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SUMMARY:Developing a Semi-Automated Assay for Measuring Particulate Matter 
 Oxidative Potential
LOCATION:Chemistry A101
TZID:America/Denver
DTSTART:20188201T000000
UID:2026-04-25-10-36-36@natsci.colostate.edu
DTSTAMP:20260425T103636
Description:4th Year Research Seminar:\n\nAmbient particulate matter (PM) a
 ir pollution is associated with negative health effects\, including respir
 atory and cardiovascular diseases\, and is estimated to cause millions of 
 deaths worldwide each year.1 The current hypothesis is that PM produces re
 active oxygen species (ROS) in the body\, which leads to oxidative stress.
 2 Dithiothreitol (DTT) is commonly used as a model antioxidant to measure 
 oxidative potential from PM-containing samples.3 PM catalyzes DTT oxidatio
 n\, and the DTT loss rate is correlated to the PM’s oxidative potential.
  The traditional DTT assay is an indirect spectroscopic method that requir
 es addition of the chromophore 5\,5-dithio-bis-(2-nitrobenzoic acid) (DTNB
 ). DTT concentration can also be directly measured electrochemically witho
 ut dilution and correlates 1:1 with the absorbance assay.4 Electrodes for 
 DTT measurement are carbon based\, modified with the catalyst cobalt(II) p
 hthalocyanine (CoPC)\, to reduce oxidation overpotential and electrode fou
 ling.4 Presented here is an electrochemical assay that uses commercially a
 vailable equipment\, for labs that do not have access to electrode fabrica
 tion tools\, that validates an end-point assay instead of the traditional 
 kinetic assay\, enabling batch processing of four samples per hour. The el
 ectrochemical assay is then applied to a large (&gt\;100) set of PM filter
  samples\, collected as part of a cookstove replacement project in Hondura
 s\, for the first time. The commercial electrode system is compared to hom
 emade graphite-thermoplastic electrodes (TPEs)\, which are easily modified
  with CoPC for DTT detection. Since large-scale PM health studies are hind
 ered by the lack of sample analysis automation\,5 the DTT assay is further
  improved to six samples per hour with a developed semi-automated system. 
 The semi-automated system can use either electrochemical or absorbance det
 ection\, and the two detection motifs are compared. The semi-automated ass
 ay is validated with a model oxidant and then tested on real PM filter sam
 ples from chamber experiments.\n\nReferences\n\n 	Cohen\, A. J.\; Brauer\,
  M.\; Burnett\, R.\; Anderson\, H. R.\; Frostad\, J.\; Estep\, K.\; Balakr
 ishnan\, K.\; Brunekreef\, B.\; Dandona\, L.\; Dandona\, R.\; Feigin\, V.\
 ; Freedman\, G.\; Hubbell\, B.\; Jobling\, A.\; Kan\, H.\; Knibbs\, L.\; L
 iu\, Y.\; Martin\, R.\; Morawska\, L.\; Pope\, C. A.\, III\; Shin\, H.\; S
 traif\, K.\; Shaddick\, G.\; Thomas\, M.\; van Dingenen\, R.\; van Donkela
 ar\, A.\; Vos\, T.\; Murray\, C. J. L.\; Forouzanfar\, M. H.\, Estimates a
 nd 25-year trends of the global burden of disease attributable to ambient 
 air pollution: an analysis of data from the Global Burden of Diseases Stud
 y 2015. The Lancet 2017\, 389 (10082)\, 1907-1918.\n 	Chung\, M. Y.\; Laza
 ro\, R. A.\; Lim\, D.\; Jackson\, J.\; Lyon\, J.\; Rendulic\, D.\; Hasson\
 , A. S.\, Aerosol-Borne Quinones and Reactive Oxygen Species Generation by
  Particulate Matter Extracts. Environmental Science &amp\; Technology 2006
 \, 40 (16)\, 4880-4886.\n 	Crobeddu\, B.\; Aragao-Santiago\, L.\; Bui\, L.
 -C.\; Boland\, S.\; Baeza Squiban\, A.\, Oxidative potential of particulat
 e matter 2.5 as predictive indicator of cellular stress. Environ. Pollut. 
 2017\, 230\, 125-133.\n 	Sameenoi\, Y.\; Koehler\, K.\; Shapiro\, J.\; Boo
 nsong\, K.\; Sun\, Y.\; Collett\, J.\; Volckens\, J.\; Henry\, C. S.\, Mic
 rofluidic Electrochemical Sensor for On-Line Monitoring of Aerosol Oxidati
 ve Activity. J. Am. Chem. Soc. 2012\, 134 (25)\, 10562-10568.\n 	Fang\, T.
 \; Verma\, V.\; Guo\, H.\; King\, L.\; Edgerton\, E.\; Weber\, R.\, A semi
 -automated system for quantifying the oxidative potential of ambient parti
 cles in aqueous extracts using the dithiothreitol (DTT) assay: results fro
 m the Southeastern Center for Air Pollution and Epidemiology (SCAPE). Atmo
 spheric Measurement Techniques 2015\, 8 (1)\, 471.\n\n&nbsp\; 4:00 pm
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