2 research outputs found
Microfluidic Electrochemical Sensor for On-Line Monitoring of Aerosol Oxidative Activity
Particulate matter (PM) air pollution has a significant
impact
on human morbidity and mortality; however, the mechanisms of PM-induced
toxicity are poorly defined. A leading hypothesis states that airborne
PM induces harm by generating reactive oxygen species in and around
human tissues, leading to oxidative stress. We report here a system
employing a microfluidic electrochemical sensor coupled directly to
a particle-into-liquid sampler (PILS) system to measure aerosol oxidative
activity in an on-line format. The oxidative activity measurement
is based on the dithiothreitol (DTT) assay, where, after being oxidized
by PM, the remaining reduced DTT is analyzed by the microfluidic sensor.
The sensor consists of an array of working, reference, and auxiliary
electrodes fabricated in a poly(dimethylsiloxane)-based microfluidic
device. Cobalt(II) phthalocyanine-modified carbon paste was used as
the working electrode material, allowing selective detection of reduced
DTT. The electrochemical sensor was validated off-line against the
traditional DTT assay using filter samples taken from urban environments
and biomass burning events. After off-line characterization, the sensor
was coupled to a PILS to enable on-line sampling/analysis of aerosol
oxidative activity. Urban dust and industrial incinerator ash samples
were aerosolized in an aerosol chamber and analyzed for their oxidative
activity. The on-line sensor reported DTT consumption rates (oxidative
activity) in good correlation with aerosol concentration (<i>R</i><sup>2</sup> from 0.86 to 0.97) with a time resolution
of approximately 3 min