14 research outputs found
EuroTracker (R) dyes: design, synthesis, structure and photophysical properties of very bright europium complexes and their use in bioassays and cellular optical imaging
The development of the brightest luminescent europium(III) complexes is traced, including analysis of
the C3-symmetric core complex based on a functionalized triazacyclononane and identification of the
most suitable strongly absorbing chromophore. Strategies for the synthesis of the complexes, including
enantiopure analogues, are outlined and opportunities for applications in time-resolved microscopy and
spectral imaging emphasised. Practicable examples are introduced, including selective organelle staining
for cellular optical imaging at 65 nm resolution and the development of new bioassays using time resolved
FRET methods
Anion binding in water at lanthanide centres: from structure and selectivity to signalling and sensing
Reversible anion binding at lanthanide centres in aqueous media has emerged as an effective means of signalling and sensing the presence of selected anions. The constitution and configuration of a wide range of anion adducts has been defined by X-ray analyses and NMR methods, and both chelating and monodentate binding modes characterised. Variation of the lanthanide ion modulates charge density, and ligand modification allows alteration of both the peripheral electrostatic gradient and the local steric demand at the metal centre. Thus, selectivity for a target anion can be engineered, and the affinity constant modulated to target the desired concentration range. Changes in anion concentration can be monitored rapidly, accurately and with high spatial resolution using optical emission spectroscopy and microscopy, facilitating the measurement of anions such as bicarbonate, lactate, citrate and urate in a variety of bio-fluids
EuroTracker dyes: highly emissive europium complexes as alternative organelle stains for live cell imaging
Nine very bright europium(III) complexes with different macrocyclic ligands have been prepared that exhibit
excellent cell uptake behaviour and distinctive sub-cellular localisation profiles, allowing the use of
fluorescence microscopy and time-gated spectral imaging to track their fate in cellulo. Their use as
cellular imaging stains is described for the selective illumination of mitochondria, lysosomes or the
endoplasmic reticulum of various mammalian cell types
Additional file 1: Figure S1. of DATATOC: a novel conjugate for kit-type 68Ga labelling of TOC at ambient temperature
RadioTLC for kit-type 68Ga-labelling of DATATOC at 1, 3, 5, 10 and 15Â min. Figure S2: Radioactive (gamma) and UV traces for the kit-type labelling of DATATOC with 68Ga. The unlabelled ligand is evident at 9.1 min (confirmed by injection of the free ligand only) and the 68Ga-labelled complex at 13.0 min. Figure S3: Illustrative example of RadioTLC for stability study of 68Ga-DATATOC 30, 60, 90 and 120Â min after exposure to human serum. (DOCX 107Â kb
Intracellular and Extracellular Antimicrobial Resistance Genes in the Sludge of Livestock Waste Management Structures
The sludge compartment in livestock
waste management structures
is a potential hotbed for the emergence and proliferation of antimicrobial
resistance among bacteria. Little is known about the distribution
of antimicrobial resistance genes (ARGs) between the intracellular
and extracellular DNA pools in the sludge. The overall objective of
this study was to assess the significance of extracellular ARGs to
the total ARGs in the sludge of livestock waste management structures.
In this study, sludge samples were collected from four cattle manure
storage ponds and three swine waste treatment lagoons and analyzed
for genetic indicators of resistance. Intracellular DNA (iDNA) and
extracellular DNA (eDNA) in the sludge were separately extracted using
an optimized protocol. ARGs [<i>sul</i>(I), <i>sul</i>(II), <i>tet</i>(O), <i>tet</i>(Q), and <i>tet</i>(X)] in both the iDNA and eDNA extracts were quantified
using quantitative polymerase chain reaction (qPCR), and antimicrobials,
including sulfonamides and tetracyclines, were measured using liquid
chromatography tandem mass spectrometry. Results showed that eDNA
constituted less than 1.5% of the total DNA in sludge. All ARGs tested
were detected in nearly all eDNA and iDNA samples. Furthermore, every
gram of dry sludge contained from 1.7 Ă 10<sup>3</sup> to 4.2
Ă 10<sup>8</sup> copies of extracellular ARG and from 3.2 Ă
10<sup>7</sup> to 3.2 Ă 10<sup>10</sup> copies of intracellular
ARG. Chlortetracycline concentrations ranged between 187 and 2674
ÎŒg/g of sludge wet weight (ww), while sulfonamide concentrations
were lower than 6.3 ÎŒg/g of sludge ww. The detection of ARGs
in eDNA extracts suggests that transformation is a potential mechanism
in ARG proliferation in the sludge of livestock waste management structures
Development of the Detection Threshold Concept from a Close Look at Sorption Occurrence Inside a Glass Vial Based on the In-Vial Vaporization of Semivolatile Fatty Acids
Headspace
(HS) analysis has been recommended as one of the most
optimal methods for extracting and analyzing volatile organic compounds
from samples in diverse media such as soil and water. Short-chain
volatile fatty acids (VFA, C<sub>3</sub>âC<sub>7</sub>) with
strong adsorptivity were selected as the target compounds to assess
the basic characteristics of the HS analysis through simulation of
HS conditions by in-vial vaporization of liquid-phase standards (VL)
in 25 mL glass vials. The reliability of the VL approach was assessed
by apportioning the in-vial VFA mass into three classes: (1) vaporized
fraction, (2) dynamic adsorption on the vial walls (intermediate stage
