Labeled calcium indicators are molecules that exhibit an increase in fluorescence upon binding Ca
2+. Fluo-3 has been used to image the spatial dynamics of Ca
2+ signaling, in flow cytometry experiments involving photoactivation of caged chelators, second messengers, and neurotransmitters, and for cell-based pharmacological screening. Fluo-4 is an analog of fluo-3 with the two chlorine substituents replaced by fluorines, which results in increased fluorescence excitation at 488 nm and consequently higher fluorescence signal levels. Cells may be loaded with the AM ester forms of these calcium indicators by adding the dissolved indicator directly to dishes containing cultured cells. These indicators are useful for fluorescence and confocal microscopy, flow cytometry, and microplate screening applications.
Learn more about ion indicators including calcium, potassium, pH, and membrane potential indicators ›Calcium Indicator (AM Ester) Specifications:
• Label (Ex/Em of Ca2+–bound form): Fluo-4 (494/506 nm)
• Fluorescence intensity increase upon binding Ca2+: >100 fold
• Kd for Ca2+ in buffer: ∼335 nM
• Exhibit fluorescence increase upon binding Ca2+ with little shift in wavelengthUsing TPEN to Control Heavy Metal Cations In addition, BAPTA-based indicators such as these bind various heavy metal cations (e.g., Mn
2+, Zn
2+, Pb
2+) with substantially higher affinity than Ca
2+. Perturbations to calcium measurements caused by presence of these ions can be controlled using the heavy metal-selective chelator
TPEN.
More Choices for Fluorescent Calcium Indicators We offer a large selection of Molecular Probes™ calcium indicators for use in various experimental scenarios. For more information, review
Fluorescent Ca2+ Indicators Excited with Visible Light—Section 19.3 in the Molecular Probes™ Handbook.
For UV-excitable Ca
2+ indicators, protein-based Ca
2+ indicators, conjugates of Ca
2+ indicators, and for fluorescence-based indicators of other metal ions (i.e., Mg
2+, Zn
2+) review
Indicators for Ca2+, Mg2+, Zn2+ and Other Metal Ions—Chapter 19 in the Molecular Probes™ Handbook.
For Research Use Only. Not for human or animal therapeutic or diagnostic use.
For Research Use Only. Not for use in diagnostic procedures.