上转换纳米粒子的Y(OH)CO3壳层包覆及壳层转化

Along with the promising applications of lanthanide doped upconversion nanomaterials in diverse fields such as biology, anti-counterfeiting, and lasering, the demand for multifunctional upconversion nanomaterials is increasing. One effective means of obtaining these nanomaterials is to fabricate upconversion nanomaterial-based heterostructures, which may provide superior properties as compared to the sum of the parts. However, obtaining heterostructured upconversion nanomaterials remains challenging mainly because of the crystal lattice mismatch between upconversion nanomaterials and other materials. Typically used strategies for synthesizing upconversion nanomaterial-based heterostructures are applicable only to limited types of materials. Alternatively, transformation of the intermediate layer is a promising strategy used to obtain these heterostructures. Nevertheless, this method remains in its infancy and, to date, only a few intermediate layers have been developed. New types of intermediate layers are therefore highly desirable. In this study, we show that amorphous Y(OH)CO₃ can be a promising candidate as an intermediate layer for fabricating upconversion nanoparticle-based heterostructures. As a proof-of-concept experiment, ligand-free NaGdF₄:Yb/Tm upconversion nanoparticles were first prepared as core nanoparticles. The Y(OH)CO₃ shell was then directly coated on the NaGdF₄:Yb/Tm upconversion nanoparticles in an aqueous solution using urea and Y(NO₃)₃, by a homogeneous precipitation approach. The thickness of the resulting Y(OH)CO₃ shell could be tuned by adjusting the amounts of either urea or Y(NO₃)₃. The as-coated Y(OH)CO₃ shell could be easily converted to YOF by heating at 300 ℃, yielding NaGdF₄:Yb/Tm@YOF core-shell heterostructured nanoparticles. In addition, we found that the NaGdF₄ core could be transformed to lanthanide oxide fluoride if the NaGdF₄:Yb/Tm@Y(OH)CO₃ core-shell nanoparticles were heated at 350 ℃. We also observed that treating the NaGdF₄:Yb/Tm@Y(OH)CO₃ core-shell nanoparticles at even higher temperatures (e.g., 400 ℃) produced aggregations of nanoparticles without regular morphologies. The transformation of the shell can be attributed to the decomposition of Y(OH)CO₃ and reactions between the Y(OH)CO₃ shell and NaGdF₄ core. Meanwhile, the transformation of the NaGdF₄ core at relatively high temperatures could be primarily due to the reactions between Y(OH)CO₃ and NaGdF₄. Notably, in this study, the core-shell structured nanoparticles, with either a Y(OH)CO₃ or YOF shell, maintained the photon upconversion properties of NaGdF₄:Yb/Tm upconversion nanoparticles. In addition, the method used here could be extended to the coating of other shells such as Tb(OH)CO₃ and Yb(OH)CO₃ on upconversion nanoparticles. Moreover, the NaGdF₄:Yb/Tm@Y(OH)CO₃ core-shell nanoparticles could be transformed to other nanoparticles with novel structures such as yolk-shell nanoparticles. These results can pave the way for preparing upconversion nanoparticle-based heterostructures and multifunctional composites, thus promoting new applications of upconversion nanoparticles.     

碱性介质中制备纳米四氧化三锰及其超级电容特性

比较了不同碱溶液中纳米Mn₃O₄的制备及其超级电容性能。用X射线粉末衍射仪、扫描电子显微镜和原子力显微镜等技术手段分别测试了晶体结构和表面形貌。用循环伏安、恒流充放电和交流阻抗测试了材料的电化学性能。结果表明,在氢氧化钠、氨水中Mn²⁺沉淀氧化可以直接制备纳米Mn₃O₄;碳酸钠中先生成MnCO₃,加氢氧化钠可转化为纳米Mn₃O₄。NaOH、NH₃和Na₂CO₃ 3种介质中制备的Mn₃O₄晶粒尺寸分别为29.5、20.2和36.3 nm。纳米Mn₃O₄经连续充放电循环后可活化为Birnessite-type MnO₂。氨水中制备的Mn₃O₄活化后比容量最大,达到239 F/g,是一种具有应用前景的超级电容器材料。     

Preparation of Functionalized Fe3O4@SiO2 Magnetic Nanoparticles for Monoclonal Antibody Purification

