A fluorophore is the part of a molecule responsible for creating a fluorescent emission in the visible light spectrum. Known as chromophores, different wavelengths of light are absorbed by fluorophores, creating the light that is visible. This is essentially a region in which the orbits of two different molecules' electrons are located. The light impacts this region and excites the electrons to create the light. In the case of a fluorophore, this causes the stimulation of a less energetic wavelength.
Photons are absorbed by the fluorophore spectrum, but instead of creating a higher rate of excitement within the electron, it produces a lower rate. This causes the bright imagery usually associated with fluorescence. Essentially, the brighter the exposure light, the less fluorescence is seen. That is the reason that many fluorescent colors are seen best in light sources such as black lights.
Fluorophores can exist naturally or are introduced using artificial methods. Many fish and rocks maintain natural levels of this chromophore. However, it is most prevalent in the scientific community when used for research. It assists in the analysis of certain properties of materials, enabling researchers to identify reactions and changes in the fields of biochemistry and protein study. For example, the discipline of immunofluorescense uses the technique to help label antigens and antibodies at the subcellular level.
The most commonly used fluorophore in research is fluorescein isothiocyanate, a substance that can be chemically attached to molecules. This gives scientists a way to visualize the changes in non-fluorescent substances. Other examples include coumarin, cyanine and rhodamine. Certain substances using fluorescence can have adverse effects to the research, due to changes in the pH levels. As research progresses, new dyes are developed, each with different applications allowing for less intrusive changes to molecules.
Besides pure science, fluorophore modification has become a popular way to market products to consumers. One primary example of this is the GloFish™, genetically modified zebrafish available for purchase in red, green or orange fluorescent colors. In 1999, scientists from the National University of Singapore attempted to create a fish that could detect pollution. By merging the green fluorescent protein of a jellyfish with the zebrafish, the animal exhibited a bright fluorescence, especially under black lights. Soon, it was discovered that additional attributes from other sources, such as sea coral, could be used to create new colors, opening the way for living fluorescent animals to be sold as pets.