Fabrication and properties of 3D printed zirconia scaffold coated with calcium silicate/hydroxyapatite

The scaffold of bone repair needs a variety of material combinations to meet its intended performance; a typical single material such as zirconia has excellent mechanical properties, while hydroxyapatite and calcium silicate are bioactive materials with different degradation rates. In this paper, porous zirconia scaffolds were fabricated using 3D printing technology. The surface of the scaffold was coated by dipping with different contents of calcium silicate and hydroxyapatite to improve the biological activity and mechanical properties. Mechanical tests show that the coating material can effectively fill the pores of the porous scaffold, increasing its compressive strength by an average of 55%. The simulated body fluid (SBF) test showed that the higher calcium silicate in the coating increased the degradation rate. Cell experiments showed that the coated scaffolds exhibited good cytocompatibility and were beneficial to the proliferation and differentiation of cells. In conclusion, coated scaffolds have potential applications in the field of bone repair.     

Fabrication of a zirconia/calcium silicate composite scaffold based on digital light processing

Zirconia (ZrO₂) and calcium silicate (CS) are widely used in bone repair. Zirconia has excellent mechanical properties, while calcium silicate has exceptional biological activity. A porous ZrO₂/CS composite ceramic scaffold was formed by digital light processing (DLP) technology in this study. The microstructure analysis demonstrated that CS was embedded between ZrO₂ particles. Mechanical tests showed that interconnected CS particles could improve mechanical properties, while discrete CS particles led to a decrease in that. Cell experiments showed that adding CS to ZrO₂ had a positive effect on cell proliferation and differentiation. In vitro degradation test showed that the weight loss of scaffolds in four weeks increased form ?0.63%–1.42% with the increase of CS content. Moreover, the degradation of scaffold promoted the deposition of apatite, which was beneficial to the integration of the scaffold with living bone. In conclusion, the ZrO₂/CS composite scaffold had better biocompatibility compared with the ZrO₂ scaffold, which showed a potential solution for 3D printing bone repair scaffolds.     

医用钛合金表面羟基磷灰石/二氧化锆梯度复合涂层的制备

用恒电流沉积方法分别在ZrO(NO3)2电解液和由Ca(NO3)2及NH4H2PO4组成的电解液中制备出羟基磷灰石/二氧化锆(HA/ZrO2)梯度医用复合涂层.通过扫描电镜观察,研究了沉积电流和沉积时间对涂层形貌的影响.结果表明,当沉积电流为11.1 mA,沉积时间为400 s时,在锆电解液中可获得均匀的钛基Zr(OH...     

Fabrication of polymer/drug‐loaded hydroxyapatite particle composite fibers for drug sustained release

The aim of this study is to fabricate polymer/hydroxyapatite (HA) particle composite fibers for drug encapsulation and sustained release. Firstly, drug‐loaded hydroxyapatite particles are synthesized in one step, then by electrospinning of the blends of drug‐loaded hydroxyapatite particles and polymer solution the drug‐loaded polymer/hydroxyapatite particle composite fibers are successfully prepared. Effect of loading ratio of drug‐loaded hydroxyapatite particles in the fibers and pH value of the release medium on the drug release kinetics are both investigated, and the results demonstrate that, as compared with the polymer/drug electrospun fibers, the drug in the polymer/drug‐loaded hydroxyapatite particle composite fibers shows a sustained release manner, and the drug release rate can be regulated by both the loading ratio of drug‐loaded hydroxyapatite particles in the composite fibers and pH value of the buffer solution. The results indicate that the developed drug‐loaded polymer/hydroxyapatite particle composite fibers show great potential in bone regeneration and other related biomedical fields. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42871.     

