Fig. 1. CPP-mediated siRNA intracellular delivery.
A). Schematic illustration of formulation schemes for CPP-mediated siRNA cell entry. (1) CPP-siRNA conjugate; (2) CPP-siRNA nanocomplex; (3) siRNA anchored on an antibody-CPP conjugate; (4) hairpin-structured activatable CPP conjugated with siRNA. B) The helical wheel showing the amphiphilicity of α-helical CPPs: Penetratin, CADY, and KALA. Amino acids are color coded (red: charged; orange: apolar; yellow: polar; gray: hydrophobic).