Search results for "ARTICLES"
showing 10 items of 9626 documents
A Step into the Future: Applications of Nanoparticle Enzyme Mimics.
2018
We describe elementary concepts, up-to-date developments, and perspectives of the emerging field of nanoparticle enzyme mimics (so-called "nanozymes") at the interface of chemistry, biology, materials, and nanotechnology. The design and synthesis of functional enzyme mimics is a long-standing goal of biomimetic chemistry. Metal complexes, polymers and engineered biomolecules capturing the structure of natural enzymes or their active centers have been made to achieve high rates and enhanced selectivities. Still, the design of new "artificial enzymes" that are not related to proteins but with capacity of production and stability at industrial level, remains a goal. Inorganic nanoparticles bea…
Identification of Novel Principles of Keratin Filament Network Turnover in Living Cells
2004
It is generally assumed that turnover of the keratin filament system occurs by exchange of subunits along its entire length throughout the cytoplasm. We now present evidence that a circumscribed submembranous compartment is actually the main site for network replenishment. This conclusion is based on the following observations in living cells synthesizing fluorescent keratin polypeptides: 1) Small keratin granules originate in close proximity to the plasma membrane and move toward the cell center in a continuous motion while elongating into flexible rod-like fragments that fuse with each other and integrate into the peripheral KF network. 2) Recurrence of fluorescence after photobleaching i…
Functional Nanohybrids Based on Dyes and Upconversion Nanoparticles
2020
Upconversion nanoparticles (UCNPs) and dyes are combined to make nanohybrid systems, which take advantage of the synergic relationship between lanthanide (Ln)-based UCNPs and dyes. Ln-UCNPs are inorganic nanophosphors which absorb NIR light and emit narrow emission bands in the UV-NIR region with long luminescence lifetimes. These unique properties, when coordinated properly with dyes of the appropriate photophysical features, produce nanosystems with new photophysical properties. In this context, the UCNP-dye nanohybrids are very promising for potential sensing (ions and biomolecules) and theragnosis (imaging and therapy, e.g. photodynamic therapy).
Magnetic Soret effect in a hydrocarbon based colloid containing surfacted Mn–Zn ferrite particles
1999
Abstract The Soret effect has been investigated in a hydrocarbon based magnetic fluid containing surfacted Mn 0.5 Zn 0.5 Fe 2 O 4 nanoparticles with a magnetic volume concentration of 2.3%. The magnetic fluid fills up a vertical diffusion column which consists of a flat vertical channel between two walls and two reservoirs at the ends of the channel. One wall of the channel is being heated while the another one is cooled, maintaining a temperature gradient over the channel's width that leads to separation of particles due to the Soret effect as well as the convective flow in the channel. The combination of the two mentioned effects brings up a measurable change of the concentration of magne…
Fast and continuous synthesis of nanostructured iron spinel in supercritical water: influence of cations and citrates
2014
International audience; Spinel iron oxide nanoparticles were obtained under supercritical water conditions in a continuous and fast (less than 10s) way by modifying the initial stoichiometric Fe II /Fe III molar ratio from (1/2) to (3/0), without base solution, and using citrates directly with iron precursors. This result opens the way of an economical and environmentally benign approach to synthesize superparamagnetic iron oxide nanoparticles (SPIONs) in important yields.
Silica-coated Au@ZnO Janus particles and their stability in epithelial cells
2020
Multicomponent particles have emerged in recent years as new compartmentalized colloids with two sides of different chemistry or polarity that have opened up a wide field of unique applications in medicine, biochemistry, optics, physics and chemistry. A drawback of particles containing a ZnO hemisphere is their low stability in biological environment due to the amphoteric properties of Zn2+. Therefore we have synthesized monodisperse Au@ZnO Janus particles by seed-mediated nucleation and growth whose ZnO domain was coated selectively with a thin SiO2 layer as a protection from the surrounding environment that imparts stability in aqueous media while the Au domain remained untouched. The thi…
Iron and iron-oxide magnetic nanoparticles as signal-amplification elements in electrochemical biosensing
2015
Abstract Growing demands for ultrasensitive biosensing have led to the development of numerous signal-amplification strategies. Based on their unique properties (i.e., electro-conductivity, bio-compatibility and ease of synthesis), various iron magnetic nanoparticles (MNPs) have proved to be an excellent nanomaterial for applications in electrochemical biosensing. This review shows how iron MNPs have made significant contributions in the development of electrochemical nanobiosensors, including immuno-, enzyme, DNA and aptamer types. More importantly, we discuss in detail different aspects of the electrochemical biosensors (e.g., modes of magnetic particles, detection techniques, analytes an…
Dendrimer-encapsulated and cored metal nanoparticles for electrochemical nanobiosensing
2014
Abstract We discuss nanosized dendrimers from the point of view of electrochemical-biosensor design. We review electrochemical biosensors based on dendrimer-encapsulated metal nanoparticles (NPs) and their various applications (e.g., measurement of small biological and toxic molecules, detection of DNA, and immunosensing of disease biomarkers). Finally, we discuss some future applications of electrochemical biosensors based on dendrimer-encapsulated metal NPs.
Magnetic Composite Thin Films of FexOy Nanoparticles and Photocrosslinked Dextran Hydrogels
2012
Abstract Magnetic hydrogel composites are promising candidates for a broad field of applications from medicine to mechanical engineering. Here, surface-attached composite films of magnetic nanoparticles (MNP) and a polymeric hydrogel (HG) were prepared from magnetic iron oxide nanoparticles and a carboxymethylated dextran with photoreactive benzophenone substituents. A blend of the MNP and the dextran polymer was prepared by mixing in solution, and after spin-coating and drying the blend film was converted into a stable MNP–HG composite by photocrosslinking through irradiation with UV light. The bulk composite material shows strong mobility in a magnetic field, imparted by the MNPs. By util…
Halloysite Nanotubes for Cleaning, Consolidation and Protection
2017
Herein, we report our recent research concerning the development of halloysite based protocols for cleaning, consolidation and protection purposes. Surface modification of halloysite cavity by anionic surfactants was explored to fabricate inorganic micelles able to solubilize hydrophobic contaminants. Hybrid dispersions based on halloysite and ecocompatible polymers were tested as consolidants for paper and waterlogged archaeological woods. Encapsulation of deacidifying and flame retardant agents within the halloysite lumen was conducted with aim to obtain nanofiller with a long-term protection ability. The results prove the suitability and versatility of halloysite nanotubes, which are per…