Since the hybridization power of the bis-conjugates against RNA sequences was shown to be higher than that of the structurally related mono-conjugates due to additional electrostatic interaction (see Figure S1) [39], the gel-shift experiments and the measurements of Ka values were limited to the mono-conjugates miR-17–BC-α, miR-17–BC-β, miR-21–BC-α1, and miR-21–BC-β1. Here, PPIB is linked to breast cancer.