DynaBeads - mixing procedure (Sep/12/2008 )
Does anyone have some advice on how to mix the RNA sample and magnetic beads within the microfuge tube when using Invitrogen's DynaBeads mRNA extraction kit? I am currently flicking the tube till no beads remain on the bottom, but I can see small droplets remain on the wall of the tube after doing this. If I do a short spin to collect these I am back at square one as all the beads go down as well. I am working with very limited samples, so the beads on the wall are probably causing a small but avoidable loss in the amount of mRNA recovered. Any advice would be greatly appreciated.
Flicking the tubes probably isn't the best. I mix each step, slowly/gently, with my pipette and ensure that the tip is always just below the meniscus as as I do it. You can always reload the beads into the lysis mixture after you have eluted the first pass. Just keep the two elutions separate until you know that you are getting a good yield off the second pass before mixing. Hope that made sense to you. The results I had using this kit were very very good and it was very fast. A good combo.
With a bit of searching you can find the pre-Invitrogen Dynabead mRNA protocols. They give you a much better indication of how to scale reactions and regenerate beads if you are preparing batches of the same sample.