Hi,
I'm performing cell cytotoxicity assay using XTT. I seed cells on a 96-well plate, after 24h add a drug and incubate for different time (6, 12, 24, 50, 56, 62, 72h) to the stop point (xtt adding).
Because of testing different incubation times I have few questions:
1. Is it necessary to create growth curves for each time variant?
2. Should I always seed the same number of cells for 6, 12, 24, 50, 56, 62, 72h treatment (but then for 6 and 12 hours density is ok, but for 24 and later it is overgrown)?
3. Should I seed different amount of cells for each time point, to achieve confluence about 80% in stop point (and than I have similar number of cells in negative control)?
Thank you in advance.