聚多巴胺修饰钛表面纳米载银及其抗菌和细胞相容性

通过多巴胺自聚合在钛表面构建了仿生聚多巴胺(PDA)膜层, 有利于类骨羟基磷灰石在钛表面的沉积, 体现了良好的生物活性。利用聚多巴胺的螯合效应及还原性, 将纳米银颗粒载入聚多巴胺修饰钛表面; 利用场发射扫描电镜(FE-SEM)、X射线光电子能谱(XPS)、显微激光拉曼光谱(Raman)和石墨炉原子吸收光谱(GF-AA5)对聚多巴胺/纳米银修饰钛表面的银粒径、含量及离子释放进行表征。采用杀菌率和表面细菌粘附对聚多巴胺/纳米银修饰钛表面的体外抗菌性能进行检测, 研究结果表明: 纳米银对金黄色葡萄球菌具有较强的杀菌能力, 且MC3T3-E1细胞早期粘附和增殖结果证实本研究得到的聚多巴胺/纳米银修饰钛表面具有良好的体外细胞相容性。     

钛表面制备羟基磷灰石/壳聚糖复合涂层研究

通过原位水热合成和溶胶-凝胶浸提涂敷法在碱处理的钛表面制备了HA/CS复合涂层. 接触角检测表明碱处理使钛表面具有超亲水性.X射线衍射分析表明复合涂层成分为HA和CS, 各组分含量由热重分析确定. 用扫描电镜对复合涂层的形貌进行观察,发现不同HA含量的复合涂层具有不同的形貌. 通过培养成骨细胞考察了复合涂层的细胞相容性.Alamar Blue检测表明HA/CS复合涂层表面细胞粘附及增殖能力较好. ALP检测表明HA/CS复合涂层表面的细胞分化能力较好. 综合研究结果表明, 复合涂层有较好的细胞相容性.     

亲水改性剂表面修饰纳米羟基磷灰石对其分散性的影响

纳米羟基磷灰石(n HA)的分散性差,导致制备的n HA/聚乳酸(PLA)生物工程材料中存在团聚的大颗粒n HA,对复合材料的性能产生不利的影响。实验中分别用多巴胺(DA)、聚乙二醇、壳聚糖等亲水改性剂对n HA进行改性效果分析,发现DA可以改善n HA的分散性;同时发现DA可以氧化自聚在n HA表面生成聚多巴胺(PDA)纳米层,且生物活性良好。用DA对n HA进行表面修饰改性,通过红外光谱、X射线衍射、扫描电镜等分析其改性效果,结果表明,DA可以改善n HA的分散性,当DA的用量达到6%、8%时改性效果较好,改性后的n HA颗粒在PLA基体中的团聚现象减弱,实现了较好的分散。     

壳聚糖/羟基磷灰石表面修饰聚己内酯多孔骨支架的制备及性能

采用选择性激光烧结技术构建多孔聚己内酯(PCL)骨支架,用原位合成的方法制得壳聚糖/羟基磷灰石(CS/HA)悬浮液,并采用真空浸泡、低速离心和冷冻凝胶的方法使CS/HA黏附在PCL支架的表面,以改善骨支架的生物相容性和细胞增殖活性。通过X射线衍射(XRD)和扫描电子显微镜(SEM)观测复合支架的物相和形貌,测量支架的压缩强度和杨氏模量,测量支架表面的水接触角,并通过体外细胞实验研究复合支架的生物学性能。实验结果表明,原位合成的方法制得了羟基磷灰石(HA);CS/HA凝胶与PCL骨支架表面黏附良好;CS/HA改善了PCL支架表面的亲水性,提升了骨支架的生物相容性和细胞增殖活性。     

钛材料表面固定多聚赖氨酸-肝素纳米颗粒以改善血液相容性的研究

通过将多聚赖氨酸(PLL)-肝素纳米颗粒固定在多巴胺涂覆的钛表面,以改善其血液相容性。利用zeta电位仪及甲苯胺蓝法检测纳米颗粒的粒径及成分,通过傅立叶变换红外光谱(FT-IR)、X射线光电子能谱(XPS)及水接触角等对颗粒固定前后表面理化性质的变化进行表征。通过体外血小板粘附实验、肝素释放及活化部分凝血活酶时间(APTT)检测对改性样品的血液相容性进行评价。结果表明,PLL-肝素纳米颗粒成功固定在多巴胺沉积的钛表面,纳米颗粒的固定有效降低钛材料表面血小板的粘附行为,大大提高了血液相容性。     

