Zellkultur

Phase contrast is an optical contrast technique for making unstained phase objects (e.g. flat cells) visible under the optical microscope. Cells that appear inconspicuous and transparent in brightfield can be viewed in high contrast and rich detail using a phase contrast microscope.

Differential interference contrast (DIC) microscopy is a good alternative to brightfield microscopy for gaining proper images of unstained specimens that often only provide a weak image in brightfield.

Hoffman modulation contrast has established itself as a standard for the observation of unstained, low-contrast biological specimens. Its innovative technical implementation permits significantly simpler handling and greater flexibility in deployment.

Many fields of biomedical research, like cancer research, drug development and tissue engineering, require the use of living cells to perform a variety of assays. Mammalian cell cultures are an essential tool in biology because they allow rapid growth and proliferation of different cell types for experimental analysis.

The prospects of fluorescence microscopy changed dramatically with the discovery of fluorescent proteins in the 1950s. The starting point was the detection of the jellyfish Aequorea victoria green fluorescent protein (GFP) by Osamo Shimomura. Hundreds of GFP mutants later, the range of fluorescent proteins reaches from the blue to the red spectrum.

Fluorescence is an effect which was first described by George Gabriel Stokes in 1852. He observed that fluorite begins to glow after being illuminated with ultraviolet light. Fluorescence is a form of photoluminescence which describes the emission of photons by a material after being illuminated with light. The emitted light is of longer wavelength than the exciting light. This effect is called the Stokes shift.