scholarly journals A Simple Method for Forming Hybrid Core-Shell Nanoparticles Suspended in Water

2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
Jean-Christophe Daigle ◽  
Jerome P. Claverie
Keyword(s):  
Raft Polymerization ◽  
Inorganic Nanoparticles ◽  
Hybrid Nanoparticles ◽  
Polymerization Process ◽  
Organic Polymer ◽  
Core Shell ◽  
Step Method ◽  
Shell Nanoparticles ◽  
Simple Method ◽  
Reversible Addition

Core-shell hybrid nanoparticles, where the core is an inorganic nanoparticle and the shell an organic polymer, are prepared by a two-step method. Inorganic nanoparticles are first dispersed in water using poly(acrylic acid) (PAA) prepared by reversible addition fragmentation chain transfer (RAFT) polymerization as dispersant. Then, the resulting dispersion is engaged in a radical emulsion polymerization process whereby a hydrophobic organic monomer (styrene and butyl acrylate) is polymerized to form the shell of the hybrid nanoparticle. This method is extremely versatile, allowing the preparation of a variety of nanocomposites with metal oxides (alumina, rutile, anatase, barium titanate, zirconia, copper oxide), metals (Mo, Zn), and even inorganic nitrides (Si3N4).

scholarly journals Core@shell Nanoparticles: Greener Synthesis Using Natural Plant Products

2018 ◽  
Vol 8 (3) ◽  
pp. 411 ◽  
Author(s):  
Mehrdad Khatami ◽  
Hajar Alijani ◽  
Meysam Nejad ◽  
Rajender Varma
Keyword(s):  
Large Scale ◽  
Hybrid Nanoparticles ◽  
Target Cells ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Environmental Friendliness ◽  
Shell Nanostructures ◽  
Greener Synthesis ◽  
Core Shell Nanoparticles ◽  
Synthesis Of Nanostructures

Among an array of hybrid nanoparticles, core-shell nanoparticles comprise of two or more materials, such as metals and biomolecules, wherein one of them forms the core at the center, while the other material/materials that were located around the central core develops a shell. Core-shell nanostructures are useful entities with high thermal and chemical stability, lower toxicity, greater solubility, and higher permeability to specific target cells. Plant or natural products-mediated synthesis of nanostructures refers to the use of plants or its extracts for the synthesis of nanostructures, an emerging field of sustainable nanotechnology. Various physiochemical and greener methods have been advanced for the synthesis of nanostructures, in contrast to conventional approaches that require the use of synthetic compounds for the assembly of nanostructures. Although several biological resources have been exploited for the synthesis of core-shell nanoparticles, but plant-based materials appear to be the ideal candidates for large-scale green synthesis of core-shell nanoparticles. This review summarizes the known strategies for the greener production of core-shell nanoparticles using plants extract or their derivatives and highlights their salient attributes, such as low costs, the lack of dependence on the use of any toxic materials, and the environmental friendliness for the sustainable assembly of stabile nanostructures.

scholarly journals Performance Improving Method of Aligned Silver Nanorod by Grafting Au@Ag Core–Shell Nanoparticles for Surface-Enhanced Raman Scattering

NANO ◽  
2017 ◽  
Vol 12 (11) ◽  
pp. 1750131 ◽  
Author(s):  
Jian Chen ◽  
Peitao Dong ◽  
Chaoguang Wang ◽  
Chenyu Zhang ◽  
Junfeng Wang ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Surface Enhanced Raman Scattering ◽  
Core Shell ◽  
Sers Substrate ◽  
Shell Nanoparticles ◽  
Simple Method ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
Core Shell Nanoparticles

A simple method for improving surface-enhanced Raman scattering (SERS) performance of aligned silver nanorod (Ag NR) array was investigated. This method was to construct a kind of hybrid substrate by grafting Au@Ag core–shell nanoparticles (NPs) into Ag NR array using poly(2-vinylphridine) (P2VPy) as a bridging agent. The hybrid substrate yielded excellent SERS performance as its detection limit improved from 10[Formula: see text] M to 10[Formula: see text] M using trans-1,2-bis(4-pyridyl)ethylene (BPE) as probe molecule, which was increased by two orders of magnitude compared with Ag NR array substrate. The significant improvement of SERS performance of Ag NR arrays was attributed to the addition of Au@Ag core–shell NPs. As a result of surface plasmon resonance generated by the interaction of electromagnetic (EM) (IAEM) filed between NP and NR structures, increasing hotspots were found at the connections of NPs and NRs, the gaps of adjacent rods, and the gaps of two particles consequently. These results were validated by the finite difference time domain (FDTD) calculation. Besides, hybrid substrate shows good performance in stability and reproducibility. The proposed method was simple and robust, which promoted SERS performance of Ag NR array effectively, showing great potential in the application of SERS substrate fabrication and SERS-based bio-chemical sensing.

