Particles adsorbed on cells accumulate in the first organ downstream from injection site

Iron oxide particles and hydrogen peroxide bust biofilms on teeth in rat study

Hayden Library - TA418.9.N35 F87 2018

Nanoparticles are essential electrocatalysts in chemical production, water treatment and energy conversion, but engineering efficient and specific catalysts requires understanding complex structure–reactivity relations. Recent experiments have shown that Bragg coherent diffraction imaging might be a powerful tool in this regard. The technique provides three-dimensional lattice strain fields from which surface reactivity maps can be inferred. However, all experiments published so far have investigated particles an order of magnitude larger than those used in practical applications. Studying smaller particles quickly becomes demanding as the diffracted intensity falls. Here, in situ nanodiffraction data from 60 nm Au nanoparticles under electrochemical control collected at the hard X-ray nanoprobe beamline of MAX IV, NanoMAX, are presented. Two-dimensional image reconstructions of these particles are produced, and it is estimated that NanoMAX, which is now open for general users, has the requisites for three-dimensional imaging of particles of a size relevant for catalytic applications. This represents the first demonstration of coherent X-ray diffraction experiments performed at a diffraction-limited storage ring, and illustrates the importance of these new sources for experiments where coherence properties become crucial.

Radiation damage is the most fundamental limitation for achieving high resolution in electron cryo-microscopy (cryo-EM) of biological samples. The effects of radiation damage are reduced by liquid-helium cooling, although the use of liquid helium is more challenging than that of liquid nitrogen. To date, the benefits of liquid-nitrogen and liquid-helium cooling for single-particle cryo-EM have not been compared quantitatively. With recent technical and computational advances in cryo-EM image recording and processing, such a comparison now seems timely. This study aims to evaluate the relative merits of liquid-helium cooling in present-day single-particle analysis, taking advantage of direct electron detectors. Two data sets for recombinant mouse heavy-chain apoferritin cooled with liquid-nitrogen or liquid-helium to 85 or 17 K were collected, processed and compared. No improvement in terms of resolution or Coulomb potential map quality was found for liquid-helium cooling. Interestingly, beam-induced motion was found to be significantly higher with liquid-helium cooling, especially within the most valuable first few frames of an exposure, thus counteracting any potential benefit of better cryoprotection that liquid-helium cooling may offer for single-particle cryo-EM.

With the emergence of X-ray free-electron lasers, it is possible to investigate the structure of nanoscale samples by employing coherent diffractive imaging in the X-ray spectral regime. In this work, we developed a refinement method for structure reconstruction applicable to low-quality coherent diffraction data. The method is based on the gradient search method and considers the missing region of a diffraction pattern and the small number of detected photons. We introduced an initial estimate of the structure in the method to improve the convergence. The present method is applied to an experimental diffraction pattern of an Xe cluster obtained in an X-ray scattering experiment at the SPring-8 Angstrom Compact free-electron LAser (SACLA) facility. It is found that the electron density is successfully reconstructed from the diffraction pattern with a large missing region, with a good initial estimate of the structure. The diffraction pattern calculated from the reconstructed electron density reproduced the observed diffraction pattern well, including the characteristic intensity modulation in each ring. Our refinement method enables structure reconstruction from diffraction patterns under difficulties such as missing areas and low diffraction intensity, and it is potentially applicable to the structure determination of samples that have low scattering power.

