The MTT assay is primarily used to assess cellular proliferation, which is indicative of cell viability or the cytotoxicity of nanomaterials. It may not be entirely accurate to refer to "inhibition" in this context. Thus, the parameter you are interested in with the MTT assay might be the LD50. This could be a matter of nomenclature, and I could be mistaken.

Determining the LD50 relies heavily on the impact of the tested agent on cell viability. Essentially, you need to evaluate the agent's cytotoxicity across a range of concentrations, ensuring that the lowest or zero concentration is non-toxic and the highest concentration results in 100% mortality. Afterward, you fit an appropriate equation to the data. If the cellular response is linear, you can use a linear equation 𝑦=𝑎𝑥+𝑏. However, if the cytotoxicity follows a sigmoidal or logarithmic pattern, you should fit a corresponding model instead. Once you have the mathematical equation, set 𝑦y to 50 (since you are looking for the concentration at which 50% of the cells are dead) and solve for 𝑥x, which will give you the LD50 concentration.

Jakub Jagielski Thank you for the information. And I had another doubts, among the mentioned methods to calculate the IC50 value, which gives the accurate results for our readings?

Karthick Mk I reconsidered what I have written before and I should provide an erratum. MTT is used to examine metabolic activity, which indeed is an indicator of cell viability. However, it is still an inhibition assay.

Summing up: YES, YOU CAN USE MTT ASSAY TO EVALUATE INHIBITORY CONCENTRATION IC50 AS I DESCRIBED BEFORE!

My mind went blank for a while when I wrote about LD50. So, to clear it up, LD50 is used for populations. LD50 is expressed as a mass of the factor per unit mass of the test subject over a given period of time. For example, the paracetamol LD50 in rats is 1205 mg/kg over a period of a month. In contrast, the IC50 in HeLa cells is 2.568 mg/ml with a 24-hour incubation.

I hope that I have made it clear now :)