静电自组装表面修饰HA/PA6膜:表征及其细胞相容性研究

通过表面改性引入活性生物分子可以用来增强材料表面的生物相容性。采用静电自组装技术将明胶和聚乙烯亚胺引入羟基磷灰石/聚酰胺6(HA/PA6)材料表面,最终获得大分子修饰的复合材料。利用水接触角测量(WCA)、X射线光电子能谱(XPS)和原子力显微镜(AFM)测试手段对表面改性前后HA/PA6膜的表面化学、亲水性和表面形貌进行表征。并研究了其对细胞活性的影响。结果表明,改性后膜表面的亲水性增强,粗糙度增大。体外细胞实验表明,明胶涂层后的HA/PA6表面细胞更利粘附、铺展和生长。该固定方法模拟细胞外基质组成制备出的生物活性膜能进一步满足生物医学工程需求。     

羟基磷灰石/钛合金骨替代材料体外培养成骨细胞的实验研究

实验选用小鼠头盖骨成骨细胞,采用体外细胞培养技术对具有羟基磷灰石涂层的钛合金(HA/Ti)与未经过表面改性的钛合金两种骨替代材料进行细胞相容性评价,动态观察两种骨替代材料对成骨细胞生长、附着的影响。结果表明两种骨替代材料对成骨细胞生长无抑制作用,未发生细胞毒性反应,细胞在两种材料表面均能正常粘附、生长、增殖,均具有良好的细胞附着形态和细胞增殖率,而HA/钛合金材料具有更好的成骨性,是一种骨细胞相容性良好的骨替代材料。     

胶原/HA复合涂层多孔钛的细胞响应行为

为提高医用多孔钛的表面活性及生物相容性,以纤维烧结多孔钛为载体,采用碱热处理+模拟体液等化学方法进行羟基磷灰石(HA)沉积,随后进行水溶性胶原涂覆,制备具有三维贯通孔结构的胶原/HA复合涂层多孔钛。研究了胶原/HA复合涂层的表面形貌及化学成分,探讨复合涂层的形成机理;进行体外细胞毒性实验并分析了多孔钛表面细胞响应行为。结果表明,胶原/HA复合涂层在钛纤维表面均匀附着,胶原的填充连接可修复HA涂层表面的微裂纹,有利于小鼠前成骨细胞的黏附、增殖及分化,促进细胞的孔内跨纤维生长。胶原/HA复合涂层可以得到更好的细胞响应,对于促进早期骨与植入体的固定有很大的潜力。     

纯钛表面磷酸氢钙-羟基磷灰石膜层的化学转化及成骨细胞反应

为了提高医用纯钛的骨修复效果,利用化学转化技术在纯钛表面制备了一层含钙磷化合物的磷酸盐(CaP)转化膜,并通过碱处理,对该转化膜进行羟基转化。利用XRD、FESEM和电化学工作站对CaP转化膜的成分、微观结构和耐蚀性能分别进行分析表征,通过MC3T3-E1小鼠成骨细胞培养,对覆膜样本的细胞相容性进行评价。研究结果表明,纯钛表面CaP转化膜的主要成分为磷酸氢钙(CaHPO_4·2H_2O),膜层晶体呈块状无规则多级排列,经过碱处理后,膜层晶体表面粗糙度增加,并有新的细小颗粒生成,晶体部分转化为羟基磷灰石(HA)。电化学分析结果表明,经过碱液处理的HA转化膜在生理盐水中表现出了比CaHPO_4·2H_2O转化膜更好的耐蚀性能。体外细胞培养试验证明,覆膜纯钛样本能够有效促进成骨细胞黏附、细胞增殖和分化。     

基于多巴胺自聚合及多肽固定的聚三亚甲基碳酸酯的细胞相容性评价

针对聚三亚甲基碳酸酯(PTMC)内皮细胞相容性不足的特点,通过在其表面沉积聚多巴胺涂层并固定精氨酸-谷氨酸-天冬氨酸-缬氨酸(REDV)多肽改善PTMC的细胞相容性。水接触角测试表明PTMC表面沉积聚多巴胺及固定REDV后亲水性得到显著改善;原子力显微镜观察可以发现相比于PTMC,沉积聚多巴胺及固定REDV后的表面粗糙度明显增加;QCMD结果显示表面固定的REDV密度可达到98.4 ng/cm2,证明REDV可实现对PTMC薄膜的固定修饰。体外内皮细胞和平滑肌细胞粘附与增殖评价表明REDV改性的PTMC薄膜可促进内皮细胞的粘附与增殖,但对平滑肌细胞粘附增殖的促进作用并不显著。     

