Controlling the Growth and Differentiation of Human Mesenchymal Stem Cells by the Arrangement of Individual Carbon Nanotubes

Carbon nanotube (CNT) networks on solid substrates have recently drawn attention as a means to direct the growth and differentiation of stem cells. However, it is still not clear whether cells can recognize individual CNTs with a sub-2 nm diameter, and directional nanostructured substrates such as aligned CNT networks have not been utilized to control cell behaviors. Herein, we report that human mesenchymal stem cells (hMSCs) grown on CNT networks could recognize the arrangement of individual CNTs in the CNT networks, which allowed us to control the growth direction and differentiation of the hMSCs. We achieved the directional growth of hMSCs following the alignment direction of the individual CNTs. Furthermore, hMSCs on aligned CNT networks exhibited enhanced proliferation and osteogenic differentiation compared to those on randomly oriented CNT networks. As a plausible explanation for the enhanced proliferation and osteogenic differentiation, we proposed mechanotransduction pathways triggered by high cytoskeletal tension in the aligned hMSCs. Our findings provide new insights regarding the capability of cells to recognize nanostructures smaller than proteins and indicate their potential applications for regenerative tissue engineering

Universal Parameters for Carbon Nanotube Network-Based Sensors: Can Nanotube Sensors Be Reproducible?

Carbon nanotube (CNT) network-based sensors have been often considered unsuitable for practical applications due to their unpredictable characteristics. Herein, we report the study of universal parameters which can be used to characterize CNT network-based sensors and make their response predictable. A theoretical model is proposed to explain these parameters, and sensing experiments for mercury (Hg2+) and ammonium (NH4+) ions using CNT network-based sensors were performed to confirm the validity of our model