Impact of Polyethylenimine Conjugation Mode on the Cell Transfection Efficiency of Silica Nanovectors

The conjugation of polyethylenimine (PEI) to silica nanoparticles has emerged as a useful strategy in gene delivery. Here we investigate the influence of the PEI conjugation mode on the transfection ability of plain silica nanoparticles. Surface functionalization with sulfonate- and chloride-bearing silanes modulates the amount and conformation of PEI and therefore the particles' affinity for the plasmid, without impacting on cytotoxicity. transfection efficiency in both immortalized and primary cells is more directly correlated to the nature and strength of the particle PEI interactions. It suggests that PEI detachment from the particle surface at the stage of endosomal escape is a key event in the plasmid delivery process. These data should provide fruitful guidelines for the fine tuning of colloidal surfaces intended for intracellular delivery of bioactive molecules.