共查询到20条相似文献,搜索用时 15 毫秒
1.
《Current Applied Physics》2015,15(11):1482-1487
Nanocomposites containing two or more functional constituents are attractive candidates for advanced nanomaterials. In this study, multifunctional Ag/Fe3O4-CS nanocomposites were successfully prepared, using chitosan as a stabilizing and cross-linking agent. The as-synthesized nanocomposites were characterized by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), UV–visible spectrophotometer (UV–Vis) and vibrating sample magnetometer (VSM). The results demonstrated that Ag/Fe3O4-CS composite nanoparticles (NPs) were composed of parent components, Fe3O4 and Ag NPs, which were uniformly dispersed in the chitosan matrix. The hybrid NPs exhibited strong antibacterial property against Pseudomonas aeruginosa. With high magnetization value (67 emu/g), the synthesized Ag/Fe3O4-CS composite can be easily separated or recycled in potential biomedical applications. Furthermore, the results showed that the multicomponent hybrid nanostructures appeared to be the promising material for local hyperthermia, which can be used as thermoseeds for localized hyperthermia treatment of cancers. 相似文献
2.
Yongxia Huang Lan Sun Kunpeng Xie Yuekun Lai Biju Liu Bin Ren Changjian Lin 《Journal of Raman spectroscopy : JRS》2011,42(5):986-991
In this work, Ag nanoparticles (NPs) were deposited on patterned TiO2 nanotube films through pulse‐current (PC) electrodeposition, and as a result patterned Ag NPs films were achieved. Scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and X‐ray diffraction (XRD) were used, respectively, to study the morphology, uniformity, and phase structure of the patterned Ag NP films. The size and density of the as‐deposited Ag NPs could be controlled by changing the deposition charge density, and it was found that the patterned Ag NP films produced under a charge density of 2.0 C cm−2 gave intense UV–vis and Raman peaks. Two‐dimensional surface‐enhanced Raman scattering (SERS) mapping of rhodamine 6G (R6G) on the patterned Ag NP films demonstrated a high‐throughput, localized molecular adsorption and micropatterned SERS effect. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
3.
Christian Porsch Yuning Zhang Åsa Östlund Peter Damberg Cosimo Ducani Eva Malmström Andreas M. Nyström 《Particle & Particle Systems Characterization》2013,30(4):381-390
Eight fluorinated nanoparticles (NPs) are synthesized, loaded with doxorubicin (DOX), and evaluated as theranostic delivery platforms to breast cancer cells. The multifunctional NPs are formed by self‐assembly of either linear or star‐shaped amphiphilic block copolymers, with fluorinated segments incorporated in the hydrophilic corona of the carrier. The sizes of the NPs confirm that small circular NPs are formed. The release kinetics data of the particles reveals clear hydrophobic core dependence, with longer sustained release from particles with larger hydrophobic cores, suggesting that the DOX release from these carriers can be tailored. Viability assays and flow cytometry evaluation of the ratios of apoptosis/necrosis indicate that the materials are non‐toxic to breast cancer cells before DOX loading; however, they are very efficient, similar to free DOX, at killing cancer cells after drug encapsulation. Both flow cytometry and confocal microscopy confirm the cellular uptake of NPs and DOX‐NPs into breast cancer cells, and in vitro 19F‐MRI measurement shows that the fluorinated NPs have strong imaging signals, qualifying them as a potential in vivo contrast agent for 19F‐MRI. 相似文献
4.
本文提出一种基于气相沉积银纳米粒子和三维石墨烯-镍泡沫的复合等离激元结构.该结构是利用气相纳米团簇束流技术将高密度的银纳米粒子直接沉积于三维石墨烯-镍泡沫的表面制备而成.与传统银纳米结构相比,复合三维等离激元纳米结构具有"热点"数量多,局域场更强的特点,可作为基于表面增强拉曼技术的高灵敏度化学传感器.拉曼测试实验结果表明,该三维纳米结构在表面增强拉曼检测中可获得灵敏度高,重复性好的探针拉曼信号.通过进一步的理论模拟,发现该三维等离激元结构中增强的拉曼信号主要归因于纳米粒子与纳米粒子之间以及纳米粒子与石墨烯-镍泡沫衬底之间的多重近场耦合效应. 相似文献
5.
