Fura-2 is a high affinity, UV excitable intracellular calcium indicator that exhibits the unique property of ratiometry, it is the most popular indicator to accurately quantify calcium. By applying the ratio of the two wavelengths, variable effects such as indicator concentration, degree of cell loading, photobleaching, detector sensitivity, cell thickness and optical path are all eliminated. Typically, Fura-2 is excited at 335 and 362 nm while monitoring the 505 nm emission. Fura-2 is available in the following forms:
Acetoxymethyl (AM) ester for non-invasive intracellular loading, >95% purity by HPLC
1 mg, (Cat.# 0102, $90)
20 x 50 µg, (Cat.# 0103, $115)
Potassium salt for calibration and invasive loading, >90% purity by HPLC
TEFLabs will work to accommodate special requests; if you need a different form please let us know at email@example.com.
Want long wavelength ratiometry? Learn more about our new Asante Calcium Red
Special Application Variants of Fura-2
TEFLabs also offers the low affinity, and near membrane specialty applications as well as leakage resistant enhanced-performance versions of Fura-2 and other calcium indicators.
Low affinity Fura-2 has several advantages over its high affinity counterparts:
- Fluorescent response does not saturate at micromolar calcium levels
- Reduced buffering of intracellular calcium and reduced perturbation of calcium transients
- Faster dissociation from calcium allows for measurement of shorter-lived transients.
Our low affinity Fura-2 is based on the electron-withdrawing effect of fluorine on the affinity of the parent dye. Their Kds shift from the nanomolar to the micromolar range, with high selectivity for calcium over magnesium, unlike their APTRA based counterparts. We offer Fura-2 LowAff (Cat.#0135 formerly Fura-2 FF), Indo-1 LowAff (Cat.#0138 formerly Indo-1 FF), Fluo-2 LowAff, and Asante Calcium Red LowAff (Cat.# 3050) low affinity indicators.
These modified indicators are retained in the cell for hours, with little to no change in the properties of their parent compounds. Numerous publications have emanated since their inception in 1994.
TEFLabs is the sole manufacturer of the leakage resistant dyes Fura-2 LeakRes (Cat.#0108, formerly Fura-PE3), Indo-1 LeakRes (Cat.#0144, formerly Indo-PE3), Fluo-2 LeakRes and Asante Calcium Red LeakRes (Cat.# 3150).
The near-membrane calcium indicators continue to be highly successful in their niche applications. Unlike other hydrophobic indicators, these have a piperazine collar to latch into the membrane, leaving the chelating portion to measure calcium in the gates and not lost in the membrane. TEFLabs offers Fura-2 NearMem (Cat.# 0125, formerly FFP-18), Indo-1 NearMem (Cat.# 0127, formerly FIP-18 ), Fluo-2 NearMem, and Asante Calcium Red NearMem (Cat.# 3200).