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With recent advances in nanotechnology, carbon nanotubes (CNTs) have been extensively studied as substrates for cell culture, drug delivery systems, and medical implant materials. However, surprisingly little is known about the effect of CNTs on collective cellular processes (e.g., adhesion, proliferation, and differentiation). This leads to the need for quantitative characterization of the proliferation, differentiation, and mineralization of mesenchymal stem cells (MSCs) on multiwalled CNT-s (MWCNTs-) collagen scaffolds. In here, a set of MWCNTs-collagen scaffolds where three different types of MWCNTs are, respectively, entrapped in reconstituted type I collagen at four different concentrations less than 100 ppm are prepared; the MSC differentiation thereon is investigated by monitoring the transcription factor RunX2 (RunX), transforming growth factorβ(TGF-β), alkaline phosphatase (AP), osteocalcin, and mineralized nodules of extracellular matrix (ECM). In short, the MWCNT-collagen scaffolds induced significant increases in AP activity and ECM mineralization due to the increased stiffness and strength of the scaffold by entrapping MWCNTs. This offers a potential for controlling MSC differentiation using MWCNT-collagen scaffolds.

Carbon Nanotube (CNT) materials has superior properties in electric current carrying capacity, thermal conductivity, and thermal stability. Due to their structure with high aspect ratio, they have structural unusual toxicity and complicate safety issue in a target tissue. In optimized quantities with limited functionality, special type of CNT assembly such as "buckyball" can be used as a potential drug carrier of bioactive molecules and display with increased circulating time and acceptable functionality. We analyzed cytoxicity and inflammatory response following exposure of CNTs. Slow damaging effects of CNT to epidermis and dermis of rat skin was shown using microimaging. Physiological perturbation of lung barrier function was observed by measuring transepithelial electrical resistance (TER) during the exposure of different concentrations of CNTs to human lung epithelial cell monolayers in the presence of fibroblast-embedded collagen. The mechanisms of CNTs' toxicity may be closely related to their structure, functional group, and surface charge on the molecule. Further studies are required to probe the mechanisms of cytotoxic and inflammatory responses. We also established the nanoscale toxicity of fullerenes of CNTs.

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