A fluorophore is a molecule or a portion of a molecule that has the ability to emit light upon excitation by an external energy source, such as ultraviolet or visible light. The process by which a fluorophore absorbs and then re-emits light is known as fluorescence. Fluorophores are widely used in various scientific and technological applications, including fluorescence microscopy, flow cytometry, medical imaging, and molecular biology.
Key features of fluorophores include:
Excitation and emission: Fluorophores absorb photons of a specific wavelength (excitation) and subsequently emit photons at a longer wavelength (emission). The emitted light is often of a different color than the absorbed light.
Fluorescence quantum yield: Fluorophores vary in their efficiency of light emission, known as the fluorescence quantum yield. A higher quantum yield indicates a more efficient conversion of absorbed photons into emitted fluorescence.
Spectral properties: Fluorophores have distinct spectral properties, including absorption and emission spectra, which define the range of wavelengths at which they absorb and emit light.
Chemical structure: The chemical structure of a fluorophore plays a crucial role in determining its fluorescent properties. Different fluorophores may have distinct chemical structures, conjugated systems, and functional groups that influence their fluorescence behavior.
Applications: Fluorophores find extensive use in various applications, including fluorescence imaging, molecular labeling, tracking biological molecules, studying cellular processes, and detecting specific targets in biological samples.
Fluorescent dyes and probes: Many fluorophores are used as fluorescent dyes or probes to label and visualize specific structures, molecules, or cells in biological and biomedical research. These dyes can be designed to target specific biomolecules, such as DNA, proteins, or cellular organelles.
Fluorescent proteins: Some naturally occurring proteins, such as green fluorescent protein (GFP), exhibit intrinsic fluorescence. These fluorescent proteins are widely employed as molecular markers in live-cell imaging studies.
Examples of commonly used fluorophores include fluorescein, rhodamine, cyanine dyes, and various quantum dots. The selection of a specific fluorophore depends on factors such as its spectral properties, photostability, compatibility with experimental conditions, and the intended application.