Size-dependent properties of M-PEIs nanogels for gene delivery in cancer cells

Polyethyleneimine nanogels (named as M-PEIs) with different sizes were prepared by photo-Fenton reaction in aqueous solution from which samples of 38, 75, 87, 121, 132 and 167 nm were selected for in vitro transfection. The homogeneous structure and the same component made it possible to study the size effect of M-PEIs nanogels on gene transfection efficiency when loading the same quantity of plasmid DNA (pLEGFP-C1) into A549, Bel7402, BGC-823 and Hela cells. M-PEIs and its DNA complexes were characterized by photo correlation spectroscopy and atomic force microscopy. The protein expression was observed by flow cytometry and fluorescence microscopy. All of the DNA complexes had no obvious cytotoxicity and the surface charges were positive charged at the optimum weight ratio. Therefore, the expressed protein was affected by the size of M-PEIs when the same quantity of DNA was used to transfect cells. In addition, the samples of 75 and 87 nm yielded the highest transfection efficiency about 30% in all of the four cell lines which were also cell line independent.