209 research outputs found
Single particle and single cell ICP-MS applications in nanomaterial safety assessment
This thesis describes the development of single particle (spICP-MS) and single cell inductively coupled plasma mass spectrometry (SC-ICP-MS) analytical techniques for environmental and ecotoxicological analysis. Single particle and single cell ICP-MS protocols and application notes were developed within this thesis for a nanomaterials characterisation and interactions with living systems.
It was shown that the composition of complex multi-element nanoparticles could be determined by measuring each of the individual elements and converting particle volume to particle size, using a quadrupole based ICP-MS. The resulting particle sizes and density of multiple, multi-element nanoparticles results were comparable to other analytical techniques (DLS, DCS and TEM), but the measurement is faster and easier.
Using single particle ICP-MS, gold nanoparticles that had been ingested by isopods were analysed and quantified. A surprising result from this investigation was that irrespective of the form in which gold was presented to the isopods, i.e. as gold nanoparticles of 80 nm or ions, the gold measured in the Isopods was consistently characterised as being nanoparticle of around 60nm found within the main body and hepatopancreas of the isopods, indicating nanoparticle formation and transformation in situ.
Single cell ICP-MS was used to measure the intrinsic metal within multiple cell lines, but was found to be inconsistent or irreproducible between biological replicates, but it was possible to measure the metal concentration reliably within cells that had been spiked with a target metal.
Finally, single organism ICP-MS was developed, with the analysis of entire daphnids (daphnia magna and daphnia pulex), pushing the instrument capabilities further
Core-shell NaHoF4@TiO2 NPs: A labelling method to trace engineered nanomaterials of ubiquitous elements in the environment
Understanding the fate and behavior of nanoparticles (NPs) in the natural environment is important to assess
their potential risk. Single particle inductively coupled plasma mass spectrometry (spICP-MS) allows for the detection of NPs at
extremely low concentrations, but the high natural background of the constituents of many of the most widely utilized nanoscale
materials makes accurate quantification of engineered particles challenging. Chemical doping, with a less naturally abundant
element, is one approach to address this; however, certain materials with high natural abundance, such as TiO2 NPs, are
notoriously difficult to label and differentiate from natural NPs. Using the low abundance rare earth element Ho as a marker,
Ho-bearing core -TiO2 shell (NaHoF4@TiO2) NPs were designed to enable the quantification of engineered TiO2 NPs in real
environmental samples. The NaHoF4@TiO2 NPs were synthesized on a large scale (gram), at relatively low temperatures, using
a sacrificial Al(OH)3 template that confines the hydrolysis of TiF4 within the space surrounding the NaHoF4 NPs. The resulting
NPs consist of a 60 nm NaHoF4 core and a 5 nm anatase TiO2 shell, as determined by TEM, STEM-EDX mapping, and spICPMS. The NPs exhibit excellent detectability by spICP-MS at extremely low concentrations (down to 1 × 10−3 ng/L) even in
complex natural environments with high Ti background
Evaluation of cell disruption technologies on magnetosome chain length and aggregation behaviour from Magnetospirillum gryphiswaldense MSR-1
Magnetosomes are biologically-derived magnetic nanoparticles (MNPs) naturally produced by magnetotactic bacteria (MTB). Due to their distinctive characteristics, such as narrow size distribution and high biocompatibility, magnetosomes represent an attractive alternative to existing commercially-available chemically-synthesized MNPs. However, to extract magnetosomes from the bacteria, a cell disruption step is required. In this study, a systematic comparison between three disruption techniques (enzymatic treatment, probe sonication and high-pressure homogenization) was carried out to study their effect on the chain length, integrity and aggregation state of magnetosomes isolated from Magnetospirillum gryphiswaldense MSR-1 cells. Experimental results revealed that all three methodologies show high cell disruption yields (>89%). Transmission electron microscopy (TEM), dynamic light scattering (DLS) and, for the first time, nano-flow cytometry (nFCM) were employed to characterize magnetosome preparations after purification. TEM and DLS showed that high-pressure homogenization resulted in optimal conservation of chain integrity, whereas enzymatic treatment caused higher chain cleavage. The data obtained suggest that nFCM is best suited to characterize single membrane-wrapped magnetosomes, which can be particularly useful for applications that require the use of individual magnetosomes. Magnetosomes were also successfully labelled (>90%) with the fluorescent CellMaskâ„¢ Deep Red membrane stain and analysed by nFCM, demonstrating the promising capacity of this technique as a rapid analytical tool for magnetosome quality assurance. The results of this work contribute to the future development of a robust magnetosome production platform
Core-Shell NaHoF<sub>4</sub>@TiO<sub>2</sub> NPs:a labeling method to trace engineered nanomaterials of ubiquitous elements in the environment
Understanding
the fate and behavior of nanoparticles (NPs) in the
natural environment is important to assess their potential risk. Single
particle inductively coupled plasma mass spectrometry (spICP-MS) allows
for the detection of NPs at extremely low concentrations, but the
high natural background of the constituents of many of the most widely
utilized nanoscale materials makes accurate quantification of engineered
particles challenging. Chemical doping, with a less naturally abundant
