Exploring cellular behaviour with multi-walled carbon nanotube constructs

The extracellular matrix (ECM) provides a natural network of intricate nanofibres that supports cells and presents a multidimensional map that guides cellular behaviour. Three dimensional nanofibre constructs offer the ability to mimic the topographical environment of the ECM. Here we synthesise nanostructured constructs using catalytic chemical vapour deposition (CCVD) techniques to grow multi-walled carbon nanotubes (MWCNTs) on quartz substrates by injecting a ferrocene and toluene solution into a reaction furnace. Nanotube diameters were varied to assess the effects on cellular responses. Human osteoblastic cells (SaOs-2) were cultured on the MWCNT constructs and compared to a control based on flat highly ordered pyrolytic graphite (HOPG) surfaces to investigate cellular attachment, cell metabolic activity, and construct cytocompatibility. Scanning electron microscopy and immunofluorescent staining for actin and vinculin proteins were used to investigate osteoblastic cell attachment and morphology, whilst cell metabolic activity and construct cytocompatibility were assessed for up to 7 days using standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide and lactate dehydrogenase assays, respectively. The study demonstrates that cells attach and survive on the MWCNT constructs, with higher metabolic activity on the MWCNT constructs compared to control surfaces and metabolic activity negatively correlating with nanotube diameter. The SaOs-2 cells maintained a spherical morphology on the MWCNT constructs and displayed a disorganised actin cytoskeleton compared with the well-spread SaOs-2 cells cultured on the control surfaces. The MWCNT constructs provide a simple, yet effective, model system with which to develop a better understanding of cell responses to nanofibrous geometries relevant to tissue engineering.