To understand the nucleolin-aptamer binding interactions, we had to perform molecular docking simulations, and to do that after 3d structure should be obtained. Therefore, we have performed these two steps to get the aptamer 3D structure. First, Vfold2D predicted aptamers' secondary structures, as seen in Figure and Table . The 3D shape of the aptamer depends on its base pair interactions (hydrogen bonds) in its secondary structure. Nucleic acids, particularly aptamers, are often represented by dot-bracket notation. This notation indicates paired and unpaired bases using dots, brackets, and other symbols. Second, the 2D images also provide dot-bracket notations of the specific aptamers, which helps determine their 3D structure. Many researchers use these 2D images to predict the similarity/difference between aptamers based on the hypothesis that similar 2D aptamers should have similar binding patterns. In this situation, all aptamer secondary structures have distinct binding patterns.