Substrats fluorescents

5-Carboxyfluorescein (5-FAM) is a self-quenching dye and one of the most common labelling agents for biomolecules, cell staining and localisation studies. The fluorescence is pH dependent, therefore it has been used to measure the internal pH of cells. As it is only membrane permeable to dead cells, it can be used as a staining agent to distinguish viable and non-viable cells. It is also used in PCR to label the 5’ end of oligonucleotides in the presence of a quencher at the 3’ end (dual labelled probe). During the amplification process, the dye is cleaved and the fluorescence increases proportionally with the amount of the specific sequence amplified during the PCR process. The development of the fluorescence signal is therefore specifically related to the amplification of the target sequence. The carboxylic acid can be activated to react with a primary amine.