Template free solvothermal synthesis of single crystal magnetic Fe3O4 hollow spheres,their interaction with bovine serum albumin and antibacterial activities

Uniform sized single crystal magnetic Fe₃O₄ hollow spheres (MFHS) have been synthesized through simple solvothermal method using ferric chloride hexahydrate and 1,3-propanediamine. The reaction time and the amount of 1,3-propanediamine play major roles in the formation of magnetic Fe₃O₄ hollow spheres. The synthesized products are characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry techniques. The crystalline Fe₃O₄ materials are composed of well-aligned hollow sphere magnetite nanoparticles and exhibit high saturation magnetization of 57.9?emu/g and a remnant magnetization of 17.6?emu/g at room temperature. MFHS interact strongly with bovine serum albumin (BSA) and brings out considerable conformational changes in BSA as evident from the UV–vis absorption, fluorescence and circular dichroism (CD) spectroscopic studies pertaining to the interaction of synthesized MFHS and BSA. The prepared MFHS effectively inhibit the growth of Pseudomonas aeruginosa and Staphylococcus aureus.     

Exploring the structure–property relationships of ultrasonic/MRI dual imaging magnetite/PLA microbubbles: magnetite@Cavity versus magnetite@Shell systems

Two types of magnetite/PLA composite microbubbles with different magnetite loading sites (magnetite nanoparticles [MNPs] were loaded in shell or core part), named as Fe₃O₄@Shell and Fe₃O₄@Cavity microbubbles, were respectively fabricated by an improved W₁/O/W₂ double emulsification approach and by an interfacial coprecipitation joint double emulsification approach. The preparation parameters were crucial factors for controlling the morphologies and structures of the microbubbles. To clarify the relationship between their structural characteristics and their properties, the T ₂-weighted magnetic resonance imaging (MRI) capabilities as well as the sound attenuation behavior of the microbubbles were investigated. The results demonstrate that the encapsulation of MNPs in either the inner cavity or the shell provides improved sound attenuation, the two types of microbubbles provide comparable sound attenuation enhancement properties, whereas Fe₃O₄@Shell microbubbles exhibit better T ₂-weighted MRI capabilities. The T ₂ relaxation time decreased from 219.5 to 62.1?ms for the Fe₃O₄@Cavity microbubbles and from 163.8 to 45.7?ms for the Fe₃O₄@Shell microbubbles, as the iron concentration increased from 0.05 to 1?mM. In addition, both types of microbubbles exhibit no cytotoxicity to either NRK or BRL-3A metabolic cell cultures. These results suggest that these magnetite-containing microbubbles have great potential as ultrasonic/MR dual contrast imaging agents.     

水热沉淀法制备掺铁二氧化钛中空球及其光催化性能

 以碳球为模板剂, 采用水热沉淀法制备了不同配比掺 Fe 的 TiO2 (Fe-TiO2) 中空球, 并运用 X 射线粉末衍射、扫描电子显微镜、元素分析能谱、红外光谱和热重等方法对其进行了表征. 结果表明, 中空球为锐钛矿相, 大小为 0.5~3.20 ?m, 壳层厚度为 30~60 nm, 比表面积为 150~300 m2/g. 随着 Fe 掺杂量的增加, 中空球在可见光区的吸收强度逐渐增加. 光催化降解实验表明, 掺 Fe 后, TiO2 中空球的可见光催化活性升高, 其中 0.5% Fe-TiO2 在 80 min 内降解亚甲基蓝超过 75%. 同时还讨论了光催化机制.     

Synthesis of tri-layer hybrid microspheres with magnetic core and functional polymer shell

Tri-layer magnetite/silica/poly(divinylbenzene) (Fe₃O₄/SiO₂/PDVB) core-shell hybrid microspheres were prepared by distillation precipitation polymerization of divinylbenzene (DVB) in the presence of magnetite/3-(methacryloxyl)propyl trimethoxysilane (MPS) modified silica core-shell particles as seeds. The polymerization of DVB was performed in neat acetonitrile with 2,2′-azobisisobutyronitrile (AIBN) as initiator to coat magnetite/MPS-modified silica particles through the capture of DVB oligomers with the aid of vinyl groups on the surface of inorganic seeds in absence of any stabilizer or surfactant. Other magnetite/silica/polymer tri-layer hybrid particles, such as magnetite/silica/poly(ethyleneglycol dimethacrylate) (Fe₃O₄/SiO₂/PEGDMA) and magnetite/silica/poly(ethyleneglycol dimethacrylate-co-methacrylic acid) (Fe₃O₄/SiO₂/P(EGDMA-co-MAA)) with various polarity and functionality, were also prepared by this procedure. Magnetite/silica/poly(N,N′-methylenebisacrylamide-co-methacrylic acid) (Fe₃O₄/SiO₂/P(MBAAm-co-MAA)) were synthesized with unmodified magnetite/silica particles as seeds. The resultant tri-layer hybrid particles were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), dynamic light scattering, and vibrating sample magnetometer (VSM).     

