Expanding the application potential of DNA aptamers by their functionalization

Side-by-side development of two competing technologies for obtaining affinity antibody-based and aptamer-based molecules opens new horizons for the creation of diagnostic and therapeutic agents of extremely high efficiency. Benefits of aptamers, such as relatively small size and selection simplicity, have been jeopardized for a long time by their intrinsic downsides, i.e., obscure process of obtaining aptamers against certain targets because of a low diversity of functional groups (purine and pyrimidine bases) in DNA and RNA aptamers. Another side effect of the aptamer technique inherent to the traditional SELEX method is unspecific enrichment with aptamers with high affinity to off-target reaction components. Today, due to current progress in the development of new technology methods and chemical coupling reactions, the modern aptamer technology helps to avoid its disadvantages and become capable of being the source of new diagnostic and therapeutic tools, which are properly unique in their efficiency. The review focuses on modern methods of increasing efficiency of the aptamer selection and on synthetic nucleotide modifications, which make it possible to prepare high-affinity aptamers against traditionally ‘hard’ targets.