Magnetic Fe₃O₄@SiO₂ nanoparticles with superparamagnetic properties were prepared via a reverse mi-croemulsion method at room temperature. The as-prepared samples were characterized by transmission electron mi-croscopy(TEM), X-ray diffractometry(XRD), and vibrating sample magnetometry(VSM). The Fe₃O₄@SiO₂ nanoparticles were modified by (3-aminopropyl)triethoxysilane(APTES) and subsequently activated by glutaraldehyde(Glu). Protein A was successfully immobilized covalently onto the Glu activated Fe₃O₄@SiO₂ nanoparticles. The adsorption capacity of the nanoparticles was determined on an ultraviolet spectrophotometer(UV) and approximately up to 203 mg/g of protein A could be uniformly immobilized onto the modified Fe₃O₄@SiO₂ magnetic beads. The core-shell of the Fe₃O₄@SiO₂ magnetic beads decorated with protein A showed a good binding capacity for the chime-ric anti-EGFR monoclonal antibody(anti-EGFR mAb). The purity of the anti-EGFR mAb was analyzed by virtue of HPLC. The protein A immobilized affinity beads provided a purity of about 95.4%.     

纳米Fe2O3和Fe3O4的制备及其催化高氯酸铵热分解性能的研究——一个仪器分析综合实验

介绍一个仪器分析综合实验——纳米Fe_2O_3和Fe_3O_4的制备及其催化高氯酸铵热分解性能的研究。采用水热法合成纳米Fe_3O_4,进而煅烧得到纳米Fe_2O_3。使用X射线粉末衍射(XRD)对制得的样品结构进行表征,通过透射电镜(TEM)可以发现其为球形颗粒,粒径在10–20 nm范围内。将制得的纳米Fe_2O_3和纳米Fe_3O_4按不同比例加入高氯酸铵(AP)中,通过对混合物进行热分析(TG-DSC),发现纳米Fe_2O_3和纳米Fe_3O_4可以明显促进AP的分解,且Fe_2O_3的催化效果优于Fe_3O_4的催化效果,并对催化机理进行了简单讨论。通过该实验,可以让学生学习水热反应的方法,掌握利用XRD、热分析等多种手段对化合物结构及性能进行表征的技能。     

High-efficient Isolation of Plant Viral RNA via TMAOH-modified Fe3O4 Magnetic Nanoparticles

Magnetic nanoparticles show great potential in RNA enrichment and separation for rapid detection of viral infection.Fundamental studies on the interaction between RNA and nanoparticles with uniform size and surface property are necessary for designing better adsorbent and optimizing the conditions.In this study,monodispersed superparamagnetic magnetite（Fe3O4） nanoparticles were synthesized by thermal decomposition and modified with tetramethylammonium hydroxide[N（CH3）4OH,TMAOH] that become highly dispersible and stable in water.High-efficiency plant viral RNA adsorption onto TMAOH/Fe3O4 nanoparticles in the extracted solution of plant leaves was demonstrated.The changes of surface charge of TMAOH on the Fe3O4 nanoparticles with pH contribute to the RNA adsorption and elution.Separating viral RNA with magnetic nanoparticles could be a simple,quick andhighly efficient method.     

Photothermal performance of MFe2O4 nanoparticles

In this paper, we synthesized three kinds of ferrites and investigated their photothermal property. The result indicated that the photothermal effect of Fe₃O₄ and MnFe₂O₄ nanoparticles declined while that of ZnFe₂O₄ nanoparticles maintained relatively stable after preservation for 70 days, and then ZnFe₂O₄ nanoparticles could effectively kill cancer cells under NIR laser.     

Pd/Fe3O4-C催化剂对甲醇、乙醇和丙醇氧化的电催化活性

制备对醇氧化反应具有优异电活性的钯催化剂是醇燃料电池研究的重要内容。本文用硼氢化钠还原法制备了钯纳米颗粒, 然后沉积在Fe3O4/C复合物表面, 得到了不同Fe₃O₄负载量的Pd/Fe₃O₄-C催化剂. 透射电镜（TEM）图显示钯纳米颗粒均匀地分散在Fe₃O₄/C表面. 对制备好的Pd/Fe₃O₄-C催化剂进行了循环伏安法（CV）、计时电流（CA）和电化学阻抗谱（EIS）的测试, 研究了其在碱性介质中对C1-C3醇类（甲醇、乙醇和丙醇）氧化的电催化活性. 结果表明, 所制备的不同Fe₃O₄负载量的Pd/Fe₃O₄(2%)-C,Pd/Fe₃O₄(5%)-C, Pd/Fe₃O₄(10%)-C和Pd/C催化剂中, Pd/Fe₃O₄(5%)-C催化剂表现出最高的醇氧化电流密度. 依据循环伏安（CV）数据,Pd/Fe₃O₄(5%)-C催化剂对甲醇、乙醇、正丙醇和异丙醇氧化的阳极峰电流密度分别是Pd/C催化剂的1.7、1.4、1.7和1.3倍. Pd/Fe₃O₄(5%)-C催化剂对乙醇氧化的电荷传递电阻也远低于Pd/C催化剂. 制备的所有催化剂对C1-C3醇类电氧化的电流密度大小排序如下: 正丙醇﹥乙醇﹥甲醇﹥异丙醇. 此外, 碳粉中Fe₃O₄纳米颗粒的存在提高了钯纳米颗粒的电化学稳定性.     

