AMPure XP beads are tiny magnetic particles suspended in a solution of water, salt, polyethylene glycol and Tris buffer. When this solution is added to DNA suspended in water, it causes the DNA to precipitate out of solution. This allows the DNA to be cleaned and concentrated. I use these beads extensively in Whole-Genome-Shotgun (WGS) library preparation as well as Genotyping-by-Sequencing (GBS) library preparation.
The only problem with AMPure XP beads is that they are too expensive for me to use on a regular basis. Luckily, this paper describes a cost-efficient method of producing a home-made version and after a bit of searching I also located this blog post that included a step-by-step protocol for making home-made AMPure XP beads.
The total cost of the reagents came to approximately $950.00, and I was able to produce 750 mL of solution. This comes out to $1.27 per mL. Wow! The savings!
To test the beads, I cleaned up a 100 bp ladder with both the commercial AMPure XP beads and the home-made ‘Speed Beads’ and ran the results on an agarose gel. I found that the home-made version performs the same as the commercial version. Since then, I have done further testing and am very happy with the quality of the home-made beads.