbula defect model.The tibioflbula defects were created in the right legs of 12 dogs,which were randomly assigned to either the scaffold group or the autograft group （six dogs per group）.Radiographic evaluation was performed at 0,4,8,and 12 weeks post-surgery.The involved tibias were extracted at 12 weeks and were tested to failure via a three-point bending.After the biomechanical analysis,specimens were subsequently processed for scanning electron microscopy analysis and histological evaluations.Results Radiographic evaluation at 12 weeks post-operation revealed many newly formed osseous calluses and bony unions in both groups.Both the maximum force and break force in the scaffold group （n=6） were comparable to those in the autograft group （n=6,P ＞0.05）,suggesting that the tissue-engineered bone repair achieved similar biomechanical properties to autograft bone repair.At 12 weeks post-operation,obvious new bone and blood vessel formations were observed in the artificial bone of the experimental group.Conclusions The results demonstrated that new bone formation and high bone strength were achieved in the β-TCP/ BG scaffold group,and suggested that the β-TCP/BG scaffold could be used as a synthetic alternative to autografts for the repair of bone defects.

Whisker of biphasic calcium phosphate ceramics: Osteoimmunomodulatory behaviors

Immune systems play a critical role in the regulation of bone formation and homeostasis,which arouses a growing interest in the development of biomaterials that can modulate both immune response and osteogenesis.In this study,biphasic calcium phosphate(BCP)ceramics were modified with different whiskered surface,and their effects on macrophage polarization and functional status were investigated.The results showed that compared to BCP-W ceramics with long and solid whiskers,BCPHW ceramics with short and hollow whiskers surface were conducive to protein adsorption and macrophage elongation.Furthermore,BCP-HW ceramics down-regulated the expression of M1 macrophage markers(Il1β,Tnfα,and iNos),promoted the expression of M2 macrophage markers(Il10 and Arg)and growth factors(Tgfβ1 and Bmp2),which might be attributed to the differential integrin expression regulated by different whisker structures.The conditioned medium derived from the supernatant of macrophage/whiskered ceramic co-culture was further used to culture MC3T3-E1 pre-osteoblasts to evaluate the effects of whiskered ceramic-mediated macrophage secretion on osteogenesis in vitro.Compared with BCP-W ones,the secretion pattern induced by BCP-HW ceramics could promote the expression of bone markers in pre-osteoblasts,which might due to the activation of intracellular signaling cascades like BMP/Smad and TGF-β/Smad signaling pathways.A murine intramuscular implantation model suggested that after implantation for 1,2,and 3 weeks,BCP-HW ceramics drove the switch of macrophages to ARG+wound-healing M2 phenotype,while BCP-W ceramics increased the proportion of iNOS+M1 inflammatory macrophages.At 2 months,only BCP-HW could induce ectopic bone formation.Taken together,these results indicated that BCP ceramics with hollow whiskers were capable of creating a proper inflammatory microenvironment to induce bone formation.These whiskered BCP ceramics with good osteo-immunomodulatory capacity hold promise in serving as bone grafts to achieve desired bone repair and regeneration.

多孔Nano-dHA/PLA/BCP复合支架的制备及性能研究

为改善常规的多孔聚乳酸/双相钙磷陶瓷(PLA/BCP)支架表面亲水性不佳及降解时呈酸性等不足,采用马弗炉烧结制备的BCP多孔支架浸入纳米缺钙羟基磷灰石/聚乳酸(nano-dHA/PLA)混悬液后,真空干燥得到多孔纳米缺钙羟基磷灰石/聚乳酸/双相钙磷陶瓷(nano-dHA/PLA/BCP)复合支架,利用万能测试机测试支架抗压强度,阿基米德法测定支架孔隙率,扫描电子显微镜(SEM)观察支架表面形貌,并对其保水率和体外降解过程中pH值的变化情况等进行了研究.结果表明:多孔nano-dHA/PLA/BCP复合支架表面粗糙,保水率和强度均有较大提高,在磷酸盐缓冲液(PBS)浸泡过程中pH值下降较慢,在模拟体液(SBF)中浸泡1个月后发现有较多的类骨磷灰石形成.

