Ternary si-NP synthesis and structural characterization. (A) The four RAFT-synthesized polymers utilized for siRNA packaging and delivery. (B) Three sub-classes of ternary si-NPs were formed with a balance of hydrophobic BMA monomer copolymerized with cationic DMAEMA in either the core (DB-PD), corona (D-PDB), or both (DB-PDB). For formulation of ternary si-NPs, (C) core-forming, binary pre-NPs were made at varying N:P ratios (D: 0.5:1, 2:1; DB: 2:1, 4:1). (D) Ternary si-NPs were then formed by adding a PEGylated, corona-forming polymer to the binary complexes. The relative amount of the second polymer added dictates the degree of surface PEGylation. (E) Nomenclature used to identify ternary si-NPs.