In vitro testing strategies for hazard assessment of nanoparticles

Abstract

A549 lung cells exposed to SiO2 NPs in serum-free medium (to prevent corona formation) had higher cellular internalization, association and cytotoxicity compared to exposure to the SiO2 NPs under serum-rich conditions (Lesniak et al. 2012). Not only the presence of the protein corona has an effect on the biological interactions and effects of the NPs, but also the composition of the corona affects these characteristics (Tedja et al. 2012). Recently, it has been shown that SiO2 NPs with a different protein corona can be recognized by different cell receptors, resulting in different mechanisms of cellular uptake (Francia et al. 2019). The main protein candidates in the protein corona would be mainly lung surfactant proteins, serum proteins, or enzymes and food biomolecules depending on whether the exposure took place via the inhalation, intravenous, or oral route, respectively (Riediker et al. 2019). Dissolution The potential of part of the NPs, especially metal-based NPs, to dissolve is another property of the NPs that defines their biological interactions and influences their biopersistence and possible accumulation (Borm et al. 2006). Dissolution and ion release could take place before, during or after the contact of NPs with biological media, e.g. in stock suspensions containing NPs or in the cell culture medium used in in vitro cell models (Maurer et al. 2014; Borm et al. 2006). The dissolution rate of NPs differs between the NPs, as the dissolution of AuNPs was limited (0.6 -3) (Carlander et al. 2019) while AgNPs were found to dissolve up to 90% (Kittler et al. 2010) and ZnO NPs (Eixenberger et al. 2017) and CuO NPs (Liu et al. 2020) can dissolve completely. Dissolution of NPs is a dynamic process that is influenced by intrinsic properties of the NPs like the size, surface chemistry or chemical composition and by properties of the surrounding environment like the temperature, pH, ionic strength, light and presence of organic components in the suspensions (Misra et al. 2012). The size of the NPs is an important factor influencing the NP dissolution, as it was found that small AgNPs with a size of 10 nm dissolved and released relatively more silver ions (Ag + ) than the larger AgNPs (40, 50 and 75 nm) (Gliga et al. 2014). Furthermore, the study of Studer et al. demonstrated that the surface chemistry of the NPs also affects the dissolution of the NPs where coating of metal oxide NPs