Size controlled synthesis of well-distributed nano-silver on hydroxyapatite using alkanolamine compounds

A well-distributed nano-silver hydroxyapatite composite has been successfully prepared by a one-pot synthesis method. Hydroxyapatite was separately synthesized by a sol-gel method, then impregnated with silver nanoparticles with the mediation of Uncaria gambir Roxb. leaf extract in the presence of three kinds of alkanolamine compound; monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA) as capping agents. The effect of different capping agents on the properties of the silver nanoparticles and the nano-silver hydroxyapatite composite were studied. UV–visible spectrophotometer analysis exhibited absorbance peaks at 402–439 nm which specifically corresponds to spherical silver nanoparticles. Higher optical absorbance was observed in TEA-capped silver nanoparticles, than in DEA and MEA-capped ones. X-ray diffraction (XRD) analysis showed a highly crystalline hexagonal structure for hydroxyapatite and no detected metallic silver. However, the presence of 1.65% silver was confirmed by energy dispersive x-ray (EDX) spectroscopy analysis. Transmission electron microscopy (TEM) analysis revealed spherical silver nanoparticles with a size range of 2–62 nm (smallest mean diameter of 2 nm) adhered to the hydroxyapatite surface. The TEA capped impregnated silver nanoparticles were the smallest, corresponding to the best capping performance, followed by those capped by DEA and MEA. Small-sized nanoparticles on hydroxyapatite are beneficial for highly antibacterial bone implants.     

Hydroxyapatite/bioactive glass functionally graded materials (FGM) for bone tissue engineering

In this work, HA/bioactive glass Functionally Graded Materials (FGMs) are obtained for the first time by means of Spark Plasma Sintering (SPS). Two series of highly dense 5 layered products, namely FGMS1 and FGMS2, are prepared under optimized SPS conditions, i.e. 1000 °C/2 min/16 MPa and 800 °C/2 min/50 MPa, respectively, using a die with varying cross section.Results arising from XRD, SEM, mechanical and biological characterization in SBF, evidence that lower temperature and higher-pressure levels used for FGMS2 samples provide better materials in terms of microstructure, compactness, hardness, elastic modulus and in vitro bioactivity. Indeed, a fully sintered and crack-free microstructure with no crystallisation at the top layer (100% bioactive glass) is correspondingly produced.The obtainment of such FGMs is quite promising, since it permits to vary the relative volume fractions of the two constituents and, consequently, tailor the biological response for specific clinical applications.     

A comparative study on in vitro behavior of calcium silicate ceramics synthesized from biowaste resources

Calcium silicate ceramics have received significant attention for biomedical applications for their excellent bioactivity and osteoconduction properties. Sol-gel process is extensively used for the fabrication of calcium silicates. In sol-gel process, calcium nitrate tetra hydrate (Ca(NO₃)₂·4H₂O) and tetraethylorthosilicate (TEOS) are used as precursors. However, these precursors are expensive. The objective of this work was to compare in vitro behavior of calcium silicate (CaSiO₃) produced using biowaste such as rice husk ash (RHA) and eggshells (coded; NCS) with CaSiO₃ prepared using TEOS and Ca(NO₃)₂·4H₂O (coded; CCS). Thermal investigation results revealed that the crystallization temperature for NCS is relatively lower (772°C) than for CCS (870°C). Bioactivity was studied in vitro using simulated body fluid (SBF) with respect to mineralization rate of hydroxyapatite. Mineralization of a greater hydroxyapatite was observed on NCS ceramics than CCS ceramics after incubation for 3, 7, 14 days in SBF solution, which was confirmed using X-ray diffractometer, Fourier transform infrared spectroscopy, scanning electron microscopy-energy dispersive spectroscopy. Degradation studies were conducted in Tris-HCl solution and the test results revealed that NCS ceramics has lower dissolution rate than CCS ceramics. The antimicrobial assay has shown that NCS samples exhibit significant zone of inhibition against Escherichia coli and Staphylococcus aureus which confirmed that the CaSiO₃ prepared from RHA and eggshell can prevent bacteria from adhering to the surface. In addition cell culture studies revealed that NCS ceramics possess good cytocompatibility with MG-63 cells and significantly promoted cell proliferation.     

碳羟基磷灰石/钾长石复合材料对镍的吸附性能研究

以钾长石为原料,用液相合成法制备碳羟基磷灰石/钾长石吸附剂（CHAK）去除水中的重金属镍,用静态吸附实验考察了CHAK添加量、溶液初始pH、吸附时间、镍初始浓度等因素对镍去除效果的影响,并结合动力学及热力学拟合探究吸附机理。结果表明：随着CHAK量的增加,对Ni ²⁺的去除率增加,但吸附量会降低;溶液pH=6时吸附效果达到最佳;吸附时间为10 h时吸附达到平衡;Ni ²⁺溶液的初始质量浓度为50~4 000 mg/L时,CHAK对Ni ²⁺的吸附量呈先增长后平稳趋势,饱和吸附量与原材料相比增大7.1倍。动力学及热力学拟合结果显示：准二级模型更符合描述该吸附行为。ΔH>0,表明该吸附过程为吸热反应,升温有利于吸附。ΔG<0,表明该反应能自发进行。     