Fast synthesis of dopamine-coated Fe3O4 nanoparticles through ligand-exchange method

A fast approach was described for the synthesis of water-dispersible monodisperse dopamine-coated Fe₃O₄ nanoparticles（DA-Fe₃O₄） with uniform size and shape via ligand-exchange of oleic acid on Fe₃O₄ using only 2 min.The prepared DA-Fe₃O₄ nanoparticles were characterized by transmission electron microscopy,Fourier transform infrared spectrometry,and vibrating sample magnetometer.The results indicated that the resulting DA-Fe₃O₄ nanoparticles had an average diameter of about 19.2 nm. The magnetic saturation value of the prepared DA-Fe₃O₄ nanoparticles was determined to be 72.87 emu/g,which indicating a well-established superparamagnetic property.     

表面分子印迹磁性纳米粒子的制备及其血红蛋白传感应用

以Fe₃O₄磁性纳米粒子为载体、多巴胺（DA）为功能单体、血红蛋白（Hb）为模板分子,用氯铂酸氧化DA生成聚多巴胺（PDA）,同时氯铂酸还原为铂纳米粒子（PtNPs）,与Hb一起负载于Fe₃O₄纳米粒子表面,洗脱Hb后合成了表面分子印迹磁性纳米粒子（印迹Fe₃O₄/PDA-PtNPs）. 将印迹Fe₃O₄/PDA-PtNPs修饰于磁性玻碳基底表面,制得印迹Fe₃O₄/PDA-PtNPs修饰电极. 实验结果表明,印迹Fe₃O₄/PDA-PtNPs具有良好的水溶性,粒径分布均匀,生成的PtNPs具有良好的导电性和刚性. 用印迹Fe₃O₄/PDA-PtNPs构建的传感器对Hb具有良好的识别性,在0.14 ~ 2.7 μg·mL^-1 Hb浓度范围与交流阻抗变化值呈良好的线性关系,检出限（S/N=3）为0.05 μg·mL^-1.     

水杨酸盐敏化BaF2∶Tb3+纳米粒子中的Tb3+离子发光

采用水热法制备了均匀、单分散的BaF₂∶Tb³⁺纳米粒子,并采用离子交换法制备了水杨酸钠敏化的BaF₂∶Tb³⁺纳米粒子(SS-BaF₂∶Tb³⁺)。 系统地研究了样品的结构、形貌和光致发光性质。 结果表明,监测Tb³⁺离子在547 nm的⁵D₄→⁷F₅跃迁,SS-BaF₂∶Tb³⁺纳米粒子获得了从200 nm到385 nm波长范围宽的激发带;激发SS的π-π^*电子跃迁吸收,由于SS到Tb³⁺的能量传递(“天线效应”),SS-BaF₂∶Tb³⁺纳米粒子产生了增强的Tb³⁺离子绿光发射;敏化纳米粒子中Tb³⁺离子光致发光寿命比未敏化纳米粒子中Tb³⁺离子寿命长。     

Combined investigation of experimental characterization and theoretic calculation on the structure of dextran-Fe3O4 clusters

Dextran-Fe₃O₄ hybrid clusters were fabricated by coprecipitating ferric and ferrous ions in the presence of dextran, and after characterization of these clusters combined with calculation based on classical nucleation theory, a structure model of these hybrid clusters was proposed. The hybrid cluster was believed including small Fe₃O₄ nanoparticles and dextran which acted as both nucleating agent and stabilizer, so that exist in both the inside of magnetite nanoparticles and the periphery of the hybrid clusters. Besides, the effects of W_CD (weight_{iron cation}:weight_dextran) and molecular weight of dextran on the size, morphology and magnetic property of clusters were also investigated in this paper. It was found that the variation of W_CD and molecular weight of dextran have great effect on the size of the hybrid clusters, but have almost no effect on the size of the Fe₃O₄ nanoparticles. The characterization of magnetic property demonstrated that the Fe₃O₄ nanoparticles are of a single domain and the saturation magnetization was affected by the size of dextran-Fe₃O₄ hybrid clusters.     

