scholarly journals A semi-automated instrument for cellular oxidative potential evaluation (SCOPE) of water-soluble extracts of ambient particulate matter

2021 ◽  
Vol 14 (12) ◽  
pp. 7579-7593
Author(s):  
Sudheer Salana ◽  
Yixiang Wang ◽  
Joseph V. Puthussery ◽  
Vishal Verma
Keyword(s):  
Particulate Matter ◽  
Chemical Species ◽  
Positive Control ◽  
Water Soluble ◽  
Ros Generation ◽  
Ambient Particulate Matter ◽  
Oxidative Potential ◽  
Cellular Assays ◽  
Potential Evaluation ◽  
Automated Instrument

Abstract. Several automated instruments exist to measure the acellular oxidative potential (OP) of ambient particulate matter (PM). However, cellular OP of the ambient PM is still measured manually, which severely limits the comparison between two types of assays. Cellular assays could provide a more comprehensive assessment of the PM-induced oxidative stress, as they incorporate more biological processes involved in the PM-catalyzed reactive oxygen species (ROS) generation. Considering this need, we developed a semi-automated instrument, the first of its kind, for measuring the cellular OP based on a macrophage ROS assay using rat alveolar macrophages. The instrument named SCOPE – semi-automated instrument for cellular oxidative potential evaluation – uses dichlorofluorescein diacetate (DCFH-DA) as a probe to detect the OP of PM samples extracted in water. SCOPE is capable of analyzing a batch of six samples (including one negative and one positive control) in 5 h and is equipped to operate continuously for 24 h with minimal manual intervention after every batch of analysis, i.e., after every 5 h. SCOPE has a high analytical precision as assessed from both positive controls and ambient PM samples (coefficient of variation (CoV)<17 %). The results obtained from the instrument were in good agreement with manual measurements using tert-butyl hydroperoxide (t-BOOH) as the positive control (slope =0.83 for automated vs. manual, R2=0.99) and ambient samples (slope =0.83, R2=0.71). We further demonstrated the ability of SCOPE to analyze a large number of both ambient and laboratory samples and developed a dataset on the intrinsic cellular OP of several compounds, such as metals, quinones, polycyclic aromatic hydrocarbons (PAHs) and inorganic salts, commonly known to be present in ambient PM. This dataset is potentially useful in future studies to apportion the contribution of key chemical species in the overall cellular OP of ambient PM.

scholarly journals A Semi-automated Instrument for Cellular Oxidative Potential Evaluation (SCOPE) of Water-soluble Extracts of Ambient Particulate Matter

2021 ◽  
Author(s):  
Sudheer Salana ◽  
Yixiang Wang ◽  
Joseph Puthussery ◽  
Vishal Verma
Keyword(s):  
Particulate Matter ◽  
Chemical Species ◽  
Positive Control ◽  
Water Soluble ◽  
Ros Generation ◽  
Ambient Particulate Matter ◽  
Oxidative Potential ◽  
Cellular Assays ◽  
Potential Evaluation ◽  
Automated Instrument

Abstract. Several automated instruments exist to measure the acellular oxidative potential (OP) of ambient particulate matter (PM). However, cellular OP of the ambient PM is still measured manually, which severely limits the comparison between two types of assays. Cellular assays could provide a more comprehensive assessment of the PM-induced oxidative stress, as they incorporate more biological processes involved in the PM-catalyzed reactive oxygen species (ROS) generation. Considering this need, we developed a first of its kind semi-automated instrument for measuring the cellular OP based on a macrophage ROS assay using rat alveolar macrophages. The instrument named SCOPE – Semi-automated instrument for Cellular Oxidative Potential Evaluation, uses dichlorofluorescein diacetate (DCFH-DA) as a probe to detect the OP of PM samples extracted in water. SCOPE is capable of analyzing a batch of six samples (including one negative and one positive control) in five hours and is equipped to operate continuously for 24-hours with minimal manual intervention after every batch of analysis, i.e., after every five hours. SCOPE has a high analytical precision as assessed from both positive controls and ambient PM samples (CoV < 17 %). The results obtained from the instrument were in good agreement with manual measurements using tert-Butyl hydroperoxide (t-BOOH) as the positive control (slope = 0.83 for automated vs. manual, R2 = 0.99) and ambient samples (slope = 0.83, R2 = 0.71). We further demonstrated the ability of SCOPE to analyze a large number of both ambient and laboratory samples, and developed a dataset on the intrinsic cellular OP of several compounds, such as metals, quinones, PAHs and inorganic salts, commonly known to be present in ambient PM. This dataset is potentially useful in future studies to apportion the contribution of key chemical species in the overall cellular OP of ambient PM.