Silver nanoparticles (Ag NPs) were prepared via in situ reduction of silver nitrate (AgNO3) using polymeric micelles as nanoreactors without any additional reductant. The micelles were constructed from the amphiphilic star-shaped copolymer composed of poly(?-caprolactone) (PCL) segment, 2-(dimethylamino)ethyl methacrylate (DMAEMA or DMA) units and oligo(ethylene glycol)monomethyl ether methacrylate (OEGMA or OEG) units. The Ag NPs stabilized by those star-shaped copolymers were characterized using UV-vis spectrum, DLS, TEM and FTIR. It confirmed that PDMAEMA exhibited the reducing property unless pH was above 7. The Ag NPs were sphere-like with a diameter of 10-20 nm, which was independent of the architecture of the copolymer and AgNO3 concentration. Furthermore, the catalytic activity of these Ag NPs was investigated by monitoring the reduction of p-nitrophenol (4-NP) by NaBH4. The result showed that the Ag NPs formed by coordination reduction can be effectively applied in catalytic reaction. 相似文献
6.
We report the experimental results on temperature-dependent studies of interactions between a novel biocompatible thermosensitive
polymer hydrogel and different stabilizing agent capped gold nanoparticles (Au NPs) with particle size ranging from 5 to 20 nm.
Stabilizing agents such as thioglycolic acid, tryptophan, and phenylalanine have been used as capping agents for Au NPs. The
poly-N-isopropyl acrylamide-co-acrylic acid (pNIPAm-AAc) with 3.0 ± 0.7 μm in size was synthesized by radical polymerization of
a selected mixture of N-isopropyl acrylamide (NIPAm), methylene-bis-acrylamide and acrylic acid (AAc). The capped Au NPs were mixed with a solution
of pNIPAm-AAc hydrogel. The temperature-dependent properties of the mixture were studied by UV–vis spectroscopy, dynamic light
scattering based particle size analysis, and transmission electron microscopy (TEM). The observations indicated change in
the lower critical solution temperature (LCST) depending on the nature of the stabilizer, with hydrophobic ones lowering the
value while hydrophilic stabilizers increasing the same. Also, the optical absorption due to Au NPs, when stabilized with
hydrophobic groups, reduced significantly at above LCST along with significant blue shift of wavelength maximum. 相似文献
7.
Chih-Kai Huang Chia-Yin Chen Jin-Lin Han Chii-Chang Chen Meng-Dan Jiang Jen-Sung Hsu Chia-Hua Chan Kuo-Huang Hsieh 《Journal of nanoparticle research》2010,12(1):199-207
The silver nanoparticles (Ag NPs) have been immobilized onto silica microspheres through the adsorption and subsequent reduction
of Ag+ ions on the surfaces of the silica microspheres. The neat silica microspheres that acted as the core materials were prepared
through sol–gel processing; their surfaces were then functionalized using 3-mercaptopropyltrimethoxysilane (MPTMS). The major
aims of this study were to immobilize differently sized Ag particles onto the silica microspheres and to understand the mechanism
of formation of the Ag nano-coatings through the self-assembly/adsorption behavior of Ag NPs/Ag+ ions on the silica spheres. The obtained Ag NP/silica microsphere conglomerates were characterized by field-emission scanning
electron microscopy (FE-SEM), transmission electron microscopy (TEM), and energy-dispersive spectroscopy (EDS). Their electromagnetic
wave shielding effectiveness were also tested and studied. The average particle size of the obtained Ag NPs on the silica
microsphere was found that could be controllable (from 2.9 to 51.5 nm) by adjusting the ratio of MPTMS/TEOS and the amount
of AgNO3. 相似文献
8.
