How to detect drug's cytotoxcity by MTS - (Sep/25/2002 )

Recenty, i have been trying to examin an antitumor drug's cytotoxity by MTS( promega). I want get the IC50 value. The absorbane values do not always increase as the drug concentration decreases. I solubilized the drug with DMSO, so i make a negative control containing corresponding concentration of DMSO. Then Viability=absorbance of a well containing certain con of drug/absorbance of its negative conrol. But for some wells, its viability value is more than 1.
And i've heard that there is so-called edge effect in 96 well plate, so the well on the edge should not be used. Is it right?
Help me.

Hi:

I have used the MTT assay and found the following things
1) cell media additives can result in reduction of the MTT to formazan (ie ascorbic acid)
2) we saw crystals both inside and outside cells over time suggesting that we may be getting reduction due to more than just the viable cells
3) we had difficulty solubilizing the crystals

consequently we started using Alamar Blue and are much happier. It is a non toxic dye that in both its oxidized and reduced states is water soluble and cell permiable and so can be collected from the cell medium.

If you want any more info cantact me at seanpeel@yahoo.com

Dear Sir,

Can we use Resazurin instead of Alamar Blue? If yes, could you please send me a protocol for this.

Thanks,
Devender