Manufacturing Strategy for Multiwalled Carbon Nanotubes as a Biocompatible and Innovative Material

We investigated the relationship between differences in multiwalled carbon nanotubes (MWCNTs) and the biological responses they elicit in order to develop biocompatible MWCNTs. We exposed human bronchial epithelial (BEAS-2B) cells to two sizes and six grades of MWCNTs and measured the resulting cell viability, total reactive oxygen and/or nitrogen species (tROS/RNS) production, and cytokine secretion. Although differences in cellular tROS production were associated with differences in grades of MWCNTs, the graphitization temperature ofMWCNTs apparently did not influence tROS production. However, cell viability was affected byMWCNT graphitization temperature and diameter. Moreover, cytokine secretion was apparently affected by treatment temperature, but not MWCNT diameter. We concluded that the highest temperature resulted in the most biocompatibility because impurities and carbon defects were removed from the MWCNTs. However, other mechanisms are possible. Therefore, it is important to optimize each type of MWCNT by monitoring biological responses that type elicits during the manufacturing stage for applications involving biology and medicine.