A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution and may require a mordant to improve the fastness of the dye on the fiber.
Paubrasilia echinata is a species of flowering plant in the legume family, Fabaceae, that is endemic to the Atlantic Forest of Brazil. It is a Brazilian timber tree commonly known as Pernambuco wood or brazilwood and is the national tree of Brazil. This plant has a dense, orange-red heartwood that takes a high shine, and it is the premier wood used for making bows for stringed instruments. The wood also yields a historically important red dye called brazilin, which oxidizes to brazilein.
Staining is a technique used to enhance contrast in samples, generally at the microscopic level. Stains and dyes are frequently used in histology, in cytology, and in the medical fields of histopathology, hematology, and cytopathology that focus on the study and diagnoses of diseases at the microscopic level. Stains may be used to define biological tissues, cell populations, or organelles within individual cells.
Congo red is an organic compound, the sodium salt of 3,3′-([1,1′-biphenyl]-4,4′-diyl)bis(4-aminonaphthalene-1-sulfonic acid). It is an azo dye. Congo red is water-soluble, yielding a red colloidal solution; its solubility is greater in organic solvents. The use of Congo red in the textile industry has long been abandoned, primarily because of its carcinogenic properties, but it is still used for histological staining.
Fuchsine (sometimes spelled fuchsin) or rosaniline hydrochloride is a magenta dye with chemical formula C20H19N3·HCl. There are other similar chemical formulations of products sold as fuchsine, and several dozen other synonyms of this molecule.
Crystal violet or gentian violet, also known as methyl violet 10B or hexamethyl pararosaniline chloride, is a triarylmethane dye used as a histological stain and in Gram's method of classifying bacteria. Crystal violet has antibacterial, antifungal, and anthelmintic (vermicide) properties and was formerly important as a topical antiseptic. The medical use of the dye has been largely superseded by more modern drugs, although it is still listed by the World Health Organization.
An acid dye is a dye that is typically applied to a textile at low pH. They are mainly used to dye wool, not cotton fabrics. Some acid dyes are used as food colorants, and some can also be used to stain organelles in the medical field.
Trichrome staining is a histological staining method that uses two or more acid dyes in conjunction with a polyacid. Staining differentiates tissues by tinting them in contrasting colours. It increases the contrast of microscopic features in cells and tissues, which makes them easier to see when viewed through a microscope.
Auramine O is a diarylmethane dye used as a fluorescent stain. In its pure form, Auramine O appears as yellow needle crystals. It is insoluble in water and soluble in ethanol and DMSO.
Bismarck brown Y also called C.I. 21000 and C.I. Basic Brown 1, is a diazo dye with the idealized formula [(H2N)2C6H3N2]2C6H4. The dye is a mixture of closely related compounds. It was one of the earliest azo dyes, being described in 1863 by German chemist Carl Alexander von Martius. It is used in histology for staining tissues.
Orange G also called C.I. 16230, Acid Orange 10, or orange gelb is a synthetic azo dye used in histology in many staining formulations. It usually comes as a disodium salt. It has the appearance of orange crystals or powder.
Hematoxylin and eosin stain is one of the principal tissue stains used in histology. It is the most widely used stain in medical diagnosis and is often the gold standard. For example, when a pathologist looks at a biopsy of a suspected cancer, the histological section is likely to be stained with H&E.
Neutral 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. It can be used for staining the Golgi apparatus in cells and Nissl granules in neurons.
Aniline 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.
Acridine 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.
SYBR Green I (SG) is an asymmetrical cyanine dye used as a nucleic acid stain in molecular biology. The SYBR family of dyes is produced by Molecular Probes Inc., now owned by Thermo Fisher Scientific. SYBR Green I binds to DNA. The resulting DNA-dye-complex best absorbs 497 nanometer blue light and emits green light. The stain preferentially binds to double-stranded DNA, but will stain single-stranded (ss) DNA with lower performance. SYBR Green can also stain RNA with a lower performance than ssDNA.
Brazilin is a naturally occurring, homoisoflavonoid, red dye obtained from the wood of Paubrasilia echinata, Biancaea sappan, Caesalpinia violacea, and Haematoxylum brasiletto. Brazilin has been used since at least the Middle Ages to dye fabric, and has been used to make paints and inks as well. The specific color produced by the pigment depends on its manner of preparation: in an acidic solution brazilin will appear yellow, but in an alkaline preparation it will appear red. Brazilin is closely related to the blue-black dye precursor hematoxylin, having one fewer hydroxyl group. Brazilein, the active dye agent, is an oxidized form of brazilin.
Alcian blue is any member of a family of polyvalent basic dyes, of which the Alcian blue 8G has been historically the most common and the most reliable member. It is used to stain acidic polysaccharides such as glycosaminoglycans in cartilages and other body structures, some types of mucopolysaccharides, sialylated glycocalyx of cells etc. For many of these targets it is one of the most widely used cationic dyes for both light and electron microscopy. Use of alcian blue has historically been a popular staining method in histology especially for light microscopy in paraffin embedded sections and in semithin resin sections. The tissue parts that specifically stain by this dye become blue to bluish-green after staining and are called "Alcianophilic". Alcian blue staining can be combined with H&E staining, PAS staining and van Gieson staining methods. Alcian blue can be used to quantitate acidic glycans both in microspectrophotometric quantitation in solution or for staining glycoproteins in polyacrylamide gels or on western blots. Biochemists had used it to assay acid polysaccharides in urine since the 1960s for diagnosis of diseases like mucopolysaccharidosis but from 1970's, partly due to lack of availability of Alcian and partly due to length and tediousness of the procedure, alternative methods had to be developed e.g. Dimethyl methylene blue method.
Carl Alexander von Martius was a German chemist and entrepreneur.
