Rapid Development of DNA Aptamers for Agent Identification, Tracking and Neutralization

DNA aptamers are artificial nucleotide sequences that bind to target molecules with affinity and specificity similar to those of antibodies. High specificity, stability and low cost of aptamers make them superior modalities for detection of biodefense toxin and biological threat agents. Specific DNA aptamers are selected from combinatorial libraries by series of iterative selection/amplification cycles called SELEX (Systemic Evolution of Ligands by EXponential enrichment). Separation of aptamer/target complexes from unbound aptamers is a key step in the enrichment process and a variety of technical approaches have been used. However, all of currently available protocols for selection of aptamers require numerous selection cycles with enzymatic amplification steps that may produce artifacts. Ultimate improvement of both selection time and selection specificity could be achieved by developing a single step selection protocol. We propose a novel NON-SELEX-based approach for single step DNA aptamer selection. The Phase I effort will provide essential data for the proof of methodology concept and will set the stage for identification of specific aptamers. Further evaluation of PSI’s novel technology will be carried out by extending it to selection of aptamers against biodefense-relevant targets in Phase II.