ABSTRACT
This chapter describes several selection strategies employed for the selection of aptamers. Aptamers are rare functional nucleic acids that are isolated from a library of combinatorial nucleic acids by iterative rounds of selection and amplification. Aptamers are isolated from completely random pools of nucleic acids in libraries that typically consist of 10 molecules using a specific ligand. The general procedure for the selection of aptamers involves incubating a pool of nucleic acids with a target of choice under an appropriate buffer condition, in which the ligand acquires its native conformation, followed by separating the free from ligand-bound nucleic acids. The selection of aptamers involves primarily three important steps: random pool design and preparation, selection of target-bound aptamers, and amplification of the bound aptamers. Several methodologies are available to separate the free, or target-unbound, aptamers from the complexed, or target-bound, aptamers.
