I am currently sorting PU1+ and PU1- nuclei populations from mouse tissue, but am having issues with losing the nuclei post sort, presumably as they are sticking to the sides of the tube. The collected PU1+ nuclei range from around 70-100k per hemisphere currently. I am using low bind eppendorfs to sort with, into PBS + EDTA. It seems that adding FBS or BSA to the sorting buffer seems to help this situation, however the samples are intended for mass spectrometry and these will interfere. Is there any other solution that may help with the sticking situation that is compatible with mass spect? Currently we are centrifuging at 500g post-sort, as unfixed tissue was used, is it possible that slightly faster centrifugation (1000g) would help pelleting or would be detrimental to the nuclei?
Try to use PVP in that solution. I use to use for early embryos or blastomeres to avoid sticking to glass. In IVF, people use this to avoid sperm sticking to glass needle. You can prepare your own PVP solution or buy ready made solution, you can use lower concentration of PVP than people have used.