Skeletal myotube formation enhanced by electrospun polyurethane carbon nanotube scaffolds

Sirinrath Sirivisoot, Benjamin S Harrison Wake Forest Institute for Regenerative Medicine, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC, USA Background: This study examined the effects of electrically conductive materials made from electrospun single- or multiwalled carbon nanotubes with polyurethane to promote myoblast differentiation into myotubes in the presence and absence of electrical stimulation. Methods and results: After electrical stimulation, the number of multinucleated myotubes on the electrospun polyurethane carbon nanotube scaffolds was significantly larger than that on nonconductive electrospun polyurethane scaffolds (5% and 10% w/v polyurethane). In the absence of electrical stimulation, myoblasts also differentiated on the electrospun polyurethane carbon nanotube scaffolds, as evidenced by expression of Myf-5 and myosin heavy chains. The myotube number and length were significantly greater on the electrospun carbon nanotubes with 10% w/v polyurethane than on those with 5% w/v polyurethane. The results suggest that, in the absence of electrical stimulation, skeletal myotube formation is dependent on the morphology of the electrospun scaffolds, while with electrical stimulation it is dependent on the electrical conductivity of the scaffolds. Conclusion: This study indicates that electrospun polyurethane carbon nanotubes can be used to modulate skeletal myotube formation with or without application of electrical stimulation. Keywords: myoblasts, electrical field, single-walled, multiwalled, carbon nanotubes, nanocomposites, musculoskeletal, tissue engineerin

Bacterial Stress and Osteoblast Responses on Graphene Oxide-Hydroxyapatite Electrodeposited on Titanium Dioxide Nanotube Arrays

To develop bone implant material with excellent antibacterial and biocompatible properties, nanotubular titanium surface was coated with hydroxyapatite (HA) and graphene oxide (GO). Layer-by-layer deposition was achieved by coating HA on an anodic-grown titanium dioxide nanotube array (ATi) with electrolytic deposition, followed by coating with GO using anodic-electrophoretic deposition. The antibacterial activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria was determined based on the percentage of surviving bacteria and the amount of ribonucleic acid (RNA) leakage and correlated with membrane disruption. The oxidative stress induced in both strains of bacteria by GO was determined by cyclic voltammetry and is discussed. Importantly, the antibacterial GO coatings on HA-ATi were not cytotoxic to preosteoblasts and promoted osteoblast proliferation after 5 days and calcium deposition after 21 days in standard cell culture conditions