An integrated approach to determine interactive genotoxic and global gene expression effects of multiwalled carbon nanotubes (MWCNTs) and benzo[a]pyrene (BaP) on marine mussels: evidence of reverse ‘Trojan Horse’ effects

Abstract

The interactions between carbon-based engineered nanoparticles (ENPs) and organic pollutants might enhance the uptake of contaminants into biota. The present integrated study aimed to assess this potential ‘Trojan Horse’, probing the interactive effects of purpose-made multi-walled carbon nanotubes (MWCNTs), a representative ENP, and benzo[a]pyrene (BaP), a ubiquitous polycyclic aromatic hydrocarbon (PAH) pollutant, on the marine mussel Mytilus galloprovincialis. Mussels were exposed to MWCNTs and BaP either alone or in various combinations. The co-exposure of BaP with MWCNTs revealed that the presence of MWCNTs enhanced the aqueous concentrations of BaP, thereby reducing the uptake of this pollutant by mussels as evidenced by lowering BaP concentrations in the tissues. Determination of DNA damage (comet assay) showed a concentration-dependent response for BaP alone which was absent when MWCNTs were present. Global gene expression using microarray analyses indicated that BaP and MWCNTs, in combination, differentially activated those genes which are involved in DNA metabolism compared to the exposures of BaP or MWCNTs alone, and the gene expression response was tissue-specific. Mechanisms to explain these results are discussed and relate primarily to the adsorption of BaP on MWCNTs, mediated potentially by van der Waals interactions. The use of a novel approach based on gold-labeled MWCNTs to track their uptake in tissues improved the traceability of nanotubes in biological samples. Overall, our results did not indicate the ‘Trojan Horse’ effects following co-exposure to the contaminants and clearly showed that the adsorption of BaP to MWCNTs modified the uptake of the pollutant in marine mussels.

Keywords:

• Mytilus galloprovincialis
• benzo[a]pyrene
• multi-walled carbon nanotubes
• van der Waals interactions
• adsorption

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Acknowledgements

The views expressed in this article are those of the authors and not necessarily of the funding agencies including the National Health Service, the National Institute for Health Research, the Department of Health and Social Care or Public Health England.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study is mainly supported by Natural Environment Research Council (NERC), UK (Grant No. NE/L006782/1; PI: ANJ). Additional Support from the Engineering and Physical Sciences Research Council (EPSRC) [Grant No. EP/L022494/1] and the University of Nottingham is acknowledged. Work at King’s College London was further supported by the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Health Impact of Environmental Hazards at King’s College London in partnership with Public Health England (PHE) and Imperial College London.