Single molecule detection at surfaces

Fluorescence fluctuation spectroscopy based on an evanescent field excitation scheme leads to an alternative concept for single molecule detection with interesting experimental features. This concept is described and analyzed regarding the total fluorescence process including excitation, fluorescence emission and collection close to a dielectric interface. The realized experimental scheme showed superior performance of this concept with substantially enhanced molecular brightness when compared to the classical confocal setup based on water immersion objectives. Selected applications in life sciences including dual-color surface fluorescence correlation spectroscopy, enzyme kinetics and receptor--ligand binding are underlining the interest of this experimental approach.

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Related concepts (3)

Fluorescence

Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, than the absorbed radiation. A perceptible example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the electromagnetic spectrum (invisible to the human eye), while the emitted light is in the visible region; this gives the fluorescent substance a distinct color that can only be seen when the substance has been exposed to UV light.

Optical coherence tomography

Optical coherence tomography (OCT) is an imaging technique that uses low-coherence light to capture micrometer-resolution, two- and three-dimensional images from within optical scattering media (e.g., biological tissue). It is used for medical imaging and industrial nondestructive testing (NDT). Optical coherence tomography is based on low-coherence interferometry, typically employing near-infrared light. The use of relatively long wavelength light allows it to penetrate into the scattering medium.

Fluorescence microscope

A fluorescence microscope is an optical microscope that uses fluorescence instead of, or in addition to, scattering, reflection, and attenuation or absorption, to study the properties of organic or inorganic substances. "Fluorescence microscope" refers to any microscope that uses fluorescence to generate an image, whether it is a simple set up like an epifluorescence microscope or a more complicated design such as a confocal microscope, which uses optical sectioning to get better resolution of the fluorescence image.