@article{AstSchwarzeMuelleretal.2013, author = {Ast, Sandra and Schwarze, Thomas and M{\"u}ller, Holger and Sukhanov, Aleksey and Michaelis, Stefanie and Wegener, Joachim and Wolfbeis, Otto S. and K{\"o}rzd{\"o}rfer, Thomas and D{\"u}rkop, Axel and Holdt, Hans-J{\"u}rgen}, title = {A highly K+-Selective Phenylaza-[18]crown-6-Lariat-Ether-Based Fluoroionophore and its application in the sensing of K+ Ions with an optical sensor film and in cells}, series = {Chemistry - a European journal}, volume = {19}, journal = {Chemistry - a European journal}, number = {44}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.201302350}, pages = {14911 -- 14917}, year = {2013}, abstract = {Herein, we report the synthesis of two phenylaza-[18]crown-6 lariat ethers with a coumarin fluorophore (1 and 2) and we reveal that compound 1 is an excellent probe for K+ ions under simulated physiological conditions. The presence of a 2-methoxyethoxy lariat group at the ortho position of the anilino moiety is crucial to the substantially increased stability of compounds 1 and 2 over their lariat-free phenylaza-[18] crown-6 ether analogues. Probe 1 shows a high K+/Na+ selectivity and a 2.5-fold fluorescence enhancement was observed in the presence of 100 mm K+ ions. A fluorescent membrane sensor, which was prepared by incorporating probe 1 into a hydrogel, showed a fully reversible response, a response time of 150 s, and a signal change of 7.8\% per 1 mm K+ within the range 1-10 mm K+. The membrane was easily fabricated (only a single sensing layer on a solid polyester support), yet no leaching was observed. Moreover, compound 1 rapidly permeated into cells, was cytocompatible, and was suitable for the fluorescent imaging of K+ ions on both the extracellular and intracellular levels.}, language = {en} } @misc{BeisnerGrossartGasol2019, author = {Beisner, Beatrix E. and Grossart, Hans-Peter and Gasol, Josep M.}, title = {A guide to methods for estimating phago-mixotrophy in nanophytoplankton}, series = {Journal of plankton research}, volume = {41}, journal = {Journal of plankton research}, number = {2}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0142-7873}, doi = {10.1093/plankt/fbz008}, pages = {77 -- 89}, year = {2019}, abstract = {Growing attention to phytoplankton mixotrophy as a trophic strategy has led to significant revisions of traditional pelagic food web models and ecosystem functioning. Although some empirical estimates of mixotrophy do exist, a much broader set of in situ measurements are required to (i) identify which organisms are acting as mixotrophs in real time and to (ii) assess the contribution of their heterotrophy to biogeochemical cycling. Estimates are needed through time and across space to evaluate which environmental conditions or habitats favour mixotrophy: conditions still largely unknown. We review methodologies currently available to plankton ecologists to undertake estimates of plankton mixotrophy, in particular nanophytoplankton phago-mixotrophy. Methods are based largely on fluorescent or isotopic tracers, but also take advantage of genomics to identify phylotypes and function. We also suggest novel methods on the cusp of use for phago-mixotrophy assessment, including single-cell measurements improving our capacity to estimate mixotrophic activity and rates in wild plankton communities down to the single-cell level. Future methods will benefit from advances in nanotechnology, micromanipulation and microscopy combined with stable isotope and genomic methodologies. Improved estimates of mixotrophy will enable more reliable models to predict changes in food web structure and biogeochemical flows in a rapidly changing world.}, language = {en} } @article{BroekerRoskeVallerianietal.2019, author = {Broeker, Nina K. and Roske, Yvette and Valleriani, Angelo and Stephan, Mareike Sophia and Andres, Dorothee and Koetz, Joachim and Heinemann, Udo and Barbirz, Stefanie}, title = {Time-resolved DNA release from an O-antigen-specific Salmonella bacteriophage with a contractile tail}, series = {The journal of biological chemistry}, volume = {294}, journal = {The journal of biological chemistry}, number = {31}, publisher = {American Society for Biochemistry and Molecular Biology}, address = {Bethesda}, issn = {1083-351X}, doi = {10.1074/jbc.RA119.008133}, pages = {11751 -- 11761}, year = {2019}, abstract = {Myoviruses, bacteriophages with T4-like architecture, must contract their tails prior to DNA release. However, quantitative kinetic data on myovirus particle opening are lacking, although they are promising tools in bacteriophage-based antimicrobial strategies directed against Gram-negative hosts. For the first time, we show time-resolved DNA ejection from a bacteriophage with a contractile tail, the multi-O-antigen-specific Salmonella myovirus Det7. DNA release from Det7 was triggered by lipopolysaccharide (LPS) O-antigen receptors and notably slower than in noncontractile-tailed siphoviruses. Det7 showed two individual kinetic steps for tail contraction and particle opening. Our in vitro studies showed that highly specialized tailspike proteins (TSPs) are necessary to attach the particle to LPS. A P22-like TSP confers specificity for the Salmonella Typhimurium O-antigen. Moreover, crystal structure analysis at 1.63 angstrom resolution confirmed that Det7 recognized the Salmonella Anatum O-antigen via an E15-like TSP, DettilonTSP. DNA ejection triggered by LPS from either host showed similar velocities, so particle opening is thus a process independent of O-antigen composition and the recognizing TSP. In Det7, at permissive temperatures TSPs mediate O-antigen cleavage and couple cell surface binding with DNA ejection, but no irreversible adsorption occurred at low temperatures. This finding was in contrast to short-tailed Salmonella podoviruses, illustrating that tailed phages use common particle-opening mechanisms but have specialized into different infection niches.