Reduction reactions and densification during TEM heating of iron oxide nanochains.

The reduction reactions and densification of nanochains assembled from -FeO nanoparticles were investigated using transmission electron microscopy (TEM). Morphological changes and reduction of the metal oxide nanochains were observed during TEM annealing through simultaneous imaging and quantitative analysis of the near-edge fine structures of Fe L absorption edges acquired by spatially resolved electron energy loss spectroscopy. A change in the oxidation states during annealing of the iron oxide nanochains was observed with phase transformations due to continuous reduction from FeO over FeO, FeO to metallic Fe.

Physicochemical properties of iron oxide nanoparticles that contribute to cellular ROS-dependent signaling and acellular production of hydroxyl radical.

While nanoparticles (NPs) are increasingly used in a variety of consumer products and medical applications, some of these materials have potential health concerns. Macrophages are the primary responders to particles that initiate oxidative stress and inflammatory reactions. Here, we utilized six flame-synthesized, engineered iron oxide NPs with various physicochemical properties (e.

Novel multi-functional europium-doped gadolinium oxide nanoparticle aerosols facilitate the study of deposition in the developing rat lung.

Ambient ultrafine particulate matter (UPM), less than 100 nm in size, has been linked to the development and exacerbation of pulmonary diseases. Age differences in susceptibility to UPM may be due to a difference in delivered dose as well as age-dependent differences in lung biology and clearance. In this study, we developed and characterized aerosol exposures to novel metal oxide nanoparticles containing lanthanides to study particle deposition in the developing postnatal rat lung.

FRET-based homogeneous immunoassay on a nanoparticle-based photonic crystal.

The potential of fluorescence resonance energy transfer (FRET) in a photonic crystal (PC) nanostructured array to enhance the speed and sensitivity of a protein-based immunoassay was tested. Forty-nanometer carboxylated particles conjugated with donor-labeled capture antibodies were trapped by electrophoresis and used as a FRET energy donor. The PC array was able to enhance fluorescent excitation and emission by phase matching.

On-chip detection of a single nucleotide polymorphism without polymerase amplification.

A nanoparticle-assembled photonic crystal (PC) array was used to detect single nucleotide polymorphism (SNP). The assay platform with PC nanostructure enhanced the fluorescent signal from nanoparticle-hybridized DNA complexes due to phase matching of excitation and emission. Nanoparticles coupled with probe DNA were trapped into nanowells in an array by using an electrophoretic particle entrapment system.

Ultra-long Magnetic Nanochains for Highly Efficient Arsenic Removal from Water.

The contamination of drinking water with naturally occurring arsenic is a global health threat. Filters that are packed with adsorbent media with a high affinity for arsenic have been used to de-contaminate water - generally iron or aluminium oxides are favored materials. Recently, nanoparticles have been introduced as adsorbent media due to their superior efficiency compared to their bulk counter-parts.

Potential toxicity of up-converting nanoparticles encapsulated with a bilayer formed by ligand attraction.

The cellular toxicity of nanoparticles that were capped with a bilayered ligand was studied using an up-converting (UC) phosphor material as a representative nanoparticle (NP). The results indicate that although UC NPs are known to be nontoxic, the toxicity of the NPs depends strongly on ligand coordination conditions, in addition to the other commonly known parameters such as size, structure, surface charge etc. Oleate-capped hydrophobic NaYF4:Yb,Er NPs were surface modified to yield three extreme conditions: bare particles that were stripped of the oleate ligands; particles with covalently bound poly(ethylene glycol) (PEG) ligands; and particles with an bilayer of PEG-oleate ligands using the oleate surface group that was remained after synthesis.

NaGdF:Eu Nanoparticles for Enhanced X-ray Excited Optical Imaging.

