磷灰石-硅灰石生物活性玻璃陶瓷对谷氨酸的吸附

背景:磷灰石-硅灰石生物玻璃陶瓷足近年发展起来的优良骨修复支架材料,可为种子细胞提供良好的生长环境.但是细胞与载体的相互作用及变化机制尚未完全清楚.目的:考察溶胶-凝胶法制备的磷灰石-硅灰石生物活性玻璃陶瓷对谷氨酸的吸附行为,探讨温度、溶液pH值、质量浓度对谷氨酸吸附量的影响.设计、时间及地点:观察实验,于2008-03/09在四川大学材料科学与工程学院完成.材料:用溶胶凝胶法制备的磷灰石-硅灰石生物活性玻璃陶瓷.方法:将片状磷灰石-硅灰杆生物活性玻璃陶瓷浸泡于谷氨酸溶液中,改变谷氨酸溶液质量浓度、pH值、温度等吸附条件.主要观察指标:测量不同条件下的谷氨酸吸附量.结果:①磷灰石-硅灰石生物活性玻璃陶瓷仞次对谷氨酸吸附时,属于Freundlich型吸附,包括物理吸附和化学吸附.②谷氨酸较适宜的吸附条件为DH 3.4或者8,温度为37℃左右.结论:磷灰石-硅灰石生物活性玻璃陶瓷对谷氨酸的吸附受溶液pH值、温度,谷氨酸质量浓度等因素的影响,且存在一定的规律.     

肝动脉注射锰锌铁氧体磁性纳米颗粒治疗兔VX2肝癌

背景:与传统的热疗方法相比,磁流体热疗具有很好的磁响应性,在一定高频交变磁场下能实现肿瘤热疗的自动控温和靶向治疗等优点。目的:制备锰锌铁氧体磁性纳米颗粒,观察其介入治疗兔VX2肝癌的效果。方法:采用开腹后瘤粒悬浮液针头注入法制作兔VX2肝癌模型,造模后14d随机数字表法分为对照组(生理盐水)、锰锌铁氧体磁性纳米颗粒非热疗组、锰锌铁氧体磁性纳米颗粒热疗组、阿霉素组,均采用3F导管从右侧股动脉选择至肝固有动脉动脉注入药物后拔管。锰锌铁氧体磁性纳米颗粒热疗组于介入后行热疗3次。介入治疗后14d取肝脏组织测量肿瘤大小,并做病理组织学检查。结果与结论:透射电镜下观察制备的锰锌铁氧体磁性纳米颗粒为球形,大小为20～30nm,在交变磁场下有良好的磁感应升温能力。治疗后14d,锰锌铁氧体磁性纳米颗粒热疗组肿瘤大面积坏死,肿瘤抑制率达到70.84%,明显高于锰锌铁氧体磁性纳米颗粒非热疗组、阿霉素组与对照组(P<0.05或P<0.01)。说明锰锌铁氧体磁性纳米颗粒可吸收电磁波转化为热能,通过介入治疗可显著抑制兔VX2肝癌生长。     

肝动脉注射锰锌铁氧体磁性纳米颗粒治疗兔VX2肝癌

背景：与传统的热疗方法相比,磁流体热疗具有很好的磁响应性,在一定高频交变磁场下能实现肿瘤热疗的自动控温和靶向治疗等优点。目的：制备锰锌铁氧体磁性纳米颗粒,观察其介入治疗兔VX2肝癌的效果。方法：采用开腹后瘤粒悬浮液针头注入法制作兔VX2肝癌模型,造模后14d随机数字表法分为对照组（生理盐水）、锰锌铁氧体磁性纳米颗粒非热疗组、锰锌铁氧体磁性纳米颗粒热疗组、阿霉素组,均采用3F导管从右侧股动脉选择至肝固有动脉动脉注入药物后拔管。锰锌铁氧体磁性纳米颗粒热疗组于介入后行热疗3次。介入治疗后14d取肝脏组织测量肿瘤大小,并做病理组织学检查。结果与结论：透射电镜下观察制备的锰锌铁氧体磁性纳米颗粒为球形,大小为20～30nm,在交变磁场下有良好的磁感应升温能力。治疗后14d,锰锌铁氧体磁性纳米颗粒热疗组肿瘤大面积坏死,肿瘤抑制率达到70.84%,明显高于锰锌铁氧体磁性纳米颗粒非热疗组、阿霉素组与对照组（P〈0.05或P〈0.01）。说明锰锌铁氧体磁性纳米颗粒可吸收电磁波转化为热能,通过介入治疗可显著抑制兔VX2肝癌生长。     