Synthesis of N,N-difluoroboryl complexes of 3,3′-diarylazadiisoindolylmethenes

N,N-Difluoroboryl complexes of 3,3′-diarylazadiisoindolylmethenes were synthesized by the reaction of BF₃·OEt₂ and 3,3′-diarylazadiisoindolylmethenes, which were easily prepared from a reaction between phthalonitrile and aryl Grignard reagents. These novel dyes exhibit strong absorption in the visible region and intense fluorescence in the vis/NIR region. Their synthesis, characterization, and optical properties are reported in this Letter.     

Ultrasonic-assisted synthesis of magnetite/carbon nanocomposite for electrochemical supercapacitor

Iron oxides are considered as the promising pseudocapacitive materials for high-performance supercapacitors due to their high theoretical specific capacitance, low cost, environmental benignity, and natural abundance. In this work, we study capacitive behavior of different magnetite (Fe₃O₄) nanoparticles/carbon black (CB) composites ratios. These composites are synthesized by the coprecipitation method in the presence of ultrasonic waves. The structural and morphological characteristics of the magnetite/CB composites are investigated by X-ray diffraction and scanning electron microscopy, respectively. The electrochemical performance of magnetite/CB composite electrodes is tested by cyclic voltammetry and galvanostatic charge/discharge in a Na₂SO₄ electrolyte. The results indicate that the magnetite/CB electrodes show typical pseudo-capacitive behavior in Na₂SO₄ solution. Moreover, in comparison to the pure Fe₃O₄ (37 F g^?1) and carbon black (23 F g^?1), the as-prepared 45 % magnetite/CB nanocomposite electrode shows a higher specific capacitance (300 F g^?1). Additionally, the supercapacitor device of the magnetite/CB nanocomposite exhibits excellent long cycle life along with 98.5 % specific capacitance retained after 10,000 cycle tests.     

Bis(N-benzyl-N-furfuryldithiocarbamato-S,S′)mercury(II) as a precursor for the preparation of mercury sulfide nanoparticles

Bis(N-benzyl-N-furfuryldithiocarbamato-S,S′)mercury(II), [Hg(bzfdtc)₂] (1) and bis(N,N-difurfuryldithiocarbamato-S,S′)mercury(II), [Hg(dfdtc)₂] (2) were synthesized and characterized by IR, NMR and single-crystal X-ray crystallography. Single-crystal X-ray structures of 1 and 2 indicate that both complexes are dimeric, with each mercury in a distorted [HgS₅] square pyramidal geometry. The thioureide (N¹³CS₂) carbon signals were observed at 206.8 and 206.7 ppm for 1 and 2, respectively, with very weak intensity, characteristic of the quaternary carbon signal. Complex 1 has been used as a precursor for the preparation of HgS nanoparticles. The as-prepared HgS nanoparticles have been characterized by powder XRD, FESEM, EDAX, UV–visible and IR spectroscopies. FESEM images of HgS nanoparticles show that the particles are spherical in shape. The blue shift in the absorption maxima in the UV–visible spectra of HgS1 and HgS2 is a consequence of the quantum confinement effect.     

Synthesis of diazafluorene- and diazafluorenone-N,N′-dioxides using HOF·CH3CN

A variety of diazafluorenes and diazafluorenones were oxidized using the HOF·CH₃CN complex to form the corresponding N,N′-dioxide derivatives under mild conditions. The products exhibit red-shift absorptions in the UV/visible spectrum relative to the parent compounds. Many such oxidations could not be achieved with any other oxygen-transfer agent.     

