基于氧化铁纳米材料特性的生物分离和生物检测

氧化铁纳米粒子是一种新型的磁功能材料,被广泛应用于生物、材料以及环境等众多领域.本文介绍了超顺磁氧化铁纳米粒子的制备方法,比较了各种方法的优缺点;评述了磁性氧化铁纳米粒子在细胞、蛋白质和核酸分离及生物检测中的应用,对多功能复合磁性氧化铁纳米粒子的构建, 在生物医学领域中的应用具有的指导意义.     

基于催化应用调控氧化铈纳米材料的形貌

催化剂的设计、合成和结构调控是获得优异性能的关键.传统的策略主要是尽量减小催化剂颗粒尺寸以增加活性中心的数目,即尺寸效应.近年来,材料科学的快速发展使得在纳米尺度上调变催化剂的尺寸和形貌成为可能,特别是通过形貌调控可暴露更多的高活性晶面,大幅度提高催化性能,即纳米催化中的形貌效应.因此,调节催化剂的尺寸与形貌可以单独或协同优化材料的性能.氧化铈作为催化剂的重要组分与结构、电子促进剂被广泛应用于多相催化剂体系.本文总结了近期氧化铈材料形貌可控合成的进展,包括主要的合成策略和表征方法; 进而分析了氧化铈和金-氧化铈催化材料的形貌效应,指出金-氧化铈之间独特的相互作用与载体形貌密切相关; 阐述了氧化铈纳米材料因暴露晶面的差异而获得不同催化性能的化学机制.     

纳米氧化铁的制备及其对砷的吸附作用

用均匀沉淀法、溶胶-凝胶相转移法和溶胶-凝胶蒸发干燥法制备了纳米氧化铁,研究了制备条件,并对产品进行了表征。扫描电镜和X射线衍射分析结果表明,以上3种方法制备的氧化铁,颗粒均在100~300 nm之间。用溶胶-凝胶蒸发干燥法制备的样品C和样品D具备典型α型Fe2O3的物相特征。吸附实验表明,合成的纳米氧化铁对砷(Ⅴ)均有较强的吸附性能,在初始砷质量浓度为2 mg/L,pH值在4.0~6.0的范围内,能使溶液中的砷含量降到0.01 mg/L以下,且吸附速度快,平衡时间短。溶胶-凝胶蒸发干燥法制备的纳米氧化铁在pH值为3.0、7.0和10.0时的最大砷吸附容量分别为30.96、30.58和17.06 mg/g,与其他纳米氧化物相比,用此方法制备的纳米氧化铁对As(V)有较大的吸附能力,较普通块体氧化铁的吸附除砷性能更优。其吸附等温线能用Langmuir方程进行拟合,确定系数R2>0.95。     

基于氧化铁颗粒与聚合物的纳米复合材料磁电容特性研究

对由Fe3O4纳米颗粒-聚二甲基硅烷(PDMS)聚合物材料所组成纳米复合材料磁电容特性进行了研究,提出了该复合材料的制备方法,并对其进行了表征、磁化特性测试以及零磁场环境下介电特性测试;分析了该复合材料的相对介电常数随环境磁场的变化关系以及具有不同含量、粒径纳米颗粒的复合材料磁电容特性差异.实验结果显示,该复合材料的相对介电常数随环境磁场的增大而增大,其变化曲线有一定的滞后特性;复合材料的相对介电常数变化量随材料中纳米颗粒粒径以及含量的增大而增大,但含有较大颗粒复合材料的相对介电常数变化曲线具有较大的滞后性.研究表明,该复合材料在环境磁场中能够产生磁电容效应,其相对介电常数随环境磁场的变化率、饱和值以及滞后性都会受到材料中包含的纳米颗粒的含量以及磁化特性(磁导率、饱和磁化强度、矫顽力)所影响.     

新型树脂基水合氧化铁对水体中微量砷的吸附性能研究

将水合氧化铁固载于凝胶型强碱阴离子树脂N201上并合成出新型除砷吸附剂N201-Fe.研究了不同实验条件下N201-Fe对去除水溶液As(V)的影响.实验结果表明,N201-Fe对砷的吸附受pH值的影响较小;N201-Fe对As(V)具有很高选择性,在Cl-、HCO3-、SO42-等竞争离子共存时,N201对As(V)的去除率不到2%,而N201-Fe却高达90%.N201-Fe对As(V)的高选择性归因于N201-Fe中水合氧化铁与As(V)之间的络合配位能力及树脂表面的Donnan膜效应.静态吸附实验表明N201-Fe吸附As(V)的等温线符合Freundlich模型,热力学结果显示,该吸附过程为吸热过程.动态穿透实验表明,模拟水中的As(V)经N201-Fe处理后可达到中国和美国的饮用水标准,且N201-Fe的吸附处理量较N201提高30多倍.     

