Fabrizio Frontalini, University of Urbino (Italy)
Rodolfo Coccioni, University of Urbino (Italy)
Antonietta Gatti, UniversitÓ degli Studi di Modena e Reggio Emilia (Italy)
Carla Bucci, University of Urbino (Italy)
Nanoparticles have, by definition, a size of a few hundred nanometers at maximum. Apart from particle size providing a very large surface to volume ratio, their biocompatibility surface properties depend on the charges carried by the particle and its chemical reactivity. Polycationic macromolecules show a strong interaction with cell membranes in vitro, and the interaction of nanoparticles with the surface lining layers of biological tissues is determined by their surface chemistry and reactivity. Nanoparticles have a proportionately very large surface area and this surface can have a high affinity for metals (e.g., iron) and organic chemical combustion products such as polycyclic aromatic hydrocarbons (PAHs). This affinity can result in the direct generation of harmful oxyradicals (ROS) causing cell injury by attacking DNA, proteins and membranes. Indeed, inhaled and ingested inorganic nanoparticles in the terrestrial environments can be responsible for the development of nanopathologies. Nevertheless, our knowledge of the harmful effects of nanoparticles is very limited and is almost non-existent in aquatic animals. Uptake of nanoparticles into the aquatic biota is a major concern. Potential routes include direct ingestion or entry across epithelial boundaries such as gills, olfactory organs or body wall. At the cellular level, prokaryotes like bacteria may well be largely protected against the uptake of many types of nanomaterials, since they do not have mechanisms for the bulk transport of supramolecular and colloidal particles across the cell wall. However, with eukaryotes (i.e., metazoans and protists like benthic foraminifera) the situation is very different, since they have highly developed processes for the cellular internalization of nanoscale and microscale particles. It is experienced that in heavy metal polluted aquatic ecosystems, benthic foraminifera show morphological abnormalities.
Research on benthic foraminiferal tests, which come from different polluted settings and display various types of injury, are in progress to verify if nanoparticles present ecotoxicological risks for these sensitive microorganisms.