WAcridine orange is an organic compound that serves as a nucleic acid-selective fluorescent dye with cationic properties useful for cell cycle determination. Acridine orange is cell-permeable, which allows the dye to interact with DNA by intercalation, or RNA via electrostatic attractions. When bound to DNA, acridine orange is very similar spectrally to an organic compound known as fluorescein. Acridine orange and fluorescein have a maximum excitation at 502nm and 525 nm (green). When acridine orange associates with RNA, the fluorescent dye experiences a maximum excitation shift from 525 nm (green) to 460 nm (blue). The shift in maximum excitation also produces a maximum emission of 650 nm (red). Acridine orange is able to withstand low pH environments, allowing the fluorescent dye to penetrate acidic organelles such as lysosomes and phagolysosomes that are membrane-bound organelles essential for acid hydrolysis or for producing products of phagocytosis of apoptotic cells. Acridine orange is used in epifluorescence microscopy and flow cytometry. The ability to penetrate the cell membranes of acidic organelles and cationic properties of acridine orange allows the dye to differentiate between various types of cells. The shift in maximum excitation and emission wavelengths provides a foundation to predict the wavelength at which the cells will stain.
WAniline Yellow is a yellow azo dye and an aromatic amine. It is a derivative of azobenzene. It has the appearance of an orange powder. Aniline Yellow was the first azo dye. it was first produced in 1861 by C. Mene. The second azo dye was Bismarck Brown in 1863. Aniline Yellow was commercialized in 1864 as the first commercial azo dye, a year after Aniline Black. It is manufactured from aniline.
WCarboxyfluorescein diacetate succinimidyl ester (CFDA-SE) is a cell permeable dye generally used in animal cell proliferation research. High concentrations of the dye are toxic to animal cells, however concentrations in the region of 10 micromolar are typically sufficient to give strong staining with minimal cell death.
WDiOC6 (3,3′-dihexyloxacarbocyanine iodide) is a fluorescent dye used for the staining of a cell's endoplasmic reticulum, vesicle membranes and mitochondria. Binding to these structures occurs via the dye's hydrophilic groups. DiOC6 can be used to label living cells, however they are quickly damaged due to the dye's extreme phototoxicity, so cells stained with this dye can only be exposed to light for short periods of time. When exposed to blue light, the dye fluoresces green.
WGreen S is a green synthetic coal tar triarylmethane dye with the molecular formula C27H25N2O7S2Na.
WNeutral red is a eurhodin dye used for staining in histology. It stains lysosomes red. It is used as a general stain in histology, as a counterstain in combination with other dyes, and for many staining methods. Together with Janus Green B, it is used to stain embryonal tissues and supravital staining of blood. Can be used for staining Golgi apparatus in cells and Nissl granules in neurons.
WNile blue is a stain used in biology and histology. It may be used with live or fixed cells, and imparts a blue colour to cell nuclei.
WNile red is a lipophilic stain. Nile red stains intracellular lipid droplets yellow. In most polar solvents, Nile red will not fluoresce; however, when in a lipid-rich environment can be intensely fluorescent, with varying colours from deep red to strong yellow-gold emission. The dye is highly solvatochromic and its emission and excitation wavelength both shift depending on solvent polarity and in polar media will hardly fluoresce at all.
WSafranin is a biological stain used in histology and cytology. Safranin is used as a counterstain in some staining protocols, colouring cell nuclei red. This is the classic counterstain in both Gram stains and endospore staining. It can also be used for the detection of cartilage, mucin and mast cell granules.