蜜胺-巴比妥酸衍生物有机复合物纳米结构组装的化学微环境调控

综述了从互补的蜜胺和巴比妥酸衍生物分子组分出发, 通过调节组装过程中的化学微环境, 可控制分子组分所包含的信息表达从而制备不同有机纳米结构的研究进展. 研究结果表明, 在经严格无水处理的氯仿中进行组装得到的是一种周期为4.1 nm的非中心对称的层状结构. 如果在含有微量的极性溶剂如乙醇的氯仿进行组装得到的是一种直径为6 nm、长度为数百纳米的有机纳米管结构, 这种有机纳米管在合适的极性溶剂诱导下可以进一步组装形成直径为300 nm, 长度为几十微米的超螺旋结构. 这是由于诱导组装的分子间非共价键相互作用其焓变较小, 外部环境的微小变化就会打破原有的平衡条件, 从而导致组装体结构的重排和转化.     

基于Donnan膜效应的树脂基水合氧化铁的制备及对砷的吸附性能研究

以大孔强碱性离子交换树脂D201为载体, 利用FeCl₃-HCl-NaCl溶液特有的性质制备出一种基于Donnan膜效应的新型树脂基水合氧化铁D201-HFO. 研究结果表明, D201-HFO对砷的吸附容量较美国同类专利产品ArsenX有较大提高, 同时该材料表现出对砷良好的吸附选择性和吸附动力学性能. 固定床吸附结果表明, 通过D201-HFO的吸附处理, 受污染水体中砷的含量可降至10 μg/L(我国生活饮用水新标准GB5749-2006)以下, 吸附后的D201- HFO可被NaOH-NaCl溶液彻底再生. 稳定性实验表明, HFO在D201树脂孔道内较为稳定, D201-HFO是一种性能优良、具有广泛应用前景的除砷吸附剂.     

基于配位调控机制的纳米钴电化学传感研究

以钴离子(Co2+)与5-(5-碘-2-吡啶偶氮)-2,4-二氨基甲苯(5-I-PADAT)形成的配合物(Co2+-5-IPADAT)为支持电解质,采用循环伏安法,扫描电位范围-1. 5～0. 5 V,沉积50圈,制备获得Co NPs-5-I-PADAT修饰电极。采用扫描电子显微镜成像、X射线晶体衍射对其形貌及组成进行分析,并研究其对肼的电催化氧化行为。结果表明:在p H 7. 0的磷酸缓冲溶液中,电压位于0. 55 V处呈现显著的肼氧化峰。据此,建立了肼的定量分析方法,其线性范围为0. 64～2 150μmol/L,相关系数为0. 998 0,检出限(S/N=3)为0. 28μmol/L,回收率为95. 3%～102%。Co NPs-5-I-PADAT/GCE修饰电极具有良好的稳定性和选择性,可满足环境样品中肼的检测需求。     

基于1,4-双(咪唑-1-基)苯的Mn(Ⅱ)/Co(Ⅱ)配位聚合物的合成、晶体结构及性质

在溶剂热条件下,合成了3个新的配位聚合物{[Mn3(oba)3(bib)(DMF)(H2O)]·DMF}n(1)、[Co(Hoba)2(bib)]n(2)和{[Co(aip)(bib)]·DMF}n(3)(bib=1,4-双(咪唑-1-基)苯,H2oba=4,4′-二苯醚二甲酸,H2aip=5-氨基间苯二甲酸,DMF=...     

基于中空多孔金纳米/石墨烯复合纳米材料的葡萄糖氧化酶直接电化学及其生物传感研究

采用溶液相牺牲模板法制备中空多孔金纳米粒子（HPAuNPs）,并将该材料与还原氧化石墨烯（rGO）复合,用于葡萄糖氧化酶（GOx）在玻碳电极（GCE）表面的有效固定,构建GOx/HPAuNPs/rGO/GCE传感界面。利用扫描和透射电镜、X射线光电子能谱、X射线衍射谱、红外光谱及电化学等方法对材料的形貌与结构,GOx的固定化过程,以及传感器的直接电化学和电催化性能进行表征。结果表明,HPAuNPs和rGO的协同作用能有效促进GOx与电极之间的直接电子转移（DET）。基于GOx/HPAuNPs/rGO/GCE对葡萄糖的良好电催化性能,该方法有效实现了对葡萄糖的高灵敏度检测,其电流响应的线性范围为0.05～7.0 mmol/L,检出限（S/N=3）为16μmol/L。该传感器具有良好的选择性、重现性及稳定性,对实际样品血清中血糖的测定结果令人满意,回收率为98.0%～103%,相对标准偏差不大于5.0%。     