Cu3V2O8 hollow spheres in photocatalysis and primary lithium batteries

In this paper, Cu₃V₂O₈ hollow spheres have been successfully synthesized via a liquid precipitation method with colloidal carbon spheres as template followed by a subsequent heat treatment process. On the basis of XRD analysis, SEM observation, and TG-DSC analysis of the precursor and products, the formation mechanism of Cu₃V₂O₈ hollow spheres was proposed. UV–vis diffuse reflectance spectra showed that the Cu₃V₂O₈ hollow spheres exhibit strong absorption in a wide wavelength range from UV to visible light. The photocatalytic activity experiment indicated that the as-prepared Cu₃V₂O₈ hollow spheres exhibited good photocatalytic activity in degradation of methyl orange (MO) under 150-W xenon arc lamp light irradiation. Furthermore, electrochemical measurements showed that the Cu₃V₂O₈ hollow spheres exhibited high discharge capacity and excellent high-rate capability, indicating potential cathode candidates for primary lithium batteries used in long-term implantable cardiac defibrillators (ICDs).     

静电纺丝制备g-C3N4/C纳米纤维及其可见光降解性能

采用g-C_3N_4纳米片与聚丙烯腈进行静电复合纺丝,再经预氧化和碳化制得g-C_3N_4/C纳米纤维。利用傅立叶变换红外光谱仪(FTIR)、X射线衍射仪(XRD)、拉曼光谱(Raman)和扫描电子显微镜(SEM)对样品结构和形貌进行表征,通过紫外-可见漫反射光谱(UV-Vis DRS)分析可见光响应性。研究表明,复合纳米纤维对罗丹明B表现出较好的可见光降解活性,源于无定形相/石墨相混合结构的碳基体能够降低g-C_3N_4的光生电子-空穴对复合的几率。复合纳米纤维膜在光催化降解搅拌条件下始终能保持完整,经过多次回收和光催化实验,对罗丹明B的光降解率依然较高,表现出较优异的循环利用稳定性。     

Formation of Triple‐Shelled Molybdenum–Polydopamine Hollow Spheres and Their Conversion into MoO2/Carbon Composite Hollow Spheres for Lithium‐Ion Batteries

Unique triple‐shelled Mo‐polydopamine (Mo‐PDA) hollow spheres are synthesized through a facile solvothermal process. A sequential self‐templating mechanism for the multi‐shell formation is proposed, and the number of shells can be adjusted by tuning the size of the Mo‐glycerate templates. These triple‐shelled Mo‐PDA hollow spheres can be converted to triple‐shelled MoO₂/carbon composite hollow spheres by thermal treatment. Owing to the unique multi‐shells and hollow interior, the as‐prepared MoO₂/carbon composite hollow spheres exhibit appealing performance as an anode material for lithium‐ion batteries, delivering a high capacity of ca. 580 mAh g^?1 at 0.5 A g^?1 with good rate capability and long cycle life.     

静电纺丝制备g-C3N4/C纳米纤维及其可见光降解性能

采用g-C₃N₄纳米片与聚丙烯腈进行静电复合纺丝,再经预氧化和碳化制得g-C₃N₄/C纳米纤维。利用傅立叶变换红外光谱仪（FTIR）、X射线衍射仪（XRD）、拉曼光谱（Raman）和扫描电子显微镜（SEM）对样品结构和形貌进行表征,通过紫外-可见漫反射光谱（UV-Vis DRS）分析可见光响应性。研究表明,复合纳米纤维对罗丹明B表现出较好的可见光降解活性,源于无定形相/石墨相混合结构的碳基体能够降低g-C₃N₄的光生电子-空穴对复合的几率。复合纳米纤维膜在光催化降解搅拌条件下始终能保持完整,经过多次回收和光催化实验,对罗丹明B的光降解率依然较高,表现出较优异的循环利用稳定性。     

Preparation of the visible light responsive TiO2 thin film photocatalysts by the RF magnetron sputtering deposition method

TiO₂ thin film photocatalysts which could induce photoreactions under visible light irradiation were successfully developed in a single process by applying an ion engineering technique, i.e., the radio frequency (RF) magnetron sputtering deposition method. The TiO₂ thin films prepared at temperatures greater than 773 K showed the efficient absorption of visible light; on the other hand, the TiO₂ thin films prepared at around 573 K were highly transparent. This clearly means that the optical properties of TiO₂ thin films, which absorb not only UV but also visible light, can be controlled by the preparation temperatures of the RF magnetron sputtering deposition method. These visible light responsive TiO₂ thin films were found to exhibit effective photocatalytic reactivity under visible light irradiation (λ > 450 nm) at 275 K for the reductive decomposition of NO into N₂ and N₂O. From various characterizations, the orderly aligned columnar TiO₂ crystals could be observed only for the visible light responsive TiO₂ thin films. This unique structural factor is expected to modify the electronic properties of a TiO₂ semiconductor, enabling the efficient absorption of visible light.     

