81 research outputs found
Intracellular Zn2+ detection with quantum dot-based FLIM nanosensors
Fluorescence Lifetime Imaging Microscopy (FLIM) has been
employed for the detection of intracellular Zn2+ levels, implicated
in various signalling pathways, using a family of quantum dot (QD)
nanosensors. The sensing mechanism was based on photoinduced
electron transfer (PET) between an azacycle receptor group and the
QD nanoparticles.This work was supported by Fundación Ramon Areces and grant CTQ2014-56370-R from Ministerio de Economia y Competitividad of Spain
Metallofluorescent Nanoparticles for Multimodal Applications
Herein, we describe
the synthesis and application of cross-linked
polystyrene-based dual-function nano- and microparticles containing
both fluorescent tags and metals. Despite containing a single dye,
these particles exhibit a characteristic dual-band fluorescence emission.
Moreover, these particles can be combined with different metal ions
to obtain hybrid metallofluorescent particles. We demonstrate that
these particles are easily nanofected into living cells, allowing
them to be used for effective fingerprinting in multimodal fluorescence-based
and mass spectrometry-based flow cytometry experiments. Likewise,
the in situ reductions of the metal ions enable other potential uses
of the particles as heterogeneous catalysts
Novel ortho-OPE metallofoldamers: binding-induced folding promoted by nucleating Ag(i)-alkyne interactions
We have developed a new family of ortho-oligophenylene ethynylene (o-OPE) metallofoldamers. The folding of these helicates is induced by nucleating carbon-metal interactions between Ag(i) cations and the alkynes of the inner core of the o-OPEs. These o-OPEs form metal-organic assemblies where at least three alkyne moieties are held in close proximity to form novel Ag(i)-complexes with the metal ion lodged into the helical cavity. NMR titration experiments and photokinetic studies have provided quantitative data about the thermodynamic and kinetic features of such binding/folding phenomena. X-ray diffraction and DFT studies have been performed to extract structural information on how the Ag(i) cation is accommodated into the cavity. The great simplicity and versatility of these new metallofoldamers open up the possibility to develop novel structures with applications in material science and/or in asymmetric catalysisThis research was funded by the Regional Government of Andalucía (project P09-FQM-4571) and the ICIQ Foundation. DM thanks Regional Government of Andalucía for her contract. AML thanks MICINN for her FPU fellowship. The authors thank the Centro de Servicios de Informática y Redes de Comunicaciones (CSIRC), Universidad de Granada, for providing the computing tim
Early Amyloidogenic Oligomerization Studied through Fluorescence Lifetime Correlation Spectroscopy
Amyloidogenic protein aggregation is a persistent biomedical problem. Despite active research in disease-related aggregation, the need for multidisciplinary approaches to the problem is evident. Recent advances in single-molecule fluorescence spectroscopy are valuable for examining heterogenic biomolecular systems. In this work, we have explored the initial stages of amyloidogenic aggregation by employing fluorescence lifetime correlation spectroscopy (FLCS), an advanced modification of conventional fluorescence correlation spectroscopy (FCS) that utilizes time-resolved information. FLCS provides size distributions and kinetics for the oligomer growth of the SH3 domain of α-spectrin, whose N47A mutant forms amyloid fibrils at pH 3.2 and 37 °C in the presence of salt. The combination of FCS with additional fluorescence lifetime information provides an exciting approach to focus on the initial aggregation stages, allowing a better understanding of the fibrillization process, by providing multidimensional information, valuable in combination with other conventional methodologies.This work is funded by grant P10-FQM-6154 from the Consejeria de Innovacion, Ciencia y
Empresa (Junta de Andalucia)
Phosphorescent Sensor for Robust Quantification of Copper(II) Ion
A phosphorescent sensor based on a multichromophoric iridium(III) complex was synthesized and characterized. The construct exhibits concomitant changes in its phosphorescence intensity ratio and phosphorescence lifetime in response to copper(II) ion. The sensor, which is reversible and selective, is able to quantify copper(II) ions in aqueous media, and it detects intracellular copper ratiometrically.National Institute of General Medical Sciences (U.S.) ((Grant GM065519)Ewha Woman's University (Korea) (RP-Grant 2009
Fluorescence Lifetime Imaging Microscopy for the Detection of Intracellular pH with Quantum Dot Nanosensors
While the use of quantum dot (QD) nanoparticles for bioimaging and sensing has been improved and exploited during the last several years, most studies have used emission intensity-based techniques. Fluorescence lifetime imaging microscopy (FLIM) can also be employed for sensing purposes, overcoming many of the limitations of the aforementioned systems. Herein, we show that the photoluminescence (PL) lifetime of mercaptopropionic acid-capped QDs (MPA-QDs) collected from FLIM images can be used to determine intracellular pH. The PL average lifetime of MPA-QDs varied from 8.7 ns (pH < 5) to 15.4 ns (pH > 8) in media mimicking the intracellular environment. These long decay times of QD nanoparticles make them easily distinguishable from intrinsic cell autofluorescence, improving selectivity in sensing applications. We demonstrate, for the first time, the successful detection of changes in the intracellular pH of different cell types by examining the PL decay time of QDs. In particular, the combination of FLIM methodologies with QD nanoparticles exhibits greatly improved sensitivity compared with other fluorescent dyes for pH imaging. A detailed description of the advantages of the FLIM technique is presented
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