Filtern
Erscheinungsjahr
Dokumenttyp
- Wissenschaftlicher Artikel (81)
- Postprint (12)
- Sonstiges (1)
- Rezension (1)
Gehört zur Bibliographie
- ja (95) (entfernen)
Schlagworte
- LIBS (9)
- Ion mobility spectrometry (8)
- ion mobility spectrometry (5)
- IR-MALDI (4)
- PCA (4)
- Electrospray ionization (3)
- Fluorescence (3)
- HPLC (3)
- APCI (2)
- Bacteria (2)
- Base pairing (2)
- Genetics (2)
- Imaging (2)
- Irradiation (2)
- Laser (2)
- Mass spectrometry (2)
- OTDR (2)
- PLS regression (2)
- PLSR (2)
- Photodynamics (2)
- REMPI (2)
- UVR (2)
- atmospheric effects (2)
- copper-bearing minerals (2)
- elemental composition (2)
- gas chromatography (2)
- gaussian processes (2)
- iPLS regression (2)
- instrumentation: miscellaneous (2)
- laser-induced breakdown spectroscopy (2)
- lasso (2)
- mass spectrometry (2)
- minerals (2)
- molecular oxygen (2)
- nutrients (2)
- optical sensing (2)
- precision agriculture (2)
- proximal soil sensing (2)
- quantum dots (2)
- rare earth elements (2)
- reaction monitoring (2)
- soil (2)
- soil nutrients (2)
- triangular-[4] phenylene (2)
- 2P cross section (1)
- Acoustic levitation (1)
- Ambient pressure laser ionization (1)
- Amino acids (1)
- Aptamer (1)
- Collision cross-section (1)
- Cyclic GMP (1)
- Diode laser (1)
- ESI (1)
- Electrospray Ionization (1)
- Epithelial ion transport (1)
- FRET (1)
- Fabry-Perot etalon (1)
- Fluorescence lifetime (1)
- Fluorescence spectroscopy (1)
- Fluorescent nanoconjugate (1)
- Fluoroassay (1)
- Gas chromatography (1)
- Gaseous Ions (1)
- High-resolution spectrometer (1)
- Hydrogen sulfide (1)
- IMS (1)
- Ion optics (1)
- Ionization (1)
- Ionmobility spectrometry (1)
- Isotope detection (1)
- L-selectin (1)
- Lanthanide (1)
- Laser ablation (1)
- Laser ionization (1)
- Laser-induced breakdown spectroscopy (1)
- Lucigenin (1)
- Luminescence spectroscopy (1)
- Mars (1)
- Methane (1)
- Methanogens (1)
- Molecular dynamics (1)
- Nanosensor (1)
- Naphthyridine receptor (1)
- Naphthyridines (1)
- Near infrared (1)
- Neuroleptics (1)
- Nucleotide nanosensor (1)
- OGB-1 (1)
- OH suppression (1)
- Olefin isomerization (1)
- Peptides (1)
- Pesticides (1)
- Plume (1)
- Proton transfer reaction (1)
- Pulse duration (1)
- Quantum dots (1)
- Raman spectroscopy (1)
- Rhodamine 6G (1)
- Shadowgraphy (1)
- Sub-zero temperature (Celsius) (1)
- Subambient pressure (1)
- TCSPC (1)
- Two-dimensional separations (1)
- Two-photon excitation (1)
- Wavelength modulation gas spectroscopy (1)
- Wavelength modulation spectroscopy (laser spectroscopy) (1)
- X-ray (1)
- [N]phenylene dyads (1)
- [N]phenylenes (1)
- acceptors (1)
- alkyl nitrates (1)
- amphiphilic polymer assembly (1)
- astrophotonics (1)
- bioanalysis (1)
- biosensor (1)
- biosensors (1)
- cGMP (1)
- complexes (1)
- continuous-flow (1)
- contrast agents (1)
- dual-frequency phase-modulation (1)
- dub-ambient (1)
- efficient (1)
- electrospray ionization (1)
- endogenous sensor proteins (1)
- europium (1)
- europium complex (1)
- explosives (1)
- fibre Bragg gratings (1)
- fluoroimmunoassay (1)
- fungus (1)
- high field mobility (1)
- infrared: diffuse background (1)
- infrared: general (1)
- labels (1)
- lanthanide luminescence (1)
- light (1)
- mass (1)
- microchip (1)
- microsensors (1)
- mold (1)
- mold fungi (1)
- nanobioconjugate (1)
- nanosensors (1)
- neuroleptics (1)
- oxygen sensor (1)
- peptides (1)
- pesticides (1)
- phenanthrenes (1)
- phosphorescence quenching (1)
- photocatalysis (1)
- photochemical synthesis (1)
- photochemistry (1)
- photoinduced electron transfer (1)
- photoionization (1)
- plant science (1)
- pressure (1)
- protein-kinase inhibitors (1)
- reaction mechanisms (1)
- resonance energy-transfer (1)
- soft X-radiation (1)
- soft X-ray (1)
- spectrometry (1)
- spectroscopy (1)
- spray imaging (1)
- surfactants (1)
- time-resolved fluorescence (1)
- volatile organic compounds (1)
Institut
