Synthesis and characterization of oligopeptide modified C6 polymer library. (a) Structure and synthetic scheme of oligopeptide-modified pBAEs. R” terminal can be arginine-, lysine-, histidine-, glutamic acid- and aspartic acid- oligopeptides. (b) Polyplexes with different surface proprieties were obtained by combining different oligopeptide moieties. (c) Average hydrodynamic diameter, polydispersity, and zeta potential determination of pBAE:siICAM2 nanoparticles prepared at 75:1 ratio (w:w) with different oligopeptide-modified pBAE polymers were determined by DLS. n = 3, data shown as mean ± SEM.