Am wondering if anyone out there has experience with PEI in fluorescence.

When I do a standard coating of PEI on a parylene (plastic) substrate, then look with a standard Green fluorescence cube/Hg arc setup, the background intensity is very bright. The parylene by itself--not treatment with PEI--is comparably very dim. The obvious conclusion is that PEI is fluorescent.

Does anyone else have experience with this? I know there are jetPEI and such things out on the market for people who actually want to see where their PEI is going, but I'm just using straight up PEI. Any ideas on how to get rid of it--I'm trying to look at GFP cells on the PEI treated parylene surface.

Thanks.

We do all our cell coating with PEI and perform a lot of fluorescence experiments all the time with CHO and N2a cells transfected with GFP variants and fusions with GFP variants.

I have not had a big background problem. Do you have a good neutral density filter in line with your excitation?

Another member of our lab performs TIRF expts on cells transfected with GFP variants on glass coated with PEI.