scholarly journals Synthesis and Comparative Biological Properties of Ag-PEG Nanoparticles with Tunable Morphologies from Janus to Multi-Core Shell Structure

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1787 ◽  
Author(s):  
Mengda Xu ◽  
Jie Liu ◽  
Xiankui Xu ◽  
Shanhu Liu ◽  
František Peterka ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Silver Nitrate ◽  
Shell Structure ◽  
Irradiation Time ◽  
Antibacterial Activities ◽  
Biological Properties ◽  
Hybrid Nanoparticles ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Core Shell Structure

Silver nanoparticles synthesized with polymers as coating agents is an effective method to overcome their poor stability and aggregation in solution. Silver-polyethylene glycol (Ag-PEG) nanoparticles were synthesized with the thiol-functionalized polyethylene glycol (SH-PEA) as the coating, reducing and stabilizing agent. The UV irradiation time, polymer and silver nitrate concentration for the synthesis were investigated. The concentration of silver nitrate had significant effect on the morphology of Ag-PEG nanoparticles. When increasing the concentration of silver nitrate, SEM and TEM images showed that Ag-PEG nanoparticles changed from Janus to multi-core shell structure. Meanwhile, pure silver particles in the two hybrid nanoparticles presented spherical shape and had the similar size of 15 nm. The antibacterial activities and cytotoxicity of the two structural Ag-PEG nanoparticles were investigated to understand colloid morphology effect on the properties of AgNPs. The results of antibacterial activities showed that the two structural Ag-PEG nanoparticles exhibited strong antibacterial activities against Staphylococcus aureus, Escherichia coli and Bacillus subtilis. The Janus nanoparticles had larger minimal inhibitory concentration (MIC) and minimum bacterial concentration (MBC) values than the multi-core shell counterparts. The results of cytotoxicity showed the Janus Ag-PEG nanoparticles had lower toxicity than the multi-core shell nanoparticles.

Preparation of Silica/Polymer Hybrid Nanoparticles via a Semi-Continuous Soup-Free Emulsion Polymerization

2015 ◽  
Vol 1120-1121 ◽  
pp. 233-242
Author(s):  
Joshua Qing Song Li ◽  
Hai Wang ◽  
Yan Qiu Wang
Keyword(s):  
Emulsion Polymerization ◽  
Early Stage ◽  
Size Exclusion ◽  
Hybrid Nanoparticles ◽  
Core Shell ◽  
Particle Coagulation ◽  
Shell Nanoparticles ◽  
Sem Images ◽  
Spectra Analysis ◽  
Polymer Hybrid

Hybrid nanoparticles were prepared by direct polymerization of methyl methacrylate, vinyl acetate, and styrene monomers onto the unmodified hydrophilic surfaces of 33 nm silica nanoparticles in a semi-continuous soap-free emulsion polymerization at a monomer starved condition. The polymerization was initiated by potassium persulfate with constant monomer feed at 0.01, 0.02, or 0.04 mL/min. The growth of the core-shell nanoparticles were measured by a laser particle size analyzer. FT-IR spectra analysis confirmed the hybrid structures of the synthesized nanoparticles. SEM images and size exclusion chromatography (SEC) results indicated regular core-shell microsphere structures. The hybrid nanoparticles increased in monodispersity and size over 100 nm with the reaction. However, SiO2/polystyrene (PS) nanoparticles grew much faster compared with SiO2/polymethyl methacrylate (PMMA) and SiO2/polyvinyl acetate (PVAC). There was particle coagulation, about 12 SiO2/PS particles aggregating to one, in the early stage of the seeded process. In addition, PS secondary particles were formed before the particle coagulation, and then merged with the SiO2/PS nanoparticles in the particle coagulation. The formation of SiO2/polymer hybrid nanoparticles depended on the hydrophilic characteristics of the polymer, and the size of silica seeds.

