Questions and Answers (5) View all
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Answer added in Fluorescent Dye5 Is there any way to evaluate antibody - dye conjugation?What you need is called "degree of labeling" (DOL): (average) number of dye residues attached to one protein molecule. Please consult www.abberior.de,... [more]
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Answer added in Fluorescence Imaging10 Can you visualise individual fluorescent particles using regular light microscopy methods?If you need photostable and/or photoactivable fluorophores, you may look for them by www.abberior.com
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Answer added in Heterocyclic Chemistry58 How can I know that my prepared organic molecules are novel (not prepared)?It may be too late to check the novelty of the prepared compounds AFTER their synthesis...
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Answer added in Organic Chemistry140 How could I dry dichloromethane?Dear colleagues, you have forgotten a good old method: just start distilling dichloromethane and look at the fore-run: if it is turbid (azeotrope with... [more]
Publications (37) View all
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Article: Carborhodol - a New Hybrid Fluorophore Obtained by Combination of Fluorescein and Carbopyronine Dye Cores.
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ABSTRACT: Asymmetric hybrid fluorophores are built from the structural elements of two (or even more) symmetric dyes and can develop valuable new features which their parents do not possess. A new hybrid carborhodol dye was obtained by the combination of fluorescein and carbopyronine fluorophores. The brightly fluorescent hybrid dye with a linker and reactive group was prepared in 12 steps with overall yield of 1.6%. In aqueous solutions, it has absorption and emission maxima at 586 and 613 nm, respectively. Antibodies labeled with a carborhodol dye possess broad absorption and emission bands, so that the effective Stokes shift is increased (compared with small Stokes shifts of the parent dyes) and the fluorescence quantum yield of 39% at a degree of labeling of 5.2. Two samples of secondary antibodies labeled with caborhodol and the benchmark red-emitting rhodamine dye (KK114) were used in two-color imaging experiments with excitation at 514-532 (carborhodol dye) and 633-640 nm (KK114). When emitted light was detected above 650 nm, the novel carborhodol dye provided a lower crosstalk than spectrally similar emitters (e. g., Atto594; crosstalk 40-60% with KK114 under the same conditions). The optical resolution of ca. 70 nm was attained using the new dye in stimulated emission depleted (STED) microscopy. The relatively short fluorescence lifetime in conjugates with antibodies (1.2-1.6 ns) suggests the possibility of dual FLIM with numerous dyes having lifertime values in the range of 3-5 ns. All of these features make the carborhodol fluorophore a valuable addition to the family of the red-emitting fluorescent dyes.Bioconjugate Chemistry 03/2013; · 4.93 Impact Factor -
Article: Quantification of four major metabolites of embryotoxic N-methyl- and N-ethyl-2-pyrrolidone in human urine by cooled-injection gas chromatography and isotope dilution mass spectrometry.
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ABSTRACT: N-Methyl- and N-ethyl-2-pyrollidone (NMP and NEP) are frequently used industrial solvents and were shown to be embryotoxic in animal experiments. We developed a sensitive, specific, and robust analytical method based on cooled-injection (CIS) gas chromatography and isotope dilution mass spectrometry to analyze 5-hydroxy-N-ethyl-2-pyrrolidone (5-HNEP) and 2-hydroxy-N-ethylsuccinimide (2-HESI), two newly identified presumed metabolites of NEP, and their corresponding methyl counterparts (5-HNMP, 2-HMSI) in human urine. The urine was spiked with deuterium-labeled analogues of these metabolites. The analytes were separated from urinary matrix by solid-phase extraction and silylated prior to quantification. Validation of this method was carried out by using both, spiked pooled urine samples and urine samples from 56 individuals of the general population with no known occupational exposure to NMP and NEP. Interday and intraday imprecision was better than 8% for all metabolites, while the limits of detection were between 5 and 20 μg/L depending on the analyte. The high sensitivity of the method enables us to quantify NMP and NEP metabolites at current environmental exposures by human biomonitoring.Analytical Chemistry 03/2012; 84(8):3787-94. · 5.86 Impact Factor -
Article: Partitioning, diffusion, and ligand binding of raft lipid analogs in model and cellular plasma membranes.
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ABSTRACT: Several simplified membrane models featuring coexisting liquid disordered (Ld) and ordered (Lo) lipid phases have been developed to mimic the heterogeneous organization of cellular membranes, and thus, aid our understanding of the nature and functional role of ordered lipid-protein nanodomains, termed "rafts". In spite of their greatly reduced complexity, quantitative characterization of local lipid environments using model membranes is not trivial, and the parallels that can be drawn to cellular membranes are not always evident. Similarly, various fluorescently labeled lipid analogs have been used to study membrane organization and function in vitro, although the biological activity of these probes in relation to their native counterparts often remains uncharacterized. This is particularly true for raft-preferring lipids ("raft lipids", e.g. sphingolipids and sterols), whose domain preference is a strict function of their molecular architecture, and is thus susceptible to disruption by fluorescence labeling. Here, we analyze the phase partitioning of a multitude of fluorescent raft lipid analogs in synthetic Giant Unilamellar Vesicles (GUVs) and cell-derived Giant Plasma Membrane Vesicles (GPMVs). We observe complex partitioning behavior dependent on label size, polarity, charge and position, lipid headgroup, and membrane composition. Several of the raft lipid analogs partitioned into the ordered phase in GPMVs, in contrast to fully synthetic GUVs, in which most raft lipid analogs mis-partitioned to the disordered phase. This behavior correlates with the greatly enhanced order difference between coexisting phases in the synthetic system. In addition, not only partitioning, but also ligand binding of the lipids is perturbed upon labeling: while cholera toxin B binds unlabeled GM1 in the Lo phase, it binds fluorescently labeled GM1 exclusively in the Ld phase. Fluorescence correlation spectroscopy (FCS) by stimulated emission depletion (STED) nanoscopy on intact cellular plasma membranes consistently reveals a constant level of confined diffusion for raft lipid analogs that vary greatly in their partitioning behavior, suggesting different physicochemical bases for these phenomena.Biochimica et Biophysica Acta 03/2012; 1818(7):1777-1784. · 4.66 Impact Factor -
Article: Synthesis of Photochromic Compounds for Aqueous Solutions and Focusable Light
Annalen der Chemie und Pharmacie 05/2011; 2011(18):3301 - 3312. · 3.10 Impact Factor -
Article: New GM1 Ganglioside Derivatives for Selective Single and Double Labelling of the Natural Glycosphingolipid Skeleton
Annalen der Chemie und Pharmacie 09/2009; 2009(30):5162 - 5177. · 3.10 Impact Factor