L-selectin is a protein with potential importance for numerous diseases and clinical disorders. In this paper, we present a new aptamer-based luminescent assay developed to detect L-selectin. The sensing system working principle is based on Forster Resonance Energy Transfer (FRET) from a donor terbium complex (TbC) to an acceptor cyanine dye (Cy5). In the present approach, the biotinylated aptamer is combined with Cy5-labelled streptavidin (Cy5-Strep) to yield an aptamer-based acceptor construct (Apta-Cy5-Strep), while L-selectin is conjugated using luminescent TbC. Upon aptamer binding to the TbC-labelled L-selectin (L-selectin-TbC), permanent donor-acceptor proximity is established which allows for radiationless energy transfer to occur. However, when unlabelled L-selectin is added, it competes with the L-selectin-TbC and the FRET signal decreases as the L-selectin concentration increases. FRET from the TbC to Cy5 was observed with time-gated time-resolved luminescence spectroscopy. A significant change in the corrected luminescence signal was observed in the dynamic range of 10 -500 ng/mL L-selectin, the concentration range relevant for accelerated cognitive decline of Alzheimer's disease, with a limit of detection (LOD) equal to 10 ng/mL. The aptasensor-based assay is homogeneous and can be realized within one hour. Therefore, this method has the potential to become an alternative to tedious heterogeneous analytical methods, e.g. based on enzyme-linked immunosorbent assay (ELISA). (C) 2015 Elsevier B.V. All rights reserved.
Total protein concentration (TPC) is a key parameter in many biochemical experiments and its quantification is often necessary for isolation, separation, and analysis of proteins. A sensitive and rapid nanobead-based TPC quantification assay based on Forster Resonance Energy Transfer (FRET) has been developed. A new, highly luminescent Tb(III) complex has been synthesised and applied as donor in this FRET assay with an organic dye (Cy5) as acceptor. FRET-induced changes in luminescence have been investigated both at donor and acceptor emission wavelength using time-resolved luminescence spectroscopy with time-gated detection. In the assay, the Tb(III) complex and fine-tuned polyglycidyl methacrylate (PGMA) nanobeads ensure that an improvement in sensitivity and background reduction is achieved. Using 40 nm large PGMA nanobeads loaded with the Tb(III) complex, it is possible to determine TPC down to 50 ng mL(-1) in just 10 minutes. Through specific assay components the sensitivity has been improved when compared to existing nanobead-based assays and to currently known commercial methods. Additionally, the assay is relatively insensitive to the presence of contaminants, such as non-ionic detergents commonly found in biological samples. Due to no need for any centrifugal steps, this mix-and-measure bioassay can easily be implemented into routine TPC quantification protocols in biochemical laboratories.
A new functional luminescent lanthanide complex (LLC) has been synthesized with terbium as a central lanthanide ion and biotin as a functional moiety. Unlike in typical lanthanide complexes assembled via carboxylic moieties, in the presented complex, four phosphate groups are chelating the central lanthanide ion. This special chemical assembly enhances the complex stability in phosphate buffers conventionally used in biochemistry. The complex synthesis strategy and photophysical properties are described as well as the performance in time-resolved Förster Resonance Energy Transfer (FRET) assays. In those assays, this biotin-LLC transferred energy either to acceptor organic dyes (Cy5 or AF680) labelled on streptavidin or to quantum dots (QD655 or QD705) surface-functionalised with streptavidins. The permanent spatial donor–acceptor proximity is assured through strong and stable biotin–streptavidin binding. The energy transfer is evidenced from the quenching observed in donor emission and from a decrease in donor luminescence decay, both associated with simultaneous increase in acceptor intensity and in the decay time. The dye-based assays are realised in TRIS and in PBS, whereas QD-based systems are studied in borate buffer. The delayed emission analysis allows for quantifying the recognition process and for auto-fluorescence-free detection, which is particularly relevant for application in bioanalysis. In accordance with Förster theory, Förster-radii (R0) were found to be around 60 Å for organic dyes and around 105 Å for QDs. The FRET efficiency (η) reached 80% and 25% for dye and QD acceptors, respectively. Physical donor–acceptor distances (r) have been determined in the range 45–60 Å for organic dye acceptors, while for acceptor QDs between 120 Å and 145 Å. This newly synthesised biotin-LLC extends the class of highly sensitive analytical tools to be applied in the bioanalytical methods such as time-resolved fluoroimmunoassays (TR-FIA), luminescent imaging and biosensing.