Characterizing and controlling the uniformity of nanoparticles is crucial for their application in science and technology because crystalline defects in the nanoparticles strongly affect their unique properties. Recently, ultra-short and ultra-bright X-ray pulses provided by X-ray free-electron lasers (XFELs) opened up the possibility of structure determination of nanometre-scale matter with Å spatial resolution. However, it is often difficult to reconstruct the 3D structural information from single-shot X-ray diffraction patterns owing to the random orientation of the particles. This report proposes an analysis approach for characterizing defects in nanoparticles using wide-angle X-ray scattering (WAXS) data from free-flying single nanoparticles. The analysis method is based on the concept of correlated X-ray scattering, in which correlations of scattered X-ray are used to recover detailed structural information. WAXS experiments of xenon nanoparticles, or clusters, were conducted at an XFEL facility in Japan by using the SPring-8 Ångstrom compact free-electron laser (SACLA). Bragg spots in the recorded single-shot X-ray diffraction patterns showed clear angular correlations, which offered significant structural information on the nanoparticles. The experimental angular correlations were reproduced by numerical simulation in which kinematical theory of diffraction was combined with geometric calculations. We also explain the diffuse scattering intensity as being due to the stacking faults in the xenon clusters.

Solute carriers are a large class of transporters that play key roles in normal and disease physiology. Among the solute carriers, heteromeric amino-acid transporters (HATs) are unique in their quaternary structure. LAT1–CD98hc, a HAT, transports essential amino acids and drugs across the blood–brain barrier and into cancer cells. It is therefore an important target both biologically and therapeutically. During the course of this work, cryo-EM structures of LAT1–CD98hc in the inward-facing conformation and in either the substrate-bound or apo states were reported to 3.3–3.5 Å resolution [Yan et al. (2019), Nature (London), 568, 127–130]. Here, these structures are analyzed together with our lower resolution cryo-EM structure, and multibody 3D auto-refinement against single-particle cryo-EM data was used to characterize the dynamics of the interaction of CD98hc and LAT1. It is shown that the CD98hc ectodomain and the LAT1 extracellular surface share no substantial interface. This allows the CD98hc ectodomain to have a high degree of movement within the extracellular space. The functional implications of these aspects are discussed together with the structure determination.

Electron microscopy of macromolecular structures is an approach that is in increasing demand in the field of structural biology. The automation of image acquisition has greatly increased the potential throughput of electron microscopy. Here, the focus is on the possibilities in Scipion to implement flexible and robust image-processing workflows that allow the electron-microscope operator and the user to monitor the quality of image acquisition, assessing very simple acquisition measures or obtaining a first estimate of the initial volume, or the data resolution and heterogeneity, without any need for programming skills. These workflows can implement intelligent automatic decisions and they can warn the user of possible acquisition failures. These concepts are illustrated by analysis of the well known 2.2 Å resolution β-galactosidase data set.

The laser annealing process for AuNi nanoparticles has been visualized using coherent X-ray diffraction imaging (CXDI). AuNi bimetallic alloy nanoparticles, originally phase separated due to the miscibility gap, transform to metastable mixed alloy particles with rounded surface as they are irradiated by laser pulses. A three-dimensional CXDI shows that the internal part of the AuNi particles is in the mixed phase with preferred compositions at ∼29 at% of Au and ∼90 at% of Au.

Active cathode particles are fundamental architectural units for the composite electrode of Li-ion batteries. The microstructure of the particles has a profound impact on their behavior and, consequently, on the cell-level electrochemical performance. LiCoO2 (LCO, a dominant cathode material) is often in the form of well-shaped particles, a few micrometres in size, with good crystallinity. In contrast to secondary particles (an agglomeration of many fine primary grains), which are the other common form of battery particles populated with structural and chemical defects, it is often anticipated that good particle crystallinity leads to superior mechanical robustness and suppressed charge heterogeneity. Yet, sub-particle level charge inhomogeneity in LCO particles has been widely reported in the literature, posing a frontier challenge in this field. Herein, this topic is revisited and it is demonstrated that X-ray absorption spectra on single-crystalline particles with highly anisotropic lattice structures are sensitive to the polarization configuration of the incident X-rays, causing some degree of ambiguity in analyzing the local spectroscopic fingerprint. To tackle this issue, a methodology is developed that extracts the white-line peak energy in the X-ray absorption near-edge structure spectra as a key data attribute for representing the local state of charge in the LCO crystal. This method demonstrates significantly improved accuracy and reveals the mesoscale chemical complexity in LCO particles with better fidelity. In addition to the implications on the importance of particle engineering for LCO cathodes, the method developed herein also has significant impact on spectro-microscopic studies of single-crystalline materials at synchrotron facilities, which is broadly applicable to a wide range of scientific disciplines well beyond battery research.

