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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 Fe3O4 nanoparticles (NPs) by dopamine (DA) self‐polymerization, and then magnetic Fe3O4 NPs were prepared by the Michael addition between amino groups in polyethyleneimine (PEI) and PDA. The prepared Fe3O4 NPs (named Fe3O4@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 Fe3O4@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 Fe3O4@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 Fe3O4@PDA@PEI NPs have higher safety than PEI. Further, the Fe3O4@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 Fe3O4@PDA@PEI NPs have the potential to be developed into a novel gene vector.

Polyethylenimine (PEI) is considered as the gold standard for evaluating non‐viral gene vectors due to its proton sponge effect and high transfection efficiency. However, its cytotoxicity limits its application. Rice bran polysaccharide (RBP) is rich in nature and beneficial for preparation of biodegradable biomaterials. In this work, three PEI modified RBP‐Fe complexes (PIP‐1, PIP‐2, and PIP‐3) were prepared based on RBP with different molecular weight (Mw). Then the potential of PIP complexes for plasmid DNA (pDNA) delivery and the influence of Mw was studied. PIP complexes showed better safety and higher gene transfection efficiency than PEI. PIP‐1 was prepared by RBP with lower Mw and could formed PIP‐1/pDNA nanoparticle with lower particle size which exhibited higher gene transfection efficiency than other PIP complexes prepared by RBP with higher Mw. The results indicate that the PIP/pDNA complex exhibits a multi‐pathway cellular uptake mechanism. Clathrin dependent and caveolin dependent endocytosis and macropinocytosis were involved in the cellular uptake process of PIP/pDNA complex. It is hoped that this study can provide useful enlightenment for the research and development of gene vector based on polysaccharide.