Carbon nanofibers (CNF) as scaffolds for osteochondral tissue regenerative medicine

摘要

Different forms of carbon are well known in biomedical applications. Some of them could be used separately (i.e. carbon nanotubes which play a role in gene delivery, drug targeting), while others play a role of additives in ceramic or polymer matrix (scaffolds with short carbon fibers, CNTs or graphene or composite system with long 1D or 2D carbon fibers used in biomechanical applications). Results of many different investigations showed successful application of carbon fibers in bone and cartilage tissue defects treatment as scaffolds or fibrous membranes inducting proliferation of osteoblast cells or initiating osteogenic effect. Amorphous structure, low Young's modulus and possibilities to modification of carbon fibers by ceramic (nano)fillers (i.e. HA, TCP, SiO2) in the bulk but also in the surface create suitable properties of these materials. Moreover, microstructure combining fibers and particles seems to be the best composition which mimics natural bone and cartilage tissue. Novel possibilities of applications of carbon fibers in medicine can be granted by their nanometric form i.e. carbon nanofibers (CNF). This form can be obtained by various processes (reaction from a gas phase, pitch-based fibres and electrospinning process of polymer precursors and their subsequent carbonization of fibrous precursor). The carbon nanofibres, similarly to nanowires and nanotubes, belong to the group of one-dimensional nanometric objects. The nanofibers characterize by small cross section and a significant length, which corresponds to higher specific surface area than conventional fibres. The small diameter significantly affects amount of structural defects which in turn affects mechanical properties as well as specific surface properties. The carbon nanofibres can be used in treatment and stimulation of bone system as well as in construction of nanocomposite or fibrous substrates in in situ tissue engineering. Based on this information the aim of work was preparation and characterization of material properties of carbon nanofibers based on PAN precursor and assessment of their biological potential for stimulation of osteoblasts and chondrocyte cells. Nanometric fibrous materials (diameter of single fibers ～150 nm, Fig 1) with high total porosity (～75%) and amorphous structure were contacted with osteobiast-like cells line (MG63) and primary osteoblast line (NHOst). Cytotoxicity of the materials was tested after 7 days of incubation and measurement of the cells viability. Morphology of the cells was observed using a fluorescence microscope. Both types of the cells were characterized by larger proliferation than cells contacted with a reference samples (TCPS). The same preliminary tests were also made with chondrocyte cells.