Clays and soils produce strong small-angle X-ray scattering (SAXS) because they contain large numbers of nanoparticles, namely allophane and ferrihydrite. These nanoparticles are amorphous and have approximately spherical shape with a size of around 3–10 nm. The weight ratios of these nanoparticles will affect the properties of the clays and soils. However, the nanoparticles in clays and soils are not generally quantified and are sometimes ignored because there is no standard method to quantify them. This paper describes a method to quantify nanoparticles in clays and soils with SAXS. This is achieved by deriving normalized SAXS intensities from unit weight of the sample, which are not affected by absorption. By integrating the normalized SAXS intensities over the reciprocal space, one obtains a value that is proportional to the weight ratio of the nanoparticles, proportional to the square of the difference of density between the nanoparticles and the liquid surrounding the nanoparticles, and inversely proportional to the density of the nanoparticles. If the density of the nanoparticles is known, the weight ratio of the nanoparticles can be calculated from the SAXS intensities. The density of nanoparticles was estimated from the chemical composition of the sample. Nanoparticles in colloidal silica, silica gels, mixtures of silica gel and α-aluminium oxide, and synthetic clays have been quantified with the integral SAXS method. The results show that the errors of the weight ratios of nanoparticles are around 25% of the weight ratio. It is also shown that some natural clays contain large fractions of nanoparticles; montmorillonite clay from the Mikawa deposit, pyrophillite clay from the Shokozan deposit and kaolinite clay from the Kanpaku deposit contain 25 (7), 10 (2) and 19 (5) wt% nanoparticles, respectively, where errors are shown in parentheses.

An X-ray cross-correlation study of the impact of ligand composition and salt content on the self-assembly of soft-shell nanoparticles is presented, indicating symmetry-selective formation of order.

The sasPDF method, an extension of the atomic pair distribution function (PDF) analysis to the small-angle scattering (SAS) regime, is presented. The method is applied to characterize the structure of nanoparticle assemblies with different levels of structural order.

A novel approach for finding and evaluating structural models of small metallic nanoparticles is presented. Rather than fitting a single model with many degrees of freedom, libraries of clusters from multiple structural motifs are built algorithmically and individually refined against experimental pair distribution functions. Each cluster fit is highly constrained. The approach, called cluster-mining, returns all candidate structure models that are consistent with the data as measured by a goodness of fit. It is highly automated, easy to use, and yields models that are more physically realistic and result in better agreement to the data than models based on cubic close-packed crystallographic cores, often reported in the literature for metallic nanoparticles.

Today’s post is by Owen Paul, who is a Student Ambassador Technical Program Specialis. He himself was a student ambassador before joining MathWorks, and he was featured in the Community... read more >>

Fragments of crushed rock released into the ocean during oil and gas exploration can physically bury organisms that live on the seafloor, accounting for 55% of offshore drilling???s environmental impact, according to a recent study. To allow more informed marine policy decisions, this physical impact must be recognised alongside the impact of chemicals released in drilling waste.

Researchers have discovered high levels of plastic particles and fibres, as well as black carbon (BC), which is formed by the incomplete burning of fossil fuels, in the waters of the Jade Bay, an inshore basin off the coast of Germany in the Southern North Sea. The concentration of suspended particles are of concern because they have the potential to be ingested by fish and other marine life, and enter the food chain.

The presence of plastics in aquatic environments is a growing concern across the EU. This study explored the amount of microplastic particles present in raw and treated water at three water-treatment plants in the Czech Republic. While treated water contained fewer particles than raw1 fresh water, the amount found in treated water was not negligible, and largely comprised tiny particles of <10 micrometres (μm) in diameter. Ways to filter microplastics from potable water must be identified and their risk to humans, sources and routes into drinking water determined, say the researchers.

