# will the drug concentration change according to dish/flask size? - (Sep/19/2016 )

Hi,

I need to perform  a cell culture based assay, wherein I need to grow cells in presence of drug and test the effect of that on the cells. This has been already done by someone in the lab. I need to reproduce the results. The problem is, the assay was done in 15cm dish and that is not currently available with us. I need to do this experiment ASAP. We have T75 flasks, and surface area to grow cells is half of 15 cm dish.Therefore I am planning to do exp with 2 T 75 flasks.

Can drug concentration  given for 15cm dish be used for T75 flask also? Or do I need to make it half?

I have calculated seeding density accordingly, however I am confused about drug conc. Eventually I have to pool both the flask to get same number of cells to make lysate.

Thanks

-neuron-

If you are using a concentration such as X ug/ml then you can keep the concentration the same. However, if you are adding a total amount per dish, then you should keep that consistent with the dish vs plate size. For example if you added 15 ug in a 15 cm dish, then you would add 7.5 ug to a half area flask.

I note that a t75 is not half of a 15 cm dish... 15 cm diameter will give you 7.5 cm radius: area= r2 x pi = 7.52 x 3.14159 = 176 cm2, T75 flasks have 75 cm2 area, which would  be 150 cm2 for 2, you would need to add a t25 to get close to the area. You could otherwise use a T175 flask, as these are almost the same area as a 15 cm plate.

-bob1-

Thanks bob1! The concentration is in molarity. For 15 cm dish, they have given add 100nM. Should I keep constant for T75 flask also?

I found the information for surface area on thermofisher website, check the link-

https://www.thermofisher.com/in/en/home/references/gibco-cell-culture-basics/cell-culture-protocols/cell-culture-useful-numbers.html

Should I take two t75 and one t25 then?

-neuron-

You can keep the concentration - this will not change irrespective of the area of the vessel.

Today I learned that 100 mm dishes are not actually 100 mm wide, more like 85 mm, which accounts for the difference. Based on this premise, you should be fine with 2 T-75s.

-bob1-

Thanks bob!

-neuron-