Shunsuke Nishimoto Xintong Zhang Noriaki Taneichi Taketoshi Murakami Akira Fujishima 《Applied Surface Science》2008,254(18):5891-5894
A hydrophobic/super-hydrophilic pattern was prepared on a TiO2 thin film by a new fabrication process. The process consists of five key steps: (1) photocatalytic reduction of Ag+ to Ag (nucleation), (2) electroless Cu deposition, (3) oxidation of Cu to CuO, (4) deposition of a self-assembled monolayer (SAM), and (5) photocatalytic decomposition of selected areas of the SAM. A hydrophobic/super-hydrophilic pattern with 500-μm2 hydrophilic areas was obtained in this process. It is particularly noteworthy that a UV irradiation time of only 1 s was sufficient for the nucleation step in the patterning process. 相似文献
9.
Design of Enhanced Catalysts by Coupling of Noble Metals (Au,Ag) with Semiconductor SnO2 for Catalytic Reduction of 4‐Nitrophenol 下载免费PDF全文
Mei Lei Wei Wu Shuanglei Yang Xingang Zhang Zhuo Xing Feng Ren Xiangheng Xiao Changzhong Jiang 《Particle & Particle Systems Characterization》2016,33(4):212-220
The reduction of 4‐nitrophenol (Nip) into 4‐aminophenol (Amp) by NaBH4, which is catalyzed by both binary and ternary yolk–shell noble‐metal/SnO2 heterostructures, is reported. The binary heterostructures contain individual Au or Ag nanoparticles (NPs) and the ternary heterostructures contain both Au and Ag NPs. The Au@SnO2 yolk–shell NPs are synthesized via a silica seeds‐mediated hydrothermal method. Subsequently, the Au@SnO2@Ag and Au@SnO2@Au yolk–shell–shell (YSS) NPs are synthesized, whereby SnO2 is located between the Au and Ag NPs. The morphology, composition, and optical properties of the as‐prepared samples are analyzed. For the binary heterostructures, the rate of the reduction reaction increases with decreasing particle size. The catalytic results demonstrate the synergistic effect of Au and Ag in the ternary metal–semiconductor heterostructures, which is beneficial to the catalytic reduction of Nip into Amp. Both the binary and ternary heterostructures exhibit significantly better catalytic performances than the corresponding bare Au and Ag NPs. It is envisaged that the current synthesized strategy will promote further interest in the field of bimetal NP‐based catalysis. 相似文献
10.
Jae-hyun Kim Bo-hyun Lee Hansaem Kang Jaeyeal Kim Geesung Chae Inbyeong Kang In-jae Chung 《Applied Surface Science》2009,255(23):9386-9390
Ag ink was spontaneously patterned on glass substrate by using the surface energy difference of a pre-patterned octadecyltrichlorosilane (OTS) layer. Ag ink was confined into the hydrophilic area, where OTS layer was not formed. OTS layer was selectively transferred by micro-contact printing (μCP) method and significantly decreased surface energy. As a result, surface of glass substrate was separated as hydrophobic and hydrophilic with and without OTS layer, respectively. Ag line could be successfully patterned with the width of below 10 μm on the glass. The patterned Ag line was dense and abrupt on the edge and the thickness was about 0.25 μm. Ag film showed good adhesion on a glass substrate after anneal above 200 °C. The minimum resistivity was about 4 μΩ cm. 相似文献
11.
Xiaomiao Hou Xiaoling Zhang Yan Fang Shutang Chen Na Li Qi Zhou 《Journal of nanoparticle research》2011,13(5):1929-1936
1-Hexadecylamine (HDA)-capped Au and Ag nanoparticles (NPs) have been successfully prepared by a one-pot solution growth method.
The HDA is used as both reducing agent and stabilizer in the synthetic process is favorable for investigating the capping
mechanism of Au and Ag NPs’ surface. The growth process and characterization of Au and Ag NPs are determined by Ultraviolet–visible
(UV–vis) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD). Experimental results demonstrate
that the HDA-capped Au and Ag NPs are highly crystalline and have good optical properties. Furthermore, surface-enhanced Raman
scattering (SERS) spectra of 2-thionaphthol are obtained on the Au and Ag NPs modified glass surface, respectively, indicating
that the as-synthesized noble metal NPs have potentially high sensitive optical detection application. 相似文献
12.
