Synthesis and Characterization of Polyethylenimine-Coated Magnetic Nanoparticles for DNA Binding Toward Pollen-Directed Gene Delivery Applications

Abstract

Ensuring global food security remains a pressing challenge due to the growing world population and accelerating climate change. Genetic modification provides a pathway to developing crops with improved traits, yet conventional approaches rely heavily on tissue culture regeneration, which is complex, time-consuming, and often impractical for many crop species. Recently, pollen magnetofection has emerged as a tissue culture-independent alternative for plant genetic transformation. In this study, we investigated polyethylenimine (PEI)-coated Fe₃O₄ (Fe₃O₄@PEI) magnetic nanoparticles (MNPs) as potential carriers for pollen-mediated gene delivery, focusing on their synthesis, characterization, and DNA-binding capacity. The Fe₃O₄@PEI MNPs were synthesized via a one-step in situ coating method and their properties were compared with bare Fe₃O₄ MNPs synthesized separately. The nanostructures were systematically characterized in terms of size, morphology, crystal structure, surface functionalization, elemental composition, and magnetic behavior, confirming successful in situ PEI coating without post-synthesis modification. Compared to bare Fe₃O₄ MNPs, Fe₃O₄@PEI MNPs displayed reduced agglomeration, a more uniform size distribution, and improved colloidal stability. The nanoparticles had an average particle size of approximately 30 nm and an enhanced DNA-binding performance: up to 6 ng of linear DNA per $\mu $ g of MNPs (DNA/MNP mass ratio of 0.006:1) and complete retention of plasmid DNA across the tested range. These results support the feasibility of Fe₃O₄@PEI nanocarriers for pollen-directed gene delivery in plants.