Gene expression profiles in rat lung following intratracheal instillation with impurity-free single-wall carbon nanotubes

To further development of our gene expression approach to assess the effects of manufactured nanomaterials at the transcriptional level, we have employed whole genome microarray expression profiling as a discovery platform to identify genes with the potential to distinguish characterization of physicochemical properties of impurity-free single-wall carbon nanotubes (SWCNTs). We have prepared two types of dispersed the SWCNTs, namely relatively small bundles and a short linear shape (CNT-1) and large bundles and a long linear shape (CNT-2), and attempted to characterize time-dependent changes in the gene expression of lung tissues until 90 days after intratracheal instillation with SWCNTs suspensions at 0.4 mg injected dose per rat. Groups of nine-week-old male Wistar rats (n= 4 per group/ time point) were intratracheally instilled with single-wall carbon nanotubes (SWCNTs) suspended in 0.4 ml of 1.0mg/mL bovine serum albumin (BSA) as a single injection 0.4 mg SWCNTs/ rat. Control groups received 1.0mg/mL BSA (vehicle control). After intratracheal instillation treatment, rats were housed within polycarbonate cages at a controlled temperature of 22 °C with a chow diet ad libitum, and dissected at 1day, 3 days, 7 days, 30 days, and 90 days post-instillation. Right lungs of anesthetized rats were perfused with physiological saline, excised, and used for DNA microarray analysis.