Synthesis and assembly of rare earth nanostructures directed by the principle of coordination chemistry in solution-based process

In this review, several typical nanomaterials are selected to demonstrate the coordination effect on the control of structure/microstructure/texture, surface/interface, particle size and morphology. Based on the principle of coordination chemistry, with some solution-based methods including solvothermal treatment and the thermolysis of metal complex precursors, a series of novel nanostructured rare earth compounds, such as ultra-small colloidal ceria nanoparticles, highly homogenous and stable ceria–zirconia solid solutions, and high-quality rare earth oxide and fluoride nanocrystals, etc., have been prepared by elaborately controlling the synthetic parameters and reaction kinetics. In order to reveal the mechanisms of synthesis, assembly, and properties, the phase, microstructure, texture, and surface state have been characterized systematically. The main applications of coordination chemistry principle in the synthesis and assembly of rare earth nanocrystals have been summarized, which also can be extended to direct the fabrication of other nanomaterials.     

One-pot aqueous solution syntheses of iron oxide nanostructures with controlled crystal phases through a microbial-mineralization-inspired approach

Iron-oxidizing bacteria produce trivalent iron oxides with the controlled crystal phases outside of their cells. Herein we have synthesized iron oxides with controlled oxidation states and crystal phases through a microbial-mineralization-inspired approach in an aqueous solution at low temperature. Trivalent iron oxides, such as lepidocrocite, ferrihydrite, goethite, and hematite, are selectively obtained from an aqueous solution containing divalent iron ions below 90 °C. The presence of a chelating agent facilitates the control of the oxidation states through the ligand-controlled approach because the precipitation of the divalent iron species is inhibited by the complexation between divalent iron ion and a chelating agent. The control of the crystal phases is achieved by the tuning of the synthetic conditions, such as the initial pH, the concentration of a chelating agent, and the reaction temperature. Furthermore, the resultant iron oxides have hierarchically organized structures consisting of nanoscale objects. The microbial-mineralization-inspired approach by using a chelating agent has potentials for the further morphological control of iron oxides and the further application to aqueous-solution syntheses of other metal oxides.     

Synthesis, characterization and formation process of transition metal oxide nanotubes using carbon nanofibers as templates

Mono and binary transition metal oxide nanotubes could be synthesized by the immersion of carbon nanofiber templates into metal nitrate solutions and removal of the templates by heat treatment in air. The transition metal oxide nanotubes were composed of nano-crystallites of metal oxides. The functional groups on the carbon nanofiber templates were essential for the coating of these templates: they acted as adsorption sites for the metal nitrates, ensuring a uniform metal oxide coating. During the removal of the carbon nanofiber templates by calcination in air, the metal oxide coatings promoted the combustion reaction between the carbon nanofibers and oxygen.     

甲烷在金属铁及氧化铁表面还原NO的研究

在程序控温电加热水平陶瓷管反应器、N₂气氛和模拟烟气气氛及300~1 100℃时,对甲烷在金属铁及其氧化铁表面还原NO的特性进行了实验研究。为使甲烷在脱硝反应后完全燃尽以及脱硝反应过程生成的CO等中间产物完全燃尽,在第一段加热炉后串联了第二段加热炉,补充氧气,实现燃尽。结果表明,甲烷在金属铁及氧化铁表面能够高效地还原NO。在N₂气氛中,在900℃以上温度范围内甲烷在金属铁表面的脱硝效率超过95%,与甲烷在氧化铁表面的脱硝效率差别很小。在模拟烟气条件下,当过量空气系数小于1.0时,在900℃以上时,甲烷在金属铁和氧化铁表面的脱硝效率都能超过90%,且未燃尽和燃尽两种条件下NO的还原率相差不大。NO同时通过金属铁的直接还原和甲烷的再燃还原两种反应机理脱除。而甲烷则通过还原氧化铁为金属铁,从而使金属铁直接还原NO可持续进行。同时,甲烷再燃反应的中间产物HCN/NH₃等被氧化铁还原,从而使燃尽后的脱硝效率不下降。研究结果表明,甲烷和金属铁或氧化铁在富燃料条件下可有效地还原NO。     

纳米级零价铁的湿化学法制备及性能表征

采用湿化学法制备了纳米级零价铁,研究了湿法化学还原过程中工艺条件对产物的影响.对纳米级零价铁制备过程中物质微观结构随工艺条件的变化规律有了明确地认识.最终确认湿化学还原过程的最佳工艺条件是:在有机反应介质中,加入分散剂,以一定的滴加速度加入还原剂,同时在修饰剂的作用下得到产物,最终在合适的清洗制度下得到纳米零价铁.     

