SELEX protocols comprise multiple rounds of selection, each of which require regeneration of bound ligands, which in turn require fixed primer sequences flanking the random library regions. These fixed primer sequences can interfere with the selection process (false positives and negatives). Here we present a primer-free protocol.
Pan, W., Xin, P., Patrick, S., Dean, S., Keating, C., Clawson, G. Primer-Free Aptamer Selection Using A Random DNA Library. J. Vis. Exp. (41), e2039, doi:10.3791/2039 (2010).