Oxidative Potential of Selected PM Components

Abstract

Abstract:The role of the single PM components in inducing the catalytic generation of reactive oxygen species (ROS), has not yet been clarified. Different a-cellular assay are currently used in the literature for the determination of the PM oxidative potential (OP), which is considered as a predictive index of its capacity to generate ROS in biological organisms. In order to better understand the existing correlations between PO and PM generated by specific emission sources, the water soluble and insoluble fractions of seven dust coming from specific sources were chemically characterised and analysed by three PO assays: the dithiothreitol (DTT, the acid ascorbic (AA) and the 2′,7′-dichlorofluorescin (DCFH) assays. PO and chemical data were elaborated by principal constituent analysis. The three methods responded in a very different way to each dust; they are then no-interchangeable and probably none of them is able to correctly predict the ROS generation in biological organisms. DTT was particularly sensitive to organic compounds, while AA was mostly influenced by inorganic components. DCFH results are more difficult to interpret and need to be further deepened. Furthermore, the results confirmed the important role played by the insoluble components of dusts in generating oxidative processes.

Review of PM Oxidative Potential Measured with Acellular Assays in Urban and Rural Sites across Italy

“…In addition, OP DTT responses are also affected by traffic-related metals. In contrast, OP AA and OP GSH were mostly responsive to metals, mainly related to non-exhaust traffic emissions (Cu, Zn, Cr, Fe, Ni, Mn, Sn, Cd, Pb) [12,18,[25][26][27][28][32][33][34][35][36].…”

“…The formed DCF can be easily measured by fluorescence at the excitation and emission wavelengths of 485 and 530 nm, respectively. The ROS concentration may be then calculated in terms of H 2 O 2 equivalent [21,25,26,33].…”

“…Three PM size classes (PM >7 , PM 3-7 , PM 3 ) were characterized for OP DTT and for total elements. Others were performed on PM sampled in Rome and Ferrara, eastern Po valley, and also on PM from specific sources [25,26,33]. They used DTT, AA, and DCFH assays to measure OP of nine size-segregated PM fractions, i.e., cut-sizes: 0.18, 0.32, 0.56, 1.0, 1.8, 3.2, 5.6, 10, and 18 µm.…”

Use of Dithiothreitol Assay to Evaluate the Oxidative Potential of Atmospheric Aerosols

“…In addition to the DTT assay, the OP of atmospheric aerosols has also been assessed by several other acellular assays, such as GSH assay, AA assay, electron paramagnetic or spin resonance (EPR or ESR), and fluorescent probes for •OH, O − 2 and H 2 O 2 to characterize the particle-bound ROS generation from PM. Direct comparisons among these assays have been conducted within the scope of OP measurements [17,51,54,[93][94][95][96]. Some assays such as EPR/ESR and 2 ,7 -dichlorofluorescin (DCFH) probes can be used in either a cellular or an acellular environment.…”

Comment on acp-2021-57

“…However, due to the wide range and complex mixture of PM and the dynamic atmospheric processes to consider, the main drivers of OP can be difficult to highlight (Calas et al, 2019). Several methods have been used to assign the sources of OP, including the application of receptor modelling techniques such as Positive Matrix Factorization (PMF) and Chemical Mass Balance (CMB) (Ayres et al, 2008;Bates et al, 2015;Cesari et al, 2019;Fang et al, 2016;Paraskevopoulou et al, 2019;Verma et al, 2014;Weber et al, 2018Weber et al, , 2021Yu et al, 2019;Zhou et al, 2019), Principal Component Analysis (PCA) (Borlaza et al, 2018;Conte et al, 2017), and Robotic Chemical Mass Balance (RCMB) coupled with Multiple Linear Regression (MLR) analysis (Argyropoulos et al, 2016). With these current techniques, the OP of PM has been linked to specific emission sources and their estimated contributions.…”