I used to patch in acute slices and in slice cultures (whole cell), without any unresovled problems. As I now (after a break) moved "back" to dissociated cortical neurons, I was surprised how difficult the switch was. In the meantime I managed to get a few recordings, but still have technical problems.
The most annoying is, that every second (or even more often) pipette gets clogged very fast. I do not need more than a few minutes to approach the cell, but often I can already see that there is something in the tip (a bright dot, as if the pipette would have no opening at all). Then, when trying to get a gigaseal through sucking, no pressure is arriving at the membrane.
Ok here some details what I did to prevent some sources of clogging:
All solutions are sterile-filtered (0,2 µm), the intra even twice, because I use another filter on the filling syringe. To avoid scraping (and thus creating flushable particles) of my Microfil, I firepolished my glasware before pulling the pipettes. I am NOT using positive pressure to approach the cells, this did not prevent clogging anyway.
So my feelings at the moment are, that something is wrong with my intra. Do you think wrong osmolarity could cause this problem? So that something precipitates at the pipette tip? Because I am not used to adjust the osmolarity form my former experience, I did not do it now.