ABSTRACT
Since the first reports of the isolation of protein-and nucleotide-
binding oligonucleotides isolated from a combinatory library1,2
of molecules, oligonucleotide aptamers have become a widely
established class of binders being an alternative to protein-
based antibodies. Oligonucleotide aptamers are short sequences
of single-stranded DNA and RNA molecules. The spectrum of
targets is large, ranging from small molecules, such as caffeine
and peptides over proteins, to complex molecular structures, such
as viruses and bacteria. This wide variety of molecules can be
addressed with high specificity and affinity. So far reports exist
about hundreds of different targets that have successfully been
used for aptamer selection.2a In addition, the animal-free in vitro
selection of specific aptamers from a library of about 1012 to
1016 randomized oligonucleotide sequences enables the use of
haptens and toxic substances as targets.3 The chemical synthesis
of the identified binders enables a site-directed introduction of a
large variety of modifications. Bulk-scale synthesis guaranties fast
and relatively uncomplicated upscaling and high batch stability.
Moreover, oligonucleotide aptamers possess proteinase and heat
stability.3 The heat treatment permits sterilization processes, which
makes aptamers attractive binder alternatives for antibodies but
also for specific affinity materials in downstream processes or
plasmaphresis. DNA aptamers show an appropriate stability toward
DNases, permitting their use in biological fluids such as blood
and serum. Moreover, known from the antisense technology, small
chemical variations of the molecules will improve their stability.3
