Quantitative Techniques for Assessing and Controlling the Dispersion and Biological Effects of Multiwalled Carbon Nanotubes in Mammalian Tissue Culture Cells

Abstract

In vivo studies have demonstrated that the state of dispersion of carbon nanotubes (CNT) plays an important role in generating adverse pulmonary effects. However, little has been done to develop reproducible and quantifiable dispersion techniques to conduct mechanistic studies in vitro. This study was to evaluate the dispersion of multi-walled carbon nanotubes (MWCNT) in tissue culture media, with particular emphasis on understanding the forces that govern agglomeration and how to modify these forces. Quantitative techniques such as hydrophobicity index, suspension stability index, attachment efficiency and dynamic light scattering were used to assess the effects of agglomeration and dispersion of as-prepared (AP), purified (PD) or carboxylated (COOH) MWCNT on bronchial epithelial and fibroblast cell lines. We found that hydrophobicity is the major factor determining AP- and PD-MWCNT agglomeration in tissue culture media but that the ionic strength is the main factor determining COOH-MWCNT suspendability. Bovine serum albumin (BSA) was an effective dispersant for MWCNT, providing steric and electrosteric hindrance that are capable of overcoming hydrophobic attachment and the electrostatic screening of double layer formation in ionic media. Thus, BSA was capable of stabilizing all tube versions. Dipalmitoylphosphatidylcholine (DPPC) provided additional stability for AP-MWCNT in epithelial growth medium (BEGM). While dispersion state did not affect cytotoxicity, improved dispersion of AP- and PD-MWCNT increased TGF-β1 production in epithelial cells and fibroblast proliferation. In summary, we demonstrate how quantitative techniques can be used to assess the agglomeration state of MWCNT when conducting mechanistic studies on the effects of dispersion on tissue culture cells.

Occupational Nanosafety Considerations for Carbon Nanotubes and Carbon Nanofibers

“…[40][41][42] Aspiration of a welldispersed SWCNT preparation also caused more transient inflammation and persistent interstitial fibrosis than poorly dispersed SWCNTs. 15 In contrast, poorly dispersed SWCNTs caused a greater granulomatous response.…”

Binding of blood proteins to carbon nanotubes reduces cytotoxicity

“…CNTbased multimodality imaging and therapy have been proposed for a variety of medical applications, such as carriers for chemotherapeutic drugs (17, 18), Raman detection and imaging (19,20), photoacoustic imaging, and photothermal therapy of cancers (6, 21). Meanwhile, of equal importance there is the emerging field of nanotoxicology, which aims to address the biosafety of these engineered nanoparticles, in particular, how these nanoparticles interact with human proteins in vivo (22)(23)(24)(25).Many studies have been performed on the biological effects of carbon nanotubes, and the interactions between proteins and CNTs (nanoparticle-protein corona) are believed to play an important role in the biological effects of CNTs (26-28). For example, CNTs could bind with pulmonary surfactant proteins A and D and then lead to susceptibility of lung infection and emphysema in mice (29).…”

“…CNTbased multimodality imaging and therapy have been proposed for a variety of medical applications, such as carriers for chemotherapeutic drugs (17, 18), Raman detection and imaging (19,20), photoacoustic imaging, and photothermal therapy of cancers (6, 21). Meanwhile, of equal importance there is the emerging field of nanotoxicology, which aims to address the biosafety of these engineered nanoparticles, in particular, how these nanoparticles interact with human proteins in vivo (22)(23)(24)(25).…”

Stability, metal leaching, photoactivity and toxicity in freshwater systems of commercial single wall carbon nanotubes

“…CNTs have been shown to induce toxicity via a few mechanisms, one of which requires adsorption of a cell to the CNT and subsequent mechanical piercing of the cell by the CNT (Kang et al, 2007). Wang et al (2010) showed that degree of dispersability influences toxicity and may be mediated by improving the interaction of the CNT with cell membranes or by increased bioavailability. The ability of dye-CNT complexes to induce toxicity to microbes was shown to be mediated by the photoactivated production of ROS (Banerjee et al, 2010).…”