Surface reactions on metallic nanoparticles
Ligand adsorption, metal release, and reactive oxygen species generation
Time: Mon 2022-12-19 10.00
Location: Kollegiesalen, Brinellvägen 8, Stockholm
Subject area: Chemistry
Doctoral student: Amanda Kessler , Yt- och korrosionsvetenskap, Royal Institute of Technology, Inger Odnevall
Opponent: Professor Tommy Nylander, Lunds universitet
Supervisor: Professor Inger Odnevall, Materialvetenskap, Yt- och korrosionsvetenskap
Humans are exposed daily to metallic nanoparticles (Me NPs) from multiple sources which can have both natural and anthropogenic origins. Such exposures take place via different routes including inhalation and skin contact and may result in adverse health effects. The objectives of this thesis were to investigate surface interactions taking place on metallic nanoparticles upon simplified inhalation and how such interactions influence their toxic potency.
Except for the particle and surface characteristics, the interface to the cell environment, the extent, speciation of the released metal fraction, and the ability of the particles to form reactive oxygen species (ROS) were investigated as these parameters are known to largely govern the cell toxicity. ROS naturally form in the cells as an essential part of our immune system, but can in excess, result in cell membrane damage and harmful effects. This has been studied using a multianalytical and interdisciplinary approach combining surface and material chemistry with toxicological investigations with the main focus on ROS formation. The study has for example elucidated which reactive oxygen species that are formed due to the presence of metallic NPs, and the underlying mechanisms.
The reliability of using different ROS assays, and the possible artifacts induced by metallic NPs, have been investigated. Methods to assess ROS which previously have not been used in the field of nanotoxicology were introduced showing that copper NPs via corrosion reactions produce ROS and Haber Weiss or Fenton-reactions can decompose hydrogen peroxide into the reactive hydroxyl radical. A way to group NPs based on their surface reactions forming ROS was proposed. Other particle- and surface characteristics of metallic NPs of importance for the toxic potency and ability to induce oxidative stress, e.g. adsorption of biomolecules, particle agglomeration, surface composition, and release of metal ions including their speciation.