溶胶-凝胶法制备磷灰石-硅灰石多孔生物活性玻璃陶瓷的生物活性

背景：磷灰石-硅灰石玻璃陶瓷是生物活性优异的骨修复材料，一般通过高温熔制法制备。目的：观察新型溶胶-凝胶法制备磷灰石-硅灰石生物活性玻璃陶瓷及其生物活性。设计：材料工艺设计实验，活体外生物活性实验。单位：四川大学材料科学与工程学院。材料：磷灰石-硅灰石玻璃陶瓷。方法：实验于2002—08／2003-05在四川大学材料科学与工程学院生物材料研究实验室完成。采用溶胶-凝胶法及后续热处理工艺制备磷灰石-硅灰石玻璃陶瓷，试样在模拟体液中于37℃浸泡7d，通过观察表面磷灰石的形成情况考察材料的生物活性。采用JL-1155型激光粒度仪、X射线衍射仪、傅立叶红外转换光谱仪、扫描电子显微镜进行表征分析。主要观察指标：①新工艺溶胶-凝胶法制备的玻璃陶瓷材料的晶型结构、显微结构。②模拟体液中材料表面磷灰石形成情况。③多孔型溶胶-凝胶硅灰石／磷灰石玻璃陶瓷孔径。结果：①溶胶-凝胶工艺制备出玻璃陶瓷材料，其主晶相为羟基磷灰石、氟磷灰石和β-硅灰石，微观结构包括大量2．0-3．0μm微孔。②溶胶-凝胶磷灰石-硅灰石玻璃陶瓷生物活性优异：体外模拟体液浸泡7d后，表面生成大量磷灰石颗粒。③多孔支架材料孔隙形态优异，为300-400μm直径相互贯通的大孔结构。结论：通过溶胶-凝胶工艺制备了具有优异生物活性的磷灰石-硅灰石玻璃陶瓷；此材料可望成为优异的骨修复材料及骨组织工程支架材料。     

溶胶-凝胶法制备磷灰石-硅灰石多孔生物活性玻璃陶瓷的生物活性

背景:磷灰石-硅灰石玻璃陶瓷是生物活性优异的骨修复材料,一般通过高温熔制法制备。目的:观察新型溶胶-凝胶法制备磷灰石-硅灰石生物活性玻璃陶瓷及其生物活性。设计:材料工艺设计实验,活体外生物活性实验。单位:四川大学材料科学与工程学院。材料:磷灰石-硅灰石玻璃陶瓷。方法:实验于2002-08/2003-05在四川大学材料科学与工程学院生物材料研究实验室完成。采用溶胶-凝胶法及后续热处理工艺制备磷灰石-硅灰石玻璃陶瓷,试样在模拟体液中于37℃浸泡7d,通过观察表面磷灰石的形成情况考察材料的生物活性。采用JL-1155型激光粒度仪、X射线衍射仪、傅立叶红外转换光谱仪、扫描电子显微镜进行表征分析。主要观察指标:①新工艺溶胶-凝胶法制备的玻璃陶瓷材料的晶型结构、显微结构。②模拟体液中材料表面磷灰石形成情况。③多孔型溶胶-凝胶硅灰石/磷灰石玻璃陶瓷孔径。结果:①溶胶-凝胶工艺制备出玻璃陶瓷材料,其主晶相为羟基磷灰石、氟磷灰石和β-硅灰石,微观结构包括大量2.0～3.0μm微孔。②溶胶-凝胶磷灰石-硅灰石玻璃陶瓷生物活性优异:体外模拟体液浸泡7d后,表面生成大量磷灰石颗粒。③多孔支架材料孔隙形态优异,为300～400μm直径相互贯通的大孔结构。结论:通过溶胶-凝胶工艺制备了具有优异生物活性的磷灰石-硅灰石玻璃陶瓷;此材料可望成为优异的骨修复材料及骨组织工程支架材料。     