scholarly journals Development and field-testing of an online instrument for measuring the real-time oxidative potential of ambient particulate matter based on dithiothreitol assay

2018 ◽  
Author(s):  
Joseph V. Puthussery ◽  
Chen Zhang ◽  
Vishal Verma
Keyword(s):  
Particulate Matter ◽  
Organic Carbon ◽  
Water Soluble ◽  
Urban Site ◽  
Activity Levels ◽  
Ambient Particulate Matter ◽  
Oxidative Potential ◽  
Pump System ◽  
Activity Measurements ◽  
Diurnal Profile

Abstract. We developed an online instrument for measuring the oxidative potential (OP) of ambient particulate matter (PM) using dithiothreitol (DTT) assay. The instrument uses a mist chamber (MC) to continuously collect the ambient PM2.5 in water, followed by its DTT activity determination using an automated syringe pump system. The instrument was deployed at an urban site in the University of Illinois campus, and its field performance was evaluated by comparing the results with the offline DTT activity measurements of simultaneously collected PM-laden filters. The online DTT activity measurements correlated well with the offline measurements but were higher than both methanol (slope = 0.86, R2 = 0.93) and Milli-Q water (slope = 0.52, R2 = 0.86) extracts of the PM filters, indicating a better efficiency of MC for collecting the water-insoluble fraction of PM. The hourly measurements of ambient PM2.5 OP were obtained by running the online instrument intermittently for 50 days with minimal manual assistance. The daytime DTT activity levels were generally higher than at night. However, a four-fold increase in the hourly averaged activity was observed on the night of July 04 (Independence Day fireworks display). Diurnal profile of the hourly averaged OP during weekdays showed a bimodal trend, with a sharp peak in the morning (around 7:00 AM), followed by a broader afternoon peak, which plateaus around 2:00 PM, and starts subsiding at night (around 7:00 PM). To investigate the association of the diurnal profile of DTT activity with the emission sources at the site, we collected time-segregated composite PM filter samples in four different time periods of the day [morning (7:00 AM–10:00 AM), afternoon (10:00 AM–3:00 PM), evening (3:00 PM–7:00 PM) and night (7:00 PM–7:00 AM)] and determined the diurnal variations in the redox active components [i.e. water soluble Cu, Fe, Mn, organic carbon, elemental carbon and water soluble organic carbon]. Based on this comparison, we attributed the daytime OP of ambient PM2.5 to the water-soluble Cu from both exhaust and non-exhaust emissions, whereas secondary particles formed by the photochemical transformation of primary emissions appear to enhance the OP of PM during the afternoon and evening period.

scholarly journals Development and field testing of an online instrument for measuring the real-time oxidative potential of ambient particulate matter based on dithiothreitol assay

2018 ◽  
Vol 11 (10) ◽  
pp. 5767-5780 ◽  
Author(s):  
Joseph V. Puthussery ◽  
Chen Zhang ◽  
Vishal Verma
Keyword(s):  
Particulate Matter ◽  
Organic Carbon ◽  
Water Soluble ◽  
Urban Site ◽  
Activity Levels ◽  
Ambient Particulate Matter ◽  
Oxidative Potential ◽  
Pump System ◽  
Activity Measurements ◽  
Diurnal Profile

