Development of a 3D Collagen Model for the In Vitro Evaluation of Magnetic-assisted Osteogenesis

Abstract Magnetic stimulation has been applied to bone regeneration, however, the cellular and molecular mechanisms of repair still require a better understanding. A three-dimensional (3D) collagen model was developed using plastic compression, which produces dense, cellular, mechanically strong native collagen structures. Osteoblast cells (MG-63) and magnetic iron oxide nanoparticles (IONPs) were incorporated into collagen gels to produce a range of cell-laden models. A magnetic bio-reactor to support cell growth under static magnetic fields (SMFs) was designed and fabricated by 3D printing. The influences of SMFs on cell proliferation, differentiation, extracellular matrix production, mineralisation and gene expression were evaluated. Polymerase chain reaction (PCR) further determined the effects of SMFs on the expression of runt-related transcription factor 2 (Runx2), osteonectin (ON), and bone morphogenic proteins 2 and 4 (BMP-2 and BMP-4). Results demonstrate that SMFs, IONPs and the collagen matrix can stimulate the proliferation, alkaline phosphatase production and mineralisation of MG-63 cells, by influencing matrix/cell interactions and encouraging the expression of Runx2, ON, BMP-2 and BMP-4. Therefore, the collagen model developed here not only offers a novel 3D bone model to better understand the effect of magnetic stimulation on osteogenesis, but also paves the way for further applications in tissue engineering and regenerative medicine

Carbon nanotube deposits and CNT/SiO2 composite coatings by electrophoretic deposition

Multiwalled carbon nanotube (CNT) films have been successfully fabricated by electrophoretic deposition (EPD) on stainless steel substrates. Electrophoretic deposition was performed using optimised aqueous suspensions under constant voltage conditions. Triton X-100 was used as a surfactant to disperse CNT bundles, and iodine was added as a particle charger. CNT/SiO2 composite coatings were prepared by electrophoretic co-deposition. Experimental results show that the CNTs were efficiently mixed with SiO2 nanoparticles to form a network structure. Layered CNT/SiO2 porous composites were obtained by sequential EPD experiments alternating the deposition of CNT and SiO2 nanoparticles. The structure of all films deposited was studied in detail by scanning electron microscopy. Possible applications of CNT and CNT/SiO2 films are as porous coatings in the biomedical field, thermal management devices, biomedical sensors and other functional applications where the properties of CNTs are required