Propranolol Hydrochloride Binding in Calcium Alginate Beads

The interaction of propranolol hydrochloride with alginate molecular chains in calcium alginate beads was investigated. The drug was either incorporated into formed calcium alginate gel beads or incorporated simultaneously with the gelation of alginate beads by Ca²⁺. Bed produced by the former method had a higher drug content and lower Ca²⁺ level compared to those prepared by the latter method. The extent of drug binding to the alginate molecules increased with decreasing Ca²⁺ levels in the beads, indicating that propranolol and Ca²⁺ shared common binding sites in the alginate chains, me appearance of the beads and the molphology of the alginate polymer in the beads were affected by the amounts of both propranolol and Ca²⁺ in the beads. Differential scanning calorimetry (DSC) analyses showed that the formation of the calcium alginate gel structure was impeded in the presence of propranolol molecules.     

钙钛矿型热电氧化物Y0.95R0.05CoO3（R=Ca,Sr,Ba）的制备和热电性能

采用溶胶-凝胶法制备化合物Y_0.95R_0.05CoO₃（R=Ca,Sr,Ba）,研究了碱土元素替代对YCoO₃电输运和热电性能的影响。结果表明,随着替代离子Ca²⁺、Sr²⁺、Ba²⁺离子半径的增大,在相应温度下替代化合物Y_0.95R_0.05CoO₃的电阻率逐渐增大,Seebeck系数增大,功率因子降低。离子半径较小且与替代离子半径相近的Ca²⁺离子替代能有效提高YCoO₃体系高温热电功率因子。     

Improved optical photoluminescence by charge compensation in the phosphor system CaMoO4:Eu

It has been found that charge compensated CaMoO₄:Eu³⁺ phosphors show greatly enhanced red emission under 393 and 467 nm-excitation, compared with CaMoO₄:Eu³⁺ without charge compensation. Two approaches to charge compensation, (a) 2Ca²⁺ → Eu³⁺ + M⁺, where M⁺ is a monovalent cation like Li⁺, Na⁺ and K⁺ acting as a charge compensator; (b) 3Ca²⁺ → 2Eu³⁺ + vacancy, are investigated. The influence of sintering temperature and Eu³⁺ concentration on the luminescent property of phosphor samples is also discussed.     

Surface characterization of titanium oxide films synthesized by ion beam enhanced deposition

In this article, titanium oxide films were prepared by ion beam enhanced deposition where titanium was evaporated by electron beam and simultaneously bombarded with xenon ion beams at an energy of 40 keV in an O₂ environment. X-ray photoelectron spectroscopy and Auger electron spectroscopy were used to research the chemical state and composition of the titanium oxide films. The results show that surface of the film was fully oxidized. After the surface was removed by argon ion sputtering, the results show that Ti²⁺, Ti³⁺ and Ti⁴⁺ states exist on the sputtered surface. The atomic concentration of all the three titanium states were calculated. The chemical shift of O 1s peak was also observed on the near surface.     

Fabrication and corrosion behavior of HA/Mg-Zn biocomposites

The thermal-treated hydroxyapatite (HA) particles, Mg and Zn powders were used to prepare the HA/Mg-Zn composites with different HA contents by means of powder metallurgy technology. The microstructures, formation phases, and corrosion behaviors in simulated body fluid (SBF) were studied in comparison with pure magnesium and HA/Mg composites fabricated by the same preparation technology. As a result, no evident reaction happened between HA particles and Mg matrix during sintering process, and Zn atoms diffused into Mg matrix to form a single phase Mg-Zn alloy matrix. The addition of HA particles changed the corrosion mechanism of Mg matrix. During the corrosion process, HA particles would adsorb and Ca²⁺ ions efficiently and induce the deposition of Ca-P compounds on the surface of composites. HA could improve the corrosion resistance of magnesium matrix composites in SBF and restrain the increase of pH of SBF. Furthermore, the addition of Zn was favorable to improve the corrosion resistance of HA/Mg composites due to the densification of composites and the formation of Mg-Zn alloy matrix.     

