Cytotoxicity XTT, Neutral Red Assays

Cell Proliferation, Cell Viability, XTT Test Kit

Ready to use Test Kit for the determination of Cell Viability with XTT (Tetrazolium Hydroxide) according to OECD 431. Detailed instruction manuals are provided with the kits for a first time success.

Tetrazolium salts MTT and XTT are a valuable tools to assess quantitatively viable cells, based on the fact that formazan dies are only produced by metabolic active cells. The assay is based on the cleavage of the yellow tetrazolium salt XTT to form an orange formazan dye. The formazan dye formed from XTT is soluble in aqueous solutions and can be monitored quantitatively by a microplate spectrophotometer. The assay can be automated allowing high throughput processing.

Cells are grown in 96 well tissue culture plates and are incubated with the XTT solution and test compound during 4–24 h.  After this incubation period, formazan solution is formed, which is spectrophotometrically quantified. An increase in number of living cells results in an increase in the OD.

Test Kit

Cell Proliferation Test, Neutral Red, Phototoxicity

Ready to use kit for the determination of Cell Viability with NR (Neutral Red) according to OECD 432. Detailed instruction manuals are provided with the kits for a first time success.

The neutral red (NR) assay procedure is a cell survival/viability assay based on the ability of viable cells to incorporate and bind neutral red within lysosomes. It is best performed on adherent cells. NR is a weak cationic dye that readily penetrates the cell membrane and accumulates intracellularly in lysosomes (lysosomal pH < cytoplasmic pH), where it binds to anionic sites of the lysosomal matrix. Changes of the cell surface or the sensitive lysosomal membrane lead to lysosomal fragility and other changes that gradually become irreversible. Such alterations brought about by the action of xenobiotics result in a decreased uptake and binding of NR. It is thus possible to distinguish between viable, damaged, or dead cells.

The quantity of dye incorporated into cells is measured by spectrometry at 540 nm, and is directly proportional to the number of cells with an intact membrane.

The Test Kit can also be used for the 3T3 NRU photoxicity Test according to OECD 432. The 3T3 NRU phototoxicity test is used to measure the phototoxic potential of a test substance induced by a chemical previously exposed to light. The test evaluates photo-cytotoxicity by the relative reduction in viable cells exposed to the chemical in the presence and absence of light.

Test Kit