Differential biocompatibility of carbon nanotubes and nanodiamonds

Carbon nanomaterials are being produced in increasingly larger quantities for many applications due to their novel characteristics such as enhanced thermal, electrical, mechanical, and biological properties. However, there is a lack of data on biological interactions to assess their biocompatibility before they will be accepted as non-toxic in industrial or biomedical arenas. In the present study, we examined both neuronal and lung cell lines for biocompatibility in aqueous suspensions of carbon nanomaterials, such as nanodiamonds (NDs), single- and multi-walled carbon nanotubes (SWNTs, MWNTs), and carbon black (CB), at concentrations ranging from 25–100 μg/ml for 24 h. Our results indicated that these carbon nanomaterials displayed differential biocompatibility in these two different cell lines. The greatest biocompatibility was found after incubation with NDs and both cell types followed the trend: ND > CB > MWNT > SWNT. Macrophages were found to be more sensitive to the nanomaterials with up to five times the generation of reactive oxygen species after incubation with MWNTs or SWNTs. However, there was a lack of ROS generation from either cell line incubated with ND-raw, as well as intact mitochondrial membranes, suggesting that NDs may be useful as a benchmark nanoparticle non-toxic control in replacement of CB, and should be further investigated for use in medical applications.