Investigation into the Initialization Behaviour of RAFT-Mediated Styrene–Maleic Anhydride Copolymerizations

2006 ◽  
Vol 59 (10) ◽  
pp. 742 ◽  
Author(s):  
Eric T. A. van den Dungen ◽  
Jacques Rinquest ◽  
Nadine O. Pretorius ◽  
Jean M. McKenzie ◽  
James B. McLeary ◽  
...  
Keyword(s):  
Maleic Anhydride ◽  
Raft Polymerization ◽  
Polymerization Process ◽  
Unit Model ◽  
Reversible Addition ◽  
Raft Agent ◽  
Addition Rate ◽  
Leaving Groups ◽  
Chain Lengths ◽  
Alternating Copolymerization

The living radical alternating copolymerization of styrene and maleic anhydride mediated by the reversible addition–fragmentation chain transfer (RAFT) polymerization process has been studied at short chain lengths using two different dithiobenzoate RAFT agents. The results indicate specificity of addition of the RAFT-agent leaving groups for either styrene or maleic anhydride. The addition rate of the monomers and the fact that monomers are added individually favour the penultimate unit model of polymer propagation.

Fabrication and Biofunctionalization of Selenium-Polypyrrole Core–Shell Nanoparticles for Targeting and Imaging of Cancer Cells

2008 ◽  
Vol 8 (5) ◽  
pp. 2488-2491 ◽  
Author(s):  
Jing-Liang Li ◽  
Xiang-Yang Liu
Keyword(s):  
Cancer Cells ◽  
Polymerization Process ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Cervical Cancer Cells ◽  
Core Shell Nanoparticles ◽  
Human Cervical Cancer Cells ◽  
Thermal Stability Of ◽  
Human Cervical Cancer

Selenium-polypyrrole core–shell nanoparticles are fabricated by an in-situ polymerization process and functionalized with transferrin for targeting and imaging of human cervical cancer cells. The shell thickness and chemical composition of the as-synthesized particles can be manipulated by controlling the precursor concentration. The presence of the polymer layer can greatly increase the thermal stability of the selenium nanoparticles. The presence of transferrin molecules on the surface of the core–shell nanoparticles can significantly enhance their cellular uptake. The tranferrin-conjugated core–shell nanoparticles can be potentially used for the targeting and imaging of cancer cells.

Water-soluble ZnS:Mn/ZnS core/shell nanoparticles prepared by a novel two-step method

2010 ◽  
Vol 492 (1-2) ◽  
pp. 363-367 ◽  
Author(s):  
Bohua Dong ◽  
Lixin Cao ◽  
Ge Su ◽  
Wei Liu ◽  
Hua Qu ◽  
...  
Keyword(s):  
Water Soluble ◽  
Core Shell ◽  
Step Method ◽  
Shell Nanoparticles ◽  
Core Shell Nanoparticles

One-Pot Endgroup-Modification of Hydrophobic RAFT Polymers with Cyclodextrin by Thiol-ene Chemistry and the Subsequent Formation of Dynamic Core–Shell Nanoparticles Using Supramolecular Host–Guest Chemistry

2012 ◽  
Vol 65 (8) ◽  
pp. 1095 ◽  
Author(s):  
Firdaus Yhaya ◽  
Sandra Binauld ◽  
Manuela Callari ◽  
Martina H. Stenzel
Keyword(s):  
Raft Polymerization ◽  
Particle Surface ◽  
Terminal Group ◽  
Solid Particles ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
One Pot ◽  
Subsequent Formation ◽  
Raft Agent ◽  
Core Shell Nanoparticles

Poly(methyl methacrylate) PMMA, synthesized using reversible addition fragmentation chain transfer (RAFT) polymerization, was heated in a solvent at 100°C for 24 h leading to the loss of the RAFT endfunctionality and the complete conversion into a vinyl group. Mono(6-deoxy-6-mercapto)-β-cyclodextrin (β-CD-SH) was subsequently clicked onto the polymer by a thiol-ene reaction leading to PMMA with one β-CD as a terminal group (PMMA70–β-CD). Meanwhile, a RAFT agent with an adamantyl group has been prepared for the polymerization of 2-hydroxyethyl acrylate (HEA) leading to PHEA95–Ada. Two processes were employed to generate core–shell nanoparticles from these two polymers: a one-step approach that employs a solution of both polymers at stoichiometric amounts in DMF, followed by the addition of water, and a two step process that uses PMMA solid particles with surface enriched with β-CD in water, which have a strong tendency to aggregate, followed by the addition of PHEA95–Ada in water. Both pathways led to stable core–shell nanoparticles of ~150 nm in size. Addition of free β-CD competed with the polymer bound β-CD releasing the PHEA hairs from the particle surface. As a result, the PMMA particles started agglomerating resulting in a cloudy solution. A similar effect was observed when heating the solution. Since the equilibrium constant between β-CD and adamantane decreases with increasing temperature, the stabilizing PHEA chains cleaved from the surface and the solution turned cloudy due to the aggregation of the naked PMMA spheres. This process was reversible and with decreasing temperature the core–shell nanoparticles formed again leading to a clear solution.

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