Theoretical analysis of the evolutionary principle of aptamers

SELEX (Systematic Evolution of Ligands by Exponential enrichment, SELEX) has become a novel technology for aptamer selection from libraries of random oligonucleotides. This is an iterative process of incubation, separation and amplification through an affinity method and polymerase chain reaction. Although many SELEX experiments have been carried out, only a few theoretical studies reported on the aptamer enrichment can be found at present. This study analyzes the factors affecting SELEX enrichment under the experimental conditions (K-d1 =140 nM; K-d2 =450 nM; [Tf] =300 nM and K-CL = 100) including target concentrations, efficiencies of partitioning and dissociation constants. Investigated results suggest that decreasing target concentrations and dissociation constants K-d1 for the winning aptamers and increasing efficiencies of partitioning tend to improve enrichment fraction F-1((r))/F-2((r)).