Introduction
MTS assay is widely used in toxicology to test the cytotoxicity of certain toxic chemicals.

The principle is that NAPDH dehydrogenase, present in mitochondria within living cells, converts the chemical agent MTS into a soluble formazan dye that can be quantified by light absorption. Because dead cells lack this enzyme activity, it can serve as an indicator of cell viability.

When using cell culture techniques for MTS assay, it can test for cell death, inhibition of cell growth, and other effects caused by medical devices or their extracts.