Carbon Nanotubes Increase Cartilage Growth

A team of Brown and Purdue University scientists (Dr. Dongwoo Khang, Dr. Grace Park, and Prof. Thomas J. Webster) have created new cartilage growing materials out of carbon tubes. Specifically, the research team incorporated the novel conductivity properties and biologically-inspired nano-surface features of carbon nanotubes into polymers to promote the functions of chondrocytes (cartilage forming cells).  Cartilage is a natural nanostructured rough tissue due to the presence of collagen as well as other proteins whose geometries and dimensions can be easily mimicked by carbon nanotubes. Compared to conventional longitudinal (or vertical) electrical stimulation of chondrocytes on conducting surfaces which requires high voltage (and may damage tissue), the team developed a process which uses transverse electrical stimulation of chondrocytes to produce cartilage with just a few volts. Carbon nanotubes were essential to transferring this applied voltage to chondrocytes to promote cartilage growth. Importantly, chondrocyte functions were significantly enhanced on the carbon nanotube composites than conventional polymers used for cartilage tissue engineering applications. Since current approaches to regenerate cartilage do not involve electrical stimulation, for the first time, this study demonstrated a novel manner to regenerate cartilage electrically as mediated by a conductive carbon nanotube composite.

Figure AFM surface topography of a) Poly carbonate urethane (PCU) and b) carbon nanotube/CPU composite surfaces. c) FESEM image of CNT/PCU composites (bar is 500nm). d) Magnified image clearly showed individual CNTs coated with PCU (bar is 100 nm).Figure AFM surface topography of a) Poly carbonate urethane (PCU) and b) carbon nanotube/CPU composite surfaces. c) FESEM image of CNT/PCU composites (bar is 500nm). d) Magnified image clearly showed individual CNTs coated with PCU (bar is 100 nm).