介孔-大孔生物活性玻璃的合成及其生物活性

背景：多孔生物活性玻璃材料具有较大的比表面积、孔隙率以及贯通的孔道结构,可以加速羟基磷灰石沉积的动力学速率从而提高材料诱导形成新骨的能力。目的：利用有机酸替代无机酸来合成新型介孔-大孔生物活性玻璃。方法：将柠檬酸和P123加入到无水乙醇中,在室温下搅拌2h至溶液澄清。依次加入正硅酸乙酯、四水硝酸钙和三磷酸乙酯,继续搅拌24h。将所得溶胶倒入培养皿中,在室温下放置7d,之后高温下烧结除去有机物模板。结果与结论：①利用有机酸所制备的材料具有大孔结构,拥有较大的比表面积、孔隙率和孔径。②合成的介孔-大孔生物活性玻璃在人工模拟体液中可以诱导形成含碳羟基磷灰石,表现出了较好的生物活性,有望成为一种具有发展前景的骨缺损修复替代材料。     

介孔-大孔生物活性玻璃的合成及其生物活性

背景:多孔生物活性玻璃材料具有较大的比表面积、孔隙率以及贯通的孔道结构,可以加速羟基磷灰石沉积的动力学速率从而提高材料诱导形成新骨的能力。目的:利用有机酸替代无机酸来合成新型介孔-大孔生物活性玻璃。方法:将柠檬酸和P123加入到无水乙醇中,在室温下搅拌2h至溶液澄清。依次加入正硅酸乙酯、四水硝酸钙和三磷酸乙酯,继续搅拌24h。将所得溶胶倒入培养皿中,在室温下放置7d,之后高温下烧结除去有机物模板。结果与结论:①利用有机酸所制备的材料具有大孔结构,拥有较大的比表面积、孔隙率和孔径。②合成的介孔-大孔生物活性玻璃在人工模拟体液中可以诱导形成含碳羟基磷灰石,表现出了较好的生物活性,有望成为一种具有发展前景的骨缺损修复替代材料。     

人骨形态发生蛋白2基因转染的骨髓基质细胞复合生物活性玻璃陶瓷修复颅骨缺损

背景:目前已有将体外培养的骨髓基质细胞与支架复合修复骨缺损的临床报道.但是由于该类复合材料中缺乏骨生长因子作用,在原位的成骨作用并不十分理想.目的:探讨携带入骨形态发生蛋白2基因的骨髓基质细胞复合生物活性玻璃陶瓷材料在修复兔颅骨缺损中的原位成骨作用.设计、时间及地点:随机对照动物实验,于2005-02/2008-11在辽宁医学院解剖学实验室完成.材料:生物活性玻璃陶瓷由中国科学院四川成都光电研究所提供,转人骨形态发生蛋白2和转pcDNA3载体的骨髓间充质干细胞由辽宁医学院解剖学教研室骨组织工程研究所保存.方法:制各兔双侧颅骨骨缺损模型,将基因转染的骨髓基质细胞与生物活性玻璃陶瓷复合培养物植入骨缺损区,术后第4,8,12周对植骨区进行大体观察、X射线摄片、组织切片、组织化学检测.主要观察指标:①复苏后的转染人骨形态发生蛋白2的骨髓基质细胞的生长特性.②从大体、X射线结果和组织学等方面观察复合材料在原位修复骨缺损的作用.结果:转染的骨髓基质细胞在细胞形态及增殖特性方面与末转染的细胞无明显差异.扫描电镜显示基因转染的骨髓基质细胞在生物活性玻璃陶瓷表面呈星形紧密排列,长入生物活性玻璃陶瓷孔隙中.复合材料植入免颅骨缺损后,X射线观察术后第4周骨缺损外周骨质与复合材料之间大部分被高密度阴影充填,术后第12周骨缺损外周骨质与复合材料之间完全被高密度阴影充填:光镜观察术后第8周骨小梁大部分相连成片,术后第12周骨小梁粗大,骨髓再生.结论:基因转染的骨髓基质细胞复合生物活性玻璃陶瓷材料基本符合骨组织工程学的要求,在骨缺损区原位具有良好的成骨作用.     