One-step co-doping of ZnO and Zn^(2+)in osteoinductive calcium phosphate ceramics with synergistic antibacterial activity for regenerative repair of infected bone defect

How to endow bone grafts with long-term antibacterial activity and good bone regenerative ability to achieve the regenerative repair of infected bone defects has been the focus of the clinical treatment of osteomyelitis.The present study introduced a novel one-step route to realizing the co-doping of zinc oxide(ZnO)and zinc ion(Zn^(2+))in biphasic calcium phosphate(BCP)ceramics to utilize their synergistic antibacterial.Compared with the conventional BCP ceramics(BCP-Ca),the ZnO/Zn^(2+)co-doping ones(BCP-Zn)possessed strong antibacterial ability on E.coli and S.aureus as well as stimulated the osteogenic differentiation of bone marrow mesenchymal stem cells(BMSCs)effectively.The synergistic antibacterial mechanism of ZnO and Zn^(2+)was also investigated.BCP-Zn showed excellent osteoinductivity and angiogenesis at three months postoperatively in the canine intramuscular implantation model.Moreover,BCP-Zn exhibited excellent anti-infective ability and bone regenerative repair compared to BCP-Ca and control groups in the infected bone defect model of rat femur.Collectively,these findings suggest that the simultaneous introduction of ZnO/Zn^(2+)could have immense potential to expand the application of osteoinductive BCP ceramics in the regenerative repair of infected bone defects.

VEGF165-BMSCs复合NanoBCP陶瓷支架材料异位成骨性能的实验研究

目的:探讨VEGF165-BMSCs复合NanoBCP陶瓷支架材料异位成骨的可能性。方法:将VEGF165转染至BMSCs,并将其接种于已制备的多孔NanoBCP支架材料培养后植入裸鼠皮下,进行组织学观察和分析。结果:转染后的BMSCs表达VEGF165mRNA和蛋白,NanoBCP材料比BCP的表面和孔隙内有更多的新骨形成,并发现有血管和多核巨细胞的分布。结论:NanoBCP孔隙结构良好,具有一定的生物可降解性,用于骨组织工程支架材料异位成骨性能良好,具有潜在的应用价值。

双相磷酸钙涂覆羟基磷灰石多孔支架的制备及性能

背景:目前的人工骨大多只能制备成小体积的填充用材料,大段负重骨及大块结构性植骨材料仍面临缺乏理想骨缺损修复材料和材料成型过程难以加工调控两大难题。目的:制备与人体大段负重骨形貌结构相似且兼具一定力学性能、优良生物相容性和部分可降解性的多孔羟基磷灰石/双相磷酸钙涂层复合支架,评估其性能。方法:采用水热合成法结合喷雾干燥技术分别制备羟基磷灰石粉体、羟基磷灰石晶须和β-磷酸三钙粉体,评估羟基磷灰石粉体、β-磷酸三钙粉体浸提液的细胞毒性。在羟基磷灰石粉体中添加不同含量(5%,10%,15%)的晶须,借助3D打印技术制备成多孔骨支架,设置不同的烧结工艺,通过正交实验筛选力学性能、孔隙率等最优的晶须含量与烧结工艺组合,检测最优组合支架的流体力学。采用浸渍提拉法将双相磷酸钙涂层涂覆在多孔骨支架上,体外评估双相磷酸钙涂层中β-磷酸三钙粉体的降解性能。结果与结论:①MTT实验显示,羟基磷灰石粉体、β-磷酸三钙粉体无明显的细胞毒性;②正交实验结果显示,影响多孔支架抗压强度最主要的因素为烧结温度,其次是晶须含量,最后是烧结时间;各因素组合中的最优组合为晶须含量10%、烧结温度1300℃、烧结时间3 h,此时支架抗压强度为8.13 MPa,孔隙率为64.07%;③通过流体力学模拟仿真可知,细胞营养液等垂直人工骨横截面方向流入流出的方式更有利于支架在人体中发挥作用;④在飞纳电镜的光学模式下,浸渍涂层前多孔支架的孔径为400μm,浸渍涂层后多孔支架的孔径为250μm,涂层厚度约为75μm;复合涂层中的β-磷酸三钙具有良好的体外降解性能;⑤结果显示,制备的羟基磷灰石/双相磷酸钙涂层复合支架具有较高的孔隙率与力学性能、优异的生物相容性和部分可降解性,是一种优良的生物活性陶瓷支架。