}, language = {en} } @article{DunsingPetrichChiantia2021, author = {Dunsing, Valentin and Petrich, Annett and Chiantia, Salvatore}, title = {Multicolor fluorescence fluctuation spectroscopy in living cells via spectral detection}, series = {eLife}, volume = {10}, journal = {eLife}, publisher = {eLife Sciences Publications}, address = {Cambridge}, issn = {2050-084X}, doi = {10.7554/eLife.69687}, pages = {33}, year = {2021}, abstract = {Signaling pathways in biological systems rely on specific interactions between multiple biomolecules. Fluorescence fluctuation spectroscopy provides a powerful toolbox to quantify such interactions directly in living cells. Cross-correlation analysis of spectrally separated fluctuations provides information about intermolecular interactions but is usually limited to two fluorophore species. Here, we present scanning fluorescence spectral correlation spectroscopy (SFSCS), a versatile approach that can be implemented on commercial confocal microscopes, allowing the investigation of interactions between multiple protein species at the plasma membrane. We demonstrate that SFSCS enables cross-talk-free cross-correlation, diffusion, and oligomerization analysis of up to four protein species labeled with strongly overlapping fluorophores. As an example, we investigate the interactions of influenza A virus (IAV) matrix protein 2 with two cellular host factors simultaneously. We furthermore apply raster spectral image correlation spectroscopy for the simultaneous analysis of up to four species and determine the stoichiometry of ternary IAV polymerase complexes in the cell nucleus.}, language = {en} } @article{EerqingSubramanianRubioJimenezetal.2021, author = {Eerqing, Narima and Subramanian, Sivaraman and Rubio Jimenez, Jesus and Lutz, Tobias and Wu, Hsin-Yu and Anders, Janet and Soeller, Christian and Vollmer, Frank}, title = {Comparing transient oligonucleotide hybridization kinetics using DNA-PAINT and optoplasmonic single-molecule sensing on gold nanorods}, series = {ACS photonics / American Chemical Society}, volume = {8}, journal = {ACS photonics / American Chemical Society}, number = {10}, publisher = {American Chemical Society}, address = {Washington}, issn = {2330-4022}, doi = {10.1021/acsphotonics.1c01179}, pages = {2882 -- 2888}, year = {2021}, abstract = {We report a comparison of two photonic techniques for single-molecule sensing: fluorescence nanoscopy and optoplasmonic sensing. As the test system, oligonucleotides with and without fluorescent labels are transiently hybridized to complementary "docking" strands attached to gold nanorods. Comparing the measured single-molecule kinetics helps to examine the influence of the fluorescent labels as well as factors arising from different sensing geometries. Our results demonstrate that DNA dissociation is not significantly altered by the fluorescent labels and that DNA association is affected by geometric factors in the two techniques. These findings open the door to exploiting plasmonic sensing and fluorescence nanoscopy in a complementary fashion, which will aid in building more powerful sensors and uncovering the intricate effects that influence the behavior of single molecules.}, language = {en} } @article{GuptaPathakShrivastav2022, author = {Gupta, Banshi D. and Pathak, Anisha and Shrivastav, Anand}, title = {Optical Biomedical Diagnostics Using Lab-on-Fiber Technology}, series = {Photonics : open access journal}, volume = {9}, journal = {Photonics : open access journal}, number = {2}, publisher = {MDPI}, address = {Basel}, issn = {2304-6732}, doi = {10.3390/photonics9020086}, pages = {40}, year = {2022}, abstract = {Point-of-care and in-vivo bio-diagnostic tools are the current need for the present critical scenarios in the healthcare industry. The past few decades have seen a surge in research activities related to solving the challenges associated with precise on-site bio-sensing. Cutting-edge fiber optic technology enables the interaction of light with functionalized fiber surfaces at remote locations to develop a novel, miniaturized and cost-effective lab on fiber technology for bio-sensing applications. The recent remarkable developments in the field of nanotechnology provide innumerable functionalization methodologies to develop selective bio-recognition elements for label free biosensors. These exceptional methods may be easily integrated with fiber surfaces to provide highly selective light-matter interaction depending on various transduction mechanisms. In the present review, an overview of optical fiber-based biosensors has been provided with focus on physical principles used, along with the functionalization protocols for the detection of various biological analytes to diagnose the disease. The design and performance of these biosensors in terms of operating range, selectivity, response time and limit of detection have been discussed. In the concluding remarks, the challenges associated with these biosensors and the improvement required to develop handheld devices to enable direct target detection have been highlighted.