The oxidative and neurotoxic potentials of the ambient PM2.5 extracts: The efficient multi-solvent extraction method

The health effects of ambient air particulate matter with a diameter of ≤2.5 μm (PM2.5) on the central nervous system are well known and the induced oxidative stress has been shown as their main neuropathologic outcome. Ambient air PM2.5 sampling methods mostly use air sampler systems that collect PM2.5 on filters, which is followed by a PM2.5 extraction approach. Inefficient extraction may lead to compositional bias and unreal interpretation of the results. This study aimed to compare our proposed multi-solvent extraction (MSE) approach for PM2.5 extraction with a conventional aqueous extraction (AqE) method using the analysis of oxidative effects and cytotoxicity in the human neuroblastoma SH-SY5Y cell line. Ambient PM2.5 samples were collected from an urban traffic location in Tehran city, the capital of Iran, using a high-volume sampler. The developed MSE method was proved to have superior advantages over the AqE method including an increased extraction efficiency (as much as 96 against 48% for PMms and PMaq, respectively), and decreased artifacts and compositional biases. Ambient PM2.5, besides PMms and PMaq were analyzed for water-soluble ions, metals, and major elements. Dithiothreitol, ascorbic acid, lipid peroxidation, and cell viability assays on SH-SY5Y cells represented the significantly higher oxidative potential for PMms compared to PMaq. The increased cytotoxicity may occur because of the increased oxidative potential of PMms and possibly is associated with higher efficiency of the MSE over the AqE method for removal of total redox-active PM components.