磁性Ag@Fe3O4@C负载纳米金的制备及其SERS性能

利用一步溶剂热法制备了具有核壳结构的Ag@Fe_3O_4磁性纳米颗粒,然后以葡萄糖作为碳源对Ag@Fe_3O_4进行包覆,再利用酰胺化反应成功的将聚乙烯亚胺(PEI)修饰到Ag@Fe_3O_4@C表面,最后以N-Au共价键的方式将Au纳米粒子组装到Ag@Fe_3O_4@C表面。以4-巯基苯甲酸(4MBA)为拉曼活性探针分子来考察该复合纳米材料的表面增强拉曼(SERS)性能。通过控制Au纳米粒子的加入量,来调节Ag@Fe_3O_4@C-Au复合纳米材料的SERS活性。通过实验测试及利用时域有限差分法(FDTD)得出不同纳米金用量包覆的Ag@Fe_3O_4@C磁性纳米颗粒对4MBA的SERS效果依次为Ag@Fe_3O_4@C-Au-40Ag@Fe_3O_4@C-Au-10Ag@Fe_3O_4@C-Au-60Ag@Fe_3O_4@C,其中Ag@Fe_3O_4@C-Au-40的饱和磁化强度为411 A·g-1,其对4MBA的检测限为1×10-9 mol·L-1。这种功能性复合材料既具有良好的SERS活性,又可通过外加磁场的方式实现对待测分子的分离、富集。     

Fe3O4/PEI/Au@CdSe/CdS多功能复合材料的制备与表征

以共沉淀法制备出Fe₃O₄纳米粒子,通过聚乙烯亚胺(PEI)修饰Fe₃O₄纳米粒子,再原位复合上Au纳米粒子,制得Fe₃O₄/PEI/Au纳米颗粒微球。再将Fe₃O₄/PEI/Au纳米颗粒与巯基乙酸修饰的量子点CdSe/CdS连接,成功制备了Fe₃O₄/PEI/Au@CdSe/CdS多功能复合微球。经过傅里叶变换红外光谱仪(FTIR)、荧光分光光度计、荧光显微镜、X射线衍射(XRD)、透射电子显微镜(TEM)及振动样品磁强计(VSM)的表征。结果表明:多功能复合微球的粒径在40 nm左右,具有超顺磁性,剩磁,矫顽力近似等于零,饱和磁化强度为28.83 A·m²·kg^-1,同时兼有优越的荧光性能和金纳米粒子的特性。     

Fe3O4/PEI/Au@CdSe/CdS多功能复合材料的制备与表征

以共沉淀法制备出Fe₃O₄纳米粒子,通过聚乙烯亚胺(PEI)修饰Fe₃O₄纳米粒子,再原位复合上Au纳米粒子,制得Fe₃O₄/PEI/Au纳米颗粒微球。再将Fe₃O₄/PEI/Au纳米颗粒与巯基乙酸修饰的量子点CdSe/CdS连接,成功制备了Fe₃O₄/PEI/Au@CdSe/CdS多功能复合微球。经过傅里叶变换红外光谱仪(FTIR)、荧光分光光度计、荧光显微镜、X射线衍射(XRD)、透射电子显微镜(TEM)及振动样品磁强计(VSM)的表征。结果表明:多功能复合微球的粒径在40nm左右,具有超顺磁性,剩磁,矫顽力近似等于零,饱和磁化强度为28.83A·m₂·kg^-1,同时兼有优越的荧光性能和金纳米粒子的特性。     