Efficient photoreduction strategy for uranium immobilization based on graphite carbon nitride/activated carbon nanocomposites

Uranium removal from aqueous solutions using environmentally friendly photocatalytic technology is a novel approach for resource recovery. Herein, carbon nitride/activated carbon composite materials (CN/AC) were investigated for U(VI) reduction under visible light. An exceptional boost in photocatalytic activity was observed for CN/AC composites (up to 70 times over the conventional bulk g-C₃N₄). The strong interactive conjugated π-bond structure between g-C₃N₄ and AC accelerated the migration of carriers and then prolonged the electron lifetime. CN/AC composites exhibited excellent compatibility with different water substrates and were resilience to a wide range of pH changes and abundant competitive anions/cations. Quenching experiments and electron microscopy characterization indicated that U(VI) was reduced by photogenerated electrons and deposited on the edge of CN/AC composites. The low-cost, high-performance carbon-based composite material proposed in this work is a potential candidate for the efficient treatment of radioactive wastewater.     

氯化锌活化对炭气凝胶微球的结构与电化学性能的影响

对炭气凝胶微球在高温下进行氯化锌活化改性,并用于制作超级电容器的电极。采用扫描电镜、N2物理吸附-脱附等对炭气凝胶微球的形貌结构进行表征,采用循环伏安、恒流充放电等测定了材料的电化学性能。结果表明,氯化锌活化有效地改善了炭气凝胶微球的孔结构,通过增加炭气凝胶微球的微孔面积和体积,提高了材料的比表面积和孔隙率。经过氯化锌活化,炭气凝胶微球的电化学性能也随之得到提高,电阻明显减小,比电容提高了2倍以上。     

The imaging of nano and micro globules of short linear thermo responsive polyacrylamides formed above the lower critical solution temperature

An imaging method has been developed to examine thermo responsive polymer coagulates by optical and electron microscopy. Poly-N-isopropylacrylamide (PNIPAM), poly-N-dimethylacrylamide (PDMAM) and a 1:1 PNIPAM-PDMAM copolymer were encapsulated in a gelatin matrix as coagulates above the lower critical solution temperature (LCST), and subsequently examined by optical and electron microscopy. The linear macromolecules PNIPAM and PDMAM were synthesized by chain transfer polymerization with mercaptopropionic acid (3-MPA) as chain transfer reagent. The resulting polymers have an average molar mass of ∼1800 g/mol and low polydispersity. The LCST of thermo responsive polymers is defined in pure water but can also be stimulated at lower than the phase transition temperature employing electrolytes containing inorganic salts such as (NH₄)₂SO₄. Under such conditions the polymers show the typical thermo responsive phase transfer property in form of a visible clouding point. Gelatin was used to maintain this biphasic state by slowly adding water-softened gelatin sheets at a temperature above the LCST, followed by cooling to 3 °C in order to induce gelation. Examination of the gelatin-coagulate matrices by optical and electronic microscopy showed that PNIPAM and its copolymer (PNIPAM/PDMAM 1:1) are entrapped as globular spheres and clusters of spheres. In comparison pure PDMAM, even if it shows a clouding point, does not form typical LCST coagulates. With PNIPAM and the copolymer, micro globule formation is also possible with slow gelatin formation, without first provoking an LCST. In this particular case, the phase transition, or entropic demixing of the polymers respectively, are induced in this case by water absorption of the gelatin matrix.     

