Nanomaterials are gaining increasing attention in recent years; their unique mechanical, optical and electrical properties may result in a wide range of applications (Haynes, Citation2010). This potential includes the development of novel electronic devices, use in the manufacture of consumer goods and as drug delivery vehicles, among other uses. The rapidly developing field of nanotechnology needs information urgently on the safety and potential hazards to human and environmental health (Oberdorster et al., Citation2005). To accurately assess these concerns, an interdisciplinary investigative approach is required (Krug & Wick, Citation2011). At this point, several research groups worldwide are currently working to elucidate the mechanisms of toxicity that may result from exposure to nanomaterials. The science that studies these mechanisms is called nanotoxicology, which can be also defined as “the disciplinary identity of toxicology that analyzes the risks and consequences of exposure to nanoscale materials on the environment and human health”. Nanotoxicology is not a novel topic and is being intensively studied; several publications and journals have included wide discussions, reviews, communication and editorials to show the many aspects related to this discipline (Canady, Citation2010; Feliu & Fadeel, Citation2010; Haynes, Citation2010; Service, Citation2004), such that new results and reports are emerging continuously. For this reason, the journal Toxicology Mechanisms and Methods is presenting this special issue on Nanotoxicology. In this issue of the journal, we present excellent studies and reviews from different research groups that have the common goal of understanding toxicological mechanisms at the nanoscale.
Silver nanoparticles (SNPs) have been recognized for their antimicrobial properties (Santoro et al., Citation2007); however, some studies indicate that these nanoparticles increase cytotoxicity (Hillegass et al., Citation2010) in several models such as lung cells A549 (Foldbjerg et al., Citation2011), and intestinal cells Caco-2 (Bohmert et al., Citation2012). Singh and coworkers analyze the effect of SNPs on small intestine cells in mice to determine the degree of damage at the cellular level induced from their exposure; in addition, they analyzed if the cytotoxicity of SNPs induce mitosis.
Furthermore, Ávalos-Funes and coworkers report the effect of SNPs in four different cell lines to evaluate induced toxicity; they determine if the presence of an antioxidant molecule reduces harmful effects of these particles.
The immune system is an essential component of defense against biological, chemical and physical agents. However, the “nanomaterial clearance” mechanism of the immune system remains not fully understood. Some recent studies indicate that nanoparticle–cell interactions are important to recognize and that they initiate an immune response (Maurer-Jones et al., Citation2010). Once recognized, these particles are engulfed mainly by macrophages, neutrophils or monocytes that constitute one of the first barriers against nanoparticles (Bartneck et al., Citation2010). Nanoparticle protein binding occurs immediately after the particle enters the cell, and the physical properties of this particle–protein complex can also contribute to different biological responses (Dobrovolskaia et al., Citation2008). Nanoparticles increase the production of reactive oxygen species, mechanisms of toxicity and induce production of proinflammatory cytokines, IFN-γ, TNF-α and IL-12; nanomaterials may therefore increase cytotoxicity and death in immune cells (Hanley et al., Citation2009). Exposure to nanomaterials affects modulation of the immune system. In this issue, Wang, Reece and Brown review how an inappropriate immune response (as a consequence of nanomaterial exposure) may result in autoimmunity or impaired protection against pathogens. They also analyze how cytokine profiles, altered by nanoparticles, may exacerbate other conditions such as asthma, arthritis or other immune-related diseases.
Carbon nanotubes (CNTs) are novel materials with exceptional physicochemical properties. The versatile chemistry of CNTs allows for a wide range of applications in numerous fields (Kaiser et al., Citation2011). However, the increasing occupational and environmental exposures to CNTs are causing increasing concern for related health consequences (Kolosnjaj et al., Citation2007). The primary route of exposure to CNTs is the respiratory system, therefore, there are numerous reports about how the particles distribute in the tissue and enter into cells to cause toxicity. Exposure to CNTs may provoke several pulmonary disorders including fibrosis. Manke, Wang and Rojanasakul summarize important discoveries and discuss some key cellular and molecular events that result in fibrosis development following CNT exposure. On other hand, Rodriguez-Yañez and coworkers discuss the mechanisms related to CNT toxicity in several tissues and cells; they present current toxicokinetic data, molecular mechanisms and systemic effects. Furthermore, this review includes data on the biological interactions between CNTs and molecules inside the cell.
Cnidaria is an evolutionarily primitive group of invertebrates commonly used as a model of environmental risk assessment analysis. Some studies have examined the toxicity and effects of compounds such as nonylphenol or bisphenol A on the cnidarian, Hydra (Pachura-Bouchet et al., Citation2006; Pascoe et al., Citation2002). Analysis of their morphology, developmental stages, molecular events and the genetics of these species may represent models for probing nanoparticle toxicity as suggested in this issue by Ambrosone and Tortiglione. In this review, the authors summarize the advantages of culturing these organisms and how they could be helpful in genotoxic and cytotoxic experiments. In addition, they present practical methods to evaluate the effects of nanoparticles in development, fertility and regeneration.
Taken together, this special issue will be a valuable source of information for all readers interested in nanotoxicology. Finally, as Guest Editor of this special issue, I would like to thank all the authors for submitting their important contributions for this special issue, the reviewers for all their valuable comments and suggestions to each paper, Dr Rakesh Dixit (Editor in Chief), Luis G. Valerio (Deputy Editor in Chief), the Editorial Board of TMAM for their outstanding cooperation and support in this endeavor and Neshla Avey at Informa for her continuous help and extraordinary work.
Declaration of interest
The author reports no conflict of interest. The author alone is responsible for the content and writing of this article.
This work was supported by ITESM-CCM.
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