A Biomimetic Hybrid Hydrogel Based on the Interactions between Amino Hydroxyapatite and Gelatin/Gellan Gum

In this work, a gelatin (Gel)‐oxidized gellan gum (OG)/amino hydroxyapatite (mHap) hybrid hydrogel with Schiff base linkages is reported. The mHap is obtained by modifying hydroxyapatite with tetraethyl orthosilicate and 3‐aminopropyl‐triethoxysilane. The effects of different mHap contents on the structure, morphology, and properties of hydrogels are particularly investigated. Scanning electron microscopy coupled with energy dispersion spectroscopy reveals that mHap of around 100 nm is uniformly distributed inside the hydrogel with interconnected porous structures. Notably, the hydrogel with 1 wt% mHap possesses the highest compressive stress (2.01 ± 0.10 MPa) at 90% strain, as well as the lowest equilibrium swelling ratio (97% ± 5%) and degradation rate than other hydrogels. Besides, an ultra‐high compressive stress equivalent to 91% of the initial stress can be obtained by this hydrogel after 50 loading‐unloading cycles (85% strain). Meanwhile, after being swollen, this improved hydrogel also exhibits better structural stability than Gel‐OG hydrogel. The in vitro 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay further shows that all hydrogels are nontoxic against mouse fibroblasts. This work provides a biomimetic strategy to construct the organic/inorganic hydrogels with excellent interactions, elasticity, reversibility, and biocompatibility, which is of great importance for the practical applications in cartilage tissue engineering.     

玻璃基多孔骨水泥的制备和性能研究

将SiO2-CaO-P2O5系统生物活性玻璃粉末、甘露醇和磷酸铵调和液均匀混合制得多孔玻璃基骨水泥.利用XRD、FTIR和SEM对骨水泥的晶相和显微结构进行了观察和分析,并对其显气孔率和力学强度进行了测试.实验结果表明,随着浸泡时间的增加,骨水泥固化体中生成了HAP晶体,HAP晶体呈短柱状,交织分布于玻璃颗粒间隙,尺寸大约为200nm;甘露醇晶体能在生理模拟液的浸泡下降解,降解后留下的孔隙显著增加了骨水泥的显气孔率,并且随着甘露醇含量的增加而增加,而体积密度和力学强度则呈下降的趋势.     

添加两种不同工艺合成的HAP对磷酸钙骨水泥胶凝性能的影响

在α-TCP/TTCP系磷酸钙骨水泥中分别添加化学沉淀反应合成的低结晶度羟基磷灰石(HAP)及采用高温固相反应法制备的高结晶度HAP,探讨这两种晶体对磷酸钙骨水泥胶凝性能的影响.结果表明:低结晶度的HAP粉末可以起到晶核作用,降低核化势垒使水化反应速度加快,凝结时间缩短,但由于水化产物从饱和溶液中析出太快、太细,晶体发育不完整,易通过溶解再结晶使抗压强度有所下降.高结晶度的HAP会使水化反应速度减慢,凝固时间延长,相当于"骨料"存在于水泥基体中而使抗压强度有所提高.     

羟基磷灰石作为催化材料的研究进展

羟基磷灰石(HAP)由于具有无毒性、生物相容性、热稳定性、吸附性、离子交换性、结构稳定性等,因而被广泛应用到催化剂的制备中.作为一种新型催化材料,HAP的特殊晶体结构对一些反应表现出催化活性,并且经过改性、负载等方法处理过后的HAP催化剂显示出独特的催化优势.基于近年来HAP在催化邻域的发展,综述了HAP作为催化材料在...     

再生丝素蛋白/羟基磷灰石多孔复合材料的制备

再生丝素蛋白具有良好的生物相容性,羟基磷灰石同时还具有成骨诱导性。通过将再生丝素蛋白制备形成丝素蛋白多孔材料,并在37℃下将其浸渍于模拟体液中可以制备再生丝素蛋白/羟基磷灰石多孔复合材料。扫描电镜研究发现在再生丝素蛋白多孔材料的孔隙中羟基磷灰石由针状晶体聚集而成,红外光谱和XRD等表征表明复合材料中羟基磷灰石以羰基取代的羟基磷灰石存在。制备的再生丝素蛋白/羟基磷灰石多孔材料有望作为骨组织修复材料使用。     

镁基羟基磷灰石涂层生物复合材料的研究现状

镁基羟基磷灰石涂层生物复合材料兼备了金属材料优良的力学性能和生物陶瓷材料的生物相容性,在生物医用材料领域具有广阔的应用前景。本文综述了镁及镁合金、羟基磷灰石作为医用植入材料的特点及研究现状,并简要介绍了镁基羟基磷灰石涂层生物复合材料的制备技术及方法。