Paige M. Price Jasper W. Dittmar Kenneth Carlson Bret P. Lawson Austin K. Reilly Barry D. Stein Hu Cheng Oksana Zholobko Ananiy Kohut Andriy Voronov Lyudmila M. Bronstein 《Particle & Particle Systems Characterization》2019,36(7)
A functionalization of iron oxide nanoparticles (NPs) of different diameters by the amphiphilic invertible polymer, (PEG600‐alt‐PTHF650)k (PEG and PTHF stand for poly(ethylene glycol) and poly(tetrahydrofuran), respectively), leads to different NP/polymer architectures for dye/drug uptake and release, as is reported here for the first time. It is demonstrated that 18.6 ± 1.4 and 11.9 ± 0.6 nm NPs are individually coated by this polymer, while 5.9 ± 0.6 nm NPs form nanoparticle clusters (NPCs) which could be isolated by either ultracentrifugation or magnetic separation. This phenomenon is most likely due to the character of the (PEG600‐alt‐PTHF650)k macromolecule with alternating hydrophilic and hydrophobic fragments and its dimensions sufficient to cause NP clustering. Utilizing Rhodamine B base (RBB) and doxorubicin (DOX), the data on uptake upon mixing and further release via inversion into octanol (mimicking the penetration of the cell biomembrane) are presented. The magnetic NPCs display enhanced uptake and release of both RBB and DOX most likely due to the higher retained polymer amount. The NPCs also display exceptional magnetic resonance imaging properties. This and the high uptake/release efficiency of the NPCs combined with easy magnetic separation make them promising for theranostic probes for magnetically targeted drug delivery. 相似文献
13.
Silver (Ag) nanoparticles (NPs) were prepared by laser ablation in water with an aim to enhance the luminescence of rare earth coordinated complex in polymer host. A fixed concentration of the complex containing Samarium (Sm), Salicylic acid (Sal) and 1, 10-phenanthroline (Phen) were combined with different concentrations of silver NPs in PolyVinyl Alcohol at room temperature. Absorption spectrum and XRD patterns of the sample show that the Sm(Sal)3Phen complex is accompanied by Ag NPs. The luminescence from the complex was recorded in the presence and absence of Ag NPs using two different excitation wavelengths viz. 400 and 355 nm. Of these, 400 nm radiation falls in the surface plasmon resonance of Ag NPs. It was found that the Ag NPs led to a significant enhancement in luminescence of the complex. Surprisingly, a high concentration of Ag NPs tends to quench the luminescence. 相似文献
14.
We report an enhancement of antibacterial properties of Ag nanoparticles (NPs) synthesized at room temperature using leaf extract of Azadirachta indica (Neem) following green synthesis route. To study such antibacterial properties Ag NPs of sizes within 9 nm to 17 nm were synthesized by varying the concentration of Neam leaf extract (NLE). The NP size and size distribution were seen to increase and decrease, respectively, with increase in NLE concentration. Also Ag NPs having a fixed size (~26 nm) was also synthesized by varying the precursor (AgNO3) concentration. It is noticed that concentration of NLE has significant effects on the control of NP size as well as size distribution whereas there is almost no role of precursor concentration of the NP size. All the Ag NPs are found to have face-centred-cubic crystal structure with preferential growth along (111) plane which is stable one. The peak of X-ray diffraction at ~32.4° (2θ value), which is prominent for low concentrations of NLE and precursor, is identified as (101) plane of Ag crystal. The generation and growth of Ag NPs had also been confirmed using electron microscopic studies. These Ag NPs show prominent surface plasmon resonance (SPR) absorption at ~ 420 nm confirming again the genesis of Ag NPs. The SPR peak shifts towards longer wavelength (redshift) with a corresponding reduction in full width at half maximum with increase in NP size. All of the samples containing Ag NPs show a broad blue photoluminescence (PL) emission at ~ 471 nm. Emission peak is seen to redshift with increase in NP size and is consistent with the optical absorption data. Such PL emission is argued as due to interband transition or plasmon luminescence. Being biocompatible of the green synthesis process, antibacterial properties of these Ag NPs were studies in details considering all the samples (with varied NP size for one set and with fixed NP size for other set of samples). As per our knowledge this is the first report of size related total study of Ag NPs, showing increased antibacterial effect as size decreased and equal antibacterial effect as size equals. It is found that smaller Ag NPs has enhanced antibacterial effects due to large surface area to volume ratio in comparison with bigger sized Ag NPs. 相似文献
15.