X-ray luminescent nanoparticles (NPs), including lanthanide fluorides, have been evaluated for application to deep tissue in vivo molecular imaging using optical tomography. A combination of high material density, higher atomic number and efficient NIR luminescence from compatible lanthanide dopant ions indicates that particles that consist of ALnF (A = alkaline, Ln = lanthanide element) may offer a very attractive class of materials for high resolution, deep tissue imaging with X-ray excitation. NaGdF:Eu NPs produced an X-ray excited luminescence that was among the most efficient of nanomaterials that have been studied thus far.

Nanotechnology and toxicology.

The Pacific Basin Consortium session on Nanotechnology and toxicology brought together experts from biology and the physical sciences and engineering to discuss the environmental and health impacts of nanotechnology and nanomaterials in particular. The discussion included new findings in the area of inhalation toxicology as well as aquatic toxicology. Opportunities for engineering new forms of particles for toxicology studies were also presented.

Capture and detection of T7 bacteriophages on a nanostructured interface.

A highly ordered array of T7 bacteriophages was created by the electrophoretic capture of phages onto a nanostructured array with wells that accommodated the phages. Electrophoresis of bacteriophages was achieved by applying a positive potential on an indium tin oxide electrode at the bottom of the nanowells. Nanoscale arrays of phages with different surface densities were obtained by changing the electric field applied to the bottom of the nanowells.

Sublethal effects of CuO nanoparticles on Mozambique tilapia (Oreochromis mossambicus) are modulated by environmental salinity.

The increasing use of manufactured nanoparticles (NP) in different applications has triggered the need to understand their putative ecotoxicological effects in the environment. Copper oxide nanoparticles (CuO NP) are toxic, and induce oxidative stress and other pathophysiological conditions. The unique properties of NP can change depending on the characteristics of the media they are suspended in, altering the impact on their toxicity to aquatic organisms in different environments.

New approach to investigate the cytotoxicity of nanomaterials using single cell mechanics.

Current in vitro methods to assess nanomaterial cytotoxicity involve various assays to monitor specific cellular dysfunction, such as metabolic imbalance or inflammation. Although high throughput, fast, and animal-free, these in vitro methods suffer from unreliability and lack of relevance to in vivo situations. New approaches, especially with the potential to reliably relate to in vivo studies directly, are in critical need.

Arsenic removal from water using flame-synthesized iron oxide nanoparticles with variable oxidation states.

We utilized gas-phase diffusion flame synthesis, which has potential for large-scale production of metal oxide nanoparticles, to produce iron oxide nanoparticles (IONPs) with variable oxidation states. The efficacy of these materials in removal of arsenate (As(V) ) from water was assessed. Two different flame configurations, a diffusion flame (DF) and an inverse diffusion flame (IDF), were employed to synthesize six different IONPs by controlling flame conditions.

Photonic crystal lab-on-a-chip for detecting staphylococcal enterotoxin B at low attomolar concentration.

Nanoscale wells have been fabricated in a chip to construct a photonic crystal that is used for enhanced immunoassays of a common food-borne toxin, Staphylococcal enterotoxin B (SEB). The nanostructure of the photonic crystal (PC) in the array enhanced the fluorescent signal due to a guided mode resonance. Nanoparticles were used as the solid substrate for attachment of capture antibodies; the particles were then isolated in individual wells of the chip by using an electrophoretic particle entrapment system (EPES).

Novel lanthanide-labeled metal oxide nanoparticles improve the measurement of in vivo clearance and translocation.

The deposition, clearance and translocation of europium-doped gadolinium oxide nanoparticles in a mouse lung were investigated experimentally. Nanoparticles were synthesized by spray flame pyrolysis. The particle size, crystallinity and surface properties were characterized.

Superparamagnetic particle dynamics and mixing in a rotating capillary tube with a stationary magnetic field.

The dynamics of superparamagnetic particles subject to competing magnetic and viscous drag forces have been examined with a uniform, stationary, external magnetic field. In this approach, competing drag and magnetic forces were created in a fluid suspension of superparamagnetic particles that was confined in a capillary tube; competing viscous drag and magnetic forces were established by rotating the tube. A critical Mason number was determined for conditions under which the rotation of the capillary prevents the formation of chains from individual particles.

