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 32 emu g(-1). After the mineralization of 2 d and 4 d in the mixed solution of the concentrations of 15 w/w% SF and 0.01 M HCl, the lengths of NRs are similar to 220 nm and similar to 2 mu m, respectively. Cell tests of NRs with 220 nm length showed that the as-prepared Zn-ferrite NRs hardly produced toxicity on Escherichia coli, Staphylococcus aureus, 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 0.25 mg mL(-1)) in 1-5 d culture time. TEM images of cell ultrathin sections indicated that, although Zn-ferrite NRs were split in the cytosol for 5 d at the NR concentrations of 0.125 mg 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. (C) 2013 Elsevier Inc. All rights reserved.