Loman, Anastasia

[["dc.bibliographiccitation.firstpage","8236"],["dc.bibliographiccitation.issue","28"],["dc.bibliographiccitation.journal","The Journal of Physical Chemistry B"],["dc.bibliographiccitation.lastpage","8240"],["dc.bibliographiccitation.volume","112"],["dc.contributor.author","Müller, Claus B."],["dc.contributor.author","Loman, Anastasia"],["dc.contributor.author","Richtering, Walter"],["dc.contributor.author","Enderlein, Jörg"],["dc.date.accessioned","2018-04-23T11:47:00Z"],["dc.date.available","2018-04-23T11:47:00Z"],["dc.date.issued","2008"],["dc.description.abstract","Fluorescence correlation spectroscopy (FCS) is a powerful technique for measuring diffusion coefficients of small fluorescent molecules at pico- to nanomolar concentrations. Recently, a modified version of FCS, dual-focus FCS (2fFCS), was introduced that significantly improves the reliability and accuracy of FCS measurements and allows for obtaining absolute values of diffusion coefficients without the need of referencing again a known standard. It was shown that 2fFCS gives excellent results for measuring the diffusion of small molecules. However, when measuring colloids or macromolecules, the size of these objects can no longer be neglected with respect to the excitation laser focus. Here, we analyze how 2fFCS data evaluation has to be modified for correctly taking into a count these finite size effects. We exemplify the new method of measuring the absolute size of polymeric particles with simple and complex fluorophore distributions."],["dc.identifier.doi","10.1021/jp802280u"],["dc.identifier.gro","3142165"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/13282"],["dc.language.iso","en"],["dc.notes.intern","lifescience updates Crossref Import"],["dc.notes.status","final"],["dc.relation.issn","1520-6106"],["dc.title","Dual-Focus Fluorescence Correlation Spectroscopy of Colloidal Solutions: Influence of Particle Size"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","4322"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","Optics Express"],["dc.bibliographiccitation.lastpage","4329"],["dc.bibliographiccitation.volume","16"],["dc.contributor.author","Müller, Claus B."],["dc.contributor.author","Weiß, Kerstin"],["dc.contributor.author","Richtering, Walter"],["dc.contributor.author","Loman, Anastasia"],["dc.contributor.author","Enderlein, Jörg"],["dc.date.accessioned","2018-04-23T11:47:02Z"],["dc.date.available","2018-04-23T11:47:02Z"],["dc.date.issued","2008"],["dc.description.abstract","We present a novel calibration technique for determining the shear distance of a Nomarski Differential Interference Contrast prism, which is used in Differential Interference Contrast microscopy as well as for the recently developed dual-focus fluorescence correlation spectroscopy. In both applications, an exact knowledge of the shear distance induced by the Nomarski prism is important for a quantitative data evaluation. In Differential Interference Contrast microscopy, the shear distance determines the spatial resolution of imaging, in dual-focus fluorescence correlation spectroscopy, it represents the extrinsic length scale for determining diffusion coefficients. The presented calibration technique is itself based on a combination of fluorescence correlation spectroscopy and dynamic light scattering. The method is easy to implement and allows for determining the shear distance with nanometer accuracy."],["dc.identifier.doi","10.1364/oe.16.004322"],["dc.identifier.gro","3142169"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/13286"],["dc.language.iso","en"],["dc.notes.intern","lifescience updates Crossref Import"],["dc.notes.status","final"],["dc.relation.eissn","1094-4087"],["dc.relation.issn","1094-4087"],["dc.title","Calibrating Differential Interference Contrast Microscopy with dual-focus Fluorescence Correlation Spectroscopy"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1358"],["dc.bibliographiccitation.issue","7"],["dc.bibliographiccitation.journal","Soft Matter"],["dc.bibliographiccitation.lastpage","1366"],["dc.bibliographiccitation.volume","5"],["dc.contributor.author","Müller, Claus B."],["dc.contributor.author","Eckert, Thomas"],["dc.contributor.author","Loman, Anastasia"],["dc.contributor.author","Enderlein, Jörg"],["dc.contributor.author","Richtering, Walter"],["dc.date.accessioned","2018-04-23T11:49:39Z"],["dc.date.available","2018-04-23T11:49:39Z"],["dc.date.issued","2009"],["dc.description.abstract","Conventional