Aptamers are single-stranded DNA or RNA (ssDNA or ssRNA)
molecules that can bind to pre-selected targets including proteins,
small organic compounds and nucleic acids with high affinity and
specificity. Aptamers specifically bind to the target molecule due to
their unique three-dimensional folded structures [3]. Several techniques
have been suggested to use aptamers as affinity ligands on
the stationary phase including on-line aptamer affinity chromatography
[4],