Nanocomposites With Strong Optical Resonances: Silver Nanoparticles-Organic Molecules Systems

2008 ◽  
Author(s):  
Petr Smejkal ◽  
Blanka Vlckova ◽  
Ioana Pavel ◽  
Martin Moskovits ◽  
Magdalena Sladkova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ag Nanoparticles ◽  
Hot Spots ◽  
Spectral Measurements ◽  
Optical Fields ◽  
Optical Resonances ◽  
Transmission Electron ◽  
Surface Enhanced ◽  
Positively Charged ◽  
Subsequent Incorporation

The ability of selected molecular species to link Ag nanoparticles into dimers and/or small aggregates has been tested. Dimercaptocarborane and ethidium bromide have been shown to link Ag nanoparticles via their bonding to Ag nanoparticle surface probably by the two strongly argentophilic groups in para-positions. Alternatively, dimers and small aggregates were assembled through an electrostatic interaction between negatively charged citrate-modified and positively charged polylysine-modified Ag nanoparticles, and a subsequent incorporation of 5, 10, 15, 20-tetrakis(4-sulphonato-phenyl)porphine (TSPP) into such preprepared nanoobjects has been probed by SERRS (surface-enhanced resonance Raman scattering). Formation of dimers and small aggregates has been established by TEM (transmission electron microscopy) and SEM (scanning electron microscopy). SE(R)RS spectral measurements from specific locations of samples containing molecularly-linked dimers and aggregates have shown temporal fluctuations (blinking) of the SE(R)RS signal, which indicates, that the signal likely originates from molecules located in the strong, nanoscale localized optical fields dubbed hot spots. In addition to that, characteristic bands of graphitic carbon were observed in the spectra and their intensities (together with the spectral background intensities) strongly varied with time and from one spectrum to another. One of the possible explanations of these observations is a photochemical and/or thermal decomposition of the molecules located in hot spots combined with diffusion of unperturbed molecules into hot spots.

scholarly journals Preparation of Fe3O4-Ag Nanocomposites with Silver Petals for SERS Application

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1288
Author(s):  
Thi Thuy Nguyen ◽  
Fayna Mammeri ◽  
Souad Ammar ◽  
Thi Bich Ngoc Nguyen ◽  
Trong Nghia Nguyen ◽  
...  
Keyword(s):  
Self Assembly ◽  
Hot Spots ◽  
Surface Enhanced Raman Spectroscopy ◽  
Electrical Field ◽  
Stabilizing Agents ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Sers Sensing ◽  
Applied Electrical Field ◽  
Positively Charged

The formation of silver nanopetal-Fe3O4 poly-nanocrystals assemblies and the use of the resulting hetero-nanostructures as active substrates for Surface Enhanced Raman Spectroscopy (SERS) application are here reported. In practice, about 180 nm sized polyol-made Fe3O4 spheres, constituted by 10 nm sized crystals, were functionalized by (3-aminopropyl)triethoxysilane (APTES) to become positively charged, which can then electrostatically interact with negatively charged silver seeds. Silver petals were formed by seed-mediated growth in presence of Ag+ cations and self-assembly, using L-ascorbic acid (L-AA) and polyvinyl pyrrolidone (PVP) as mid-reducing and stabilizing agents, respectively. The resulting plasmonic structure provides a rough surface with plenty of hot spots able to locally enhance significantly any applied electrical field. Additionally, they exhibited a high enough saturation magnetization with Ms = 9.7 emu g−1 to be reversibly collected by an external magnetic field, which shortened the detection time. The plasmonic property makes the engineered Fe3O4-Ag architectures particularly valuable for magnetically assisted ultra-sensitive SERS sensing. This was unambiguously established through the successful detection, in water, of traces, (down to 10−10 M) of Rhodamine 6G (R6G), at room temperature.

scholarly journals Facile synthesis of Au/ZnO/Ag nanoparticles using Glechoma hederacea L. extract, and their activity against leukemia

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Renata Dobrucka ◽  
Aleksandra Romaniuk-Drapała ◽  
Mariusz Kaczmarek
Keyword(s):  
Electron Microscopy ◽  
Ag Nanoparticles ◽  
Mononuclear Cells ◽  
Leukemia Cell ◽  
Leukemia Cell Line ◽  
Mtt Test ◽  
Transmission Electron ◽  
Almost All ◽  
Glechoma Hederacea

