Aptamers in clinical diagnostics

Aptamers are single-stranded DNA or RNA oligonucleotides selected in vitro from combinatorial libraries in a process called SELEX (Systematic Evolution of Ligands by EXponential Enrichment). Aptamers play a role of artificial nucleic acid ligands that can recognize and bind to various organic or inorganic target molecules with high specificity and affinity. They can discriminate even between closely related targets and can be easily chemically modified for radioactive, fluorescent and enzymatic labeling or biostability improvement. Aptamers can thus be considered as universal receptors that rival antibodies in diagnostics as a tool of molecular recognition. To date aptamers have been successively used instead of monoclonal antibodies in flow cytometry, immunochemical sandwich assays and in vivo imaging as well to detect wide range of small or large biomolecules.