Figure 1: (a) Chemical structure of chitosan-PEG-CP15 polymer; (b) 1H NMR spectra of chitosan-PEG-CP15 (CS-O-PEG-CONH-CP15). The multiple peaks of oxymethyl groups in PEG at δ 3.3 to 3.7 cover over the signals of pyranose ring of chitosan. The multiple peaks at δ 6.0–9.0 belong to the peptide CP15 sequence, respectively. (c) A nanoparticle formulation with a core formed by chitosan polymer, surface functionalized with PEG, and a cell-targeting peptide (CP15). The formulation encases a biotin-tagged siRNA.