@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{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} } @misc{Regenstein2023, author = {Regenstein, Wolfgang}, title = {Optische Spektroskopie d{\"u}nner organischer Schichten in Stichpunkten}, doi = {10.25932/publishup-60813}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-608135}, pages = {65}, year = {2023}, abstract = {Es wird ein {\"U}berblick {\"u}ber verschiedene spektroskopische Techniken, mit denen d{\"u}nne organische Schichten, wie sie in der Fotovoltaik, bei Leuchtdioden oder organischen Halbleitern Anwendung finden, gegeben. Mit einfachen Zusatzger{\"a}ten lassen sich Schichtdicke, Schichtaufbau und Zusammensetzung untersuchen. Die Schichtdicke kann monomolekular sein. Unter bestimmten Voraussetzungen sind einzelne Molek{\"u}le in einer Schicht charakterisierbar.}, language = {de} } @article{SchwarzeRiemer2020, author = {Schwarze, Thomas and Riemer, Janine}, title = {Highly K+ selective probes with fluorescence emission wavelengths higher than 500 nm in water}, series = {ChemistrySelect}, volume = {5}, journal = {ChemistrySelect}, number = {42}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2365-6549}, doi = {10.1002/slct.202003785}, pages = {13174 -- 13178}, year = {2020}, abstract = {Herein, we report on the synthesis of highly K+/Na+ selective fluorescent probes in a feasible number of synthetic steps. These K+ selective fluorescent probes, so called fluoroionophores, 1 and 2 consists of different highly K+/Na+ selective building blocks the alkoxy-substituted N-phenylaza-18-crown-6 lariat ethers (ionophores) and "green" (cf. coumarin unit in 1) or "red" (cf. nile red unit in 2) fluorescent moieties (fluorophores). The fluorescent probes 1 and 2 show K+ induced fluorescence enhancement factors of 4.1 for 1 and 1.9 for 2 and dissociation constants for the corresponding K+ complexes of 43 mM (1+K+) and 18 mM (2+K+) in buffered aqueous solution. The fluorescence signal of 1 and 2 is changed by less than 5 \% by pH values in the range of 6.8 to 8.8. Thus, 1 and 2 are capable fluorescent tools to determine extracellular K+ levels by fluorescence enhancements at wavelengths higher than 500 nm.}, 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{SchwarzeSprengerRiemer2020, author = {Schwarze, Thomas and Sprenger, Tobias and Riemer, Janine}, title = {1,2,3-Triazol-1,4-diyl-Fluoroionophores for Zn2+, Mg2+ and Ca2+ based on Fluorescence Intensity Enhancements in Water}, series = {ChemistrySelect}, volume = {5}, journal = {ChemistrySelect}, number = {41}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2365-6549}, doi = {10.1002/slct.202003695}, pages = {12727 -- 12735}, year = {2020}, abstract = {Herein, we represent cation-responsive fluorescent probes for the divalent cations Zn2+, Mg2+ and Ca2+, which show cation-induced fluorescence enhancements (FE) in water. The Zn2+-responsive probes Zn1, Zn2, Zn3 and Zn4 are based on o-aminoanisole-N,N-diacetic acid (AADA) derivatives and show in the presence of Zn2+ FE factors of 11.4, 13.9, 6.1 and 8.2, respectively. Most of all, Zn1 and Zn2 show higher Zn2+ induced FE than the regioisomeric triazole linked fluorescent probes Zn3 and Zn4, respectively. In this set, ZN2 is the most suitable probe to detect extracellular Zn2+ levels. For the Mg2+-responsive fluorescent probes Mg1, Mg2 and Mg3 based on o-aminophenol-N,N,O-triacetic acid (APTRA) derivatives, we also found that the regioisomeric linkage influences the fluorescence responds towards Mg2+ (Mg1+100 mM Mg2+ (FEF=13.2) and Mg3+100 mM Mg2+ (FEF=2.1)). Mg2 shows the highest Mg2+-induced FE by a factor of 25.7 and an appropriate K-d value of 3 mM to measure intracellular Mg2+ levels. Further, the Ca2+-responsive fluorescent probes Ca1 and Ca2 equipped with a 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) derivative show high Ca2+-induced FEs (Ca1 (FEF=22.1) and Ca2 (FEF=23.0)). Herein, only Ca1 (K-d=313 nM) is a suitable Ca2+ fluorescent indicator to determine intracellular Ca2+ levels.}, 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{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} } @article{SchwarzeRiemerHoldt2018, author = {Schwarze, Thomas and Riemer, Janine and Holdt, Hans-J{\"u}rgen}, title = {A Ratiometric Fluorescent Probe for K+ in Water Based on a Phenylaza-18-Crown-6 Lariat Ether}, series = {Chemistry - a European journal}, volume = {24}, journal = {Chemistry - a European journal}, number = {40}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.201802306}, pages = {10116 -- 10121}, year = {2018}, abstract = {This work presents two molecular fluorescent probes 1 and 2 for the selective determination of physiologically relevant K+ levels in water based on a highly K+/Na+ selective building block, the o-(2-methoxyethoxy)phenylaza-18-crown-6 lariat ether unit. Fluorescent probe 1 showed a high K+-induced fluorescence enhancement (FE) by a factor of 7.7 of the anthracenic emission and a dissociation constant (K-d) value of 38mm in water. Further, for 2+K+, we observed a dual emission behavior at 405 and 505nm. K+ increases the fluorescence intensity of 2 at 405nm by a factor of approximately 4.6 and K+ decreases the fluorescence intensity at 505nm by a factor of about 4.8. Fluorescent probe 2+K+ exhibited a K-d value of approximately 8mm in Na+-free solutions and in combined K+/Na+ solution a similar K-d value of about 9mm was found, reflecting the high K+/Na+ selectivity of 2 in water. Therefore, 2 is a promising fluorescent tool to measure ratiometrically and selectively physiologically relevant K+ 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} }