Microwave‐Hydrothermal Preparation and Visible‐Light Photoactivity of Plasmonic Photocatalyst Ag‐TiO2 Nanocomposite Hollow Spheres

Visible‐light‐driven plasmonic photocatalyst Ag‐TiO₂ nanocomposite hollow spheres are prepared by a template‐free chemically‐induced self‐transformation strategy under microwave‐hydrothermal conditions, followed by a photochemical reduction process under xenon lamp irradiation. The prepared samples are characterized by using scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, N₂ adsorption‐desorption isotherms, X‐ray photoelectron spectroscopy, UV/Vis and Raman spectroscopy. Production of ?OH radicals on the surface of visible‐light illuminated TiO₂ was detected by using a photoluminescence method with terephthalic acid as the probe molecule. The photocatalytic activity of as‐prepared samples was evaluated by photocatalytic decolorization of Rhodamine B (RhB) aqueous solution at ambient temperature under visible‐light irradiation. The results show that the surface plasmon absorption band of the silver nanoparticles supported on the TiO₂ hollow spheres was red shifted, and a strong surface enhanced Raman scattering effect for the Ag‐TiO₂ nanocomposite sample was observed. The prepared nanocomposite hollow spheres exhibits a highly visible‐light photocatalytic activity for photocatalytic degradation of RhB in water, and their photocatalytic activity is higher than that of pure TiO₂ and commercial Degussa P25 (P25) powders. Especially, the as‐prepared Ag‐TiO₂ nanocomposite hollow spheres at the nominal atomic ratio of silver to titanium ( R ) of 2 showed the highest photocatalytic activity, which exceeds that of P25 by a factor of more than 2.     

MoS_2/g-C_3N_4复合材料的制备及可见光催化性能

首先在N-甲基吡咯烷酮溶液中超声剥离得到少层的MoS_2,将其与石墨相氮化碳(g-C_3N_4)复合,制得MoS_2/g-C_3N_4复合材料。采用X射线衍射(XRD),扫描电镜(SEM),X射线光电子能谱(XPS),傅里叶变换红外光谱(FTIR),Raman光谱,紫外-可见漫反射吸收光谱(DRS)和光致荧光(PL)技术对复合材料进行表征。可见光下考察MoS_2/g-C_3N_4复合材料光催化降解罗丹明B(Rh B)的活性,结果表明:将少量MoS_2与g-C_3N_4复合可明显提高光催化活性,且1%(w/w)MoS_2/g-C_3N_4复合物的光催化活性最高,可能的原因是MoS_2和g-C_3N_4匹配的能带结构,增大了界面间电荷的传输,降低了光生电子-空穴的复合,进而提高了光催化活性。     

凹凸棒土/g-C3N4-Pt/聚苯胺复合材料的制备及其可见光催化性能

石墨氮化碳(g-C₃N₄)是一种窄带隙的n型半导体材料,具有可见光降解有机污染物能力;凹凸棒土(ATP)具有很强的表面活性和吸附能力,可作为催化剂的载体。我们以g-C₃N₄和ATP杂化材料(ATP/g-C₃N₄)为基础,通过简单的化学还原法将纳米Pt颗粒沉积到ATP/g-C₃N₄表面,随后利用纳米金属Pt颗粒催化苯胺无电聚合,促使聚苯胺(PANI)在ATP/g-C₃N₄表面或孔道中原位生成,获得ATP/g-C₃N₄-Pt/PANI复合材料。以阴离子染料甲基橙(MO)为模型体系,考察了复合材料的可见光催化性能。研究表明,共轭结构的PANI和g-C₃N₄在复合材料中保持完好,说明其具有良好的兼容性。由于多组分材料之间的协同效应,使得ATP/g-C₃N₄     

MoS2/g-C3N4复合材料的制备及可见光催化性能

首先在N-甲基吡咯烷酮溶液中超声剥离得到少层的MoS₂,将其与石墨相氮化碳（g-C₃N₄）复合,制得MoS₂/g-C₃N₄复合材料。采用X射线衍射（XRD）,扫描电镜（SEM）,X射线光电子能谱（XPS）,傅里叶变换红外光谱（FTIR）,Raman光谱,紫外-可见漫反射吸收光谱（DRS）和光致荧光（PL）技术对复合材料进行表征。可见光下考察MoS₂/g-C₃N₄复合材料光催化降解罗丹明B（RhB）的活性,结果表明：将少量MoS₂与g-C₃N₄复合可明显提高光催化活性,且1%（w/w）MoS₂/g-C₃N₄复合物的光催化活性最高,可能的原因是MoS₂和g-C₃N₄匹配的能带结构,增大了界面间电荷的传输,降低了光生电子-空穴的复合,进而提高了光催化活性。