A hydrothermal approach was used to prepare large-scale, aligned ultrafine bone-like apatite nanorod arrays on electrospun nylon 6 (N6) nanofibers using simulated body fluid. X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectoron spectroscopy and Fourier transform infrared spectroscopy (FTIR) were used to study structural features and the chemical composition of the synthesized biocomposites. Apatite nanorods of similar to 60 nm length and 10-17 nm width were uniformly distributed onto the surface of individual nanofibers. Deposition of apatite on pristine nanofiber surfaces at an initial pH of 6.5-7.5 accelerated when the reaction time was extended. Nanofibers and the ultrathin fibers that generated a spiderweb-like structure after coating maintained a unique fibrous morphology. FTIR and thermal analysis demonstrated strong intermolecular hydrogen bonding between the polymer molecules and mineralized compounds from the hydrothermal reaction. Our results also indicated a change in the chain conformation of the N6 backbone from the fabrication process. Thus, our investigation found that the hydrothermal process did not notably degrade the N6, but transformed it from a metastable gamma-form to thermodynamically stable chain conformation (alpha-form). Further, the biological response induced by the surface modifications of N6 nanofibers was studied by in vitro cell culture with MC3T3-E1 osteoblasts cells. (C) 2013 Elsevier B.V. All rights reserved.