Fabrication and properties of reduced graphene oxide reinforced yttria-stabilized zirconia composite ceramics

Fully dense yttria-stabilized zirconia (YSZ) ceramics reinforced with reduced graphene oxide (RGO) were fabricated by spark plasma sintering (SPS), and their electrical, thermal, and mechanical properties were investigated. Graphene oxide (GO) was exfoliated by a short sonification in dimethylformamide (DMF)/water solution and uniformly mixed with ZrO₂ powders. The microstructure of the composites showed that undamaged RGO sheets were homogeneously distributed throughout matrix grains. The electrical conductivity of YSZ composites drastically increased with the addition of RGO, and it reached 1.2 × 10⁴ S/m at 4.1 vol.%. However, the thermal diffusivity increased only 12% with RGO addition. The hardness decreased slightly with RGO addition, whereas the fracture toughness significantly increased from 4.4 to 5.9 MPa^1/2. The RGO pull-out and crack bridging contributed to the improved fracture toughness.     

羟基磷灰石/壳聚糖复合材料研究进展

综述了羟基磷灰石/壳聚糖复合材料的研究现状,对其制备、特点、性能进行了探讨,羟基磷灰石基人工骨作为最有前途的生物硬组织替代材料之一,在生物医用材料和医学研究领域有着广泛的应用前景。主要从化学的角度对材料复合、表征、应用进行了阐述。进而对壳聚糖/羟基磷灰石复合材料的研究发展前景予以展望。     

Fracture of composite alumina/yttria-stabilized zirconia joints

Four-point bend tests have been performed on samples consisting of yttria-stabilized zirconia containing 0–80% alumina joined by plastic deformation to the same or different composition. The fracture strength of joints between the same composition was equal to the strength of the monolithic material. Fracture of joints made between different compositions occurred at the position of maximum tensile residual stress, as determined by finite-element analysis, not at the interface. Measured strengths were in accord with fracture mechanics and the calculated residual stresses.     

Natural and synthetic hydroxyapatite/zirconia composites: A comparative study

Zirconia precursor was precipitated in a HAp particles suspension using two HAp powders of natural origin and a synthetic powder. The first natural HAp was extracted from animal bones by treatment with hot NaOH solution and the second one by treatment under hydrothermal conditions with water.Hydrous zirconia was precipitated in the HAp suspension. Pressureless sintering was performed at 1000–1300 °C and hot pressing at 1050–1300 °C.It was found that zirconia additive promotes decomposition of both HAp of natural origin as well as the synthetic one. The most stable HAp was the one extracted from bovine bones by treatment with water in an autoclave. This reaction leads to the formation of β–TCP and the CaO–ZrO₂ solid solution.The hot pressed composites show essentially higher strength and fracture toughness as compared to the pure hydroxyapatite polycrystals.     

Fabrication of corrosion resistant, bioactive and antibacterial silver substituted hydroxyapatite/titania composite coating on Cp Ti

The present work is aimed at developing a bioactive, corrosion resistant and anti bacterial nanostructured silver substituted hydroxyapatite/titania (AgHA/TiO₂) composite coating in a single step on commercially pure titanium (Cp Ti) by plasma electrolytic processing (PEP) technique. For this purpose 2.5 wt% silver substituted hydroxyapatite (AgHA) nanoparticles were prepared by microwave processing technique and were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM) methods. The as-synthesized AgHA particles with particle length ranging from 60 to 70 nm and width ranging from 15 to 20 nm were used for the subsequent development of coating on Cp Ti. The PEP treated Cp Ti showed both titania and AgHA in its coating and exhibited an improved corrosion resistance in 7.4 pH simulated body fluid (SBF) and 4.5 pH osteoclast bioresorbable conditions compared to untreated Cp Ti. The in vitro bioactivity test conducted under Kokubo SBF conditions indicated an enhanced apatite forming ability of PEP treated Cp Ti surface compared to that of the untreated Cp Ti. The Kirby-Bauer disc diffusion method or antibiotic sensitivity test conducted with the test organisms of Escherichia coli (E. coli) for 24 h showed a significant zone of inhibition for PEP treated Cp Ti compared to untreated Cp Ti.     