AbstractMetal combinations have been attracting the attention of scientists for some time. They usually exhibit new characteristics that are different from the ones possessed by their components. In this work, Au/ZnO/Ag nanoparticles were synthesized biologically using Glechoma hederacea L. extract. The synthesized Au/ZnO/Ag nanoparticles were characterized by UV-Vis, Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and Atomic Force Microscopy (AFM). The microscopic methods confirmed the presence of spherical nanoparticles of 50–70 nm. The influence of biologically synthesized Au/ZnO/Ag nanoparticles on the vitality of human cells was evaluated in vitro with the use of established human Acute T Cell Leukemia cell line, Jurkat (ATCC® TIB-152™), as well as mononuclear cells isolated from peripheral blood (PBMC) of voluntary donors. Cell survival and the half-maximal inhibitory concentration index (IC50) were analyzed by the MTT test. The studies showed that the total loss of cell viability occurred at the Au/ZnO/Ag nanoparticle concentration range of 10 µmol–50 µmol. The use of Au/ZnO/Ag nanoparticles at the concentration of 100 µmol eliminated almost all living cells from the culture in 24h. The above observation confirms the result obtained during the MTT test.

scholarly journals Self-assembly of chiral fluorescent nanoparticles based on water-soluble L-tryptophan derivatives of p-tert-butylthiacalix[4]arene

2017 ◽  
Vol 8 ◽  
pp. 1825-1835 ◽  
Author(s):  
Pavel L Padnya ◽  
Irina A Khripunova ◽  
Olga A Mostovaya ◽  
Timur A Mukhametzyanov ◽  
Vladimir G Evtugyn ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Self Assembly ◽  
Water Soluble ◽  
Fluorescent Nanoparticles ◽  
Spectral Emission ◽  
Chiroptical Properties ◽  
Transmission Electron ◽  
Derivatives Of ◽  
Tryptophan Derivatives ◽  
Positively Charged

New water-soluble tetra-substituted derivatives of p-tert-butylthiacalix[4]arene containing fragments of L-tryptophan in cone and 1,3-alternate conformations were obtained. It was shown that the resulting compounds form stable, positively charged aggregates of 86–134 nm in diameter in water at a concentration of 1 × 10−4 M as confirmed by dynamic light scattering, scanning electron microscopy and transmission electron microscopy. It was established that these aggregates are fluorescently active and chiral. A distinctive feature of the compounds is the pronounced dependence of their spectral (emission and chiroptical) properties on the polarity of the solvent and the length of the linker between the macrocyclic and fluorophore parts of the molecule.

scholarly journals SiO2 Coated Up-conversion Nanomaterial Doped with Ag Nanoparticles for Micro-CT Imaging

2021 ◽  
Author(s):  
Wei Zhang ◽  
Yanli Lu ◽  
YANG ZANG ◽  
Jinhui Han ◽  
Qingyun Xiong ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Luminescence Intensity ◽  
Ag Nanoparticles ◽  
Fluorescence Spectra ◽  
Cell Counting ◽  
Micro Ct ◽  
Transmission Electron ◽  
Before And After ◽  
Sio2 Nanocomposites ◽  
Low Cytotoxicity

In this study, a new method for synthesizing Ag-NaYF4:Yb3+/Er3+ @ SiO2 nanocomposites was introduced. Using a hydrothermal method, the synthesized Yb3+- and Er3+-codoped NaYF4 upconversion luminescent materials and Ag nanoparticles were doped into upconversion nanomaterials and coated with SiO2 up-conversion nanomaterials. This material is known as Ag-UCNPs-SiO2’ it improves both the luminous intensity because of the doped Ag nanoparticles and has low cytotoxicity because of the SiO2 coating. The morphology of UCNPs was observed using scanning electron microscopy (SEM), and the mapping confirmed the successful doping of Ag nanoparticles. Successful coating of SiO2 was confirmed using transmission electron microscopy (TEM). Fluorescence spectra were used to compare changes in luminescence intensity before and after doping Ag nanoparticles. The reason for the increase in luminescence intensity after doping with Ag nanoparticles was simulated using first-principles calculations. The cytotoxicity of Ag-UCNPs-SiO2 was tested via the cell counting kit-8 (CCK-8) method, and its imaging ability was characterized using the micro-CT method.

