Are you sure that you properly conferred resistance to the antibiotic? If it makes all of your cells die then you might have a problem with the plasmid or its transfection into cells. Depending on the cell line, you'll need to find appropriate reagents (my favorite catalog is here: https://altogen.com/products-index/) and then maybe add another marker (like GFP) to see if your cargo is getting inside cells. If it turns out you are having successful transfections, then your issue is likely that the plasmid doesn't confer resistance to the antibiotic, and you might want to look at other selection routes then.

Throw away your antibiotic and make a fresh batch. The negative control should die in the presence of the antibiotic, regardless of contamination issues.

This is a commercial antibiotic. I though about contamination and I bough a new one. Same result, and it's sealed, I opened the bottle inside the cell culture hood.

I would sterilize my hood and transfect a positive control plasmid to verify that the transfection itself is working. If you still see contamination (not apoptotic bodies), then it's best to just try again with new reagents and clean instruments.

Are you sure that you properly conferred resistance to the antibiotic? If it makes all of your cells die then you might have a problem with the plasmid or its transfection into cells. Depending on the cell line, you'll need to find appropriate reagents (my favorite catalog is here: https://altogen.com/products-index/) and then maybe add another marker (like GFP) to see if your cargo is getting inside cells. If it turns out you are having successful transfections, then your issue is likely that the plasmid doesn't confer resistance to the antibiotic, and you might want to look at other selection routes then.

Hi Danillo, Have you resolved the issue yet because I am having the same problem at the moment?