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1.
Different approaches for the synthesis of binary polyelectrolyte/inorganic layered composite capsules of micron size are described. As the polyelectrolyte part of the composite, a poly(styrene sulfonate)/poly(allylamine hydrochloride) complex was taken; the inorganic component was composed of magnetic nanoparticles (Fe3O4, CoFe2O4, MnFe2O4, ZnFe2O4), insulator nanoparticles (rare-earth fluorides) or metal nanoparticles (Ag). An inner inorganic layer was formed inside the hollow polyelectrolyte capsule via chemical or photochemical reaction in a spatially restricted capsule volume. The inorganic nanophase synthesized was characterized by transmission electron microscopy, scanning electron microscopy, and wide angle X-ray scattering techniques and weakly crystallized particles 6–9 nm in diameter were detected, presumably attached to the inner side of the capsule shell. Polyelectrolyte capsules filled with ferrite (magnetite) particles possess substantial magnetic activity and are easily manipulated in water solution by an external magnetic field.  相似文献   

2.
Two [N???I+???N] halogen‐bonded dimeric capsules using tetrakis(3‐pyridyl)ethylene cavitands with different lower rim alkyl chains are synthesized and analyzed in solution and the gas phase. These first examples of symmetrical dimeric capsules making use of the iodonium ion (I+) as the main connecting module are characterized by 1H NMR spectroscopy, diffusion ordered NMR spectroscopy (DOSY), electrospray ionization mass spectrometry (ESI‐MS), and ion mobility‐mass spectrometry (TW‐IMS) experiments. The synthesis and effective halogen‐bonded dimerization proceeds through analogous dimeric capsules with [N???Ag+???N] binding motifs as the intermediates as evidenced by the X‐ray structures of (CH2Cl2)2@[ 3 a 2?Ag4?(H2O)2?OTs4] and (CH2Cl2)2@[ 3 a 2?Ag4?(H2O)4?OTs4], two structurally different capsules.  相似文献   

3.
Cuprous oxide (Cu2O) nanoparticles and microparticles have been prepared by liquid phase chemical synthesis. The samples were characterized by means of SEM, XRD, UV/DRS and XPS. It was presented that as-prepared Cu2O nanoparticles are substantially stable in ambient atmosphere and the Cu+ as main state exists on the surface of Cu2O nanoparticles. As-prepared Cu2O microparticles can exist stably as a Cu2O/CuO core/shell structure; and the Cu2+ as main state exists on the surface of Cu2O microparticles. The behaviors of adsorption, photocatalysis and photocorrosion of Cu2O particles with different sizes were investigated in detail. The results show that Cu2O nanoparticles are very easy to photocorrosion during the photocatalytic reaction, which cannot be used as photocatalyst directly to degrade organic compound, although as-prepared Cu2O nanoparticles exhibit special property of adsorption. Cu2O microparticles have a higher photocatalytic activity than Cu2O nanoparticles because of its slower photocorrosion rate, although Cu2O microparticles have much lower adsorption capacity than Cu2O nanoparticles. The mechanisms of photocatalysis and photocorrosion for Cu2O under visible light were also discussed.  相似文献   

4.
Well-defined magnetic hybrid hollow capsules formed with magnetite (Fe3O4) and polyelectrolyte-multilayer films were successfully prepared through colloidal templating with layer-by-layer assembly of polyelectrolytes, followed by aqueous solution deposition of Fe3O4. Pd catalyst nanoparticles played an important role in the deposition of Fe3O4. Pd nanoparticles favorably adsorbed onto the polyelectrolyte layer with positively charged amino groups. Hollow capsules were obtained by the removal of the melamine–formaldehyde core particles. Although the processes were performed in aqueous solutions at temperatures less than 60 °C, X-ray diffraction patterns revealed that the deposited Fe3O4 was highly crystallized. The hollow capsules were stably dispersed in water; however, the capsules rapidly congregated around a locally applied magnet.  相似文献   

