Which types of lipids are you using?

What is the size of plasmid?

And absolutely you can't use nanodrop for determine concentration of liposome.

Do you want tranfect cell lines in vivo or in vitro?

Regards.

Each liposome system has its own instructions, so I highly recommend you to read your kit instructions to figure out how much DNA/liposome you need. Also, you should consider your plasmid size and purity and the cell type that will be transfected. Some liposomes are toxic to variant types of cells which leads to pay attention to how much of DNA/liposome complex will you add and for how long. Hope, these tips would help you.

Mr. Alireza Mordadi thank you for following up my question.

Liposome ingredients in my experiment are: pc, cholestrol, vit E and glycerol. I use PBS for hydration.

Plasmid: 4.7 kb

I want to transfect in vitro.

I would be grateful if you guided me through this. 

When you want tranfect cells in vitro it's not make sense to use liposom, first of all but if you instead you have to make your liposom loaded with plasmid and make it unilamellar liposom and then use dialysis method to wash plasmid aren't loaded. In this procedure play with con of cholesterol to find optimal for having stable liposom. After this procedure you can use gel filtration or rHPLC to determine con of liposome and loaded plasmid.

And then you can decide how much of your liposome would be enough for tranfection.

But I strongly recommended this way is wasting of time and materials while you have another points.

Every steps that I mentioned have their own protocol that you can find them easily in articles.

Regards.