element, is one approach to address this; however, certain materials
with high natural abundance, such as TiO<sub>2</sub> NPs, are notoriously
difficult to label and differentiate from natural NPs. Using the low
abundance rare earth element Ho as a marker, Ho-bearing core -TiO<sub>2</sub> shell (NaHoF<sub>4</sub>@TiO<sub>2</sub>) NPs were designed
to enable the quantification of engineered TiO<sub>2</sub> NPs in
real environmental samples. The NaHoF<sub>4</sub>@TiO<sub>2</sub> NPs
were synthesized on a large scale (gram), at relatively low temperatures,
using a sacrificial AlÂ(OH)<sub>3</sub> template that confines the
hydrolysis of TiF<sub>4</sub> within the space surrounding the NaHoF<sub>4</sub> NPs. The resulting NPs consist of a 60 nm NaHoF<sub>4</sub> core and a 5 nm anatase TiO<sub>2</sub> shell, as determined by
TEM, STEM-EDX mapping, and spICP-MS. The NPs exhibit excellent detectability
by spICP-MS at extremely low concentrations (down to 1 × 10<sup>–3</sup> ng/L) even in complex natural environments with high
Ti background
Human parvovirus 4 'PARV4' remains elusive despite a decade of study
Human parvovirus 4 ('PARV4') is a small DNA tetraparvovirus, first reported in 2005. In some populations, PARV4 infection is uncommon, and evidence of exposure is found only in individuals with risk factors for parenteral infection who are infected with other blood-borne viruses. In other settings, seroprevalence studies suggest an endemic, age-associated transmission pattern, independent of any specific risk factors. The clinical impact of PARV4 infection remains uncertain, but reported disease associations include an influenza-like syndrome, encephalitis, acceleration of HIV disease, and foetal hydrops. In this review, we set out to report progress updates from the recent literature, focusing on the investigation of cohorts in different geographical settings, now including insights from Asia, the Middle East, and South America, and discussing whether attributes of viral or host populations underpin the striking differences in epidemiology. We review progress in understanding viral phylogeny and biology, approaches to diagnostics, and insights that might be gained from studies of closely related animal pathogens. Crucial questions about pathogenicity remain unanswered, but we highlight new evidence supporting a possible link between PARV4 and an encephalitis syndrome. The unequivocal evidence that PARV4 is endemic in certain populations should drive ongoing research efforts to understand risk factors and routes of transmission and to gain new insights into the impact of this virus on human health
Apolipoprotein E and Alzheimer’s disease: The influence of apolipoprotein E on amyloid- and other amyloidogenic proteins
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Longitudinal trajectories of amyloid deposition, cortical thickness, and tau in Down syndrome: A deep-phenotyping case report.
Introduction:Comorbid Alzheimer disease pathologies are frequently found in people with Down syndrome (DS). We report a deep phenotyping study undertaken over 7 years in a participant with DS who was nondemented at baseline but developed dementia after 5 years. Methods:Throughout the course of the study, the participant was seen 4 times (2010, 2013, 2015, and 2017). Multimodal neuroimaging, including three serial scans of [11C]-PiB-PET, four structural magnetic resonance imagings, as well as a [18F]-AV1451 scan, was interpreted alongside detailed neuropsychological assessments over the study period. Results:Amyloid beta accumulation preceded the onset of dementia and cognitive decline, which in turn corresponded to the predominant deposition of tau in temporoparietal cortices. Discussion:Until now, data on the longitudinal trajectories of amyloid accumulation, tau pathology, and brain atrophy over multiple time points remain scarce in DS. This case report highlights the potential for deep phenotyping imaging to elucidate the substrates of cognitive decline in DS, although further longitudinal studies are necessary to clarify the relative contributions of both amyloid and tau
The LIGO HET Response (LIGHETR) Project to Discover and Spectroscopically Follow Optical Transients Associated with Neutron Star Mergers
The LIGO HET Response (LIGHETR) project is an enterprise to follow up optical
transients (OT) discovered as gravitational wave merger sources by the
LIGO/Virgo collaboration (LVC). Early spectroscopy has the potential to
constrain crucial parameters such as the aspect angle. The LIGHETR
collaboration also includes the capacity to model the spectroscopic evolution
of mergers to facilitate a real-time direct comparison of models with our data.
The principal facility is the Hobby-Eberly Telescope. LIGHETR uses the
massively-replicated VIRUS array of spectrographs to search for associated OTs
and obtain early blue spectra and in a complementary role, the low-resolution
LRS-2 spectrograph is used to obtain spectra of viable candidates as well as a
densely-sampled series of spectra of true counterparts. Once an OT is
identified, the anticipated cadence of spectra would match or considerably
exceed anything achieved for GW170817 = AT2017gfo for which there were no
spectra in the first 12 hours and thereafter only roughly once daily. We
describe special HET-specific software written to facilitate the program and
attempts to determine the flux limits to undetected sources. We also describe
our campaign to follow up OT candidates during the third observational campaign
of the LIGO and Virgo Scientific Collaborations. We obtained VIRUS spectroscopy
of candidate galaxy hosts for 5 LVC gravitational wave events and LRS-2 spectra
of one candidate for the OT associated with S190901ap. We identified that
candidate, ZTF19abvionh = AT2019pip, as a possible Wolf-Rayet star in an
otherwise unrecognized nearby dwarf galaxy.Comment: 26 pages, 15 figure
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