@article{RoderHille2014,
  author    = {Roder, Phillip and Hille, Carsten},
  title     = {ANG-2 for quantitative Na+ determination in living cells by time-resolved fluorescence microscopy},
  series = {Photochemical \& photobiological sciences},
  volume    = {13},
  journal   = {Photochemical \& photobiological sciences},
  number    = {12},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1474-905X},
  doi       = {10.1039/c4pp00061g},
  pages     = {1699 -- 1710},
  year      = {2014},
  abstract  = {Sodium ions (Na+) play an important role in a plethora of cellular processes, which are complex and partly still unexplored. For the investigation of these processes and quantification of intracellular Na+ concentrations ([Na+](i)), two-photon coupled fluorescence lifetime imaging microscopy (2P-FLIM) was performed in the salivary glands of the cockroach Periplaneta americana. For this, the novel Na+-sensitive fluorescent dye Asante NaTRIUM Green-2 (ANG-2) was evaluated, both in vitro and in situ. In this context, absorption coefficients, fluorescence quantum yields and 2P action cross-sections were determined for the first time. ANG-2 was 2P-excitable over a broad spectral range and displayed fluorescence in the visible spectral range. Although the fluorescence decay behaviour of ANG-2 was triexponential in vitro, its analysis indicates a Na+-sensitivity appropriate for recordings in living cells. The Na+-sensitivity was reduced in situ, but the biexponential fluorescence decay behaviour could be successfully analysed in terms of quantitative [Na+](i) recordings. Thus, physiological 2P-FLIM measurements revealed a dopamine-induced [Na+](i) rise in cockroach salivary gland cells, which was dependent on a Na+-K+-2Cl-cotransporter (NKCC) activity. It was concluded that ANG-2 is a promising new sodium indicator applicable for diverse biological systems.},
  language  = {en}
}
@article{JahnHille2014,
  author    = {Jahn, Karolina and Hille, Carsten},
  title     = {Asante calcium green and asante calcium red-novel calcium indicators for two-photon fluorescence lifetime imaging},
  series = {PLoS one},
  volume    = {9},
  journal   = {PLoS one},
  number    = {8},
  publisher = {PLoS},
  address   = {San Fransisco},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0105334},
  pages     = {13},
  year      = {2014},
  abstract  = {For a comprehensive understanding of cellular processes and potential dysfunctions therein, an analysis of the ubiquitous intracellular second messenger calcium is of particular interest. This study examined the suitability of the novel Ca2+-sensitive fluorescent dyes Asante Calcium Red (ACR) and Asante Calcium Green (ACG) for two-photon (2P)-excited time-resolved fluorescence measurements. Both dyes displayed sufficient 2P fluorescence excitation in a range of 720-900 nm. In vitro, ACR and ACG exhibited a biexponential fluorescence decay behavior and the two decay time components in the ns-range could be attributed to the Ca2+-free and Ca2+-bound dye species. The amplitude-weighted average fluorescence decay time changed in a Ca2+-dependent way, unraveling in vitro dissociation constants K-D of 114 nM and 15 nM for ACR and ACG, respectively. In the presence of bovine serum albumin, the absorption and steady-state fluorescence behavior of ACR was altered and its biexponential fluorescence decay showed about 5-times longer decay time components indicating dye-protein interactions. Since no ester derivative of ACG was commercially available, only ACR was evaluated for 2P-excited fluorescence lifetime imaging microscopy (2P-FLIM) in living cells of American cockroach salivary glands. In living cells, ACR also exhibited a biexponential fluorescence decay with clearly resolvable short (0.56 ns) and long (2.44 ns) decay time components attributable to the Ca2+-free and Ca2+-bound ACR species. From the amplitude-weighted average fluorescence decay times, an in situ K-D of 180 nM was determined. Thus, quantitative [Ca2+](i) recordings were realized, unraveling a reversible dopamine-induced [Ca2+](i) elevation from 21 nM to 590 nM in salivary duct cells. It was concluded that ACR is a promising new Ca2+ indicator dye for 2P-FLIM recordings applicable in diverse biological systems.},
  language  = {en}
}
@article{RoderHille2014,
  author    = {Roder, Phillip and Hille, Carsten},
  title     = {ANG-2 for quantitative Na+ determination in living cells by time-resolved fluorescence microscopy},
  series = {Photochemical \& Photobiological Sciences},
  volume    = {12},
  journal   = {Photochemical \& Photobiological Sciences},
  number    = {13},
  editor    = {Hille, Carsten},
  publisher = {The Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1474-905X},
  pages     = {1699 -- 1710},
  year      = {2014},
  abstract  = {Sodium ions (Na+) play an important role in a plethora of cellular processes, which are complex and partly still unexplored. For the investigation of these processes and quantification of intracellular Na+ concentrations ([Na+]i), two-photon coupled fluorescence lifetime imaging microscopy (2P-FLIM) was performed in the salivary glands of the cockroach Periplaneta americana. For this, the novel Na+-sensitive fluorescent dye Asante NaTRIUM Green-2 (ANG-2) was evaluated, both in vitro and in situ. In this context, absorption coefficients, fluorescence quantum yields and 2P action cross-sections were determined for the first time. ANG-2 was 2P-excitable over a broad spectral range and displayed fluorescence in the visible spectral range. Although the fluorescence decay behaviour of ANG-2 was triexponential in vitro, its analysis indicates a Na+-sensitivity appropriate for recordings in living cells. The Na+-sensitivity was reduced in situ, but the biexponential fluorescence decay behaviour could be successfully analysed in terms of quantitative [Na+]i recordings. Thus, physiological 2P-FLIM measurements revealed a dopamine-induced [Na+]i rise in cockroach salivary gland cells, which was dependent on a Na+-K+-2Cl- cotransporter (NKCC) activity. It was concluded that ANG-2 is a promising new sodium indicator applicable for diverse biological systems.},
  language  = {en}
}
@misc{RoderHille2014,
  author    = {Roder, Phillip and Hille, Carsten},
  title     = {ANG-2 for quantitative Na+ determination in living cells by time-resolved fluorescence microscopy},
  publisher = {The Royal Society of Chemistry},
  address   = {Cambridge},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-76851},
  pages     = {1699 -- 1710},
  year      = {2014},
  abstract  = {Sodium ions (Na+) play an important role in a plethora of cellular processes, which are complex and partly still unexplored. For the investigation of these processes and quantification of intracellular Na+ concentrations ([Na+]i), two-photon coupled fluorescence lifetime imaging microscopy (2P-FLIM) was performed in the salivary glands of the cockroach Periplaneta americana. For this, the novel Na+-sensitive fluorescent dye Asante NaTRIUM Green-2 (ANG-2) was evaluated, both in vitro and in situ. In this context, absorption coefficients, fluorescence quantum yields and 2P action cross-sections were determined for the first time. ANG-2 was 2P-excitable over a broad spectral range and displayed fluorescence in the visible spectral range. Although the fluorescence decay behaviour of ANG-2 was triexponential in vitro, its analysis indicates a Na+-sensitivity appropriate for recordings in living cells. The Na+-sensitivity was reduced in situ, but the biexponential fluorescence decay behaviour could be successfully analysed in terms of quantitative [Na+]i recordings. Thus, physiological 2P-FLIM measurements revealed a dopamine-induced [Na+]i rise in cockroach salivary gland cells, which was dependent on a Na+-K+-2Cl- cotransporter (NKCC) activity. It was concluded that ANG-2 is a promising new sodium indicator applicable for diverse biological systems.},
  language  = {en}
}