Pyramidal shaped ceria nano-biointerfaces for studying the early bone cell response

Abstract In the last decades, there is an increased interest in developing strategies for improving bio-interfaces in the field of orthopedic or dental implants. Various coating materials were used as nano and micro-structured interfaces to fine-tune the cellular response. Among these, ceria (CeO2) nanostructures are thought to improve the biointerface mechanical properties, but also to stimulate the regenerating tissue biochemical activity by neutralizing the oxidative stress and stimulating cells proliferation. Within this context, this work presents for the first-time pyramid-shaped nanostructured ceria films obtained by Pulsed Laser Deposition (PLD) targeting the early response of human osteosarcoma cells (SaOs-2). SEM and AFM images of the nanostructured surfaces revealed shapes from the quasi-pyramidal, with rounded edges and dimensions of 90 - 120 nm, to the sharp edges and dimensions up to 350 nm, obtained by varying the number of pulses. The transition from hydrophobic to moderate hydrophilic behavior, as well as the increase of the polar component for the samples with more prominent features, were correlated to the topographical characteristics and further to cell behaviour. The influence of pyramidal-shaped ceria on the in vitro biological performance of SaOs-2 cells was demonstrated by the differences in early adhesion and distribution of phenotype SaOs-2 cells. Nevertheless, as the adhesion and spreading characteristics are cell line specific, mesenchymal stem cells (MSCs) were used for comparing the different cytoskeleton response as response to the ceria nanostructure type. In perspective, the behavior of mesenchymal progenitor cells is foreseen to be analyzed in view of establishing an osteogenic response on these biomaterials and the best-suited processing approach in order to use them as substrates for future bone regeneration applications.