On-line Measurement of the Capacity of Airborne Particulate Matter to Generate Reactive Oxygen Species

Project summaryThe oxidative capacity of airborne particulate matter has been correlated with the generation of oxidative stress both in vitro and in vivoIn recent yearsepidemiological studies have associated damaged caused by cellular oxidative stress with several common diseases such as asthmachronic obstructive pulmonary diseaseCOPDAlzheimer s and other neurological diseasesEven though recent studies have identified short term peaks in particulate matter exposures as important factors in health threatcurrently available chemical and invitro assays to determine the oxidative capacity of ambient particles require large samplesand hence long sampling periodstypicallytohoursProposed is the development of an on line monitor of the oxidative capacity of aerosols to provide on linetime resolved assessment of the capacity of airborne particles to generate reactive oxygen speciesROSOur approach combines a chemical module optimized in Phase I for on line measurement of the oxidative capacity of aerosoland our firm s new particle growth technology to collect particles directly into small volumes of liquidThe aerosol collector uses the water condensational growth technology that allows collection of particles as small asnm into concentrated water suspensions with efficiencies rtThe oxidative potential of the collected particles will be measured using the chemical assay commonly known as the DTTdithiothreitolassayOur approach efficiently collects both soluble and insoluble constituents of particulate matter directly into a small volume of waterand analyzes this sample in field to provide immediatetime resolved analysisThe direct collection and rapid analysis also reduces artifacts associated with long filter collection periods and extractionThe ability to characterize the oxidative potential of aerosols accurately and in a time resolved manner will provide a more complete data set for better assessing possible adverse outcomes related to oxidative stress responses resulting from exposure to ambient particulate matterIn Phase Iwe demonstrated our approach by developing a laboratory prototype that was validated in the laboratory for reproducibility and sensitivityand that successfully ran unattended fordaysprovidinghour time resolution of the ROS capacity of ambient particulate matterIn Phase IIwe will make a portablerobust and fully automated system for unattended field operationSpecific aims areidevelopment of a compact and more sensitive version of our Phase I chemical moduleiiintegration of this chemical module with an improved version of the commercially available Liquid Spot Sampleriiiextension of analysis capability to distinguish the contribution of metals and organics to particle oxidative capacityivdemonstration of the system performance under field conditions