Makoto Matsuoka

Adhesion of human osteoblast-like cells (Saos-2) to carbon nanotube sheets

Carbon nanotubes (CNTs) exhibit excellent cell proliferation properties, which can serve as a scaffold for cell culturing. However, there are only a few reports on adhesion of osteoblast-like cells to a CNT sheet. In this study, we investigated adhesion of osteoblast-like cells to single-walled carbon nanotube (SWNT) and multi-walled carbon nanotube (MWNT) sheets and compared these adhesions with that on a cell culture polystyrene dish by using a cell adhesion test and a scanning electron microscope. The MWNT sheets exhibited faster adhesion of cells at an initial stage than SWNT sheets and cell culture polystyrene dish. The number of attached cells on the MWNT sheets seemed to be greater than on SWNT sheets and cell culture polystyrene. Moreover, the MWNT sheets exhibited both high speed and good capacity for cell adhesion. However, the surface of the MWNT sheets was such that it facilitated cell adherence but hindered the spreading of the attached cells. Interestingly, cell adhesion to CNT sheets was significantly influenced by pre-coating with serum. These results indicate that CNT sheets would play an important role in adsorption of serum proteins, which would consequently facilitate cell adhesion, and that the MWNT sheets have a high cell adhesiveness.

Improvement in cell proliferation on silicone rubber by carbon nanotube coating.

Silicone rubbers are widely used as tissue implants because of their flexibility and chemical stability. However, they have limited cellular adhesiveness and may cause problems in the long term. In this study, a coating of carbon nanotubes (CNTs) was applied to silicone rubber to improve its cellular adhesiveness. Scanning electron micrograph of this coating revealed that CNTs had formed a densely packed meshwork; the Ra values and protein adsorption capacity were enhanced. Although the contact angle did not change after coating, it decreased after immersion into a culture medium. After cultivation for 6 d, while Saos-2 cells were hardly observed on untreated silicone, the cells proliferated on CNT-coated silicone. Thus, CNT coating might be a simple and effective solution to problems associated with silicone implants.

Various Nanotube Scaffolds for Cell Proliferation

Carbon nanotubes (CNT) and their derivatives with different structure and compositions have unique features. In the present study, cell proliferation was performed on various nanotubes such as single walled CNTs, multiwalled CNTs and imogolite which is nanotubes of aluminosilicate. SEM observation of the growth of osteoblast-like cells cultured on CNTs showed the morphology fully developed for the whole direction, which was different from that extended to the one direction on the usual scaffold. Numerous filopodia were grown from cell edge, extended far long and combined with CNT meshwork. Apatite precipitation in simulated body fluid, affinity for proteins and saccharides, and nanosize meshwork structure with large porosity would be the properties responsible for these cell adhesion and growth. Imogolite showed the similar properties to CNTs. Nanotubes could be the favorable materials for biomedical applications.

Visualization of Invasion into the Body and Internal Diffusion of Nanoparticles

Nanoparticles may invade directly into the internal body through the respiratory or digestive system and diffuse inside body. The behavior of nanoparticles in the internal body is also essential to comprehend for the realization of DDS. Thus it is necessary to reveal the internal dynamics for the proper treatments and biomedical applications of nanoparticles. In the present study the plural methods with different principles such as X-ray scanning analytical microscope (XSAM), MRI and Fluorescent microscopy were applied to enable the observation of the internal diffusion of micro/nanoparticles in the (1) whole body level, (2) inner organ level and (3) tissue and intracellular level. Chemical analysis was also done by ICP-AES for organs and compared with the results of XSAM mapping.