Fabrication of polycaprolactone/zirconia nanofiber scaffolds using electrospinning technique

In the present study we have investigated the effect of Zirconia (ZrO₂) nanoparticles on the fiber morphology, swelling, degradation activity and enhanced cell adhesion of the electrospun polycaprolactone (PCL) non-woven nanofiber scaffolds. The composite nanofibers scaffolds were obtained with ZrO₂ weight contents varying in the range 6% to 30%. The effect of the ZrO₂ nanoparticles concentration on the fiber morphology was investigated using a Field effect scanning electron microscopy (FE-SEM). We also investigated the degradation and swelling activities of the fabricated material. The results demonstrated better swelling with controlled degradation in comparison to the PCL scaffolds. Cell viability studies proved the non toxic nature of the nanocomposite scaffolds. Interestingly, the scaffolds with ZrO₂ nanoparticles showed enhanced fibroblast proliferation and improved bioactivity of the scaffolds. Further, this is the first report regarding the ability of a biomaterial containing ZrO₂ nanoparticles to enhance cell adhesion and proliferation.     

TiO2/羟基磷灰石复合微球的合成

将乙酰丙酮稳定的钛酸四正丁酯分散到含有硬脂酸的水中,接着加入Ca²⁺、H₂PO₄^-源,然后通过150℃的水热过程,合成了TiO₂/羟基磷灰石(HAP)复合微球。其中的硬脂酸作为界面媒介吸附Ca²⁺,确保生成的羟基磷灰石的粒子吸附在分散的钛酸四正丁酯球形"油滴"表面。经水热过程,分散的油滴转化为TiO₂ 为内核,HAP为壳层的复合微球。HAP粒子组成的微球外壳层对内核钛酸四正丁酯水解及缩聚反应而引起的体积收缩产生抑制作用,从而对最终的TiO₂ 内核的微结构产生影响。亚甲基蓝的紫外光催化降解实验结果表明,复合微球的光催化性能与微球对亚甲基蓝的平衡吸附量有密切的关系,并取决于产品的微结构。当复合微球中羟基磷灰石的理论质量分数为1%~1.5%时,微球对亚甲基蓝显示了较高的光催化降解效率。     

Fabrication and properties of degradable poly(amino acid)/nano hydroxyapatite bioactive composite

Poly(amino acid)/nano hydroxyapatite (PAA/n-HA) bioactive composite was prepared by in situ melting polymerization. The composition, structure and morphology as well as glass transition temperature (T_g), dynamic mechanical properties of the PAA/n-HA composite were characterized by infrared spectrometer, X-ray diffractometer, X-ray photoelectron spectroscopy, scanning electron microscope, differential scanning calorimeter, and dynamic mechanical analyzer. The results indicated that the n-HA particles were uniformly distributed into PAA matrix and some interactions were found at the interface between PAA and n-HA, and the crystallinity of PAA in the composite decreased with the increase of n-HA content. The T_g and storage modulus of the composite increased with increasing n-HA content, demonstrating that the n-HA content had obvious effects on the crystallization kinetic parameters and thermo properties of the PAA/n-HA composite. In addition, the n-HA amount had evident effects on the degradation of the PAA/n-HA composite in phosphate buffered saline (PBS), and the weight loss ratio of the composite decreased with the increase with n-HA content. The pH value of the medium was stable around 7.40 after the composite immersion into PBS for 8 weeks. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Sol-gel synthesis of polyaniline/zirconia composite conducting materials