Co3O4/ZnO修饰针灸针的制备及其在葡萄糖检测领域的应用

将Co₃O₄/ZnO针状纳米棒材料修饰到针灸针表面用于检测葡萄糖浓度的变化。首先采用水热法在针灸针表面得到Co（CO₃）_0.5（OH）·0.11H₂O针状纳米棒前驱体,然后在500 ℃条件下退火3 h得到Co₃O₄针状纳米棒阵列。再采用浸渍法将预制备好的ZnO量子点修饰到Co₃O₄针状纳米棒表面,得到Co₃O₄/ZnO复合修饰的针灸针。研究发现此针灸针对葡萄糖具有较好的电流响应（2 264.27 μA·L·mmol^-1·cm^-2）、较快的响应速度（<4 s）及较低的检测极限（0.311 μmol·L^-1（S/N=3））。且该针灸针在用于检测人体模拟细胞液中葡萄糖浓度时,对抗坏血酸和尿素等表现出较强的抗干扰性。     

Z型异质结Au/CoWO4/g-C3N4的制备及其光催化降解性能

采用浸渍-煅烧方法将Au引入到g-C₃N₄纳米片（CNs）与CoWO₄复合材料中得到Z型异质结光催化剂Au/CoWO₄/CNs（Au/ CoNs-x,x=5、10、20、50）。Au作为电荷传输通道加快了光生电子从CoWO₄迁移至CNs的速度。与CoWO₄/CNs相比,Au/CoNs-10展示出优异的光催化降解亚甲基蓝和盐酸四环素活性,其表观速率常数分别从0.289和0.360 h^-1提升至0.499和0.637 h^-1。光电测试与自由基捕获实验表明,Au/CoNs-10光催化性能的显著提升主要是由于Z型异质结的构建降低了光生电子-空穴的复合速率,同时促使具有高氧化活性的羟基自由基（·OH）和超氧自由基（·O₂^-）的形成。     

氨基化修饰介孔Fe3O4@SiO2@mSiO2磁性核壳复合微球的可控制备及吸附性能

以水热法制备的高磁饱和强度Fe₃O₄纳米颗粒为核,正硅酸乙酯（TEOS）为前驱体,采用改进的Stöber法,制备介孔SiO₂包覆Fe₃O₄磁性核壳复合微球。利用XRD、SEM、TEM、N₂吸-脱附、FTIR和VSM对制备样品的物相结构、形貌和磁性能进行了测试表征。研究结果表明,制备的复合材料呈球形,粒径分布均一,材料的比表面积和磁饱和强度分别为413 m²·g^-1和68.93 emu·g^-1。研究了TEOS的添加量对复合微球形貌的影响,随着TEOS添加量的增加,SiO₂壳层增厚,复合粒子形貌均匀,饱和磁化强度有所下降,仍具有良好的超顺磁性。在此基础上,通过接枝法在复合微球的表面接枝-NH₂,制备了一种新型磁性纳米吸附剂（Fe₃O₄@SiO₂@mSiO₂-NH₂）,进而研究了其对水中重金属离子Cr（Ⅳ）的吸附性能。通过动力学拟合,Fe₃O₄@SiO₂@mSiO₂-NH₂对Cr（Ⅳ）的吸附过程是准二级动力学模型占主导地位。探究了该材料对Cr（Ⅳ）的吸附过程和吸附机理。结果表明,其吸附机理及吸附容量与Cr（Ⅳ）的离子形态及-NH₂有关,并通过吸附剂与吸附质之间的电子共用或静电吸附实现。     

SiO2/Co3O4核壳催化剂对AP热分解的催化性能研究

采用改良的Stöber法制备粒径约为200 nm的单分散球形SiO₂颗粒,以此为内核,分别通过液相沉淀法和尿素均匀沉淀法制备包覆形式不同的新型SiO₂/Co₃O₄核壳式纳米催化剂。采用X-射线衍射分析(XRD)、透射电子显微镜(TEM)、红外光谱分析(IR)、拉曼光谱分析(Raman)、BET比表面积测试等手段对产物进行表征,利用差式扫描量热仪(DSC)考察SiO₂/Co₃O₄复合物对高氯酸铵(AP)热分解反应的催化作用,探讨不同包覆形式对其催化活性的影响。结果表明,两种方法制备得到的SiO₂/Co₃O₄复合物分别为层包覆和粒子包覆,比表面积大,具有明显的核壳结构,且粒子包覆形式的SiO₂/Co₃O₄对AP热分解反应的催化效果最好,使AP的高温分解温度降低了110 ℃,放热量增加了662 J·g^-1。     

