DNA purification and isolation using a solid-phase

Preparation and manipulation of high quality DNA is a vital step in molecular biology. Although there are many methods reported for single and double stranded DNA isolations there are few procedures that are rapid, low cost and procedurally identical for all DNA types, from plasmids to single copy BAC clones. We have noted that under conditions of high polyethylene glycol (PEG) and salt concentration (10% PEG 8000 and 1.25 M NaCl final concentrations), DNA would bind to the surface of carboxyl coated magnetic particles. Once bound, the DNA-bead complex could be extensively washed and finally eluted in water to yield purified DNA. We have used carboxyl coated magnetic particles (Cat No. #8-4125B) available from PerSeptive Diagnostics (Cambridge, MA) for all our applications. These particles are 1 mu M in diameter, are superparamagnetic and display iron as well as the carboxyl groups on the surface. These surface features are important since we have obtained reduced yields when either the iron or the negative charge are removed from the solid-phase surface. We have adapted the procedure, called SPRI (solid-phase reversible immobilization) for use in all scales of template preparations and manipulations. As well as the standard mini, midi and maxi prep scales, we have also demonstrated the use of the SPRI technology in the extraction of DNA from agarose.