Preparation of PEI-modified nanoparticles by dopamine self-polymerization for efficient DNA delivery

Achieving efficient and safe gene delivery is of great significance to promote the development of gene therapy. In this work, a polydopamine (PDA) layer was coated on the surface of Fe₃ O₄ nanoparticles (NPs) by dopamine (DA) self-polymerization, and then magnetic Fe₃ O₄ NPs were prepared by the Michael addition between amino groups in polyethyleneimine (PEI) and PDA. The prepared Fe₃ O₄ NPs (named Fe₃ O₄ @PDA@PEI) were characterized by Fourier transform infrared (FTIR), atomic force microscopy (AFM), and scanning electron microscopy (SEM). As an efficient and safe gene carrier, the potential of Fe₃ O₄ @PDA@PEI was evaluated by agarose gel electrophoresis, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, fluorescence microscopy, and flow cytometry. The results show that the Fe₃ O₄ @PDA@PEI NPs are stable hydrophilic NPs with a particle size of 50-150 nm. It can efficiently condense DNA at low N/P ratios and protect it from nuclease degradation. In addition, the Fe₃ O₄ @PDA@PEI NPs have higher safety than PEI. Further, the Fe₃ O₄ @PDA@PEI/DNA polyplexes could be effectively absorbed by cells and successfully transfected and exhibit higher cellular uptake and gene transfection efficiency than PEI/DNA polyplexes. The findings indicate that the Fe₃ O₄ @PDA@PEI NPs have the potential to be developed into a novel gene vector.