磁性介孔纳米粒子的制备及对抗癌药紫杉醇的传输

以十六烷基溴化铵(CTAB)为结构导向剂, 正硅酸乙酯(TEOS)为硅源, 在碱性环境下经过自组装过程对单分散性磁性Fe₃O₄纳米粒子进行包覆, 制备出磁性硅基介孔纳米粒子Fe₃O₄@SiO₂. 结合X射线衍射、 傅里叶变换红外光谱(FTIR)、 透射电子显微镜(TEM)以及氮气吸附-脱附等技术对Fe₃O₄@SiO₂粒子进行表征. 结果表明Fe₃O₄@SiO₂纳米粒子具有球形形貌, 平均直径约为150 nm, 蠕虫状介孔结构, 比表面积为932 m²/g, 孔径为2.5 nm且分布较均匀, 包覆后Fe₃O₄的结构得以保持, 同时材料具有很好的磁响应能力. 以抗癌药紫杉醇(Paelitaxel, TXL)为模型药物进行负载, 实验结果表明, Fe₃O₄@SiO₂对TXL的负载能力为80 mg/g, TXL-Fe₃O₄@SiO₂对TXL的缓释时间持续120 h以上, 累积释放量达到30 mg/g. 通过噻唑蓝比色(MTT)法测量了TXL-Fe₃O₄@SiO₂粒子对体外培养的HeLa细胞的细胞毒性, 与相同浓度的TXL相比, TXL-Fe₃O₄@SiO₂对HeLa细胞的抑制率明显增高.     

Tunable Synthesis of Core-shell α-Fe2O3/TiO2 Composite Nanoparticles and Their Visible-light Photocatalytic Activity

Uniform α-Fe₂O₃/amorphous TiO₂ core-shell nanocomposites were prepared via a hydrolysis method and α-Fe₂O₃/anatase TiO₂ core-shell nanocomposites were obtained via a post-calcination process. The structure and morphology of the products were characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and scanning electron microscopy. Amorphous TiO₂ nanoparticles with diameters of ten to several tens nanometer were formed on the surface of α-Fe₂O₃ nanoparticles and the coverage density of the secondary TiO₂ nanoparticles in the composite can be controlled by varying the concentration of Ti(BuO)₄ in the ethanol solution. The visible-light photocatalytic properties of different products towards Rhodamine B(RhB) were investigated. The results show that the α-Fe₂O₃/amorphous TiO₂ exhibits a good photocatalytic property owing to the extension of the light response range to visible light and the efficient separation of photogenerated electrons and holes between α-Fe₂O₃ and amorphous TiO₂.     

原位限域合成介孔碳负载四氧化三铁纳米颗粒

利用废弃蟹壳做模板制备的具有均一孔道结构的介孔碳材料做载体,在孔道内限域原位合成四氧化三铁氧化物纳米颗粒。 通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线衍射(XRD)表征了材料的结构和性能。 结果表明,孔道结构呈整体式结构,孔直径在40~50 nm,长50~200 μm。 纳米颗粒为四氧化三铁,粒径在10 nm左右,尺寸单分散性好,可均匀分散在介孔孔道内。 该方法工艺路线简单,绿色环保。     

单层石墨相氮化碳负载Pt4团簇吸附O2的第一性理论研究

采用第一性原理密度泛函理论结合周期性平板模型模拟研究了Pt₄团簇吸附单层石墨相氮化碳(g-C₃N₄)的几何结构和电子性质,以及氧气在其表面上的吸附行为。同时,对比分析了氧气在纯净的石墨相氮化碳和Pt₄团簇上的吸附行为。计算结果表明, Pt₄团簇吸附在3-s-三嗪环石墨相氮化碳表面,并与四个边缘氮原子成键,形成两个六元环时为最稳定构型。Pt₄团簇倾向于吸附在三嗪环石墨相氮化碳的空位并与邻近三个氮原子成键。由于Pt与N原子较强的杂化作用,以及金属与底物之间较多电子转移增强了Pt₄团簇吸附g-C₃N₄的稳定性。另外,对比分析了氧气在纯净的g-C₃N₄和金属吸附的g-C₃N₄上吸附行为,发现金属原子的加入促进了电子转移,同时拉长了O―O键长。Pt₄吸附3-s-三嗪环g-C₃N₄比Pt₄吸附三嗪环g-C₃N₄表现出微弱的优势,表现出明显的基底扭曲以及较大的吸附能。这些结果表明,化学吸附通过调节电子结构和表面性质增强催化性能的较好方法。     