5.
Silver-7, 7, 8, 8-tetracyanoquinodimethane (AgTCNQ) microrods are synthesized through the photoelectrochemical catalysis of TiO2 nanoparticles. When illuminated by UV light, Ag nanoclusters deposit on TiO2 nanoparticles dispersed in the AgNO3/alcohol solution. When illuminated by visible light, the metallic Ag on TiO2 nanoparticles will dissolve in the solution as Ag+ while the released electron will be accepted by TCNQ to form TCNQ. Consequently, AgTCNQ microrods are obtained through a photoinduced bipolar mechanism, which is valuable in the chemical synthesis involving cooperative effect or coupling processes.  相似文献   

6.
As a conceptual study, In0 nanoparticles are obtained by NaBH4‐driven reduction of InCl3 · 4H2O and transferred from a polar/hydrophilic diethylene glycol phase to a non‐polar hydrophobic dodecane phase for purification and stabilization. Finally, the In0 nanoparticles are oxidized via a Laux‐like reaction with nitrobenzene to In2O3 nanoparticles. The challenge of the reaction is to perform the final oxidation to In2O3 under mild conditions with the colloidal stability, particle size and particle size distribution of the initial In0 nanoparticles retained. To this concern, the mean diameter of the initial In0 nanoparticles changed from 11(1) to 14(2) nm of the oxidized In2O3 nanoparticles. Such multi‐step reaction, including reduction, nucleation, phase transfer, exchange of surface capping and oxidation are of increasing importance for nanoparticles. Especially, Laux‐type conditions with nitrobenzene as a molecular oxidizing agent of nanoparticles have not been used till now. Particle size, size distribution and chemical composition of the In0 and In2O3 nanoparticles are analyzed by DLS, SEM, XRD, FT‐IR and HRTEM.  相似文献   

7.
Polymer capsules prepared by the successive adsorption of oppositely charged polyelectrolytes are modified by silver nanoparticles using the silver-mirror reaction. Substantial differences in the structure of nanocomposite polyelectrolyte shells of capsules formed on cores composed of polystyrene and CaCO3 are revealed by atomic force microscopy and transmission electron microscopy. The effect of the conditions of silver-mirror reaction (time and temperature) on the amount, size, and the distribution of silver nanoparticles over the capsule surface is studied. It is shown by small-angle X-ray scattering that, upon the formation of nanocomposite capsule shell on calcium carbonate microspherulites, the size of silver nanoparticles is limited primarily by the pore sizes of CaCO3 cores.  相似文献   

8.
Methods for preparing gold nanoparticles (NPs) surface-stabilized with di-(2-ethylhexyl)dithiophosphoric acid (DTPA) and tris(2-aminoethyl)amine (TAEA), which endow the nanoparticles with hydrophobic and hydrophilic properties, are described. In the case of DTPA, Au-NPs are first synthesized with surfactant shells by means of reducing [AuCl4]? with hydrazine in inverted micelles of oxyethylated Triton N-42 in a low-polarity medium of decane; then, the micelles are destroyed by polar chloroform in the presence of DTPA, which has a great affinity to gold due to its sulfur donor atoms and substitutes for the surfactant on the surface of the nanoparticles. In preparing hydrophilic nanoparticles, [AuCl4]? is reduced with solid NaBH4 directly in a nonaqueous solution of TAEA based on an ethanol and 2-propanol (3: 10) mixture. The nanoparticles are characterized by elemental analysis (for Au, C, H, N, and Na), X-ray powder diffraction, electronic absorption spectra, IR spectra, photon-correlation spectra, and transmission electron microscopy (TEM).  相似文献   

9.
以有机碱四甲基氢氧化铵(TMAH)为沉淀剂合成了纳米Fe3O4和Co2+掺杂的纳米Fe3O4粒子。分别讨论了碱用量,铁盐溶液浓度,反应温度,有机碱及PEG-4000的分散性等因素对纳米Fe3O4的形貌影响。结果表明,所合成的纳米Fe3O4为30nm左右的反尖晶石型面心立方结构,有机碱除了起沉淀剂作用,还能够提高纳米Fe3O4的分散性。本文还讨论了不同Co2+掺入量的纳米Fe3O4粒子的磁性质,结果表明Co2+掺杂的纳米Fe3O4粒子的矫顽力在不同掺入量的下有较大的改变。当Co2+掺入量为10.0%时,纳米Fe3O4的矫顽力达到最大值,为1628Oe。  相似文献   

