Investigation of Library Input on Aptamers Selection Efficiency Using Capillary Electrophoresis

Abstract

Capillary electrophoresis (CE) is a high-efficiency method for aptamer selection, which exhibits many merits of high resolution, rapid separation, little sample consumption, and no immobilization. However, the influence of injection input on CE systematic evolution of ligands via exponential enrichment (SELEX) is controversial because the low injection volume may result in an insufficient capacity of the oligonucleotides library. In this research, neuron-specific enolase (NSE) was used as a model protein to investigate the effects of library input capacity on aptamer selection for clarifying the validity of CE-SELEX. Four different concentrations of initial libraries (0.1, 1, 10 and 100 μmol/L) were utilized into aptamer selection. The affinity of the initial library and sub-libraries after three rounds of selection were evaluated. The results showed that there was no significant difference in the affinity of four different sub-libraries, and aptamers with micromolar dissociation constant ( K D ) were all obtained after two rounds of selection. In addition, the sequences obtained via high concentration ssDNA library screening were more diverse, but the affinity of them was not enhanced. The NSE aptamer Seq qN-01 obtained by two rounds of selection had a K D of (4.72 ± 0.15) μmol/L, and also presented a good specificity. In conclusion, library input capacity could increase the sequence diversity but had no considerable effects on the efficiency of aptamer selection. CE-SELEX was employed for screening the aptamers of neuron-specific enolase (NSE). Four ssDNA libraries of different concentrations (0.1, 1, 10 and 100 μmol/L) were utilized to investigate the effects of input capacity of library on aptamer selection efficiency by comparing the affinity between rounds, sequence diversity and candidate sequences affinity.