Investigation of the interaction between split aptamer and vascular endothelial growth factor 165 using single molecule force spectroscopy.

Understanding the binding of split aptamer/its target could become a breakthrough in the application of split aptamer. Herein, vascular endothelial growth factor (VEGF), a major biomarker of human diseases, was used as a model, and its interaction with split aptamer was explored with single molecule force spectroscopy (SMFS). SMFS demonstrated that the interaction force of split aptamer/VEGF165 was 169.44 ± 6.59 pN at the loading rate of 35.2 nN/s, and the binding probability of split aptamer/VEGF165 was dependent on the concentration of VEGF165 . On the basis of dynamic force spectroscopy results, one activation barrier in the dissociation process of split aptamer/VEGF165 complexes was revealed, which was similar to that of the intact aptamer/VEGF165 . Besides, the dissociation rate constant (koff ) of split aptamer/VEGF165 was close to that of intact aptamer/VEGF165 , and the interaction force of split aptamer/VEGF165 was higher than the force of intact aptamer/VEGF165 . It indicated that split aptamer also possessed high affinity with VEGF165 . The work can provide a new method for exploring the interaction of split aptamer/its targets at single-molecule level.