Desktop three-dimensional (3D) printers, available for use in offices and homes, can release between 20 and 200 billion ultra-fine particles (UFPs) per minute, finds new research. UFPs may pose a risk to health, and the study’s authors recommend caution when operating 3D printers inside unventilated or unfiltered indoor environments.

Available evidence from the last decade, describing the nature, behaviour and effect of engineered nanoparticles (ENPs) in the environment, has been reviewed. It identified factors that influence ENP distribution and fate and highlighted the existence of significant research gaps which, if filled, would help in understanding the impacts of long-term accumulation of nanomaterials and the changes that occur to them when they are released into the environment.

Unprotected workers exposed to airborne nanoparticles face a potential health risk from carbon black and titanium dioxide nanoparticles, according to a recent study. Reducing airborne nanoparticle contamination to acceptable levels can be achieved by using a workplace filter ventilation system and personal respirators.

Nanoparticles (NPs) have unique physical and chemical properties, but their increasing use in technological innovations has raised concerns about possible risks to the environment and human health. A new Chinese study has assessed the effects of NPs on plants and ecosystems. The findings indicated that NPs restrict wheat growth and damage soil ecosystems, which may have implications for the environment, agricultural productivity and human health.

Titanium dioxide nanoparticles are entering the environment in ever greater quantities as a result of their widespread use in consumer products and as a disinfectant of sewage. Researchers have recently discovered that titanium dioxide nanoparticles have a toxic effect on marine phytoplankton when exposed to normal levels of ultraviolet light found in natural sunlight.

The use of nanomaterials in consumer goods is growing, as is their presence in waste. A new study is the first to follow the fate of engineered nanoparticles through the entire waste incineration chain. The results indicate current filter technology is effective in removing nanoparticles from flue gas, but that nanoparticles also bind to residues, such as fly ash and slag, which eventually end up in landfill.

Recent research has found that silver nanoparticles in sewage sludge, which is used on agricultural land as a fertiliser, can be toxic to soil microorganisms. The researchers calculated that a maximum of 30mg of silver nanoparticles per kilogram of sludge can be applied to land before harm occurs, based on typical application rates in Germany of five tons per hectare of farmland every three years.

Silver nanoparticles are toxic to common bacteria at concentrations found in many aquatic environments across the globe, new research has found. Bacteria often form a key part of ecosystems and these impacts may be felt by the entire system, the researchers warn.

Fish fed polystyrene nanoparticles are less active and show changes to their brains and metabolism, according to a study by Swedish and Danish researchers. The findings suggest that nanoparticles in the environment could have a major impact on fish and aquatic ecosystems.

Weathering and abrasion are reported to cause titanium dioxide nanoparticles to escape from a self-cleaning coating for buildings. These particles may be toxic to humans and wildlife. The researchers have developed three indicators from the test results to help predict levels of nanoparticle release from these coatings.

A novel approach for identifying and isolating anthropogenic – including microplastic – particles in fish stomachs has been devised by researchers in Belgium. The new method may enable scientists and policymakers to better assess the presence, quantity and composition of particles ingested by marine life, and improve understanding of the environmental effects of marine plastic pollution.

Nanotechnology is a key enabling technology predicted to have many societal benefits, but there are also concerns about its risks to the environment. This study reviewed the effects of nanoparticles on soil microorganisms, showing that toxicity depends on the type of particle. The researchers make recommendations for improving environmental risk assessment, including performing experiments in soil and over longer time periods.

Silver nanoparticles are used in a range of household products. This study investigated the risk to plants of these nanoparticles in soil, showing that risk was overall low but increased when soils contained high levels of chlorine. The researchers, therefore, suggest that the risk of silver nanoparticles to plants may increase in salty soils or those irrigated with poor-quality water. These findings could be important for future risk assessments.

