I think a good starting point is using about 60 microliters of RNAiMAx and about 20nM concentration of the siRNA; all in 10ml medium. These are all rough cornerstone values. I am not an expert in uptake and processing of liposomes, but for siRNAs it is probably enough to get it to the cytoplasm. This might be easier than getting a plasmid to the nucleus. Therefore, transfection rates and success between cell types may be more similar for siRNAs than plasmid DNA.

Since this is a lot of RNAiMAx, it might be a good idea to first check it out in a smaller scale, e.g. a 6 well plate. You can get enough material for RNA or protein studies from a 6-well plate, and can upscale easily from there. I use 5 to 10 microliters of RNAimax for my cell types in 2ml medium for a 6-well plate. I use 10 to 50 nM concentrations of siRNAs (in the final 2 ml of medium). 

I do both, transfection of seeded cells (traditional) and recently switched to fast-forward transfection (transfect at the time of seeding; this saves a day and does not seem to affect transfection rates). 

I hope this gives you a rough idea. 

the protocol attached is quite straightforward. There is a table to scale up or down your transfection. Just follow the protocol for one experiment to get roughly an idea where to start then try to optimise the amounts as sometimes you get good knockdown with much less reagents. Best of luck.

there should be good and simple protocols on the Invitrogen website. try 1-2 siRNA concentrations (ideally 10 nM or below; but for some tough cells or targets might need to climb higher), and eg 3 different amounts of RNAiMax. find the conditions that enable maximal knockdown and at the same time minimal cell toxicity. its very important

siRNA transfection efficiency and protocols depend on the cell line you're using (and there's a lot: https://altogen.com/products-index/), so your optimal ratio will vary depending on what cells you're using. I would test a range of concentrations on smaller batches of cells, and if you need to culture a transfected population, then use the optimal concentration to transfect a larger batch.

Hi, Nupur Shah,

We always use 60ul RNAiMAx to transfect about 20nM siRNAin 10cm dish. However, siRNA transfection efficiency may vary from the cell line you're using. I suggest you carry out a preliminary experiment to test the best ratio of RNAiMAX and siRNA, then use the optimal concentration to transfect.

We launched a product of Lipogene, with higher efficiency (>80% with 293 cells) but fewer cytotoxic effect. You could find the protocol of it attached.

Hope it helps.

Here is the scaling table: