R1 AM Nanotechnology Environmental and Health Impacts
Thursday, 17 November 2005: 8:00 AM - 11:40 AM in Ballroom 1

(CUN-1117-661727) Assessing the Safety of Nanoscale Materials using a Systems Biology Approach.

Cunningham, MJ¹, Magnuson, SR², Falduto, MT ², Balzano, L³, Resasco, DE³, ¹ Houston Advanced Research Center, The Woodlands, TX, USA² GenUs BioSystems, Inc., St. Charles, IL, USA³ University of Oklahoma, Norman, OK, USA

ABSTRACT- Nanomaterials vary greatly in their composition and preliminary reports are mixed as to their toxicity. In this study, single-walled carbon nanotubes (SWNT) were manufactured using a modified chemical vapor deposition method (CoMoCAT) developed at the University of Oklahoma. SWNT were purified in hydrofluoric acid and characterized to have average lengths of approximately 100 nm and average diameters of 3 nm. The percentage of heavy metal impurities were less than 1%. Their safety was assessed by exposing primary neonatal human epidermal keratinocytes in vitro at 0.001 mg/mL (noncytotoxic) and 1 mg/mL (cytotoxic). Cells were harvested at 8 different time points within a 24 hour period for each dose curve. The same experimental design was used in studies of untreated cells (control) and known control compounds, such as silica (Min-U-Sil®5, SiO₂), carbon black (Printex®90, CB) and carbonyl iron (ferronyl iron, FI). Cell pellets were snap-frozen for subsequent total RNA isolation. Biotinylated cRNA probes were synthesized from the isolated RNA and hybridized onto CodeLink™ microarrays containing oligomers from 9,970 unique human genes. Initial data analysis analyzed by hierarchical agglomerative clustering (Euclidean distance metric, average linkage) showed that at the nontoxic dose, the profile for SWNT was more similar to the nontoxic FI than to the toxic SiO₂. In evaluating the high dose, the profile for SWNT was more similar to SiO₂ than to FI. Additional analysis involved supervised mathematical modeling methods as well as pathway analysis for up- and down-regulated genes. In most profiles, structural proteins, such as laminin, and several cytokines were significantly expressed, as had been previously reported. Two possible biomarkers for SWNT exposure are kallikrein and NICE. Min-U-Sil and Printex90 are registered trademarks of U.S. Silica Company and Degussa Corporation, respectively, and CodeLink is the trademark of GE Healthcare.

Key words: nanotube, microarray, genomics, systems biology