MTT dye need to be filtered before add into wells? - (Feb/25/2008 )

MTT is dissolved in sterilised PBS. So, do we still need to filter the MTT dye before adding into 96-well plates?

i don't think so and i don't do that for my assay. I just dissolve the powder in STERILE media without phenol red.
I think as long as you dissolve in STERILE PBS and keep the solution sterile and dark should be OK.

I prefer the ready to use kit MTT, or WST. I dont have to worry about that problem

I usually store the MTT solution in fridge (4°C).

Our lab recently switched to preparing MTT from the powder form instead of buying ready-made MTT kits to cut cost.

I tried preparing 5mg/ml MTT and a 20mg/ml stock MTT today; and, despite vortexing for close to 5minutes; I cant get the powder to fully dissolve in filtered sterile PBS. It seems that there's tiny blank particles still floating inside the 5mg/ml tube. As for the 20mg/ml stock, the powder cant be fully dissolved; a suspension was formed. Quite a substantial amount of powder is still left behind.

Is this normal? Or is there something amiss with the way I'm preparing my chemicals?

Also, is there a need to filter the solution before use?
I tried without filtering today; and it seems to be working fine..


Thanks!

We do filter MTT solution in my lab. The powder we buy isn't sterile.
For what concern dissolution, what I do is prepare the MTT solution the day before I need it then leave it in the fridge overnight. The next morning is dissolved, I just vortex it a little bit before filtering it.
We don't prepare stock solution of 20mg/ml, so I don't know if your is a problem of "oversaturation" or just a matter of patience!