柠檬酸根辅助多元醇法制备直径和磁性可控的Fe_3O_4亚微球

以柠檬酸三钠作辅助剂,用多元醇溶剂热还原法制备了纳米晶粒和微球直径可控的、单分散的超顺磁Fe3O4亚微球.发现与铁原子有强亲和力的柠檬酸根能有效吸附在还原产生的初始Fe3O4纳米粒子表面,阻碍其晶粒生长和影响其静电排斥力的大小,从而能在较大范围内调控最终产物Fe3O4亚微球的直径和饱和磁化强度.改变柠檬酸根或铁盐浓度不但可以调控初始Fe3O4纳米粒子的粒径,而且可以在220-550nm范围内调控单分散Fe3O4亚微球的直径,从而得到粒径均一的超顺磁Fe3O4亚微球.     

Synthesis and Characterization of Manganese-copper Spinel Ferrite Powders

Magnetic Mn_1-xCu_xFe₂O₄(x=0.2, 0.5, 0.8 and 1.0) nanoparticles were synthesized by single citrate precursor method. The samples were characterized by powder X-ray diffraction, vibrating sample magnetometry and electron paramagnetic resonance(EPR). For samples with a low copper content(x<0.5), the copper ions have a tendency to occupy and substitute the Fe³⁺ at the tetrahedral(A) sites. For samples with a high copper content(x>0.5), most Cu²⁺ enter into the octahedral(B) sites. Transfer of Fe³⁺ from octahedral sites to tetrahedral sites leads to the decrease of the saturation magnetization. Maximum coercivity is observed for CuFe₂O₄ nanoparticles due to the strengthened magnetic anisotropy arisen from the Jahn-Teller effect of the octahedral copper ions. The dependence of magnetic properties of Mn_0.8Cu_0.2Fe₂O₄ nanoparticles on calcination temperature was investigated. The cation distribution in Mn_0.8Cu_0.2Fe₂O₄ is sensitive to the calcination temperature.     

共同装载吴茱萸碱和Fe3O4纳米粒子的磁性药物载体的制备

以单甲醚-聚乙二醇-聚（丙交酯-乙交酯）（mPEG-PLGA）作为载体,采用溶液透析的方法共同装载抗癌药物吴茱萸碱和Fe₃O₄ 磁性纳米粒子. 通过透射电子显微镜、红外光谱、紫外-可见光谱及体外释放实验、普鲁士蓝染色、体外毒性实验和磁靶向研究,综合评价了磁性纳米药物载体的性能. 结果表明,磁性药物载体胶束分散性良好,粒径均一,有较高的载药量和包封率,能够实现药物缓释,具有磁靶向特性.     

Facile Synthesis of C3N4/Ag Composite Nanosheets as SERS Substrate for Monitoring the Catalytic Degradation of Methylene Blue

The C₃N₄/Ag composite nanosheets were facilely prepared via an in situ reduction processand Ag nanoparticles were well dispersed on the surface of C₃N₄ nanosheets. The unique two-dimensional structure and strong interactions between C₃N₄ nanosheetsand Ag nanoparticles contributed the good surface-enhanced Raman scattering(SERS) property due to the electromagnetic field enhancement. In addition, the as-prepared C₃N₄/Ag composite nanosheets could be used as catalysts or photocatalyst for the degradation of methylene blue(MB) in the presence of NaBH₄ or under visible light. Therefore, a facile SERS monitoring of the catalytic and photocatalytic degradation process of MB and the determination of the reaction kinetics were developed.     

Effect of Nanoparticle Size on Gas-sensing Properties of Tin Dioxide Sensors

Sn(OH)₄ was prepared by the conventional solution precipitate method, followed by supercritical CO₂ drying. The resultant Sn(OH)₄ was divided into three aliquots and calcined at 400, 600 and 800℃, respectively, thus SnO₂ nanoparticles with average crystallite sizes of 5, 10 and 25 nm were obtained. Furthermore, three SnO₂ thick film gas sensors(denoted as sensors S-400, S-600 and S-800) were fabricated from the above SnO₂ nanoparticles. The adhesion of sensing materials on the surface of alumina tube is good. Compared to the sensors S-600 and S-800, sensor S-400 showed a much higher sensitivity to 1000 μL/L ethanol. On the other hand, sensor S-800 showed a much lower intrinsic resistance and improved selectivity to ethanol than sensors S-400 and S-600. X-Ray diffraction(XRD), transmission electron microscopy(TEM) and selective area electron diffraction(SAED) measurements were used to characterize the SnO₂ nanoparticles calcined at different temperatures. The differences in the gas sensing performance of these sensors were analyzed on the basis of scanning electron microscopy(SEM).