Labeled calcium indicators are molecules whose fluorescence intensity increases upon binding Ca²⁺ ions. Fluo-3 is used in flow cytometric analysis, such as experiments involving photoactivation of cage chelators, second messengers and neurotransmitters, and pharmacological screening at the cellular level, for Ca²⁺ Spatial dynamics imaging. Fluo-4 is an analogue of fluo-3 in which two chlorine substituents are replaced by fluorine, resulting in enhanced fluorescence excitation at a wavelength of 488 nm and therefore higher fluorescence signal levels. The AM ester form of this calcium indicator can be loaded onto the cells by adding the dissolved indicator directly to the culture dish containing the cultured cells. These indicators are suitable for fluorescence and confocal microscopy, flow cytometry, and microplate screening applications.

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

Calcium Indicator (AM Ester) Specifications:
• Tag (excitation/emission wavelength of Ca²⁺– bound form): Fluo-4 (494/506 nm)
• Fluorescence intensity increases after binding to Ca²⁺ : >100x
• K_d for Ca²⁺ in buffer: ∼335 nM
• Binding Ca²⁺ Afterwards, 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 (e.g. Mn²⁺, Zn²⁺, Pb⁺²), 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 agents as well as 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.