Monodispersed grafted conjugated polyelectrolyte-stabilized magnetic nanoparticles as multifunctional platform for...

An anionic grafted conjugated polyelectrolyte was synthesized, and then magnetic nanoparticles stabilized with this material were successfully prepared by a convenient method and used for bioimaging and drug delivery. Grafted conjugated polymer (PFPAA) containing abundant carboxyl groups was attached to the surface of Fe₃O₄ nanoparticles through ligand exchange with oleic acid and anionic grafted conjugated polyelectrolyte-stabilized magnetic nanoparticles (MNPs@PFPANa) were then obtained by ionization with sodium carbonate. These as-synthesized nanoparticles showed good water solubility and stability, with no precipitation observed in 8 months, and had a narrow size distribution with a mean hydrodynamic diameter of 26 ± 2.4 nm. In addition, these nanoparticles exhibited superparamagnetic properties with a saturation magnetization (M_s) of 20 emu g^-1, which sufficient for bioapplications. Upon 48 h incubation with macrophage cells, the obtained nanoparticles showed good biocompatibility of 2 pg Fe per cell as measured by ICP-OES. Furthermore, MNPs@PFPANa were low toxicity as confirmed by an MTT assay using NIH-3T3 fibroblasts. Confocal microscopy results revealed that MNPs@PFPANa can be retained in cytoplasm with high fluorescence. MNPs@PFPANa exhibited good DOX drug loading efficiency of about 10 wt% and showed good therapeutic efficiency for BGC-823 cancer cells. These results indicated such multifunctional nanoparticles would be useful in bioimaging and as drug carriers for cancer treatment.