Penetration through the cell membrane, endosomal escape and nuclear entry are the main barriers that transfection agents have to overcome. We prepared multi-shell calcium phosphate nanoparticles that were functionalized with DNA, polyethyleneimine (PEI) and protamine in order to improve transfection efficiency. PEI-functionalized calcium phosphate nanoparticles showed a high transfection efficiency, which was correlated with cytotoxicity. Additional functionalization with protamine effectively reduced the cytotoxic effects of PEI, while maintaining the high transfection efficiency. Size, surface charge and morphology of multi-shell nanoparticles were analyzed by dynamic light scattering and scanning elec-tron microscopy. The influence of nanoparticle concentration on the transfection efficiency and cell viability was tested on HeLa and MG-63 cell lines. Protamine-functionalized multi-shell calcium phosphate nanoparticles can serve as an efficient and non-toxic gene carrier for cells.
Key words: calcium phosphate, nanoparticles, gene transfer, cell viability, fluorescence