AAT Bioquest

AAT Bioquest

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Ratiometric Calcium Indicators: Performance & Selection Criteria
Ratiometric calcium indicators are designed to monitor calcium mobilization with greater accuracy and sensitivity. When bound to free Ca2+, the peak wavelength of either the excitation curve or emission curve of the ratiometric indicator will undergo a shift. This allows for very precise measurements of Ca2+ concentrations by correcting for uneven dye loading, dye leakage, and varying cell thicknesses.

For any experiment, the selection criteria for a ratiometric calcium indicator will depend on the instrument platform, the expected Ca2+ concentrations, and others. In general, it is useful to consider:

-  Calcium sensitivity and response
-  Filter set compatibility
-  Signal/background ratio
-  Cell retention (can vary by cell type)

Among ratiometric calcium indicators, Fura-2 and Indo-1 are the most widely used, although both have drawbacks in the form of only moderate signal/background ratio and poor cell retention. Fura-8™ demonstrates significant improvement in the signal/background ratio, and Fura-10™ outperforms both options and remains within cells significantly longer.


ATP-stimulated calcium response of endogenous P2Y receptor in CHO-K1 cells measured with Fura-2 AM, Fura-8™ AM and Fura-10™ AM in the absence of Probenecid:
CHO-K1 cells were seeded overnight, then Fura-2 AM or Fura-8™ AM or Fura-10™ AM without probenecid was added into the cells, and ATP was added to achieve the final indicated concentrations.

Check the product brochure for more information: Calcium Detection Probes & Assay Kits

Info AAT Bioquest

Advancing Assay & Test Technologies.

AAT Bioquest, Inc. develops, manufactures and markets bioanalytical research reagents and kits to scientists engaged in life sciences research, diagnostic R&D and drug discovery. They specialize in the area of photometric detections including absorption (color), fluorescence and luminescence technologies.

AAT Bioquest constantly introduces new products, and offers a rapidly expanding list of products that are grouped into several product lines.

1) Reactive fluorescent and luminescent probes, biotins and tag enzymes are used for labeling small drug molecules and biopolymers, e.g, proteins, nucleic acids and carbohydrates;
2) Fluorescent and luminescent probes for detecting proteins, nucleic acids and live cells;
3) Novel fluorescent and luminescent probes for detecting various enzymes, in particular, hydrolytic and redox enzymes;
4) Reagents for signal transduction research;
5) Physiological and neurological probes, e.g., calcium indicators and membrane potential probes.
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