双相磷酸钙/聚醚醚酮成骨性能的研究

目的:研究经双相磷酸钙改性后的聚醚醚酮复合材料的成骨性能。方法:经复合工艺加工的双相磷酸钙/聚醚醚酮复合材料作为实验组,聚醚醚酮作为对照组。利用扫描电子显微镜、X射线光电子能谱仪、接触角测量仪检测样品表面形状、化学成分组成和亲水性。将大鼠骨髓间充质干细胞与样品共培养,利用CCK-8实验检测细胞增殖特性,通过实时荧光定量PCR检测成骨基因OCN、ALP、BMP-2、RUNX2、SP7的表达。此外,通过建立大鼠股骨植入模型,将两组种植体植入大鼠股骨远端,采用Micro-CT分析种植体骨结合情况。结果:经双相磷酸钙改性后的聚醚醚酮材料表面形貌虽然未发生明显变化,但成功引入了骨生长不可或缺的钙、磷元素,并提高了样品表面亲水性(P<0.01)。改性后的聚醚醚酮显著促进了细胞增殖活性(P<0.01),表现出了良好的生物安全性,也改善了细胞对成骨基因ALP、BMP-2、OCN、RUNX2、SP7的表达(P<0.05)。在大鼠体内实验中,双相磷酸钙/聚醚醚酮种植体表面拥有更多、致密的新骨形成(P<0.01)。结论:经过双相磷酸钙改性后的聚醚醚酮明显改善了聚醚醚酮表面生物活性,提高了亲水性能,并可以促使成骨细胞的分化、增殖,从而提高种植体骨结合率。

双相钙磷生物陶瓷研究进展

双相钙磷生物陶瓷是一类由羟基磷灰石 [HA ,Ca10 (PO4) 6(OH ) 2 ]和 β -磷酸三钙 [β -TCP ,Ca3 (PO4) 2 ]按不同比例组成的硬组织替换材料。由于其成分与人体硬组织的无机成分基本一致 ,且综合了HA的优异的生物相容性和 β -TCP的生物降解性 ,因而成为硬组织修复、替换材料的研究热点。简要综述了双相钙磷陶瓷的制备、性能及应用进展。

双相磷酸钙多孔陶瓷的制备

以羟基磷灰石为原料 ,壳聚糖微球为成孔剂 ,明胶为分散剂 ,采用注浆法制备多孔双相磷酸钙陶瓷。通过X射线衍射和扫描电子显微镜对烧结体相组成、微观结构、孔径和孔分布进行了分析和观察。结果表明 :起始粉末粒径为 2 60nm的试样 ,在 10 0 0℃～1180℃范围内烧结 ,可获得不同 β -TCP/HA比的双相多孔陶瓷。与单相 β -TCP陶瓷相比 ,β

不同分散剂制备的石墨烯纳米片/双相磷酸钙生物复合材料及其力学性能研究

以石墨烯纳米片(GNPs)为强韧相,双相磷酸钙(BCP)为基体,采用不同的分散剂,通过热压烧结制备一种力学性能优良的骨组织替代材料。主要研究不同分散剂和GNPs对复合材料的力学性能、物相组成和微观结构的影响。结果表明,添加十六烷基三甲基溴化铵(CTAB)作为分散剂时,由于表面正负电荷吸引,BCP粉体均匀包覆到GNPs的表面,可使GNPs达到较好的分散效果。当GNPs添加量为1.5wt%时,复合材料的弯曲强度和断裂韧性分别达到152 MPa和1.74 MPa.m1/2,与相同条件下制备的纯BCP陶瓷相比,分别提高了55%和76%,表明GNPs对BCP陶瓷具有明显的补强增韧的作用。

大鼠骨髓间充质干细胞与多孔双相磷酸钙陶瓷支架体外黏附的实验研究

目的研究大鼠骨髓间充质干细胞(marrowmesenchymalstemcells,MSCs)诱导培养后在多孔双相磷酸钙(biphasiccalciumphosphate,BCP)陶瓷支架材料上的黏附和生长。方法SD大鼠MSCs经矿化诱导培养、扩增,具有成骨细胞表型后,与多孔BCP陶瓷支架及普通多孔羟基磷灰石(hydroxyapatite,HA)陶瓷支架体外复合培养,扫描电镜观察比较MSCs在两种材料支架表面的黏附数量和形态;同时以0.5、1.0、2.0、3.0和4.0×106/ml浓度细胞悬液接种于多孔BCP支架材料,检测适宜的接种浓度及单位体积支架材料可黏附MSCs数量。结果大鼠MSCs经诱导培养14d后,行矿化沉积茜素红染色、型胶原免疫细胞化学染色及碱性磷酸酶细胞化学染色,结果均为阳性。大鼠MSCs黏附于多孔BCP陶瓷上的细胞数(88.00±6.58)明显高于HA陶瓷组(39.00±3.65),两组比较差异有统计学意义(P<0.01)。当接种浓度为2.0×106/ml时,单位体积的陶瓷支架材料最多可黏附MSCs数量为1.28×107个/cm3,为细胞适宜接种浓度。结论大鼠MSCs在体外经矿化诱导培养可表达成骨细胞表型,细胞浓度为2.0×106/ml时与多孔BCP陶瓷支架材料具有良好的黏附能力。