Construction of magnetic nanochains to achieve magnetic energy coupling in scaffold

Fe₃O₄ nanoparticles are highly desired for constructing endogenous magnetic microenvironment in scaffold to accelerate bone regeneration due to their superior magnetism. However, their random arrangement easily leads to mutual consumption of magnetic poles, thereby weakening the magnetic stimulation effect.

In this study, magnetic nanochains are synthesized by magnetic-field-guided interface co-assembly of Fe₃O₄ nanoparticles. In detail, multiple Fe₃O₄ nanoparticles are aligned along the direction of magnetic force lines and are connected in series to form nanochain structures under an external magnetic field. Subsequently, the nanochain structures are covered and fixed by depositing a thin layer of silica (SiO₂), and consequently forming linear magnetic nanochains (Fe₃O₄@SiO₂). The Fe₃O₄@SiO₂ nanochains are then incorporated into poly l-lactic acid (PLLA) scaffold prepared by selective laser sintering technology.

The results show that the Fe₃O₄@SiO₂ nanochains with unique core-shell structure are successfully constructed. Meanwhile, the orderly assembly of nanoparticles in the Fe₃O₄@SiO₂ nanochains enable to form magnetic energy coupling and obtain a highly magnetic micro-field. The in vitro tests indicate that the PLLA/Fe₃O₄@SiO₂ scaffolds exhibit superior capacity in enhancing cell activity, improving osteogenesis-related gene expressions, and inducing cell mineralization compared with PLLA and PLLA/Fe₃O₄ scaffolds.

In short, the Fe₃O₄@SiO₂ nanochains endow scaffolds with good magnetism and cytocompatibility, which have great potential in accelerating bone repair.