Aptamers their biological-therapeutical applications: A riview article

Aptamers are the artificial single-stranded DNA or RNA sequences (more recently, peptides) that fold into secondary and tertiary structures making them bind to certain targets with extremely high specificity. Aptamers were reported for the first time in 1990, a number of their unique features make them a more effective choice than antibodies. Aptamers typically generated through Systematic Evolution of Ligands by EXponential enrichment (SELEX) and screened and selected via in vitro process from a library, making it possible to attach to any target molecules (from small inorganic ions to intact cells). Also, aptamers, once selected, can undergo subsequent amplification through Polymerase Chain Reaction (PCR) to produce a large quantity with high purity. The simple chemical structure of aptamer makes it easily amendable to further functional modifications according to different purposes. Finally, aptamers are much more stable than antibodies, making them suitable in applications requiring harsh conditions (e.g., high temperature). The increasing studies and explorations in the fields of diagnostics and therapeutics are running. It is likely that in the near future, aptamers will increasingly find use in concert with other therapeutic molecules. In the current review article, the reasons why aptamers are known as alternatives to antibodies are presented. Furthermore, various applications of aptamers including diagnostics, therapeutics, molecular imaging and drug delivery were introduce. Several types of in vitro selection processes are explained in detail.