Experimental and theoretical investigations of the influences of one‐dimensional hydroxyapatite nanostructures on cytocompatibility

Due to their simple crystal structures, one-dimensional hydroxyapatite (HA) nanostructures are easily to be applied to understand the fundamental concepts about the influences of HA dimensionality on physical, chemical and biological properties. So, in this work, three typical HA one-dimensional nanostructures, HA nanotubes, HA nanowires and HA nanospheres, were prepared, whose theoretical structures were built also. In vitro cytocompatibility test proved that, contrasting with TCPS, HA one-dimensional nanostructures had certain degree of cytotoxicity because HA nanostructures increase the generation of intracellular reactive oxygen species (ROS) and intracellular calcium. Theoretical simulation indicated that HA nanosphere has higher intracellular ROS generation and lower ROS storage amount than HA nanowire and HA nanotube, which were the possible reasons for its stronger cytotoxicity. Among these typical one-dimensional nanostructures, owing to higher drug storage amount and sustained delivery ability, HA nanotube was more potential application in orthopedics. The tubular structure of HA nanotubes could be used as reservoirs for small molecule drugs or growth factors. The cytocompatibility of HA nanostructures can be improved obviously when they were produced into two dimensional structures. The prepared multilayer structure can simulate lamellar structures of Harvard system and enhance the cytocompatibility of Ti substrate. So, the method used in this work is a prospective method to improve the inherently bio-inert of Ti when used in hard tissue repairing.