Abstract. We developed an online instrument for measuring the oxidative potential (OP) of ambient particulate matter (PM) using the dithiothreitol (DTT) assay. The instrument uses a mist chamber (MC) to continuously collect the ambient PM2.5 in water, and then determines its DTT activity using an automated syringe pump system. The instrument was deployed at an urban site in the University of Illinois campus, and its field performance was evaluated by comparing the results with the offline DTT activity measurements of simultaneously collected PM-laden filters. The online DTT activity measurements correlated well with the offline measurements but were higher than both methanol (slope =1.08, R2=0.93) and Milli-Q water (slope =1.86, R2=0.86) extracts of the PM filters, indicating a better efficiency of the MC for collecting the water-insoluble fraction of PM. The hourly measurements of ambient PM2.5 OP were obtained by running the online instrument intermittently for 50 days with minimal manual assistance. The daytime DTT activity levels were generally higher than at night. However, a 4-fold increase in the hourly averaged activity was observed on the night of 4 July (Independence Day fireworks display). The diurnal profile of the hourly averaged OP during weekdays showed a bimodal trend, with a sharp peak in the morning (around 07:00 LT), followed by a broader afternoon peak which plateaus around 14:00 LT and starts subsiding at night (around 19:00 LT). To investigate the association of the diurnal profile of DTT activity with the emission sources at the site, we collected time-segregated composite PM filter samples in four different time periods of the day (morning, 07:00–10:00 LT; afternoon, 10:00–15:00 LT; evening, 15:00–19:00 LT; and night, 19:00–07:00 LT) and determined the diurnal variations in the redox active components (i.e., water-soluble Cu, Fe, Mn, organic carbon, elemental carbon, and water-soluble organic carbon). Based on this comparison, we attributed the daytime OP of ambient PM2.5 to the vehicular (both exhaust and non-exhaust) emissions and resuspended dust, whereas secondary photochemical transformation of primary emissions appear to enhance the OP of PM during the afternoon and evening period.

scholarly journals Oxidative potential of ambient particulate matter in Beirut during Saharan and Arabian dust events

2018 ◽  
Vol 188 ◽  
pp. 34-42 ◽  
Author(s):  
Christopher Lovett ◽  
Mohammad H. Sowlat ◽  
Najat A. Saliba ◽  
Alan L. Shihadeh ◽  
Constantinos Sioutas
Keyword(s):  
Particulate Matter ◽  
Ambient Particulate Matter ◽  
Oxidative Potential ◽  
Dust Events

Oxidative potential of particulate matter at a German motorway

2015 ◽  
Vol 17 (4) ◽  
pp. 868-876 ◽  
Author(s):  
Bryan Hellack ◽  
Ulrich Quass ◽  
Carmen Nickel ◽  
Gabriele Wick ◽  
Roel P. F. Schins ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Ambient Particulate Matter ◽  
Oxidative Potential

Ambient particulate matter (PM10) was sampled alongside a motorway at clear up- and downwind situations and analysed to their oxidative potential.

scholarly journals On dithiothreitol (DTT) as a measure of oxidative potential for ambient particles: evidence for the importance of soluble transition metals

2012 ◽  
Vol 12 (5) ◽  
pp. 11317-11350 ◽  
Author(s):  
J. G. Charrier ◽  
C. Anastasio
Keyword(s):  
Particulate Matter ◽  
Transition Metals ◽  
Fine Particulate Matter ◽  
Chemical Species ◽  
Past Research ◽  
Active Species ◽  
Oxidative Potential ◽  
Adverse Health Effects ◽  
Redox Active ◽  
Small Set

Abstract. The rate of consumption of dithiothreitol (DTT) is increasingly used to measure the oxidative potential of particulate matter (PM), which has been linked to the adverse health effects of PM. While several quinones are known to be very reactive in the DTT assay, it is unclear what other chemical species might contribute to the loss of DTT in PM extracts. To address this question, we quantify the rate of DTT loss from individual redox-active species that are common in ambient particulate matter. While most past research has indicated that the DTT assay is not sensitive to metals, our results show that seven out of the ten transition metals tested do oxidize DTT, as do three out of the five quinones tested. While metals are less efficient at oxidizing DTT compared to the most reactive quinones, concentrations of soluble transition metals in fine particulate matter are generally much higher than those of quinones. The net result is that metals appear to dominate the DTT response for typical ambient PM2.5 samples. Based on particulate concentrations of quinones and soluble metals from the literature, and our measured DTT responses for these species, we estimate that for typical fine particle samples approximately 80% of DTT loss is from transition metals (especially copper and manganese), while quinones account for approximately 20%. We find a similar result for DTT loss measured in a small set of PM2.5 samples from the San Joaquin Valley of California. Because of the important contribution from metals, we also tested how the DTT assay is affected by EDTA, a chelator that is sometimes used in the assay. EDTA significantly suppresses the response from both metals and quinones; we therefore recommend that EDTA should not be included in the DTT assay.

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