MTT assay without positive control - (Mar/08/2014 )

Hello. i wanna ask is MTT assay valid if there is no positive control included for cytotoxicity study?

In my assay, i only include

MTT control = no cell + mtt + dmso

SOLVENT control = cell + medium with solvent used to dissolved the compound (6 half serial dilution starting with 0.1% conc. of the solvent) + mtt + dmso

TEST = cell + medium with compound (6 half serial dilution) + mtt + dmso

UNTREATED control = cell + medium only + mtt + dmso

is my assay valid? and is the solvent control in my assay considered to be negative control? and what actually is the function of positive control?

The 'untreated control' should be your positive control, isn't it?

positive control is used as a reference for your sample cell viability, it is always been set as 100% cell viability.

I used the following formula to calculate cell viability:

Cell viability (%) = (OD of sample / OD of positive control) x 100

Your MTT assay is valid and the 'MTT control' should be your negative control as it supposedly wont give any result as there's no cell.