Utilization of iron oxide film obtained by CVD process as catalyst to carbon nanotubes growth

Thin films of Fe₂O₃ were obtained on silica glass substrates through the thermal decomposition of ferrocene in air. These films were characterized by Raman spectroscopy and X-ray diffractometry (XRD), and subsequently used as catalyst on the growth of carbon nanotubes, using benzene or a benzene solution of [Fe₃(CO)₁₂] as precursor. A great amount of a black powder was obtained as product, identified as multi-walled carbon nanotubes by XRD, Raman spectroscopy and transmission electron microscopy. The carbon nanotubes formed through the pyrolysis of the [Fe₃(CO)₁₂] solution were identified as structurally better than the one obtained by the pyrolysis of pristine benzene.     

The effect of the conditions for the preparation of iron oxide nanoparticles on their catalytic characteristics in the oxidation of CO

The catalytic characteristics of systems prepared by mechanically mixing iron oxide nanoparticles, produced in the thermolysis of carboxylate complexes at 300–750°C, with aluminum oxide in the oxidation of CO were studied. It was shown that increase in the size of the iron oxide nanoparticles leads to decrease in the catalytic activity of the samples as a result of their different structural and textural characteristics, which change in relation to the synthesis conditions. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 5, pp. 300–305, September–October, 2006.     

Synthesis of new lamellar materials by self-assembly and coordination chemistry in the solids

We report the preparation of a new class of lamellar hybrid organic–inorganic materials obtained by self-assembly of bridged organosilica precursors containing long alkylene chains during the sol–gel process. The self-assembly is induced by lipophilic van der Waals interactions. The introduction of –SS– bonds in the core of the alkylene chains permitted the functionalisation of lamellar materials, which were subsequently transformed into SH and –SO₃H groups. This methodology was extended to the formation of lamellar hybrid materials containing amino groups thanks to CO₂ as bridging groups as well as the formation of lamellar hybrid materials containing carboxylic groups. In this last case, the hydrolysis and polycondensation of cyanoalkyltrialkoxysilanes permitted the one pot synthesis of lamellar hybrid materials thanks to in situ hydrogen bonds formation between carboxylic acids groups. All these functional lamellar materials exhibit a very high chelating capability towards transition metal and lanthanide ions.     

Nucleation process in the cavity of a 48-tungstophosphate wheel resulting in a 16-metal-centre iron oxide nanocluster

The 16-Fe(III)-containing 48-tungsto-8-phosphate [P(8)W(48)O(184)Fe(16)(OH)(28)(H(2)O)(4)](20-) (1) has been synthesised and characterised by IR and ESR spectroscopy, TGA, elemental analyses, electrochemistry and susceptibility measurements. Single-crystal X-ray analyses were carried out on Li(4)K(16)[P(8)W(48)O(184)Fe(16)(OH)(28)(H(2)O)(4)]66 H(2)O2 KCl (LiK-1, orthorhombic space group Pnnm, a=36.3777(9) A, b=13.9708(3) A, c=26.9140(7) A, and Z=2) and on the corresponding mixed sodium-potassium salt Na(9)K(11)[P(8)W(48)O(184)Fe(16)(OH)(28)(H(2)O)(4)].100 H(2)O (NaK-1, monoclinic space group C2/c, a=46.552(4) A, b=20.8239(18) A, c=27.826(2) A, beta=97.141(2) degrees and Z=4). Polyanion 1 contains--in the form of a cyclic arrangement--the unprecedented {Fe(16)(OH)(28)(H(2)O)(4)}(20+) nanocluster, with 16 edge- and corner-sharing FeO(6) octahedra, grafted on the inner surface of the crown-shaped [H(7)P(8)W(48)O(184)](33-) (P(8)W(48)) precursor. The synthesis of 1 was accomplished by reaction of different iron species containing Fe(II) (in presence of O(2)) or Fe(III) ions with the P(8)W(48) anion in aqueous, acidic medium (pH approximately 4), which can be regarded as an assembly process under confined geometries. One fascinating aspect is the possibility to model the uptake and release of iron in ferritin. The electrochemical study of 1, which is stable from pH 1 through 7, offers an interesting example of a highly iron-rich cluster. The reduction wave associated with the Fe(III) centres could not be split in distinct steps independent of the potential scan rate from 2 to 1000 mV s(-1); this is in full agreement with the structure showing that all 16 iron centres are equivalent. Polyanion 1 proved to be efficient for the electrocatalytic reduction of NO(x), including nitrate. Magnetic and variable frequency EPR measurements on 1 suggest that the Fe(III) ions are strongly antiferromagnetically coupled and that the ground state is tentatively spin S=2.