Nucleic Acid Aptamers: New Methods for Selection, Stabilization, and Application in Biomedical Science

The adoption of oligonucleotide aptamer is well on the rise, serving an ever increasing demand for versatility in biomedical fi eld. Through the SELEX (Systematic Evolution of Ligands by EXponential enrichment), aptamer that can bind to specifi c target with high affi nity and specifi city can be obtained. Aptamers are single-stranded nucleic acid molecules that can fold into complex threedimensional structures, forming binding pockets and clefts for the specifi c recognition and tight binding of any given molecular target. Recently, aptamers have attracted much attention because they not only have all of the advantages of antibodies, but also have unique merits such as thermal stability, ease of synthesis, reversibility, and little immunogenicity. The advent of novel technologies is revolutionizing aptamer applications. Aptamers can be easily modifi ed by various chemical reactions to introduce functional groups and/or nucleotide extensions. They can also be conjugated to therapeutic molecules such as drugs, drug containing carriers, toxins, or photosensitizers. Here, we discuss new SELEX strategies and stabilization methods as well as applications in drug delivery and molecular imaging.