I have been trying to set up an injection setup in the lab : a pump driving hamilton syringe that is connected with tubing and glass pipette at the other end. All of which filled with soft mineral oil.
Then I withdraw virus into the glass pipette with the help of pump. When I tried to stick the glass pipette into the cranial window, it sucked up the residual blood sitting on top of the brain.
Does anyone have any idea what could be the reason or how I can resolve it?
Thank you.
Gokhan Senturk
Dear Gokhan:
It seems to me that surface tension/adhesion forces might be responsible for the unwanted aspiration of blood by your glass pipette. In my experience, these forces can be neutralized by a hydrodynamically rigid injection system that consists of metal and/or glass only. That being said, the key to the solution of the problem may just be the removal of the interposed tubing (and possibly free-hand injection). Good luck!
Dear Marc-Eric, thanks for the advise, but I have used that system with tubing etc. in a different lab and it was working perfectly fine. I was wondering whether the capillary action is the cause behind it. So maybe changing the dimensions of the glass pipette tip? or it is also possible that pump applies a negative pressure in the stand by position
Dear Gokhan:
Thank you for the clarification. If the pump was the cause you should be able see retraction of fluid within the pipette tip even before touching blood, correct? Just to be sure, you could clamp the tubing and check. If that doesn't show anything, I would probably try a larger-bore pipette. Is the mineral oil that you are using the same as you have used before?
Dear Marc-Eric,
Everything is the same (including mineral oil) except the pump and the dimensions of the glass pipette tip. So I will try playing around with the glass pipette puller parameters to see what is gonna happen.
Clamping sounds like a good idea.
Thanks