10.
A new method for silica‐coated CaF2:Eu3+ core‐shell nanoparticles functionalized with oxalic acid for bio‐conjugation to bovine serum albumin (BSA) proteins has been developed. Moreover, CaF2:Eu3+/SiO2 core‐shell nanoparticles modified with oxalic acid are biocompatible and can be dispersed in water. As an organic functional molecule, oxalic acid is able to react with hydroxyl groups existed on the surface of SiO2 layer by esterification reaction to form carboxylic acid for further bio‐conjugation with BSA. The final products were characterized by means of X‐ray diffraction (XRD), transmission electron microscope (TEM), field‐emission scanning electron microscopy (FE‐SEM), ultraviolet (UV) spectrophotometer, infrared (IR) spectrophotometer and photoluminescence (PL) spectra. XRD result confirmed the phase purity of CaF2:10 mol% Eu3+ and CaF2:10 mol% Eu3+/SiO2 nanoparticles obtained from the quaternary reverse micelles of cetyltrimethylammonium bromide (CTAB), cyclohexane, n‐pentanol and water. Images of TEM and FE‐SEM showed that the average grain sizes of CaF2:10 mol% Eu3+/SiO2 and bio‐conjugation of CaF2:10 mol% Eu3+/SiO2 nanoparticles with BSA were about 17 nm. The patterns of UV and IR spectra showed that BSA was linked to CaF2:10 mol% Eu3+/SiO2 nanoparticles. In the emission spectrum of CaF2:10 mol% Eu3+/SiO2 conjugated by BSA nanoparticles, characteristic emission peaks of Eu3+ within the wavelength ranging from 500 to 700 nm were observed, which is corresponding to the transitions from the excited 5D0 levels to 7FJ levels. This confirmed that the Eu3+ dopant ion is located in a Ca2+ crystal site with Td symmetry. CaF2:10 mol% Eu3+/SiO2 conjugated by BSA nanoparticles remain stable in aqueous media within 15 d with pH ranging from 2 to 9. Therefore, these luminescent colloidal nanoparticles can be potentially employed as targeted fluorescent labels in biomedical research applications.  相似文献   

11.
Oxyresveratrol, a polyphenol extracted from the plant Artocarpus lakoocha Roxb, has been reported to be an antioxidant and an oxygen-free radical scavenger. We investigated whether oxyresveratrol affects the generation of superoxide anion (O2) by human monocytes, which are powerful reactive oxygen species (ROS) producers. We found that oxyresveratrol inhibited the O2 production induced upon stimulation of monocytes with β-glucan, a well known fungal immune cell activator. We then investigated whether the inclusion of oxyresveratrol into nanoparticles could modulate its effects on O2 release. We synthesized poly(lactic-co-glycolic acid) (PLGA) nanoparticles, and we assessed their effects on monocytes. We found that empty PLGA nanoparticles induced O2 production by resting monocytes and enhanced the formation of this radical in β-glucan-stimulated monocytes. Interestingly, the insertion of oxyresveratrol into PLGA nanoparticles significantly inhibited the O2 production elicited by unloaded nanoparticles in resting monocytes as well as the synergistic effect of nanoparticles and β-glucan. Our results indicate that oxyresveratrol is able to inhibit ROS production by activated monocytes, and its inclusion into PLGA nanoparticles mitigates the oxidative effects due to the interaction between these nanoparticles and resting monocytes. Moreover, oxyresveratrol can contrast the synergistic effects of nanoparticles with fungal agents that could be present in the patient tissues. Therefore, oxyresveratrol is a natural compound able to make PLGA nanoparticles more biocompatible.  相似文献   

