Yasemin Aleyna KARADENİZ, Tülay ÖNCÜ ÖNER
Cell culture is the survival of cells belonging to organisms with special materials in the laboratory environment without contamination. One of the frequently preferred areas in cell culture is in vitro cytotoxicity tests. Cytotoxicity is used to determine the rate of toxic effects in living cells of a considered toxic substance and provides a basis for animal experiments. Cytotoxicity tests can be used in areas such as drug development, implants, biocompatibility, cosmetics, and determination of toxic agents. Cells exposed to cytotoxicity may undergo apoptosis or lose their ability to proliferate. There are many cytotoxicity tests with different mechanisms that remain up to date. With these tests, a large number of items can be analyzed in a short time. One of the most preferred are tetrazolium-based assays including MTT, MTS, XTT and WST. In these tests, tetrazolium salts are reduced by gaining electrons and turn into formazan crystals, causing a color change. Since this interaction requires mitochondrial activity, it is carried out only by living cells. Tetrazolium-formazan substances are divided into two categories in terms of their ability to enter cells and dissolve in water-medium. MTT, in the first group, is a positively charged compound, so it can cross the cell membrane and be reduced inside the cell. However, formazan crystal formed as a result of reduction does not dissolve in water, it precipitates. The compounds in the second group (MTS, XTT and WST) cannot cross the cell membrane because they are negatively charged. Therefore, when using these compounds, intermediate electron acceptor molecules should also be used. Formazan, which is formed as a result of the reduction of the compounds in this group, is soluble in water and medium. The aim of this study is to give a detail information about tetrazolium-based assays used for measuring cell viability.

Anahtar Kelimeler: Tetrazolium-based assays, Cytotoxicity, Cell viability