PEI Nanoparticles for Targeted Gene Delivery.

INTRODUCTION This protocol describes the preparation of polyethylenimine (PEI)/DNA nanoparticles for targeted gene delivery. This delivery strategy improves the efficiency of gene transfer by enhancing the entry of gene vectors into the desired cells and reducing uptake by nontarget cells. We describe here methods for the conjugation of targeting peptides to PEIs, formation of DNA complexes using the conjugated PEIs or nonconjugated PEIs together with targeting peptides, and cell transfection using these complexes. The conjugation step involves the use of the succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate (SMCC), a heterobifunctional cross-linker, to form a stable bond between PEI and peptides containing thiol groups.