First, all the facts.
I'm using SA Chips (from Xantec) where small RNA is immobilized (~300 RU). I inject a protein where the RNA is binding to, and I want to determine the binding affinity at 37°C.
All my buffers are filtered, degassed and checked for RNase contamination.
I'm using a Biacore 3000.
I did this already successfully and now I want to reproduce it, and actually fail...
I immobilized a new Chip and did some test injections. They did not look perfect, but it seems to be on the right way.
Suddenly nothing worked. Directly at the injection start, there was a very intense spike and no binding was visible afterwards.I thought that the RNA is degraded after ~1 week at 37°C.
Therefore I immobilized a new chip.
The immobilization worked, but also here again just a spike is visible.
As I did this on different days, with different chips and with different aliqouts of the protein I can neglect air spikes.