12.
Thiacalix[4]arene 2 , calix[4]arene 3 a and its tetraether fixed in the cone conformation 3 b form homo‐ and heterodimeric capsules in apolar solvents, which are held together by a seam of NH???O=P hydrogen bonds between carbamoylmethyl phospine oxide functions attached to their wide rim. Their internal volume of ~370 Å3 requires the inclusion of a suitable guest. Although neutral molecules such as adamantane (derivatives) or tetraethylammonium cations form kinetically stable complexes (1H‐ and 31P‐time scale), the included solvent is rapidly exchanged. The internal mobility of the included tetraethylammonium cation is distinctly higher (ΔG=42.5 and 49.7 kJ mol?1 for 3 a and 3 b ) than that for similar capsules of tetraurea calix[4]arenes 1 . Mixtures of 1 with 2 , 3 a , or 3 b contain only the two homodimers but the heterodimerization occurs with the tetraloop tetraurea 6 , which cannot form homodimers. Two dimers with cationic guests ( 2? (C5H5)2Co+ ?2 and 3 a? Et3NH+ ? H2O ?3 a ) were confirmed by single‐crystal X‐ray analysis.  相似文献   

13.
Commercial TiO2 nanoparticles were superficially modified through polymeric resins obtained from polymerization of citrate complexes of Y3+ and Al3+ with ethylenglycol. The materials were treated at 450 °C for 4 h to obtain modified nanoparticles, which were characterized by HR-TEM, Zeta potential and surface area through N2 fisisorption. Rhodamine B photodegradation by visible light irradiation and in presence of those modified nanoparticles was compared with the same process in presence of unmodified commercial TiO2 nanoparticles. It was observed, by UV–visible spectroscopy, that the catalytic photoactivity in presence of modified nanoparticles was smaller than that observed with commercial TiO2 nanoparticles. However, the surface modifier played an important role in the photodegradation kinetic process, showing a non-linear relation between modifier amount and photodegradation rate, presenting a maximum value at 0.8% (w/w).  相似文献   

14.
Cerium oxide (CeO2) nanoparticles display excellent antioxidant properties by scavenging free radicals. However, some studies have indicated that they can cause an adverse response by generating reactive oxygen species (ROS). Hence, it is important to clarify the factors that affect the oxidant/antioxidant activities of CeO2 nanoparticles. In this work, we report the effects of different buffer anions on the antioxidant activity of CeO2 nanoparticles. Considering the main anions present in the body, Tris‐HCl, sulfate, and phosphate buffer solutions have been used to evaluate the antioxidant activity of CeO2 nanoparticles by studying their DNA protective effect. The results show that CeO2 nanoparticles can protect DNA from damage in Tris‐HCl and sulfate systems, but not in phosphate buffer solution (PBS) systems. The mechanism of action has been explored: cerium phosphate is formed on the surface of the nanoparticles, which interferes with the redox cycling between Ce3+ and Ce4+. As a result, the antioxidant activity of CeO2 nanoparticles is greatly affected by the external environment, especially the anions. These results may provide guidance for the further practical application of CeO2 nanoparticles.  相似文献   

15.
利用共沉淀方法制备出平均粒径为20nm的有机物8-羟基喹啉铝纳米粒子,8-羟基喹啉铝纳米粒子呈球形且粒度不随老化时间的增加而改变。本文研究了8-羟基喹啉铝纳米粒子的光致发光及基于8-羟基喹啉铝纳米粒子制作的电致发光器件的电致发光特性。8-羟基喹啉铝形成纳米粒子后,其光致发光及电致发光发射光谱的谱峰均出现蓝移。随着驱动电压的增加,器件中8-羟基喹啉铝纳米粒子的发射峰逐渐红移。在驱动电压为16伏时,8-羟基喹啉铝纳米粒子器件的最大亮度达600cd/m2,电流密度为150mA/cm-2时,器件的发光效率为0.19cd/A。基于8-羟基喹啉铝纳米粒子器件的发射光谱证实了AlQ3纳米粒子具有量子尺寸效应的存在,这为有机纳米电致发光器件的研究开辟了一条新的研究路线,同时也为那些传统的有机材料如有机分子晶体的基础研究探索出新的研究方向。  相似文献   

