Rhodaminen

Rhodaminen refers to a family of synthetic fluorescent dyes based on the xanthene chromophore, collectively known as rhodamines. These dyes are typically cationic and water-soluble, exhibiting bright fluorescence in the visible range and good photostability, which makes them popular as labels in biochemical and biomedical applications.

Chemically, rhodamines consist of a tricyclic xanthene core with amino substituents, such as diethylamino groups. Variants differ by substituents and by the presence or absence of a carboxyl group, which influences solubility and conjugation. The open forms are strongly fluorescent, while spirolactam forms can be non-fluorescent, a property used in some pro-fluorophores.

Spectral properties vary by dye. Rhodamine B and rhodamine 6G typically absorb around 520–565 nm and emit around 580–625 nm; rhodamine 110 has shorter-wavelength emission around 520–540 nm. The emission can be tuned by chemical modification. They are bright, but photobleach with extended illumination, like other organic fluorophores.

Primary uses include labeling biomolecules such as antibodies, nucleic acids, and proteins for fluorescence microscopy, flow cytometry, and fluorescence in situ hybridization. They are also used in fluorescence resonance energy transfer assays and as fluorescent tracers in chromatography and gel electrophoresis.

Common derivatives include rhodamine B, rhodamine 6G, rhodamine 123, and rhodamine 110; many rhodamine dyes are commercially available as derivatives with reactive groups for conjugation.

Safety: rhodamine dyes may be irritants and can be hazardous if ingested or inhaled; appropriate handling, disposal, and PPE are recommended depending on the specific compound and regulatory guidelines.