Polyaniline (Pani) conducting polymer was successfully synthesized by an emulsion polymerization of aniline monomer in the presence of dodecyl benzene sulfonic acid (DBSA). Consequently novel Pani.DBSA/zirconia composites (PDZr) were successfully synthesized by sol-gel technique. Structural and morphological characterization of PDZr composites were carried out using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–Vis), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Upon incorporating zirconia the resulting composite material showed greater crystallinity. The FT-IR spectrum showed the characteristic peaks of Pani.DBSA shifted to higher wavenumbers. This suggests some interactions between zirconia network and Pani.DBSA polymer chains. TEM micrographs indicate morphological changes upon the formation of PDZr composites. The nanoparticles of Pani.DBSA formed rod-like structures in the resulting composite materials. A higher electrical conductivity was obtained when the PDZr composite was incorporated with 30 % weight of Zr(IV)-n-propoxide. Differential scanning calorimetry (DSC) measurements revealed two distinct glass transition temperature (T_g) for PDZr composite at low percentage of zirconia. Thermogravimetric analysis (TGA) results indicate that the maximum degradation temperature of the PDZr composites increased significantly to 484 °C.     

Fabrication of hydroxyapatite/diopside/alumina composites by hot-press sintering process

Hydroxyapatite/alumina/diopside ceramic composites were fabricated by hot-pressing. The hardness, fracture toughness and bending strength of the new fabricated composites were measured. The compositions of hydroxyapatite matrix ceramic composites were discussed by XRD and FT-IR analysis. Microstructures of the composites were studied on fracture surfaces. The bending strength and fracture toughness of 58 vol.% hydroxyapatite, 40 vol.% alumina and 2 vol.% diopside sample, were 200 MPa and 2.80 MPa m^1/2, respectively.     

Fabrication and properties of in situ reduced graphene oxide‐toughened zirconia composite ceramics

Graphene oxide and zirconia powders were mixed using a colloidal coating route. In situ reduced graphene oxide‐toughened zirconia ceramics were prepared by spark plasma sintering. Their microstructure, mechanical properties, and toughening mechanisms were investigated. The results show that graphene oxide can be easily reduced in situ during sintering and that it disperses homogeneously within the zirconia substrate. Compared with the toughness of 3 mol.% yttria‐stabilized zirconia, the fracture toughness of in situ reduced graphene oxide‐toughened zirconia increased by up to 175% (from ~6.07 to ~10.64 MPa·m^1/2) at 0.09 wt.% graphene oxide with a small increase in hardness. The improvement is more significant than that of prereduced graphene oxide‐toughened cases, and it is associated with the formation of a C‐O‐Zr bond at the interface in addition to conventional toughening mechanisms.     

海藻酸钠/羟基磷灰石一体化复合支架的制备

采用高碘酸钠对海藻酸钠(SA)进行氧化得到氧化海藻酸钠(OSA),以丁二酸酐对壳聚糖(SC)进行接枝改性得到N–琥珀酰壳聚糖(NSC),并与OSA发生Schiff碱反应生成水凝胶。采用水热合成法制备了微米级、纳米级羟基磷灰石并进行相应表征,并与OSA、SA制备复合水凝胶。利用静电纺丝技术制备了聚ε–己内酯/聚乙二醇细胞分隔膜并表征其形貌特征。采用乳化剂交联法,制备了SA竖直贯通多孔支架并研究了SA浓度、复合纳米羟基磷灰石对支架的影响。通过模块化构建,制备出多层一体化组织工程支架,将各组分材料与人皮肤成纤维细胞共培养以考察支架的生物相容性,采用吖啶橙荧光染色法观察细胞生长情况,细胞增殖定量检测采用CCK–8表征。     

Fabrication and characterization of chitosan/PVA with hydroxyapatite biocomposite nanoscaffolds

