Real-Time Cell-Electronic Sensing of Coal Fly Ash Particulate Matter for Toxicity-Based Air Quality Monitoring

The development of a unique bioassay for cytotoxicity analysis of coal fly ash (CFA) particulate matter (PM) and its potential application for air quality monitoring is described. Using human cell lines, A549 and SK-MES-1, as live probes on microelectrode-embedded 96-well sensors, impedance changes over time are measured as cells are treated with varying concentrations (1 μg/mL-20 mg/mL) of CFA samples. A dose-dependent impedance change is determined for each CFA sample, from which an IC50 histogram is obtained. The assay was successfully applied to examine CFA samples collected from three coal-fired power plants (CFPs) in China. The samples were separated into three size fractions: PM2.5 (<2.5 μm), PM10-2.5 (2.5 μm < x < 10 μm), and PM10 (>10 μm). Dynamic cell-response profiles and temporal IC50 histograms of all samples show that CFA cytotoxicity depends on concentration, exposure time (0-60 h), and cell-type (SK-MES-1 > A549). The IC50 values differentiate the cytotoxicity of CFA samples based on size fraction (PM2.5 ≈ PM10-2.5 ≫ PM10) and the sampling location (CFP2 > CFP1 ≈ CFP3). Differential cytotoxicity measurements of particulates in human cell lines using cell-electronic sensing provide a useful tool for toxicity-based air quality monitoring and risk assessment.