Deuteration effects on the vibronic structure of the emission and excitation spectra of triangular [ 4] phenylene (D-3h [4]phenylene) were studied using laser-excited Shpol'skii spectroscopy (LESS) in an octane matrix at 4.2 K. For correct assignment of the vibrational modes, the experimental results were compared with calculated frequencies (B3LYP/6-31G*). CH vibrations were identified by their characteristic isotopic shifts in the spectra of deuterated triangular [4]phenylenes. Two CC stretching modes, at 100 cm(-1) and 1176 cm(-1), suitable as probes for bond strength changes in the excited state, were identified. The isotope effect on the internal conversion rates of triangular [4] phenylene was evaluated from measurements of temperature dependent lifetime. Isotope dependency and the magnitude of the internal conversion rates indicate that internal conversion in triangular [4] phenylene is most likely induced by CH vibrations. The results obtained by LESS and lifetime measurements were compared with PM3 PECI calculations of the excited state structure. The theoretical results and the relation between ground and excited state vibration energies of the 1176 cm(-1) probe vibration indicate a reduction of bond alternation of the central cyclohexatriene ring in the excited state
First studies of electron transfer in [N]phenylenes were performed in bimolecular quenching reactions of angular [3]- and triangular [4]phenylene with various electron acceptors. The relation between the quenching rate constants kq and the free energy change of the electron transfer (ΔG0CS ) could be described by the Rehm-Weller equation. From the experimental results, a reorganization energy λ of 0.7 eV was derived. Intramolecular electron transfer reactions were studied in an [N]phenylene bichomophore and a corresponding reference compound. Fluorescence lifetime and quantum yield of the bichromophor display a characteristic dependence on the solvent polarity, whereas the corresponding values of the reference compound remain constant. From the results, a nearly isoenergonic ΔG0CS can be determined. As the triplet quantum yield is nearly independent of the polarity, charge recombination leads to the population of the triplet state.
First studies of electron transfer in [N]phenylenes were performed in bimolecular quenching reactions of angular [3]- and triangular [4]phenylene with various electron acceptors. The relation between the quenching rate constants k(q) and the free energy change of the electron transfer (Delta G(CS)(0)) could be described by the Rehm- Weller equation. From the experimental results, a reorganization energy lambda of 0.7 eV was derived. Intramolecular electron transfer reactions were studied in an [N]phenylene bichomophore and a corresponding reference compound. Fluorescence lifetime and quantum yield of the bichromophor display a characteristic dependence on the solvent polarity, whereas the corresponding values of the reference compound remain constant. From the results, a nearly isoenergonic charge separation process can be determined. As the triplet quantum yield is nearly independent of the polarity, charge recombination leads to the population of the triplet state.
In many biological and environmental applications spatially resolved sensing of molecular oxygen is desirable. A powerful tool for distributed measurements is optical time domain reflectometry (OTDR) which is often used in the field of telecommunications. We combine this technique with a novel optical oxygen sensor dye, triangular-[4] phenylene (TP), immobilized in a polymer matrix. The TP luminescence decay time is 86 ns. The short decay time of the sensor dye is suitable to achieve a spatial resolution of some meters. In this paper we present the development and characterization of a reflectometer in the UV range of the electromagnetic spectrum as well as optical oxygen sensing with different fiber arrangements.
In many biological and environmental applications spatially resolved sensing of molecular oxygen is desirable. A powerful tool for distributed measurements is optical time domain reflectometry (OTDR) which is often used in the field of telecommunications. We combine this technique with a novel optical oxygen sensor dye, triangular-[4] phenylene (TP), immobilized in a polymer matrix. The TP luminescence decay time is 86 ns. The short decay time of the sensor dye is suitable to achieve a spatial resolution of some meters. In this paper we present the development and characterization of a reflectometer in the UV range of the electromagnetic spectrum as well as optical oxygen sensing with different fiber arrangements.
The problem of atmospheric emission from OH molecules is a long standing problem for near-infrared astronomy. PRAXIS is a unique spectrograph which is fed by fibres that remove the OH background and is optimised specifically to benefit from OH-Suppression. The OH suppression is achieved with fibre Bragg gratings, which were tested successfully on the GNOSIS instrument. PRAXIS uses the same fibre Bragg gratings as GNOSIS in its first implementation, and will exploit new, cheaper and more efficient, multicore fibre Bragg gratings in the second implementation. The OH lines are suppressed by a factor of similar to 1000, and the expected increase in the signal-to-noise in the interline regions compared to GNOSIS is a factor of similar to 9 with the GNOSIS gratings and a factor of similar to 17 with the new gratings. PRAXIS will enable the full exploitation of OH suppression for the first time, which was not achieved by GNOSIS (a retrofit to an existing instrument that was not OH-Suppression optimised) due to high thermal emission, low spectrograph transmission and detector noise. PRAXIS has extremely low thermal emission, through the cooling of all significantly emitting parts, including the fore-optics, the fibre Bragg gratings, a long length of fibre, and the fibre slit, and an optical design that minimises leaks of thermal emission from outside the spectrograph. PRAXIS has low detector noise through the use of a Hawaii-2RG detector, and a high throughput through a efficient VPH based spectrograph. PRAXIS will determine the absolute level of the interline continuum and enable observations of individual objects via an IFU. In this paper we give a status update and report on acceptance tests.