Labeled calcium indicators are molecules whose fluorescence intensity increases upon binding Ca²⁺ ions. Fluo-5F, fluo-5N, and fluo-4ff are fluo-4 analogs with lower Ca²⁺ binding affinity, making them suitable for detecting intracellular calcium in the 1 µM to 1 mM range. levels, and this range would saturate the responses of fluo-3 and fluo-4. Use a patch pipette or microinjection or our Influx™ Pinocytosis Cell Loading Reagent to These indicators are physically loaded into cells in the form of cell-impermeable salts. These indicators are compatible with excitation by argon ion laser sources at 488 nm, making them suitable for confocal microscopy, flow cytometry, and microplate screening applications.

Learn more about ionic indicators including calcium, potassium, pH and membrane potential indicators›

Calcium Indicator (Cell Impermeable Salt) Specifications:
• Tag (Ca²⁺–bound form Ex/Em): Fluo-5F (494/516 nm)
• Fluorescence intensity after binding to Ca²⁺ Increase: >100-fold
• K_d for Ca²⁺ in buffer: ∼2.3 µM
• Binding Ca^{2+, the fluorescence increases and the wavelength changes slightly}

Using TPEN to control heavy metal cations
In addition, BAPTA-based indicators can bind various heavy metal cations ( For example, Mn²⁺, Zn²⁺, Pb²⁺), the affinity is much higher than Ca²⁺. The heavy metal selective chelator TPEN can be used to control perturbations in calcium measurements caused by these ions.

More choices of fluorescent calcium indicators
We provide a large number of Molecular Probes™ calcium indicators for use in various experimental scenarios. For more information, see Visible light excited fluorescent Ca²⁺ indicators—Chapter 19.3 section.

For UV excited Ca²⁺ indicators, protein-based Ca²⁺ indicators, Ca²⁺ indicators Conjugates of reagents and fluorescent indicators of other metal ions (i.e. Mg²⁺, Zn²⁺), please see Ca²⁺, Mg²⁺, Zn²⁺, and other metal ion indicators—Chapter 19.

For scientific research use only. Not for therapeutic or diagnostic use in humans or animals.