The parent aptamer, MinE07-Biotin, produced a K d of 3.70 ± 0.38 nM consistent with the literature (Fig. Overall, we can see that FABS was essential to the identification of aptamers with a higher affinity for EGFR than MinE07; The exact number, type, and position of modifications was critical in creating a more successful aptamer, with the most promising aptamers (MinE07UA and MinE07UC) having binding affinities up to 3.3-fold stronger than that of the parent aptamer. Computational docking studies of aptamers with EGFR. Computational docking studies were performed to provide structural insight into the effect of the selected modifications. The secondary structure of the aptamer was calculated using ViennaRNA 2.0, and a 3D structure was generated using RNA Composer. Modifications were then manually added using Avogadro, and each strand was energy minimised. Docking was then performed using AutoDockTools. 58 , The docking results (Fig. ) confirm that the FABS selection procedure is essential to this method, and chemically modifying aptamers can improve their affinity for their desired target. Specifically, aptamers MinE07UA and MinE07UC gave the best K d values of all tested also produced the best EGFR docking scores, -23.2 and -21.7 kcal/mol. MinE07-U-Ph, MinE07-U-Vi, MinE07-U-I, MinE07UA'-Biotin and MinE07UC'-Biotin which were not selected from the MinE07Library by FABS, all give worse EGFR docking scores than MinE07. The general structure of MinE07 consists of the 5' and 3' ends rG(1)rGrAfCrGrG(4)/fC(9)fCrGfUfCfC( ) base pairing to create a duplex. This duplex points into the cavity which binds EGF in the crystal structure. It sits such that Pro7, Tyr13, Cys20, Tyr22, Asp7, Tyr29, Glu40, Arg41, Glu90, Asn91, Tyr93, Asn151 and Lys28 all hydrogen bond with the phosphate backbone. The rest of the aptamer forms three loops, which do not interact strongly with the protein, until in the third loop rG( )fUfC( ) associates with the second EGFR in the dimer, interacting with Ser222, Glu233, Glu258 and Lys269.