Novel protein detection method based on proximity- dependent polymerase reaction and aptamers

In recent years, specific detection of proteins is one of the hot issues about aptamers in proteomics. Here we reported a simple, sensitive and specific proximity-dependent protein assay with dual DNA aptamers. Thrombin was used as the model protein, and two aptamer probes with complementary se- quence at 3′-end were designed for the two distinct epitopes of the protein. Association of the two ap- tamers with thrombin resulted in stable hybrids due to the proximity of 3′-end, then polymerase reac- tion was induced. The amount of obtained dsDNA was indicated using the fluorescence dye Sybr Green I. The results showed that the initial velocity of polymerase reaction had a positive correlation with concentration of thrombin. The advantages of this dual-aptamer-based approach included simple and flexible design of aptamer probes, high selectivity and high sensitivity. The detection limit was 6.9 pmol/L.