14 research outputs found
A Selective Luminescent Probe for the Direct Time-Gated Detection of Adenosine Triphosphate
A molecular probe for the luminescent detection of adenosine
nucleotides is presented. The probe, Tb-DOTAm-Phen, readily distinguishes
among the three adenosine nucleotides in buffered aqueous conditions
at neutral pH, a requirement for the direct monitoring of enzymatic
reactions converting adenosine triphosphate (ATP) to adenosine diphosphate
or adenosine monophosphate. The probe is most efficient under millimolar
concentrations of ATP which are relevant to intracellular conditions.
Moreover, the long luminescence lifetime of the probe readily enables
time-gating experiments
Fe- and Ln-DOTAm-F12 Are Effective Paramagnetic Fluorine Contrast Agents for MRI in Water and Blood
A series
of fluorinated macrocyclic complexes, M-DOTAm-F12, where M is La<sup>III</sup>, Eu<sup>III</sup>, Gd<sup>III</sup>, Tb<sup>III</sup>,
Dy<sup>III</sup>, Ho<sup>III</sup>, Er<sup>III</sup>, Tm<sup>III</sup>, Yb<sup>III</sup>, and Fe<sup>II</sup>, was synthesized, and their
potential as fluorine magnetic resonance imaging (MRI) contrast agents
was evaluated. The high water solubility of these complexes and the
presence of a single fluorine NMR signal, two necessary parameters
for in vivo MRI, are substantial advantages over currently used organic
polyfluorocarbons and other reported paramagnetic <sup>19</sup>F probes.
Importantly, the sensitivity of the paramagnetic probes on a per fluorine
basis is at least 1 order of magnitude higher than that of diamagnetic
organic probes. This increased sensitivity is due to a substantialup
to 100-folddecrease in the longitudinal relaxation time (<i>T</i><sub>1</sub>) of the fluorine nuclei. The shorter <i>T</i><sub>1</sub> allows for a greater number of scans to be
obtained in an equivalent time frame. The sensitivity of the fluorine
probes is proportional to the <i>T</i><sub>2</sub>/<i>T</i><sub>1</sub> ratio. In water, the optimal metal complexes
for imaging applications are those containing Ho<sup>III</sup> and
Fe<sup>II</sup>, and to a lesser extent Tm<sup>III</sup> and Yb<sup>III</sup>. Whereas <i>T</i><sub>1</sub> of the lanthanide
complexes are little affected by blood, the <i>T</i><sub>2</sub> are notably shorter in blood than in water. The sensitivity
of Ln-DOTAm-F12 complexes is lower in blood than in water, such that
the most sensitive complex in water, Ho<sup>III</sup>-DOTAm-F12, could
not be detected in blood. Tm<sup>III</sup> yielded the most sensitive
lanthanide fluorine probe in blood. Notably, the relaxation times
of the fluorine nuclei of Fe<sup>II</sup>-DOTAm-F12 are similar in
water and in blood. That complex has the highest <i>T</i><sub>2</sub>/<i>T</i><sub>1</sub> ratio (0.57) and the
lowest limit of detection (300 μM) in blood. The combination
of high water solubility, single fluorine signal, and high <i>T</i><sub>2</sub>/<i>T</i><sub>1</sub> of M-DOTAm-F12
facilitates the acquisition of three-dimensional magnetic resonance
images
Fe- and Ln-DOTAm-F12 Are Effective Paramagnetic Fluorine Contrast Agents for MRI in Water and Blood
A series
of fluorinated macrocyclic complexes, M-DOTAm-F12, where M is La<sup>III</sup>, Eu<sup>III</sup>, Gd<sup>III</sup>, Tb<sup>III</sup>,
Dy<sup>III</sup>, Ho<sup>III</sup>, Er<sup>III</sup>, Tm<sup>III</sup>, Yb<sup>III</sup>, and Fe<sup>II</sup>, was synthesized, and their
potential as fluorine magnetic resonance imaging (MRI) contrast agents
was evaluated. The high water solubility of these complexes and the
presence of a single fluorine NMR signal, two necessary parameters
for in vivo MRI, are substantial advantages over currently used organic
polyfluorocarbons and other reported paramagnetic <sup>19</sup>F probes.
