Aerosol generation and characterization of multi-walled carbon nanotubes exposed to cells cultured at the air-liquid interface.

William W. Polk,Christie M. Sayes,Monita Sharma,Jon A. Hotchkiss,Amy J. Clippinger

doi:10.1186/s12989-016-0131-y

Abstract

Aerosol generation and characterization are critical components in the assessment of the inhalation hazards of engineered nanomaterials (NMs). An extensive review was conducted on aerosol generation and exposure apparatus as part of an international expert workshop convened to discuss the design of an in vitro testing strategy to assess pulmonary toxicity following exposure to aerosolized particles. More specifically, this workshop focused on the design of an in vitro method to predict the development of pulmonary fibrosis in humans following exposure to multi-walled carbon nanotubes (MWCNTs). Aerosol generators, for dry or liquid particle suspension aerosolization, and exposure chambers, including both commercially available systems and those developed by independent researchers, were evaluated. Additionally, characterization methods that can be used and the time points at which characterization can be conducted in order to interpret in vitro exposure results were assessed. Summarized below is the information presented and discussed regarding the relevance of various aerosol generation and characterization techniques specific to aerosolized MWCNTs exposed to cells cultured at the air-liquid interface (ALI). The generation of MWCNT aerosols relevant to human exposures and their characterization throughout exposure in an ALI system is critical for extrapolation of in vitro results to toxicological outcomes in humans.

Highlights

Multi-walled carbon nanotubes (MWCNTs) are used in a number of consumer products, increasing the potential for inhalation exposure of these materials
For multi-walled carbon nanotubes (MWCNTs), all exposure apparatus discussed in this review met the critical needs to establish a robust method, but none address all aspects of an ideal in vitro exposure platform
The set-up and use of aerosol generation, exposure, and characterization systems requires knowledge about the engineering aspects of aerosol generation and characterization, in addition to the biology of morphologically distinct respiratory tract cells cultured at the air-liquid interface (ALI)

Summary

Background

Multi-walled carbon nanotubes (MWCNTs) are used in a number of consumer products, increasing the potential for inhalation exposure of these materials. Exposure chambers for MWCNT aerosolization Chambers that can be used to expose cells cultured at the ALI to aerosolized materials have been described in the literature and include both commercially available systems and those developed by independent researchers [40, 41] These chambers differ from each other in. We provide a brief description of aerosol generators that are applicable to MWCNTs, including the principle of aerosol generation, the type of material that can be aerosolized, the size and concentration of the aerosolized particle, and the duration of exposure to the aerosolized particles factors, such as cost, ease of availability and use, level of throughput, exposure time duration, and the number of examples of use in the published literature Based on these factors, chambers from three organizations — VITROCELL® Systems, Cultex® Laboratories GmbH, and the University of Bern — were selected as most relevant for testing MWCNTs (Table 2). Such models can be used to make predictions regarding MWCNT fate and transport in complex biological systems that can help in designing in vitro systems that are more predictive of in vivo conditions

Conclusions

64. Ge C et al Quantitative analysis of metal impurities in carbon nanotubes