Title: An innovative method to assess oxidative stress induced by particulate matter using a plant model organism

Abstract

It is now recognized that one of the main mechanisms by which particulate matter (PM) exerts its adverse health effects is the generation of oxidative stress. Therefore, several acellular assays, which can be performed quickly and at a relatively low cost, have been developed to measure the oxidative potential (OP) of PM. However, these assays cannot represent the complexity of a biological organism and cannot provide complete information on the toxicological potential of PM. The use of model organisms could provide more detailed information about the ability of PM to generate oxidative stress in living organisms. This study is aimed to develop and optimize a simple, rapid, and low-cost method to study the oxidative stress induced by PM exposure using the plant model organism Arabidopsis thaliana. Plantlets of A. thaliana were exposed to certified urban dust (NIST1648a) and to the dust detached from PM samples collected in Rome and in the Po Valley (Italy) and analysed for oxidative potential by applying the AA, DCFH and DTT acellular assays, and for organic and elemental carbon, ions, levoglucosan, macro- and micro-elements. Oxidative stress was evaluated in the exposed plantlets by quantifying the production of superoxide anion (O2-•) using the NBT assay which is based on the highly specific reaction that occurs between NBT and O2-•, which leads to the formation of a blue-violet precipitate named formazan measured by UV-Vis spectrophotometer. The results obtained confirmed the reliability of DTT assay in predicting ROS generation in biological organisms and the suitability of A. thaliana as model organism for bio-indicator studies on PM effects on living organisms. Through the application of this method, it is possible to obtain information on the ability of PM to generate oxidative stress in living organisms quickly and keeping costs relatively low.