}, language = {en} } @article{NazirMeilingCywinskietal.2015, author = {Nazir, Rashid and Meiling, Till Thomas and Cywinski, Piotr J. and Gryko, Daniel T.}, title = {Synthesis and Optical Properties of alpha,beta-Unsaturated Ketones Bearing a Benzofuran Moiety}, series = {Asian journal of organic chemistry : an ACES journal}, volume = {4}, journal = {Asian journal of organic chemistry : an ACES journal}, number = {9}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2193-5807}, doi = {10.1002/ajoc.201500242}, pages = {929 -- 935}, year = {2015}, abstract = {Five pi-expanded alpha,beta-unsaturated ketones have been prepared from a strongly electron-rich benzofuran derivative via Knoevenagel reaction and aldol condensation. The incorporation of two 6-didodecylaminobenzofuran-2-yl groups at the periphery of D-pi-A and D-pi-A-pi-D molecules resulted in dyes with excellent solubility in the majority of organic solvents. In contrast to the majority of alpha,beta-unsaturated ketones, these dyes emit relatively strongly in the red region with a fluorescence quantum yield up to 40\%. They also display strong solvatofluorochromism with emission shifting from 570 nm in toluene to 670 nm in CHCl3. Depending on the chemical structure, they two-photon cross-sections (sigma(2)) are up to 1700 GM (1 GM=10(50) cm(4)s photon(-1)).}, language = {en} } @article{Schwarze2021, author = {Schwarze, Thomas}, title = {Determination of Pd2+ by fluorescence enhancement caused by an off-switching of an energy- and an electron transfer}, series = {ChemistrySelect}, volume = {6}, journal = {ChemistrySelect}, number = {3}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2365-6549}, doi = {10.1002/slct.202003975}, pages = {318 -- 322}, year = {2021}, abstract = {In this paper, we introduce a fluorescent dye 1, which is able to detect selectively Pd2+ by a clear fluorescence enhancement (FE) in THF. In the presence of eight Pd2+ equivalents, we observed a fluorescence enhancement factor (FEF) of 28.3. The high Pd2+ induced FEF can be explained by an off switching of multiple quenching processes within 1 by Pd2+. In the free dye 1 a photoinduced electron transfer (PET) and energy transfer (ET) takes place and quenches the anthracenic fluorescence. The coordination of eight Pd2+ units by the alkylthio-substituted porphyrazine receptor suppresses the PET and ET quenching process and the anthracenic fluorescence is switched on.}, language = {en} } @article{SchwarzeGarzTeuchneretal.2014, author = {Schwarze, Thomas and Garz, Andreas and Teuchner, Klaus and Menzel, Ralf and Holdt, Hans-J{\"u}rgen}, title = {Two-photon probes for metal ions based on phenylaza[18]crown-6 ethers and 1,2,3-triazoles as pi-linkers}, series = {ChemPhysChem : a European journal of chemical physics and physical chemistry}, volume = {15}, journal = {ChemPhysChem : a European journal of chemical physics and physical chemistry}, number = {12}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1439-4235}, doi = {10.1002/cphc.201402232}, pages = {2436 -- 2439}, year = {2014}, language = {en} } @article{SchwarzeKellingSperlichetal.2021, author = {Schwarze, Thomas and Kelling, Alexandra and Sperlich, Eric and Holdt, Hans-J{\"u}rgen}, title = {Influence of regioisomerism in 9-anthracenyl-substituted dithiodicyanoethene derivatives on photoinduced electron transfer controlled by intramolecular charge transfer}, series = {ChemPhotoChem}, volume = {5}, journal = {ChemPhotoChem}, number = {10}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2367-0932}, doi = {10.1002/cptc.202100070}, pages = {911 -- 914}, year = {2021}, abstract = {In this paper, we report on the fluorescence behaviour of three regioisomers which consist of two 9-anthracenyl fluorophores and of differently substituted dithiodicyanoethene moieties. These isomeric fluorescent probes show different quantum yields (phi(f)). In these probes, an oxidative photoinduced electron transfer (PET) from the excited 9-anthracenyl fluorophore to the dithiodicyanoethene unit quenches the fluorescence. This quenching process is accelerated by an intramolecular charge transfer (ICT) of the push-pull pi-electron system of the dithiodicyanoethene group. The acceleration of the PET depends on the strength of the ICT unit. The higher the dipole moment of the ICT unit, the stronger the observed fluorescence quenching. To the best of our knowledge, this is the first report of a regioisomeric influence on an oxidative PET by an ICT.}, language = {en} }