I am using PEI (polysciences, cat 23966-2) to transfect HeLa. I tried Plasmid:PEI 1:2,1:3 and 1:4. however, the transfection efficiency is about 5%. There is a protocol on the website which uses NaCl solution instead of opti-MEM to dilute DNA, I don’t know if it is worth to try that.

Do you guys have any idea?

Here is the detailed protocol I used:

Seed Hela in 24 well plate 24 hrs before at 60% confluency

Next day, change for complete media without antibiotics, 500ul/well.

In a tube, dilute 1ug GFP-plasmid in 50 ul opti-MEM. Dilute separately 2,3,4ug PEI in 50 ul opti-MEM

Mix PEI with DNA by pipette 15 times.

Incubate for 15 minutes at room temperature.

Add DNA/PEI mix dropwise onto cells, gently swirl plate for a few seconds to mix the components.

24h later, check the efficiency.