Ying-Kui Yang Cheng-En He Wen-Jie He Lin-Juan Yu Ren-Gui Peng Xiao-Lin Xie Xian-Bao Wang Yiu-Wing Mai 《Journal of nanoparticle research》2011,13(10):5571-5581
Silver nanoparticles (Ag NPs) have been homogeneously deposited onto graphene oxide (GO) nanosheets by an optimal method,
in which N,N-dimethylformamide (DMF) as a co-dispersant of GO and reductant of sliver ions is added to an aqueous suspension of GO and
AgNO3. GO nanosheets are uniformly covered by Ag NPs with a narrow size distribution and inter-particle gap. Raman signals of GO
are greatly enhanced after deposition owing to the charge transfer interaction of GO with Ag NPs. The GO/Ag composite can
be further utilized as an effective surface-enhanced Raman scattering (SERS) active substrate. Several new Raman bands and
frequency shifts are clearly observed in using 4-aminothiophenol (4-ATP) as a Raman probe on GO/Ag compared to the normal
Raman spectrum of solid 4-ATP. The Raman enhancement arises from a major electromagnetic effect and a minor chemical effect. 相似文献
16.
Pulsed laser ablation (PLA) has been widely employed in industrial and biological applications and in other fields. The environmental conditions in which PLA is conducted are important parameters that affect both the solid particle cloud and the deposition produced by the plume. In this work, the generation of nanoparticles (NPs) has been developed by performing PLA of silver (Ag) plates in a supercritical CO2 medium. Ag NPs were successfully generated by allowing the selective generation of clusters. Laser ablation was performed with an excitation wavelength of 532 nm under various pressures and temperatures of CO2 medium. On the basis of the experimental result, both surface of the irradiated Ag plate and structure of Ag NPs were significantly affected by the changes in supercritical CO2 pressure and temperature. With increasing irradiation pressure, plume deposited in the surrounding crater created by the ablation was clearly observed. In Field Emission Scanning Electron Microscopy (FE-SEM) the image of the generated Ag NPs on the silicon wafer and the morphology of Ag particles were basically a sphere-like structure. Ag particles contain NPs with large-varied diameter ranging from 5 nm to 1.2 μm. The bigger Ag NPs melted during the ablation process and then ejected smaller spherical Ag NPs, which formed nanoclusters attached on the molten Ag NPs. The smaller Ag NPs were also formed around the bigger Ag NPs. Based on the results, this new method can also be used to obtain advanced nano-structured materials. 相似文献
17.
The 3D scaffold type biocomposites of gelatin/silver nanoparticles were prepared through the silver nanoparticles (Ag NPs) formation in gelatin solution using solution plasma process (SPP) and their antifungal activity was evaluated. The mixture of 3% gelatin solution and silver precursor (AgNO3; 1–10 mM) was subject to discharge at high voltage (1600 V) under the controlled conditions to form the suspension of Ag NPs in the gelatin matrix. The freeze-drying process of lyophilization was employed to fabricate the 3D scaffold type biocomposite of gelatin/Ag NPs from the suspension. The water-insoluble property was improved by cross-linking using UV-irradiation (λ = 254 nm for 15 min). The physical and chemical characteristics of the biocomposite were investigated using UV–vis spectroscopy, EDS, FE-SEM, and TEM. The results indicated that the 3D scaffold biocomposite of gelatin/Ag NPs had spherical shape with approximately 11–12 nm of diameter. The antifungal activity analysis suggested that the biocomposite with Ag NPs could inhibit the growth of Candida albicans as well as that of hyphae and spores of Aspergillus parasiticus significantly. MIC of the biocomposite for C. albicans and A. parasiticus was determined as 80 μg/ml and 240 μg/ml of Ag NPs, respectively. The growth inhibition of 92.8% was observed in the biocomposite with 10 mM Ag against C. albicans. 相似文献
18.