Electrophoretic build-up of multi nanoparticle array for a highly sensitive immunoassay.

One of the challenges in shrinking immunoassays to smaller sizes is to immobilize the biological molecules to nanometer-scaled spots. To overcome this complication, we have employed a particle-based immunoassay to create a nanostructured platform with a regular array of sensing elements. The technique makes use of an electrophoretic particle entrapment system (EPES) to immobilize nanoparticles that are coated with biological reagents into wells using a very small trapping potential.

Ultrasensitive on-chip immunoassays with a nanoparticle-assembled photonic crystal.

Electrophoretic particle entrapment system (EPES) is employed to generate 2D array of nanoparticles coated with biological molecules (i.e., antibodies).

Accelerated immunoassays based on magnetic particle dynamics in a rotating capillary tube with stationary magnetic field.

A rapid and simple magnetic particle-based immunoassay has been demonstrated in a capillary mixing system. Antibody-coated micrometer size superparamagnetic polystyrene (SPP) particles were used in an assay for rabbit IgG in a sandwich (noncompetitive) format. The kinetics of the assay was compared between a plate-based system and a single capillary tube.

Serum proteins prevent aggregation of Fe2O3 and ZnO nanoparticles.

Aggregation of metal oxide nanoparticles in aqueous media complicates interpretation of in vitro studies of nanoparticle-cell interactions. We used dynamic light scattering to investigate the aggregation dynamics of iron oxide and zinc oxide nanoparticles. Our results show that iron oxide particles aggregate more readily than zinc oxide particles.

Susceptibility to inhaled flame-generated ultrafine soot in neonatal and adult rat lungs.

Over a quarter of the U.S. population is exposed to harmful levels of airborne particulate matter (PM) pollution, which has been linked to development and exacerbation of respiratory diseases leading to morbidity and mortality, especially in susceptible populations.

Upconversion in NaYF(4):Yb, Er nanoparticles amplified by metal nanostructures.

Upconversion (UC) fluorescence in NaYF(4):Yb, Er nanoparticles amplified by metal nanostructures was compared in two nanostructure geometries: gold nanoshells surrounding nanoparticles and silver nanostructures adjacent to the nanoparticles, both placed on a dielectric silica surface. Enhanced UC luminescence signals and modified lifetimes induced by these two metals were observed in our study. The UC luminescence intensities of green and red emissions were enhanced by Ag nanostructures by a factor of approximately 4.

To duckweeds (Landoltia punctata), nanoparticulate copper oxide is more inhibitory than the soluble copper in the bulk solution.

CuO nanoparticles (CuO-NP) were synthesized in a hydrogen diffusion flame. Particle size and morphology were characterized using scanning mobility particle sizing, Brunauer-Emmett-Teller analysis, dynamic light scattering, and transmission electron microscopy. The solubility of CuO-NP varied with both pH and presence of other ions.

Age specific responses to acute inhalation of diffusion flame soot particles: cellular injury and the airway antioxidant response.

Current studies of particulate matter (PM) are confounded by the fact that PM is a complex mixture of primary (crustal material, soot, metals) and secondary (nitrates, sulfates, and organics formed in the atmosphere) compounds with considerable variance in composition by sources and location. We have developed a laboratory-based PM that is replicable, does not contain dust or metals and that can be used to study specific health effects of PM composition in animal models. We exposed both neonatal (7 days of age) and adult rats to a single 6-h exposure of laboratory generated fine diffusion flame particles (DFP; 170 µg/m(3)), or filtered air.

Alveolar epithelial cell injury due to zinc oxide nanoparticle exposure.

Rationale: Although inhalation of zinc oxide (ZnO) nanoparticles (NPs) is known to cause systemic disease (i.e., metal fume fever), little is known about mechanisms underlying injury to alveolar epithelium.