Nanofibrous biocomposite scaffolds of chitosan (CS), PVA, and hydroxyapatite (HA) were prepared by electrospinning. The scaffolds were characterized by FTIR, SEM, TEM, and XRD techniques. Tensile testing was used for the characterization of mechanical properties. Mouse fibroblasts (L929) attachment and proliferation on the nanofibrous scaffold were investigated by MTT assay and SEM observation. FTIR, TEM, and XRD results showed the presence of nanoHA in the scaffolds. The scaffolds have porous nanofibrous morphology with random fibers in the range of 100–700 nm diameters. The CS/PVA (90/10) fibrous matrix (without HA) showed a tensile strength of 3.1 ± 0.2 MPa and a tensile modulus 10 ± 1 MPa with a strain at failure of 21.1 ± 0.6%. Increase the content of HA up to 2% increased the ultimate tensile strength and tensile modulus, but further increase HA up to 5–10% caused the decrease of tensile strength and tensile modulus. The attachment and growth of mouse fibroblast was on the surface of nanofibrous structure, and cells' morphology characteristics and viability were unaffected. A combination of nanofibrous CS/PVA and HA that mimics the nanoscale features of the extra cellular matrix could be promising for application as scaffolds for tissue regeneration, especially in low or nonload bearing areas. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Electroconductive composite of zirconia and hybrid graphene/alumina nanofibers

Novel type of hybrid nanofillers representing graphene encapsulated alumina nanofibres was selected as an additive to develop toughened electroconductive partially stabilized zirconia. The sinterability, mechanical and electrical properties of the produced nanocomposites were studied as function of the filler/graphene content. Composites containing just 0.6 vol.% of graphene corresponding to 3 vol.% of hybrid nanofibres exhibited high electroconductivity of 58 S/m without deterioration of mechanical properties. They also showed a slight toughening effect that is reflected by an increase in the indentation fracture toughness by 20% as compared to monolithic zirconia.     

Compressive and flexural properties of novel polylactic acid/hydroxyapatite/yttria-stabilized zirconia hybrid nanocomposite scaffold

The mechanical property is a crucial factor in the design of bone tissue engineering scaffolds. In the current study, novel PLLA (Poly-L-lactic acid)–Hydroxyapatite (HA)–yttria-stabilized zirconia (YSZ) nanocomposite scaffold with various compositions was prepared and characterized. The effect of HA and YSZ contents on the mechanical behavior of the resultant composites was investigated. TEM micrograph revealed that HA particles are needle-like in shape and nano in size. Scanning electron microscopy (SEM) micrograph also showed that YSZ powder is in granule form and submicron size. SEM disclosed that all scaffolds had a highly interconnected porous structure and X-ray diffractometry revealed that there were some molecular interactions between PLA (Polylactic acid), HA, and YSZ in the composites. The results depicted that introducing YSZ to the nanocomposite leads to a significant increase in compressive strength, modulus, and densification strain. In addition, flexural strength and modulus showed an upward trend by adding YSZ particles to scaffolds. It should be noted that PLA–20%HA–20%YSZ indicates the highest strength and modulus in both compression and bending tests, though, it did not demonstrate the proper strain compared to other scaffolds. Thus, PLA–15%HA–15%YSZ has been reported as the best candidate due to appropriate strength and strain. Also, energy absorption in nanocomposites showed an upward trend by increasing the amount of YSZ particles. It was found that the strength of samples was declined after being soaked in simulated body fluid. However, scaffolds with HA underwent more decrease in strength compared to samples containing YSZ.     

Preparation and characterisation of laminated hydroxyapatite/chitosan composite hydrogels

Abstract

Chitosan (CS) has been proposed for the use of electrically modulated drug delivery. However, the gel fatigue makes CS hydrogel difficult to achieve precise and prolonged drug release. In this study, laminated hydroxyapatite (HAp)/CS composite hydrogels were prepared via solution intercalation method. Cyclic electrostimulation test revealed that the fatigue of neat CS was significantly improved by incorporation of laminated HAp. It is detected by transmission electron microscopy that laminated HAp distributed disorderly in the CS matrix, and the dimension of the HAp lamella is ～150 nm. Furthermore, the in vitro cytotoxicity of 2HAp/CS was evaluated by optical microscopy, scanning electron microscopy and [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The prepared composite hydrogels exhibit improved swelling fatigue property and good biocompatibility, which will further provide a wide range of potential application in the drug delivery.