三氧化二砷／锰锌铁氧体复合纳米粒体外治疗食管癌

背景：与传统的热疗方法相比,As2O3／Mn0.5Zn0.5Fe2O4复合纳米粒可以同时发挥As2O3的细胞毒性作用和磁感应加热的联合定向治疗作用,效果优于单一治疗。目的：制备As2O3／Mn0.5Zn0.5Fe2O4复合纳米粒,观察其对食管癌Eca109细胞增殖的抑制作用。方法：采用浸渍法制备As2O3／Mn0.5Zn0.5Fe2O4复合纳米粒,含砷量0．012％,以透射电镜、能谱仪、原子分光光度仪对其进行表征。向两块培养板的食管癌Ecal09细胞中分别加入DMEM培养液（阴性对照）、Mn0.5Zn0.5Fe2O4纳米材料、含AS2O3终浓度5υmol／L的As2O3／Mn0.5Zn0.5Fe2O4复合纳米粒、游离As2O3（终浓度5υmol／L）,其中一块培养板进行磁流体热疗,另一块培养板正常培养。结果与结论：As2O3／Mn0.5Zn0.5Fe2O4复合纳米粒近似球形,As2O3成功浸渍在Mn0.5Zn0.5Fe2O4纳米材料表面,砷含量在0．012％-0．066％之间。当As2O3浓度为5υmol／L时,As2O3／Mn0.5Zn0.5Fe2O4复合纳米粒组细胞增殖率明显低于阴性对照组和Mn0.5Zn0.5Fe2O4纳米材料组（P＜0．05）;而在磁流体热疗中,As2O3／Mn0.5Zn0.5Fe2O4复合纳米粒组细胞增殖率明显低于游离As2O3组或Mn0.5Zn0.5Fe2O4组（P〈0．05）;在凋亡率检测中,As2O3／Mn0.5Zn0.5Fe2O4复合纳米粒联合磁流体热疗组细胞凋亡率明显高于Mn0.5Zn0.5Fe2O4纳米材料联合磁流体热疗组或游离As2O3组（P〈0．05）。表明As2O3／Mn0.5Zn0.5Fe2O4复合纳米粒联合磁流体热疗可显著抑制食管癌细胞增殖。     