scholarly journals SiO2 Coated Up-Conversion Nanomaterial Doped with Ag Nanoparticles for Micro-CT Imaging

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3395
Author(s):  
Wei Zhang ◽  
Yanli Lu ◽  
Yang Zang ◽  
Jinhui Han ◽  
Qingyun Xiong ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Luminescence Intensity ◽  
Ag Nanoparticles ◽  
Fluorescence Spectra ◽  
Cell Counting ◽  
Micro Ct ◽  
Transmission Electron ◽  
Before And After ◽  
Sio2 Nanocomposites ◽  
Low Cytotoxicity

In this study, a new method for synthesizing Ag-NaYF4:Yb3+/Er3+ @ SiO2 nanocomposites was introduced. Using a hydrothermal method, the synthesized Yb3+- and Er3+-codoped NaYF4 up-conversion luminescent materials and Ag nanoparticles were doped into up-conversion nanomaterials and coated with SiO2 up-conversion nanomaterials. This material is known as Ag-UCNPs@SiO2, it improves both the luminous intensity because of the doped Ag nanoparticles and has low cytotoxicity because of the SiO2 coating. The morphology of UCNPs was observed using scanning electron microscopy (SEM), and the mapping confirmed the successful doping of Ag nanoparticles. Successful coating of SiO2 was confirmed using transmission electron microscopy (TEM). Fluorescence spectra were used to compare changes in luminescence intensity before and after doping Ag nanoparticles. The reason for the increase in luminescence intensity after doping with Ag nanoparticles was simulated using first-principles calculations. The cytotoxicity of Ag-UCNPs@SiO2 was tested via the cell counting kit-8 (CCK-8) method, and its imaging ability was characterized using the micro-CT method.

scholarly journals Polyelectrolyte-Stabilised Magnetic-Plasmonic Nanocomposites

Nanomaterials ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1044
Author(s):  
Shelley Stafford ◽  
Coralie Garnier ◽  
Yurii Gun’ko
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Nanocomposite Materials ◽  
Biological Applications ◽  
Polystyrene Sulfonate ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Allylamine Hydrochloride ◽  
Plasmonic Nanocomposite ◽  
Positively Charged

In this work, new magnetic-plasmonic nanocomposites have been developed through the use of two complementary polyelectrolytes–polystyrene sulfonate (PSS) and poly(allylamine hydrochloride) (PAH). PSS, a negatively charged polyelectrolyte, was utilized as a stabiliser for magnetite nanoparticles, and PAH, a positively charged polyelectrolyte, was used to stabilize gold nanoparticles. The combination of these two entities resulted in a magnetic-plasmonic nanocomposite that is highly reproducible and scalable. This approach was found to work for a variety of PSS concentrations. The produced magnetic-plasmonic nanomaterials have been characterized by vibrational sample magnetometry (VSM), transmission electron microscopy (TEM) and UV-Vis spectroscopy. These nanocomposite materials have the potential to be used in a variety of biological applications including bioseparation and biosensing.

scholarly journals In situ electron microscopy observation of the redox process in plasmonic heterogeneous-photo-sensitive nanoparticles

2019 ◽  
Vol 1 (10) ◽  
pp. 3909-3917
Author(s):  
Diego Muraca ◽  
Lucia B. Scaffardi ◽  
Jesica M. J. Santillán ◽  
David Muñetón Arboleda ◽  
Daniel C. Schinca ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ag Nanoparticles ◽  
Redox Process ◽  
Microscopy Observation ◽  
Electron Microscopy Observation ◽  
Transmission Electron ◽  
In Situ Electron Microscopy

Observation of relevant phenomena related with dynamical redox process in a plasmonic heterogeneous-photocatalyst system composed by Ag nanoparticles (NPs) in contact with amorphous AgCl NPs are reported by in situ transmission electron microscopy.

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