In vitro clonal amplification: Molecular detection methods are not sensitive enough for single molecule sequencing, so most approaches use an in vitro cloning step to amplify individual DNA molecules. Emulsion PCR isolates individual DNA molecules along with primer-coated beads in aqueous bubbles within an oil phase. Polymerase chain reaction (PCR) then coats each bead with clonal copies of the DNA molecule followed by immobilization for later sequencing.
Emulsion PCR is used in the methods by Marguilis et al. (commercialized by 454 Life Sciences), Shendure and Porreca et al. (also known as "polony sequencing") and SOLiD sequencing, (developed by Agencourt, now Applied Biosystems).
Another method for in vitro clonal amplification is bridge PCR, where fragments are amplified upon primers attached to a solid surface. The single-molecule method developed by Stephen Quake's laboratory (later commercialized by Helicos) skip