Co3O4/ZnO修饰针灸针的制备及其在葡萄糖检测领域的应用

将Co₃O₄/ZnO针状纳米棒材料修饰到针灸针表面用于检测葡萄糖浓度的变化。首先采用水热法在针灸针表面得到 Co（CO₃）_0.5（OH）·0.11H₂O针状纳米棒前驱体,然后在500 ℃条件下退火3 h得到Co₃O₄针状纳米棒阵列。再采用浸渍法将预制备好的ZnO量子点修饰到Co₃O₄针状纳米棒表面,得到Co₃O₄/ZnO复合修饰的针灸针。研究发现此针灸针对葡萄糖具有较好的电流响应（2 264.27 μA·L·mmol^-1·cm^-2）、较快的响应速度（<4 s）及较低的检测极限（0.311 μmol·L^-1（S/N=3））。且该针灸针在用于检测人体模拟细胞液中葡萄糖浓度时,对抗坏血酸和尿素等表现出较强的抗干扰性。     

用于高效去除水中孔雀石绿的三层结构磁性复合材料Fe3O4@聚丙烯酸@ZiF-8的制备

设计并合成了一种以磁性纳米粒子为核，聚合物为中间层，金属有机骨架材料为外层的三层结构磁性复合材料(Fe₃O₄@PAA@ZIF 8)。首先利用溶剂热法制备Fe₃O₄纳米粒子，然后通过蒸馏沉淀聚合法在Fe₃O₄纳米粒子表面包覆聚丙烯酸(PAA)层，最后通过原位沉积法在PAA外部包覆ZIF 8。在对Fe₃O₄@PAA@ZIF 8的组成和结构进行表征的基础上，深入研究其对孔雀石绿(MG)的吸附性能。透射电子显微镜(TEM)显示 Fe₃O₄@PAA@ZIF 8 具有明显的三层结构，Fe₃O₄的平均粒径为 117nm，PAA 层厚度约为 17 nm，ZIF 8层的厚度约为 14 nm。Fe₃O₄@PAA@ZIF 8对 MG 的吸附量随着 pH 的升高而增大，吸附过程符合准二阶动力学模型和 Langmuir等温吸附模型。此外，Fe₃O₄@PAA@ZIF 8还表现出良好的重复利用性能，8次循环利用后对MG(500 mg·L^-1)的最大吸附量仍可达982 mg·g^-1。     

超声法制备Au/Fe3O4及其催化还原4-硝基苯酚性能

通过简易的超声法以及原位还原法成功制备出了负载型可再生Au/Fe₃O₄催化剂。利用3-氨丙基三乙氧基硅烷（APTES）作为有机桥键,将Au固定在Fe₃O₄的表面,得到单分散磁性Au/Fe₃O₄。Au⁰在氨基的作用下不会团聚,因此具有较高的催化活性及稳定性。XRD、HRTEM、EDS和XPS等测试结果表明Au/Fe₃O₄已被成功制备。将其用于催化还原4-硝基苯酚得到4-氨基苯酚,表现出较高的催化活性,速率常数可达0.225 6 min^-1。重复性实验表明该催化剂具有良好的稳定性,反应9个循环之后,催化还原反应的转化率仍可达到94%。     