single-focus fluorescence correlation spectroscopy (FCS) is often used for studying molecular diffusion in crowded environments. However, these measurements usually deal with concentrations of the crowding agent far beyond the overlap-concentration, resulting in a crowding effect which slows down the diffusion coefficient by several orders of magnitude. In the present paper, we would like to study the transition range from free diffusion to crowding. Therefore, high accuracy of the determination of the diffusion coefficient is needed. In the majority of cases, the local refractive index in a sample is different from the refractive index of the immersion medium of the used objective. To achieve a high accuracy during experiments it is necessary to account for the refractive index mismatch in single-focus FCS calculations. In this work, we study theoretically and experimentally the influence of the refractive index mismatch on performance of single-focus FCS as well as the recently developed dual-focus FCS (2fFCS). By looking at the transition from free tracer diffusion to crowding it is shown that, in contrast to conventional FCS, 2fFCS allows measuring absolute values of the diffusion coefficient and its change in the range of half an order of magnitude. Even under conditions of strong refractive index mismatch between sample and immersion medium, without the need of additional calibration. This is demonstrated on a system of fluorescently labeled 70 kDa dextrane in an unlabeled 70 kDa dextrane matrix. Therefore, 2fFCS is a perfect tool for investigating molecular dynamics in crowded environments."],["dc.identifier.doi","10.1039/b812289j"],["dc.identifier.gro","3142161"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/13745"],["dc.language.iso","en"],["dc.notes.intern","lifescience updates Crossref Import"],["dc.notes.status","final"],["dc.notes.status","final"],["dc.relation.doi","10.1039/b812289j"],["dc.relation.issn","1744-683X"],["dc.title","Dual-focus fluorescence correlation spectroscopy: a robust tool for studying molecular crowding"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1248"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","Lab on a Chip"],["dc.bibliographiccitation.lastpage","1253"],["dc.bibliographiccitation.volume","9"],["dc.contributor.author","Müller, Claus B."],["dc.contributor.author","Weiß, Kerstin"],["dc.contributor.author","Loman, Anastasia"],["dc.contributor.author","Enderlein, Jörg"],["dc.contributor.author","Richtering, Walter"],["dc.date.accessioned","2018-04-23T11:49:39Z"],["dc.date.available","2018-04-23T11:49:39Z"],["dc.date.issued","2009"],["dc.description.abstract","Remote temperature measurements in microfluidic devices with micrometer spatial resolution are important for many applications in biology, biochemistry and chemistry. The most popular methods use the temperature-dependent fluorescence lifetime of Rhodamine B, or the temperature-dependent size of thermosensitive materials such as microgel particles. Here, we use the recently developed method of dual-focus fluorescence correlation spectroscopy (2fFCS) for measuring the absolute diffusion coefficient of small fluorescent molecules at nanomolar concentrations and show how these data can be used for remote temperature measurements on a micrometer scale. We perform comparative temperature measurements using all three methods and show that the accuracy of 2fFCS is comparable or even better than that achievable with Rhodamine B fluorescence lifetime measurements. The temperature dependent microgel swelling leads to an enhanced accuracy within a narrow temperature range around the volume phase transition temperature, but requires the availability of specific microgels, whereas 2fFCS is applicable under very general conditions."],["dc.identifier.doi","10.1039/b807910b"],["dc.identifier.gro","3142160"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/13744"],["dc.language.iso","en"],["dc.notes.intern","lifescience updates Crossref Import"],["dc.notes.status","final"],["dc.relation.doi","10.1039/b807910b"],["dc.relation.issn","1473-0197"],["dc.title","Remote temperature measurements in femto-liter volumes using dual-focus-Fluorescence Correlation Spectroscopy"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]