Synthesis and neuro-cytocompatibility of magnetic Zn-ferrite nanorods via peptide-assisted process.

In order to obtain magnetic nanorods (MNRs) with the neuro-cytocompatibility, silk-fibroin (SF)-coated Zn-ferrite NRs are successfully prepared via a mineralization process, and their saturation magnetization is 32emu g(-)(1). After the mineralization of 2d and 4d in the mixed solution of the concentrations of 15w/w% SF and 0.01M HCl, the lengths of NRs are ∼220nm and ∼2μm, respectively. Cell tests of NRs with 220nm length showed that the as-prepared Zn-ferrite NRs hardly produced toxicity on Escherichiacoli, Staphylococcusaureus, L929, and PC12 cells. The results of the outgrown neurites from PC12 cells indicated that the neurite length and the number of neurites were not significantly decreased at the low concentrations of SF-coated NRs (less than 0.25mg mL(-)(1)) in 1-5d culture time. TEM images of cell ultrathin sections indicated that, although Zn-ferrite NRs were split in the cytosol for 5d at the NR concentrations of 0.125mg mL(-)(1), some integrated mitochondria in a neurite suggested that SF-coated NRs inside cells did not influence the extension activity of neurites. Based on the good neuro-cytocompatibility and magnetic property of Zn-ferrite NRs, their potential applications in safe cell manipulation and axon guidance can be envisioned.