中空分级结构Fe3O4@C/rGO复合材料的合成及其储锂性能

以氧化石墨烯(GO)为基底,Fe(NO_3)_3·9H_2O、异丙醇、甘油为原料,通过溶剂热法和后续热处理过程2步合成了Fe_3O_4@C/rGO复合材料,实现了碳包覆的Fe_3O_4纳米粒子自组装形成的分级结构空心球在氧化石墨烯片上的原位生长。采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和恒流充放电等手段分析了材料的物理化学性能与储锂性能。结果表明,该复合材料在5.0 A·g~(-1)的电流密度下,仍有437.7 mAh·g~(-1)的可逆容量,在1.0 A·g~(-1)下循环200圈后还有587.3 mAh·g~(-1)的放电比容量。这主要归因于还原态氧化石墨烯(rGO)对碳包覆Fe_3O_4分级空心球整体结构稳定性和导电性的提高。     

Preparation and mechanism of Fe3O4/Au core/shell super-paramagnetic microspheres

In the presence of Fe₃O₄ nano-particles, a new type of super-paramagnetic Fe₃O₄/Au microspheres with core/shell structures was prepared by reduction of Au³⁺ with hydroxylamine. The formation mechanism of the core/shell microspheres was studied in some detail. It was shown that the formation of the complex microspheres can be divided into two periods, that is, surface reaction-controlled process and diffusion-controlled process. The relative time lasted by either process depends upon the amount of Fe₃O₄ added and the initial concentration of Au³⁺. XPS analysis revealed that along with increasing in coating amount, the strength of the characteristic peaks of Au increased, and the Auger peaks of Fe weakened and even disappeared. Size distribution analysis showed that the core/shell microspheres are of an average diameter of 180 nm, a little bit larger than those before coating.     

Mesoporous MnSiO3@Fe3O4@C Nanoparticle as pH-responsive T1-T2* Dual-modal Magnetic Resonance Imaging Contrast Agent for Tumor Diagnosis

Mesoporous structured MnSiO₃@Fe₃O₄@C nanoparticles (NPs) were prepared via a facile and efficient strategy, with negligible cytotoxicity and minor side efforts. The asprepared MnSiO₃@Fe₃O₄@C NPs hold great potential in serving as pH-responsive T₁-T₂^* dual-modal magnetic resonance (MR) imaging contrast agents. The released Mn²⁺ shortened T₁ relaxation time, meanwhile the superparamagnetic Fe₃O₄ enhanced T₂ contrast imaging. The release rate of Mn ions reaches 31.66% under the condition of pH=5.0, which is similar to tumor microenvironment and organelles. Cytotoxicity assays show that MnSiO₃@Fe₃O₄@C NPs have minor toxicity, even at high concentrations. After intravenous injection of MnSiO₃@Fe₃O₄@C NPs, a rapid contrast enhancement in tumors was achieved with a significant enhancement of 132% after 24 h of the administration. Moreover, a significant decreasement of 53.8% was witnessed in T₂ MR imaging signal. It demonstrated that MnSiO₃@Fe₃O₄@C NPs can act as both positive and negative MR imaging contrast agents. Besides, owing to the pH-responsive degradation of mesoporous MnSiO₃, MnSiO₃@Fe₃O₄@C NPs can also be used as potential drug systems for cancer theranostics.     

Microfluidic paper-based multiplex colorimetric immunodevice based on the catalytic effect of Pd/Fe3O4@C peroxidase mimetics on multiple chromogenic reactions

In this report, a non-toxic method was proposed for the simple synthesis of palladium nanoparticles (Pd)/Fe₃O₄@C peroxidase mimetics by virtue of in situ growth of Pd nanoparticles on Fe₃O₄@C magnetic nanoparticles. And a microfluidic paper-based multiplex colorimetric immunodevice (named α-sheet) was developed by site-selectively immobilizing multiple antigens owing to its intrinsic high-efficiency catalytic activity of peroxidase mimetics to multiple chromogenic reactions. The immunosensor platform was prepared by growing a layer of flower-like gold nanoparticles which could entrap the primary antibodies onto paper sensing zones, and the as-prepared Pd/Fe₃O₄@C peroxidase mimetics was used to label secondary antibodies. In the presence of 3,3′,5,5′-tetramethylbenzidine and o-phenylenediamine chromogenic substrates, Pd/Fe₃O₄@C peroxidase mimetics catalyzed chromogenic reactions and showed different colors with respective intensity. To precisely identify the intensity, a piece of black wax printed chromatographic paper with three observing windows (named β-sheet) was flatted on α-sheet. Under the optimal condition, the proposed multiplex colorimetric immunodevice displayed wide linear ranges from 0.005 to 30 ng mL⁻¹ with low detection limits of 1.7 pg mL⁻¹ for carcinoembryonic antigen (CEA) and α-fetoprotein (α-AFP). Meanwhile, the proposed method provided provided a non-toxic, low-cost and promising tool for point-of-care diagnosis.     