羟基磷灰石/聚乙烯醇水凝胶的制备与生物活性评价

背景:先前的研究表明,羟基磷灰石/聚乙烯醇水凝胶复合水凝胶(hydroxyapatite/ polyvinyl alcohol hydrogel,HA/PVA-H)具有较好的机械性能和耐摩擦磨损性能,这说明HA/PVA-H复合材料具有早期承载能力和较好的生物活性.那么HA/PVA-H复合材料能否通过羟基磷灰石粒子与周围骨组织较快地形成活性结合呢? 目的:制备羟基磷灰石/聚乙烯醇水凝胶,并对其进行生物学评价.方法:将Ca(OH)2研磨过筛后,配制成一定浓度的悬浮分散液;加入质量分数15%的PVA水溶液中,添加二甲亚砜,最后按Ca/P比1.67: 1加入H3PO4的乙醇溶液,制备HA/PVA-H.对试样进行体外模拟体液培养实验,测试浸泡前后SBF浸泡液的变化,并利用扫描电镜、FTIR、XRD 对材料的结构进行了表征和分析.结果与结论:扫描电镜观察可知羟基磷灰石/聚乙烯醇水凝胶表面有结晶体形成,经XRD分析确认为弱结晶的羟基磷灰石晶体;浸泡之后浸泡液的pH值与Ca、P离子浓度下降,同时FTIR结果显示试样中的PO43-特征峰得到增强,且有CO32-的特征峰形成.结果提示,羟基磷灰石/聚乙烯醇水凝胶复合材料具有较好的生物活性.     

Development of an automated wheelchair guided by a magnetic ferrite marker lane.

An automated wheelchair with a guide sensor, guided by a magnetic ferrite marker that is resistant to the presence of dirt, is described. The wheelchair permits the severely disabled, as well as the older population, to move about freely, both indoors and outdoors. This is due to the simple operation involved (pushing a button), and a magnetic ferrite marker lane which is minimally influenced by dirt or other nonmagnetic materials. For increased comfort, a nonlinear signal-processing circuit and pulse-steering drive method have been developed to provide a smooth running operation. In addition, a function that provides for stopping at desired destinations has been added for convenience, and a collision prevention function using infrared sensors has been added for safety.     

Tuning of spinel magnesium ferrite nanoparticles with enhanced magnetic properties

Monodispersed magnesium ferrite nanoparticles with enhanced magnetic properties were successfully fabricated by a simple solvothermal method without employing any templates, complex apparatus or techniques. The structure, morphology, composition, and magnetic properties of the products were tuned and characterized by X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy and vibrating sample magnetometry. The results show that the reaction time and temperature have an important influence on the morphology, composition, structure and particle size of the synthesized MgFe₂O₄ nanoparticles. Not only the size, size distribution, crystallization, but also the atomic ratio of Mg : Fe has a decisive effect on their magnetic properties. The MgFe₂O₄ magnetic nanoparticles synthesized at 180 °C for 12 hours have excellent dispersion, narrow size distribution, good crystallinity and a Mg : Fe atomic ratio of approximately 1 : 4.53 and an average particle size of 114.3 nm, thus the highest saturation magnetization of 67.35 emu g⁻¹. It provides a reliable synthesis method for the better application of spinel structure magnesium ferrite nanoparticles in the future.

Monodispersed magnesium ferrite nanoparticles with enhanced magnetic properties were successfully fabricated by a simple solvothermal method without employing any templates, complex apparatus or techniques.     

