I have a Polyjet that has passed its labeled expiration date for 1 year and I'm going to re-start transfection experiments. It is really needed to change it? Transfection efficiency may be lower?
No, it is better you don’t use Polyjet once it has passed its expiry date. You need to use a fresh vial. I never encourage the use of expired reagents. You will end up with unreliable results. Moreover, the experiment may have to be repeated which will only result in wastage of time and resources.