New figures on how much titanium dioxide nanomaterial (TiO2-NM) could be released into the environment from photocatalytic cement — a new type of self-cleaning cement — are presented in a recent study. Based on experimental test results, the researchers estimate that between 0.015% and 0.033% of photocatalytic cement’s TiO2-NM content could potentially escape over several years of cement use, depending on the level of cement porosity. The study could help inform environmental risk assessment of TiO2-NM, as well as safer design of nano-products (i.e. commercialised products incorporating nanomaterials).

A new study has examined the toxic effects of silver nanoparticles on plants. Using a range of spectroscopic and imaging techniques, the researchers demonstrate how silver nanoparticles can reduce the growth of wheat, as well as interfere with genes that help the plant deal with pathogens and stress.

Silver nanoparticles present in the effluent from waste-water treatment plants could have toxic effects on aquatic organisms, new research suggests. The lab-based study tested the effects of nanoparticle-containing effluent on several crustacean and algae species. The researchers observed that epibenthic crustaceans (those living in or on sediments at the bottom of water bodies) were the most sensitive; notably, a 20–45% higher death rate was observed compared with those exposed to nanoparticle-free effluent.

Fine particles in the air produced by road transport trap more radiation in the earth's atmosphere than previously estimated, and therefore may contribute more to global warming than realised, according to new research. In contrast, the impact of particles from shipping appears to reflect more radiation than previously thought, whilst the effect of particles from aviation is comparatively small.

Ultrafine particles emitted from a waste incinerator plant in Italy have been characterised in a recent study. The results suggest that a fabric filter was efficient at cleaning particulate matter from the exhaust gases. Data produced by the study could go on to be used by scientists studying the potential health impacts of ultrafine particles.

Researchers have measured the presence of carbon nanoparticles in the air over the Mediterranean Sea. The results revealed that higher concentrations are found in air that has moved over areas of industrial activity, and that the lowest layers of the atmosphere are likely to be responsible for transporting the nanoparticles.

Fires in forests contaminated by the Chernobyl nuclear accident could lead to areas of Europe and Russia being exposed to further radioactive fallout, new research has found. The study examined the spread of the fallout and the health effects on people and animals under three different scenarios: 10, 50 and 100% of the forests being burnt.

The chances of a child developing Autism Spectrum Disorder (ASD) are higher if the mother is exposed to high levels of fine particulate air pollution during pregnancy, a recent study suggests. This increased risk was associated specifically with exposure in the last three months of pregnancy, the researchers found.

Researchers have assessed the phyto-toxic effects of copper nanoparticles on vegetables grown within urban gardens, comparing increasing doses of these nanoparticles to simulate potential aerial deposition to extreme pollution of CuO-NP in a range of increasing exposure periods. Lettuce and cabbage absorbed high amounts of copper nanoparticles, after 15 days of exposure, which interfered with photosynthesis, respiration and also reduced growth. Under the specific exposure conditions of the study the researchers indicate that metal nanoparticles could lead to potential health risks to humans from the contamination of crops from pollution.

Air pollution via small particulate matter (PM) from diesel fumes and other sources is of growing concern in urban areas, and contributes to poor air quality. In European urban areas, PM pollution often exceeds World Health Organization (WHO) safe levels for human wellbeing. In response to this, the European Commission has encouraged researchers to develop a low-cost, sustainable material that captures these particles in order to clean the air1. This study created a new PM capture material using sustainable chemical processes where the carbon footprint and energy use of the production process of the remediation material is taken into account. The newly developed porous material is called ‘SUNSPACE’ (an acronym derived from ‘(SUstaiNable materials Synthesized from By-products and Alginates for Clean air and better Environment’).

The post Global carbon capture potential for rare nanoparticle appeared first on The Lead SA.

Each of us is a cloud of microscopic particles, chemicals and microorganisms swirling around us that's always there. It's called an exposome, and it's unique.

It's no substitute for simply getting rid of coal, but geo-engineering just may be our planet's Hail Mary pass.