Y. Badr 《Journal of Physics and Chemistry of Solids》2007,68(3):413-419
The silica nanoparticles (SiO2 NPs), silver (Ag) NPs and gold (Au) NPs coated with SiO2 NPs (core-shell) were prepared. The sizes and morphology of the particles were indicated. The three prepared NPs were used for photocatalytic degradation of methyl orange (MO) dye by xenon lamp. Rate of photocatalytic degradation reaction constant and lifetime were calculated for each catalyst. Moreover, the mechanism of the photocatalytic reaction was studied. 相似文献
19.
We report on the preparation and characterization of Ag/LiCoO2 nanofibers (NFs) via the sol–gel electrospinning (ES) technique. Ag nanoparticles (NPs) were produced in an aqueous polyvinyl pyrrolidone (PVP) solution by using AgNO3 precursor. A viscous lithium acetate/cobalt acetate/polyvinylalcohol/water (LiAc/(CoAc)2/PVA/water) solution was prepared separately. A Ag NPs/PVP/water solution was prepared and added to this viscous solution and magnetically stirred to obtain the final homogeneous electrospinning solution. After establishing the proper electrospinning conditions, as-spun precursor Ag/LiAc/Co(Ac)2/PVA/PVP NFs were formed and calcined in air at a temperature of 600 °C for 3 h to form well-crystallized porous Ag/LiCoO2 NFs. Various analytical characterization techniques such as UV–vis, SEM, TEM, TGA, XRD, and XPS were performed to analyze Ag NPs, as-spun and calcined NFs. It was established that Ag NPs in the precursor Ag/LiAc/Co(Ac)2/PVA/PVP NFs are highly self-aligned as a result of the behavior of Ag in the electric field of the electrospinning setup and the interaction of Ag ions with Li and Co ions in the NF. Ag/LiCoO2 NFs exhibit a nanoporous structure compared with un-doped LiCoO2 NFs because the atomic radius of Ag is larger than the radius of Co and Li ion; thus, no substitution between Ag and Li or Ag and Co atoms occurs, and Ag NPs are located at the interlayer of LiCoO2 while some are left in the fiber. 相似文献
20.
Ki Hyun Kim Kazuo Watanabe Dietrich Menzel Hans-Joachim Freund 《Surface science》2012,606(15-16):1142-1151
Adsorption states, thermal reactions, and photoreactions at photon energies 2.3–4.7 eV of NO dimers and monomers have been compared between 8-nm silver nanoparticles (Ag NPs) formed on an Al2O3/NiAl(110) substrate and flat Ag(111) surfaces, by thermal desorption (TPD) and by photodesorption using mass selected time-of flight measurements. On the Ag NPs, the (NO)2 and NO species are bound more weakly and with broader variation of adsorption states, compared to Ag(111). For (NO)2 excitation of the Mie plasmon of the Ag NPs with p-polarized 3.5-eV photons enhances the photodesorption cross section (PCS) of NO from (NO)2 by a factor 15 compared to Ag(111); even off the plasmon resonance up to 3-fold PCS enhancement is obtained which we ascribe to hot electron confinement. However, since translational energy distributions of photodesorbed NO are roughly the same on Ag NPs and on Ag(111), common mechanisms of photoexcitation and photoreactions apply on both types of surfaces, and neither enhancement modifies the photoinduced dynamics. Stronger particle-induced influences are observed for the photoinduced NO monomer by changes in its properties, chemical environments, and formation/decay kinetics.Our results show that NPs can lead to considerable changes of efficiency and, under favorable cases, also of branching of photoinduced surface reactions. 相似文献