Ca2+ doping effects in (K,Na, Li)(Nb0.8Ta0.2)O3 lead-free piezoelectric ceramics

Lead-free (K_0.5−x/2Na_0.5−x/2Li_x)(Nb_0.8Ta_0.2)O₃ (KNLNT) and (K_0.49−x/2Na_0.49−x/2- Li_xCa_0.01)(Nb_0.8Ta_0.2)O₃ (KNLNT-Ca) ceramics were prepared by a conventional ceramic processing. Structural analysis shows that the Ca²⁺ doping takes the A site of ABO₃ perovskite and decreases the phase transition temperature. Property measurements reveal that as a donor dopant, the Ca²⁺ doping results in higher room-temperature dielectric constant, lower dielectric loss, and lower mechanical quality factor. In addition, the Ca²⁺ doping does not change the positive piezoelectric coefficient d₃₃, but increases the converse piezoelectric coefficient d₃₃^* significantly. This is likely due to the increase in the relaxation, as well as the appearance of (Ca_Na/K^•--V_Na/K′) defect dipoles.     

Fabrication and Characterization of Potassium Ion-Selective Electrode Based on Porous Silicon

Porous-silicon (PS)-based potassium ion-selective microelectrode (K⁺ISME) was fabricated by using a microelectronic planar process and an electrochemical anodization etching technique. The apparent sensing area of the K⁺ISME is 100times100 mum ². The response time t_95% is 20 and 31 s when the concentration change is from low to high and vice versa, respectively. The potentials are constant at pH 2-8. The calibration curve for the K ⁺ISME is linear within a wide range of pK=2.0~6.0. Its average slope during six months is 56.5 mV per decade, which is close to the Nernst response. The detection limit was found to be on the order of 5times10^-7 M. The potentiometric selectivity coefficients (K_i,j ^pot) of the K⁺ ISE were 1.8 for NH ₄ ⁺, 3.6 for Li⁺, 4.1 for Na⁺, 4.5 for Mg²⁺, and 4.8 for Ca²⁺, respectively. Good performances of the K⁺ISME are attributed to large specific surface area and excellent adhesion between sensing membrane and the surface of PS     

One pot synthesis of monodispersed L-glutathione stabilized gold nanoparticles for the detection of Pb2+ ions

Direct mixture of Au³⁺ with glutathione (GSH), which act as both reduction agents and stabilizers, in aqueous solution gave rise to production of gold nanoparticles (Au NPs) with uniform sizes of around 21 nm. The GSH stabilizer Au NPs in solution show immediate aggregation after addition of 1 mol/L NaCl aqueous solution containing Pb²⁺ ions. The Pb²⁺-induced aggregation in Au NP solution is monitored by both colorimetric response and UV-vis spectroscopy. A rather broad linear range (from 0.1 to 30 μmol/L) and low detection limit (0.1 μmol/L) are explored for Au NP sensors used for detection of Pb²⁺ ions. Furthermore, the response of GSH-stabilized Au NPs toward Pb²⁺ ions is specific compared with other possible interferants (Hg²⁺, Mg²⁺, Zn²⁺, Ni²⁺, Cu²⁺, Co²⁺, Ca²⁺, Mn²⁺, Cd²⁺, and Ba²⁺).     

The nature of fatigue damage in bone

Bone is unusual among structural materials as it is alive and capable of self-repair. Fatigue-induced microdamage is repaired by bone remodelling, but if damage accumulates too quickly, or remodelling is deficient, fatigue failure may result. Fatigue is thought to contribute to both stress and fragility fractures which are of major clinical importance. Despite this, we do not fully understand the nature of fatigue damage in bone. Human rib sections, containing microcracks stained with basic fuchsin, were serially sectioned and microcracks identified and reconstructed in three dimensions using computer software. Microcracks were elliptical in shape, 400 μm long and 100 μm wide, typical of a transversely isotropic material. Chelating agents which bind Ca²⁺ were found to label microcracks in rib, as well as mineralising bone surfaces and resorption sites, suggesting that microcracks are Ca²⁺ ion-lined discontinuities in the hydroxyapatite matrix. Ca²⁺ ions were exposed by scratching the surface of bovine bone specimens and labelled with chelating agents in sequence. The optimal four agent sequence was: alizarin, xylenol orange, calcein and calcein blue. Two dye sequences were used to differentiate between pre-existing and test-induced microdamage in bovine samples fatigue tested in compression and longer sequences labelled microcrack growth. Microcrack dimensions can be used to calculate stress intensity values and, together with fatigue test data, can aid theoretical models to predict fatigue failure in bone.