Fluo-3

Fluo-3 is a chemical compound commonly used as a fluorescent probe for detecting and quantifying calcium ions in biological systems. It is a member of the rhodamine family of dyes and is used in a variety of biological and biochemical applications due to its high sensitivity and selectivity for calcium ions.

Structure and Properties

Fluo-3 is a single-wavelength fluorescent dye that binds to calcium ions. The structure of Fluo-3 consists of a fluorescein core, which is responsible for its fluorescent properties, and a BAPTA (1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid) moiety, which confers calcium ion selectivity. The BAPTA moiety of Fluo-3 has four carboxylate groups that form a cage-like structure around the calcium ion, allowing for high selectivity and affinity for calcium ions.

The fluorescence of Fluo-3 is greatly enhanced upon binding to calcium ions, making it an ideal probe for detecting changes in intracellular calcium concentrations. The maximum excitation and emission wavelengths of Fluo-3 are approximately 506 nm and 526 nm, respectively.

Applications

Fluo-3 is widely used in biological and biochemical research to study calcium signaling in cells. It is particularly useful for monitoring changes in intracellular calcium concentrations, which play a crucial role in many cellular processes, including muscle contraction, neurotransmission, and cell proliferation.

Fluo-3 can be loaded into cells via microinjection or incubation with the acetoxymethyl (AM) ester form of the dye, which is cell-permeable. Once inside the cell, esterases cleave the AM ester group, trapping the dye inside the cell.

Limitations

While Fluo-3 is a powerful tool for studying calcium signaling, it does have some limitations. For example, it is not suitable for use in strongly acidic or basic conditions, as these can quench its fluorescence. Additionally, it can be difficult to accurately quantify calcium concentrations using Fluo-3 due to factors such as dye leakage, photobleaching, and variations in dye loading.

See Also

• Fura-2
• Indo-1
• Calcium imaging