A stabilized multimodular assembly for intracellular delivery comprising a complex of at least one cationic transfection agent and of at least one negatively charged macromolecule, wherein the complex has a theoretical charge ratio ranging from about 0 to about 4, and an efficient amount of at least one amphiphilic block co-polymer acting as a steric colloidal stabilizer with respect to the complex, the block co-polymer having hydrophilic and hydrophobic blocks wherein at least one hydrophilic block is conjugated with at least one targeting ligand.