磁性附着体中铁素体不锈钢引起小鼠成纤维细胞L929的死亡模式

背景:作为自制磁性附着体外包裹材料的26-1超纯铁索体不锈钢在以往的实验中已初步证实其具有良好的生物学特性,但选用凋亡机制对其生物相容性进行深入研究和评价的报道较少.目的:应用L929细胞从分子生物学水平探讨26-1超纯铁素体不锈钢引起细胞的死亡模式,评价26-1超纯铁索体不锈钢是否符合临床应用的生物相容性要求.设计、时间及地点:分子生物学水平,对比观察实验,于2004-06/2005-06在中国医科大学中心实验室完成.材料:26-1超纯铁索体不锈钢(超低碳,名义成分为Fe-26%Cr-1%Mo),Tilite(含钛医用合金,名义成分为70%Ni-16%Cro(4%～6%)Ti-其他合金元素)、Co-Cr合金(名义成分为Co-30%Cr-5%Mo).利用蜡型铸造制备实验用材料,并将材料分别切割成直径12 mm的圆盘样品.方法:①将3种材料与L929细胞联合培养.阴性对照组为RPMI1640正常培养细胞,孵育18 h和24 h后应用异硫氰酸荧光素标记的膜联蛋白结合碘化丙啶染色双参数技术对细胞死亡类型进行定量检测.②25%,50%,100%浓度的3种材料浸提液体外培养小鼠成纤维细胞L929 24 h后,采用流式细胞术碘化丙啶染色法检测L929细胞的凋亡率及细胞周期分布情况.主要观察指标:①不同材料引起L929细胞凋亡和坏死的比例.②L929细胞凋亡率及细胞周期分布情况.结果:各材料组均降低了L929细胞的生存率,其中细胞坏死水平在各材料组与阴性对照组之间差异无显著性意义,说明引起的致细胞病变效应主要是由细胞凋亡引起的,各材料组之间产生的效应差异无显著性意义.并且L929细胞凋亡具有明显的浓度依赖性及时间依赖性.3种实验用金属材料引起的L929细胞凋亡率在各浓度组间差异无显著性意义.结论:26-1超纯铁索体不锈钢引起细胞的死亡方式丰要是凋亡,符合临床应用材料的生物相容性要求.     

Diluted magnetic semiconductor properties in TM doped ZnO nanoparticles

The hydrothermal method was used to create dilute magnetic semiconductor nanoparticles of Zn_1−xCo_xO (x = 0, 0.01, 0.05, 0.09). The effect of cobalt doping on the microstructure, morphological and optical properties of Zn_1−xCo_xO was also studied and the Co doping to host ZnO was confirmed from XRD and EDX analysis. The structural analysis showed that doping of cobalt into ZnO decreased the crystallinity, but the preferred orientation didn''t change. SEM analysis revealed that the cobalt dopant did not have a strong influence on the shape of the synthesized nanoparticles. No defect-related absorption peaks were observed in the UV-Vis spectra. The crystallinity of the doped samples was improved by high growth temperature and long growth time. Ferromagnetic behavior above room temperature was detected in co-doped ZnO nanoparticles. The ferromagnetic behavior increased with increasing Co (up to x = 0.05) doping. The ferromagnetic behavior declined when the Co content was further increased. Related research shows that doped ZnO nanoparticles have better dielectric, electrical conductivity, and magnetic properties than pure ZnO. This high ferromagnetism is usually a response reported for dilute magnetic semiconductors. These semiconductor nanoparticles were further used to designed spintronic based applications.

The enlarged central part M–H loop shows for the Co = 0.09 doped ZnO sample, the ferromagnetic (FM) behavior increased, i.e., a M_r of 0.2412 emu g⁻¹ with a H_c of 85 Oe.     

Structural and magnetic study of undoped and cobalt doped TiO2 nanoparticles

The present study investigates the influence of cobalt doping on the structural and magnetic properties of TiO₂ nanoparticles prepared by a simple wet chemical method. The single phase anatase structure of Co-doped TiO₂ nanoparticles was confirmed by X-ray powder diffraction. A morphological study using scanning electron microscopy and transmission electron microscopy indicates the formation of TiO₂ nanoparticles of sizes 6–10 nm. The high resolution TEM image shows clear lattice fringes indicating the highly crystalline nature of the nanoparticles which was further analysed by selected area electron diffraction pattern which indicates a polycrystalline nature of anatase TiO₂. The shifting and broadening of the most intense E_g (1) mode in micro-Raman study of Co-doped TiO₂ nanoparticles and XPS spectra indicate the incorporation of Co in TiO₂. Magnetic measurement shows ferromagnetic behavior at room temperature in undoped TiO₂ which has originated due to the presence of oxygen vacancies which are intrinsic in nature. But the M–H curve of Co-doped TiO₂ shows the coexistence of ferromagnetic and paramagnetic phases with enhanced magnetization. The enhancement in magnetization has arisen due to Co doping and the paramagnetism may be due to the presence of some undetected clusters of oxides of cobalt.