between vaporization and irreversible absorption), and (3) irreversible
absorptive loss (on the vial wall). The dynamic adsorption partitioning
inside the vial increased with n-VFA carbon number, e.g., 43% (C<sub>2</sub>: acetic acid, extrapolated value), 65% (C<sub>3</sub>: propanoic
acid), and 98% (C<sub>7</sub>: heptanoic acid). The maximum irreversible
losses for the studied n-VFAs exhibited a quadratic relationship with
carbon number. If the detection threshold limit (DTL: the onset of
mass detection after attaining the maximum irreversible loss) is estimated,
the DTL values for target VFAs were in the range of 101 ng for i-valeric
acid to 616 ng for propionic acid, which are larger than the method
detection limit by about 3 orders of magnitude. Consequently, quantitation
of VFAs using the VL approach should be critically assessed by simultaneously
considering the DTL criterion and the initial VFA masses loaded into
the vial
Structure and Band Edge Energy of Highly Luminescent CdSe<sub>1â<i>x</i></sub>Te<sub><i>x</i></sub> Alloyed Quantum Dots
CdSe<sub>1â<i>x</i></sub>Te<sub><i>x</i></sub> quantum dot (QD) alloys are
characterized by high luminescence
quantum yields and a strong band gap bowing as a function of the Se:Te
ratio, featuring longer emission wavelengths than CdTe or CdSe dots
of identical size. In this contribution, these properties are rationalized
by examining the structure and band edge energy of CdSe<sub>1â<i>x</i></sub>Te<sub><i>x</i></sub> as functions of <i>x</i>. The QDs were synthesized employing the âhot-injectionâ
method, in the presence of either trioctylphosphine oxide (TOPO) or
octadecene (ODE) as the Cd precursor solvent. Elementary analysis
of the QDs indicated that TOPO plays a crucial role in tuning the
content of Se in the alloys, as only traces of this element were found
when using ODE. Detailed studies based on X-ray diffraction (XRD),
high-resolution transmission electron microscopy (HRTEM) and selected
area electron diffraction (SAED) revealed a high degree of complexity
in the structure of the alloyed dots. The analysis concluded that
the structure of the QDs was essentially wurtzite, although features
associated with zinc blende can be seen due to the presence of stacking
faults and to a small population of nanocrystals with cubic structure.
More importantly, these studies reveal a nonlinear expansion of the
effective lattice constant with increasing Te content. The valence
band edge energy of the alloys in solution was estimated from the
first oxidation potential measured by linear sweep voltammetry at
Au microelectrodes. The results show that the valence band edge exhibits
a very weak dependence on <i>x</i> for values below 0.5,
indicating that the decrease in the optical band gap is mainly linked
to a decrease in the conduction band edge energy. For <i>x</i> > 0.5, the conduction and valence band edges shift to higher
values
with an overall increase in the band gap. The experimental trends
show, for the first time, that the characteristic red shift of the
band gap with low to intermediate Te content is determined by relaxation
of the lattice constant, whereas the contribution arising from the
change in anion electronegativity becomes predominant for <i>x</i> > 0.5
Microscopic Visualization of Metabotropic Glutamate Receptors on the Surface of Living Cells Using Bifunctional Magnetic Resonance Imaging Probes
A series of bimodal metabotropic
glutamate-receptor targeted MRI contrast agents has been developed
and evaluated, based on established competitive metabotropic Glu receptor
subtype 5 (mGluR<sub>5</sub>) antagonists. In order to directly visualize
mGluR<sub>5</sub> binding of these agents on the surface of live astrocytes,
variations in the core structure were made. A set of gadolinium conjugates
containing either a cyanine dye or a fluorescein moiety was accordingly
prepared, to allow visualization by optical microscopy <i>in
cellulo</i>. In each case, surface receptor binding was compromised
and cell internalization observed. Another approach, examining the
location of a terbium analogue via sensitized emission, also exhibited
nonspecific cell uptake in neuronal cell line models. Finally, biotin
derivatives of two lead compounds were prepared, and the specificity
of binding to the mGluR<sub>5</sub> cell surface receptors was demonstrated
with the aid of their fluorescently labeled avidin conjugates, using
both total internal reflection fluorescence (TIRF) and confocal microscopy
Tables â Supplemental material for Prevalence and determinants of physical activity and sedentary behaviour before and up to 12âmonths after total knee replacement: a longitudinal cohort study
<p>Supplemental material, Tables for Prevalence and determinants of physical
activity and sedentary behaviour before and up to 12âmonths after total
knee replacement: a longitudinal cohort study by Alison Hodges, Alison R Harmer,
Sarah Dennis, Lillias Nairn, Lyn March, Ross Crawford, David Parker and Marlene
Fransen in Clinical Rehabilitation</p
Anionic Surfactant Ionic Liquids with 1-Butyl-3-methyl-imidazolium Cations: Characterization and Application
For the first time a series of anionic surfactant ionic
liquids
(SAILs) has been synthesized based on organic surfactant anions and
1-butyl-3-methyl-imidazolium cations. These compounds are more environmentally
friendly and chemically tunable as compared to other common ionic
liquids. A detailed investigation of physicochemical properties highlights
potential applications from battery design to reaction control, and
studies into aqueous aggregation behavior, as well as structuring
in pure ILs, point to possible uses in electrochemistry