Biokinetics of nanomaterials: The role of biopersistence

Abstract

Nanotechnology risk management strategies and environmental regulations continue to rely on hazard and exposure assessment protocols developed for bulk materials, including larger size particles, while commercial application of nanomaterials (NMs) increases. In order to support and corroborate risk assessment of NMs for workers, consumers, and the environment it is crucial to establish the impact of biopersistence of NMs at realistic doses. In the future, such data will allow a more refined future categorization of NMs. Despite many experiments on NM characterization and numerous in vitro and in vivo studies, several questions remain unanswered including the influence of biopersistence on the toxicity of NMs. It is unclear which criteria to apply to characterize a NM as biopersistent. Detection and quantification of NMs, especially determination of their state, i.e., dissolution, aggregation, and agglomeration within biological matrices and other environments are still challenging tasks; moreover mechanisms of nanoparticle (NP) translocation and persistence remain critical gaps. This review summarizes the current understanding of NM biokinetics focusing on determinants of biopersistence. Thorough particle characterization in different exposure scenarios and biological matrices requires use of suitable analytical methods and is a prerequisite to understand biopersistence and for the development of appropriate dosimetry. Analytical tools that potentially can facilitate elucidation of key NM characteristics, such as ion beam microscopy (IBM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), are discussed in relation to their potential to advance the understanding of biopersistent NM kinetics. We conclude that a major requirement for future nanosafety research is the development and application of analytical tools to characterize NPs in different exposure scenarios and biological matrices.

Review of emerging concepts in nanotoxicology: opportunities and challenges for safer nanomaterial design

“…Nanotoxicological assays are able to give information on the fraction of ions to NPs in the supernatant or permeate from the biological medium supplemented silver NPs using ICP or mass spectrometry (Bohmert et al 2017). Therefore, the conducted investigations provide the actual silver ion concentration released from a given silver nanoparticle concentration in order to set up a proper control for the nanotoxicologists (Bewersdorff et al 2017;Bohmert et al 2017;Laux et al 2017a). The new technique of single particle ICP mass spectrometry can predict individual particles split with the solid particle versus the ion concentration in the solution (Reidy et al 2013).…”

Conventional and novel “omics”‐based approaches to the study of carbon nanotubes pulmonary toxicity

“…This movement is affected by (i) the particle size, shape, and possible dynamical change during breathing, (ii) the geometry of the respiratory tract and alveolar structures, (iii) the pattern of breathing (including breathing through the nose or mouth) that determines the speed of the air stream, and (iv) the residence time in the respiratory system . In addition to agglomeration, particle dissolution is also fundamental to the toxicity of inhaled particles, due to the reduction of their size and related changes of dissolution kinetics (Laux et al, 2017). Under real-life conditions, the majority of airborne nanomaterials are in an agglomerated form, and their deposition in the lungs follows the pattern of larger particles (Laux et al, 2017).…”

“…Depending on the inhaled particles diameter, which may result from the aggregation or agglomeration state of the individual particles, their regional deposition in the lungs will vary from the extra-thoracic regions (larger particles) to the alveoli (smaller particles; Kreyling et al, 2006). Under real-life conditions, the majority of airborne nanomaterials are in an agglomerated form, and their deposition in the lungs follows the pattern of larger particles (Laux et al, 2017). Furthermore, particle agglomerate volume may better explain the effects of repeated dosing leading to inflammation, as opposed to surface area that may be the dose metric applied to describe the acute effects of instilled or inhaled particles.…”

“…Furthermore, particle agglomerate volume may better explain the effects of repeated dosing leading to inflammation, as opposed to surface area that may be the dose metric applied to describe the acute effects of instilled or inhaled particles. In addition to agglomeration, particle dissolution is also fundamental to the toxicity of inhaled particles, due to the reduction of their size and related changes of dissolution kinetics (Laux et al, 2017). It is considered that particles as CNT, which are not dissolved in the epithelial lining fluid, may be phagocytized by the alveolar macrophages and be cleared by mucociliary transport, be transported across the epithelial barrier and be stored in interstitial tissue or be carried for storage in tracheobronchial and bifurcational lymph nodes (Kreyling, 1990).…”

“…This can be a consequence of the shorter distance from the alveolus to the terminal bronchiolus in rodents, compared to dogs, monkeys, and humans (Kreyling, 1990). Dosimetric risk extrapolation from animals to humans has to consider other species differences related to the biokinetics of inhaled particulate materials, for example the greater interstitial compartmentalization of retained particles in primates versus rodents (Laux et al, 2017). However, despite these differences, the distribution of cells in the alveolar tissue and their average volume and surface area seem to be constant among rats, dogs, baboons, and humans (Crapo et al, 1983).…”