16.
A novel electrogenerated chemiluminescence (ECL) sensor based on Ru(bpy)32+‐doped titania (RuDT) nanoparticles dispersed in a perfluorosulfonated ionomer (Nafion) on a glassy carbon electrode (GCE) was developed in this paper. The electroactive component‐Ru(bpy)32+ was entrapped within the titania nanoparticles by the inverse microemulsion polymerization process that produced spherical sensors in the size region of 38±3 nm. The RuDT nanoparticles were characterized by electrochemical, transmission electron and scanning microscopy technology. The Ru(bpy)32+ encapsulation interior of the titania nanoparticles maintains its ECL efficiency and also reduces Ru(bpy)32+ leaching from the titania matrix when immersed in water due to the electrostatic interaction. This is the first attempt to prepare the RuDT nanoparticles and extend the application of electroactive component‐doped nanoparticles into the field of ECL. Since a large amount of Ru(bpy)32+ was immobilized three‐dimensionally on the electrode, the Ru(bpy)32+ ECL signal could be enhanced greatly, which finally resulted in the increased sensitivity. The ECL analytical performance of this ECL sensor for tripropylamine (TPA) was investigated in detail. This sensor shows a detection limit of 1 nmol/L for TPA. Furthermore, the present ECL sensor displays outstanding long‐term stability.  相似文献   

17.
Dy-doped Y2O3 nanoparticles were synthesized by solution combustion route with urea as fuel, and their microstructural features were analyzed by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The XRD study confirms the formation of a pure cubic phase of Y2O3, with the maximum textural coefficient along the (2 2 2) plane for the Dy-doped samples. The lattice fringes in the HRTEM image and the bright spotty rings in the selected area electron diffraction (SAED) pattern reveal the highly crystalline nature of the nanoparticles. From the diffuse reflectance spectroscopy, using Kubelka-Monk theory, the direct bandgap energy is estimated to be 5.61 eV for the undoped Y2O3, which is found to decrease upon Dy3+ doping. The room-temperature excitation spectra of the nanoparticles recorded at 575 nm emission wavelength comprise several excitation bands corresponding to the f-f transitions of Dy3+ ions in the host lattice. The photoluminescence spectra of the nanoparticles excited at the wavelength of 350 nm comprise three visible emission peaks at 477 nm (blue), 573 nm (yellow), and 666 nm (red). It has been concluded that the 0.5 mol% Dy-doped Y2O3 nanoparticles are the potential candidate to be used for solid-state luminescent device applications.  相似文献   

18.
Employing immobilized metal‐ion affinity chromatography and magnetic separation could ideally provide a useful analytical strategy for purifying His‐tagged protein. In the current study, a facile route was designed to prepare CMPEI‐Ni2+@SiO2@Fe3O4 (CMPEI=carboxymethylated polyethyleneimine) magnetic nanoparticles composed of a strong magnetic core of Fe3O4 and a Ni2+‐immobilized carboxymethylated polyethyleneimine coated outside shell, which was formed by electrostatic interactions between polyanionic electrolyte of carboxymethylated polyethyleneimine and positively charged surface of 3‐(trimethoxysilyl)propylamin modified SiO2@Fe3O4. The resulting CMPEI‐Ni2+@SiO2@Fe3O4 composite nanoparticles displayed well‐uniform structure and high magnetic responsiveness. Hexa His‐tagged peptides and purified His‐tagged recombinant retinoid X receptor alpha were chosen as the model samples to evaluate the adsorption, capacity, and reusability of the composite nanoparticles. The results demonstrated the CMPEI‐Ni2+@SiO2@Fe3O4 nanoparticles possessed rapid adsorption, large capacity, and good recyclability. The obtained nanoparticles were further used to purify His‐tagged protein in practical environment. It was found that the nanoparticles could selectively capture His‐tagged recombinant retinoid X receptor protein from complex cell lysate. Owing to its easy synthesis, large binding capacity, and good reusability, the prepared CMPEI‐Ni2+@SiO2@Fe3O4 magnetic nanoparticles have great potential for application in biotechnological fields.  相似文献   

