title: Redox activity and chemical interactions of metal oxide nano- and micro-particles with dithiothreitol (DTT).
abstract: The wide application and production of nanotechnology have increased the interest in studying the toxicity of nano- and micro-sized particles escaping into air from various aspects of the production process. Metal oxides (MOs) are one particular class of particles that exist abundantly in ambient PM. Studies show an emphasis on biological mechanisms by which inhalation exposure to MOs leads to disease. However, different biological assays provide different redox activity rankings making it difficult to assess the contributions of various MOs to measures of aggregate toxicity in multi-pollutant systems such as ambient PM. Therefore, research to evaluate the chemical interaction between these particles and molecules that are relevant to cellular redox activity can help in establishing indicators of reactivity. In particular, this study assesses the redox activity of six MOs mainly emitted from anthropogenic industrial activities using the dithiothreitol (DTT) assay. DTT is commonly used in acellular assays due to its analogous structure to cellular glutathione. The structural and chemical behaviors between active MOs and DTT were elucidated using FTIR, NMR, and BET methods. The results indicate that the health risk (redox activity) associated with MOs is mainly a function of their surface reactivity demonstrated by the ability of the oxidized (S-H) bond in DTT to form a stable bond with the MO surface.
authors.affiliation: American University of Beirut, Chemistry Department, Faculty of Arts and Sciences, Beirut, Lebanon. ns30@aub.edu.lb.
authors.forename: Johny
authors.initials: J
authors.lastname: Nicolas
authors.affiliation: American University of Beirut, Chemistry Department, Faculty of Arts and Sciences, Beirut, Lebanon. ns30@aub.edu.lb.
authors.forename: Malek
authors.initials: M
authors.lastname: Jaafar
authors.affiliation: American University of Beirut, Chemistry Department, Faculty of Arts and Sciences, Beirut, Lebanon. ns30@aub.edu.lb.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Sepetdjian
authors.affiliation: American University of Beirut, Department of Chemical and Petroleum Engineering, Faculty of Engineering and Architecture, Lebanon.
authors.forename: Walid
authors.initials: W
authors.lastname: Saad
authors.affiliation: University of Southern California, Department of Civil and Environmental Engineering, Los Angeles, USA.
authors.forename: Constantinos
authors.initials: C
authors.lastname: Sioutas
authors.affiliation: American University of Beirut, Mechanical Engineering Department, Faculty of Engineering and Architecture, Lebanon.
authors.forename: Alan
authors.initials: A
authors.lastname: Shihadeh
authors.affiliation: American University of Beirut, Chemistry Department, Faculty of Arts and Sciences, Beirut, Lebanon. ns30@aub.edu.lb.
authors.forename: Najat A
authors.initials: NA
authors.lastname: Saliba
mesh_terms: D000393:Air Pollutants / Q000032:analysis / Q000737:chemistry*; D004229:Dithiothreitol / Q000737:chemistry*; D008670:Metals; D008956:Models, Chemical; D053758:Nanoparticles / Q000737:chemistry; D010084:Oxidation-Reduction; D010087:Oxides; D052638:Particulate Matter / Q000032:analysis
chemical_list: D000393:Air Pollutants; D008670:Metals; D010087:Oxides; D052638:Particulate Matter; D004229:Dithiothreitol