The present study investigates the influence of cobalt doping on the structural and magnetic properties of TiO₂ nanoparticles prepared by a simple wet chemical method.     

Fiber optic magnetic field sensor using Co doped ZnO nanorods as cladding

A fiber optic magnetic field sensor is proposed and experimentally demonstrated. Pristine and Co doped ZnO nanorods of different Co concentrations (5, 10, 15 and 20 at%) were synthesized using a hydrothermal method. The synthesized nanorods were subjected to various characterization methods like X-ray diffraction (XRD), optical absorption, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometry and X-ray photoelectron spectroscopy (XPS). XRD and XPS analysis confirms that the Co ions were successfully incorporated into the Zn site of the wurtzite ZnO lattice without altering the structure. The pristine and Co doped ZnO nanorods showed remarkable changes in the M–H loop where the diamagnetic behavior of ZnO changes to paramagnetic when doped with Co. The sensor structure is composed of cladding modified fiber coated with Co doped ZnO nanorods as a sensing material. The modified cladding is proportionally sensitive to the ambient magnetic field because of the magneto-optic effect. Experimental results revealed that the sensor has an operating magnetic field range from 17 mT to 180 mT and shows a maximum sensitivity of ∼18% for 15 at% Co doped ZnO nanorods. The proposed magnetic field sensor would be attractive due to its low cost fabrication, simplicity of the sensor head preparation, high sensitivity and reproducibility.

A fiber optic magnetic field sensor based on Co doped ZnO nanorods is proposed and demonstrated. The sensor has an operating magnetic field range of 17 mT to 180 mT and shows a maximum sensitivity of ∼18% for 15 at% Co doped ZnO nanorods.     

Structural characterization and magnetic properties of undoped and copper-doped cobalt ferrite nanoparticles prepared by the octanoate coprecipitation route at very low dopant concentrations

Nanoparticles of undoped and copper-doped cobalt ferrite Co_1−xCu_xFe₂O₄ at very low dopant concentrations (x = 0; 0.02; 0.04; 0.06; 0.08) were successfully synthesized by pyrolysis of the corresponding hetero metal octanoate precursors obtained via coprecipitation using the octanoate ligand as precipitating agent. The precursors were then characterized by FTIR, ICP-AES and TG-DTA analyses and the results reveal the formation of a copper-cobalt-iron hydroxooctanoate represented by the formula [Co_1−xCu_xFe₂(C₈H₁₅O₂)₆(OH)₂·2H₂O]. The decomposition products obtained upon pyrolysis in air at 400 °C for 3 h were characterized by FTIR, XRD, SEM, TEM, XPS and VSM analyses. FTIR and XRD analyses showed the formation of a single phase mixed spinel ferrite while TEM analysis showed that the particles have a spherical shape with a mean size of 20 nm and form spherical agglomerates with sizes reaching 500 nm in some cases as the SEM images show. The chemical states of the metallic species in the samples were revealed by XPS to be Cu²⁺, Co²⁺ and Fe³⁺. These results combined with XRD confirmed the mixed spinel structure, Co_1−xCu_xFe₂O₄ in which Cu²⁺ ions substitute Co²⁺ ions in tetrahedral sites for x lower than 0.06 and in octahedral sites for x between 0.06 and 0.08. Magnetic parameters such as saturation magnetization (M_s), coercivity (H_c), remanent magnetization (M_r), magnetocrystalline anisotropy constant (K) and reduced magnetization (M_r/M_s), obtained from magnetic hysteresis loops measured at room temperature, are in agreement with this mixed spinel structure and also indicate that these materials are ferromagnetic and could be good candidates for applications in biomedicine and in microwave devices.

Low level copper-doped CoFe₂O₄ has been synthesized and shows an increasing of saturation magnetization up to 6% Cu, subsequently decreasing above 6%.