Au nanoparticles grafted on Fe3O4 as effective SERS substrates for label-free detection of the 16 EPA priority polycyclic aromatic hydrocarbons

Several methods and materials have been explored for the sensitive and practicable detection of polycyclic aromatic hydrocarbons (PAHs). However, it is still a challenge to develop simple and cost-effective sensing techniques for PAHs. Herein we report the synthesis and construction of Fe₃O₄@Au SERS substrate. This magnetic substrate was composed by Fe₃O₄ microspheres and Au NPs. The size, morphology, and surface composition of Fe₃O₄@Au were characterized by multiple complimentary techniques including scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray powder diffraction. The spatial distributions of electro-magnetic field enhancement around Fe₃O₄@Au was calculated using finite difference time domain (FDTD) simulations. As a result of its remarkable sensitivity, the Fe₃O₄@Au-based SERS assay has been applied to detect the 16 EPA priority PAHs. The LODs achieved by our method (100–5 nM, 16.6–1.01 μg L⁻¹) make it promising for the rapid screening of highly contaminated cases. As a proof-of-concept study, the substrate was applied in SERS sensing of PAHs in river matrix. The 16 PAHs could be differentiated based upon their characteristic SERS peaks. Most importantly, the detection was successfully conducted using a portable Raman spectrometer, which could be used for on-site monitoring of PAHs.     

具备高首周库仑效率的高性能锂离子电池负极材料Li2Ni2(MoO4)3@C的制备

采用常规的固相反应法结合机械球磨制备了含碳质量分数23.7%的Li₂Ni₂（MoO₄）₃@C复合材料,并应用于锂离子电池负极。与纯Li₂Ni₂（MoO₄）₃相比,Li₂Ni₂（MoO₄）₃@C具有优异的电化学性能,在电流密度为200 mA·g^-1时,50周循环后,可逆容量高达845 mAh·g^-1。值得注意的是,Li₂Ni₂（MoO₄）₃@C的首周库仑效率高达85%。此外,运用循环伏安法对Li₂Ni₂（MoO₄）₃@C复合物存储锂行为进行了初步探索。     

Optical and magnetic properties of small-size core–shell Fe3O4@C nanoparticles

Core–shell Fe₃O₄@C magnetic nanoparticles which are of great interest for research have a widely applied prospect. However, people know little about the optical and magnetic properties of the small-size Fe₃O₄@C nanoparticles due to the difficulty of uniformly coating small size Fe₃O₄ nanoparticles. In this paper, the influence of carbon shell coating on the optical and magnetic properties of small size Fe₃O₄ nanoparticles was presented. Carbon coating can strengthen the absorption intensity in the UV–visible light region through the introduction of oxygen defects on the surface of the nanoparticles by nitric acid treatment. Fe₃O₄ and Fe₃O₄@C nanoparticles both display typical superparamagnetic behavior in the high-temperature regime and a blocked state at low temperature from hysteresis loop, zero-field cooled and field cooled curves. Carbon coating reduce the surface uniaxial anisotropy, thus the average blocking temperature <T_B> decreases from 59 K of Fe₃O₄ nanoparticles to 50 K of Fe₃O₄@C nanoparticles.