In vitro cell uptake of biocompatible magnetite/chitosan nanoparticles with high magnetization: A single-step synthesis approach for in-situ-modified magnetite by amino groups of chitosan

Current attempts for synthesizing chitosan-modified magnetite nanoparticles (CS-MNPs) as drug carrier involve use of surfactants, which brings potential cytotoxicity and decrease of saturated magnetization (Ms). To address this, we developed a facile single-step method for synthesizing CS-MNPs. The developed method offers several advantages. No surfactant was involved and the magnetite nanoparticles were in-situ-coated with a chitosan (CS) layer, which endows the CS-MNPs with enhanced physical and chemical properties. The Ms of magnetite was significantly increased (55.5 emu/g) as compared to magnetite nanoparticles modified by surfactants with oxygen ligands, indicating their potential applications as drug-delivery systems (DDSs) where high saturated magnetization (Ms) is preferred. Besides, the amount of CS layer of CS-MNPs was approx. 24 wt%, which makes the synthesized CS-MNPs highly biocompatible as no acute adverse effect of the viability on MG-63 cells was observed at doses up to 0.2 mg/ml. Macropinocytosis is the main endocytic mechanism of MG-63 cells internalize CS-MNPs, which might avoid lysosomal degradation of the CS-MNPs. The synthesized CS-MNPs have potential applications in the fields of targeted drug delivery, separation for purification and immunoassay and magnetic resonance imaging.