Importantly, the sensitivity of the paramagnetic probes on a per fluorine
basis is at least 1 order of magnitude higher than that of diamagnetic
organic probes. This increased sensitivity is due to a substantialup
to 100-folddecrease in the longitudinal relaxation time (<i>T</i><sub>1</sub>) of the fluorine nuclei. The shorter <i>T</i><sub>1</sub> allows for a greater number of scans to be
obtained in an equivalent time frame. The sensitivity of the fluorine
probes is proportional to the <i>T</i><sub>2</sub>/<i>T</i><sub>1</sub> ratio. In water, the optimal metal complexes
for imaging applications are those containing Ho<sup>III</sup> and
Fe<sup>II</sup>, and to a lesser extent Tm<sup>III</sup> and Yb<sup>III</sup>. Whereas <i>T</i><sub>1</sub> of the lanthanide
complexes are little affected by blood, the <i>T</i><sub>2</sub> are notably shorter in blood than in water. The sensitivity
of Ln-DOTAm-F12 complexes is lower in blood than in water, such that
the most sensitive complex in water, Ho<sup>III</sup>-DOTAm-F12, could
not be detected in blood. Tm<sup>III</sup> yielded the most sensitive
lanthanide fluorine probe in blood. Notably, the relaxation times
of the fluorine nuclei of Fe<sup>II</sup>-DOTAm-F12 are similar in
water and in blood. That complex has the highest <i>T</i><sub>2</sub>/<i>T</i><sub>1</sub> ratio (0.57) and the
lowest limit of detection (300 μM) in blood. The combination
of high water solubility, single fluorine signal, and high <i>T</i><sub>2</sub>/<i>T</i><sub>1</sub> of M-DOTAm-F12
facilitates the acquisition of three-dimensional magnetic resonance
images
Effect of Lanthanide Complex Structure on Cell Viability and Association
A systematic
study of the effect of hydrophobicity and charge on the cell viability
and cell association of lanthanide metal complexes is presented. The
terbium luminescent probes feature a macrocyclic polyaminocarboxylate
ligand (DOTA) in which the hydrophobicity of the antenna and that
of the carboxyamide pendant arms are independently varied. Three sensitizing
antennas were investigated in terms of their function in vitro: 2-methoxyisophthalamide
(IAM(OMe)), 2-hydroxyisophthalamide (IAM), and 6-methylphenanthridine
(Phen). Of these complexes, Tb-DOTA-IAM exhibited the highest quantum
yield, although the higher cell viability and more facile synthesis
of the structurally related Tb-DOTA-IAM(OMe) platform renders it more
attractive. Further modification of this latter core structure with
carboxyamide arms featuring hydrophobic benzyl, hexyl, and trifluoro
groups as well as hydrophilic amino acid based moieties generated
a family of complexes that exhibit high cell viability (ED<sub>50</sub> > 300 μM) regardless of the lipophilicity or the overall
complex charge. Only the hexyl-substituted complex reduced cell viability
to 60% in the presence of 100 μM complex. Additionally, cellular
association was investigated by ICP-MS and fluorescence microscopy.
Surprisingly, the hydrophobic moieties did not increase cell association
in comparison to the hydrophilic amino acid derivatives. It is thus
postulated that the hydrophilic nature of the 2-methoxyisophthalamide
antenna (IAM(OMe)) disfavors the cellular association of these complexes.
As such, responsive luminescent probes based on this scaffold would
be appropriate for the detection of extracellular species
Excessive Fibrinolysis in Amyloidosis Associated with Elevated Plasma Single-Chain Urokinase
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Highly Parallel Genome-wide Expression Profiling of Individual Cells Using Nanoliter Droplets
Cells, the basic units of biological structure and function, vary broadly in type and state. Single-cell genomics can characterize cell identity and function, but limitations of ease and scale have prevented its broad application. Here we describe Drop-seq, a strategy for quickly profiling thousands of individual cells by separating them into nanoliter-sized aqueous droplets, associating a different barcode with each cell's RNAs, and sequencing them all together. Drop-seq analyzes mRNA transcripts from thousands of individual cells simultaneously while remembering transcripts' cell of origin. We analyzed transcriptomes from 44,808 mouse retinal cells and identified 39 transcriptionally distinct cell populations, creating a molecular atlas of gene expression for known retinal cell classes and novel candidate cell subtypes. Drop-seq will accelerate biological discovery by enabling routine transcriptional profiling at single-cell resolution. VIDEO ABSTRACT
Highly Parallel Genome-wide Expression Profiling of Individual Cells Using Nanoliter Droplets
Cells, the basic units of biological structure and function, vary broadly in type and state. Single-cell genomics can characterize cell identity and function, but limitations of ease and scale have prevented its broad application. Here we describe Drop-seq, a strategy for quickly profiling thousands of individual cells by separating them into nanoliter-sized aqueous droplets, associating a different barcode with each cell’s RNAs, and sequencing them all together. Drop-seq analyzes mRNA transcripts from thousands of individual cells simultaneously while remembering transcripts’ cell of origin. We analyzed transcriptomes from 44,808 mouse retinal cells and identified 39 transcriptionally distinct cell populations, creating a molecular atlas of gene expression for known retinal cell classes and novel candidate cell subtypes. Drop-seq will accelerate biological discovery by enabling routine transcriptional profiling at single-cell resolution.National Human Genome Research Institute (U.S.) (P50 HG006193