19.
The luminophore Ru(bpy)2(dcbpy)2+ (bpy=2,2’-bipyridine; dcbpy=4,4’-dicarboxy-2,2’-bipyridine) is covalently linked to a chitosan polymer; crosslinking by tripolyphosphate produced Ru-decorated chitosan fibers (NS-RuCh), with a 20 : 1 ratio between chitosan repeating units and RuII chromophores. The properties of the RuII compound are unperturbed by the chitosan structure, with NS-RuCh exhibiting the typical metal-to-ligand charge-transfer (MLCT) absorption and emission bands of RuII complexes. When crosslinks are made in the presence of IrO2 nanoparticles, such species are encapsulated within the nanofibers, thus generating the IrO2⊂NS-RuCh system, in which both RuII photosensitizers and IrO2 water oxidation catalysts are within the nanofiber structures. NS-RuCh and IrO2⊂NS-RuCh have been characterized by dynamic light scattering, scanning electronic microscopy, and energy-dispersive X-ray analysis, which indicated a 2 : 1 ratio between RuII chromophores and IrO2 species. Photochemical water oxidation has been investigated by using IrO2⊂NS-RuCh as the chromophore/catalyst assembly and persulfate anions as the sacrificial species: photochemical water oxidation yields O2 with a quantum yield (Φ) of 0.21, definitely higher than the Φ obtained with a similar solution containing separated Ru(bpy)32+ and IrO2 nanoparticles (0.05) or with respect to that obtained when using NS-RuCh and “free” IrO2 nanoparticles (0.10). A fast hole-scavenging process (rate constant, 7×104 s−1) involving the oxidized photosensitizer and the IrO2 catalyst within the IrO2⊂NS-RuCh system is behind the improved photochemical quantum yield of IrO2⊂NS-RuCh.  相似文献   

20.
The effect of active H2S, HS·, and atomic hydrogen impurities on the condensation of highly supersaturated carbon vapor obtained in the combined laser photolysis of a mixture of C3O2 and H2S diluted with argon was studied. The concentrations of carbon vapor, HS·, and atomic hydrogen obtained in the laser photolysis of the mixture were determined using the absorption cross sections of C3O2 and H2S molecules measured in this work and the measured amount of absorbed laser radiation. The time profiles of the sizes of growing nanoparticles synthesized in C3O2 + Ar and C3O2 + H2S + Ar mixtures were measured using the laser-induced incandescence (LII) method. An improved LII model was developed, which simultaneously took into account the heating and cooling of nanoparticles and the temperature dependence of the thermophysical properties of nanoparticles, as well as the cooling of nanoparticles by evaporation and thermal emission. The size distributions of carbon nanoparticles formed in the presence and absence of active impurities were determined with the use of a transmission electron microscope. The final average size of carbon nanoparticles was found to decrease from 12 to 9 nm upon the addition of H2S to the system, whereas the rate of nanoparticle growth decreased by a factor of 3, and the properties of nanoparticles changed. In particular, the translational energy accommodation coefficient for Ar molecules at the surface of carbon nanoparticles was found to decrease from 0.44 to 0.30. A comparison of the calculated total carbon balance at the early stage of nanoparticle formation with experimental data demonstrated that the reaction C + H2S → HCS· + H, which removes a portion of carbon vapor from the condensation process, has a determining effect on the carbon balance in the system. It was found that HS· and atomic hydrogen affect the carbon balance in the system only slightly. Thus, the experimentally observed decrease in the rate of nanoparticle growth and in the sizes of nanoparticles can be explained by a decrease in the concentration of free carbon upon the addition of H2S molecules to the system.  相似文献   

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