In-situ Measurement of the Capacity of Airborne Particulate Matter to Generate Reactive Oxygen Species

 描述(申请人提供)：在体外和体内，空气中颗粒物的氧化能力与氧化应激的产生有关。近年来，流行病学研究发现，细胞氧化应激引起的损伤与哮喘、慢性阻塞性肺疾病(COPD)、阿尔茨海默病等神经系统疾病有关。然而，这些研究是基于环境颗粒物的每日暴露和平均氧化能力。颗粒的氧化潜力在很大程度上取决于它们的化学组成，更具体地说，取决于它们的氧化还原活性化合物，如过渡金属和苯二酚。众所周知，环境颗粒物的物理化学性质随排放源和光化学老化程度的不同而不同。因此，我们预计颗粒物产生活性氧物种并造成氧化损伤的能力会出现日变化。目前，有几种化学和体外分析方法来确定环境颗粒物的氧化能力。然而，需要大量的样本才能获得可量化的反应。使用常见的采集设备，需要较长的采样周期，通常为24至48小时。有了这些长时间的采集期，颗粒的化学性质可能会改变，峰值曝光可能会隐藏。最近关于空气中颗粒物暴露与有害健康影响之间关系的研究发现，颗粒物暴露的短期峰值是威胁健康的重要因素，特别是在肺部疾病方面。流行性感冒的流行病学研究 短期暴露于颗粒物浓度峰值的影响发现，哮喘症状与1小时和8小时最大PM10(直径10微米的颗粒)暴露比24小时平均PM10暴露更相关。基于这些结果，开发能够测量暴露于健康应激源峰值浓度的仪器是至关重要的。在这个项目中，我们提出了一种在线监测气溶胶氧化能力的新方法(o-MOCA)。主要目标是开发一种可现场部署的系统，允许现场、时间分辨地评估空气中颗粒物产生ROS的能力。我们的方法利用了我们公司的新颗粒生长技术，该技术可以将颗粒直接沉积到液体中，获得用于化学和体外分析的浓缩悬浮液。气雾剂收集器使用水冷凝生长技术，可以将小到10纳米的颗粒收集成效率为90%的浓缩水悬浮液。收集的颗粒的氧化潜力将使用通常称为DTT试验(二硫苏糖醇试验)的化学分析方法进行测量。与现有的实验室和在线系统相比，o-MOCA方法有几个优点：i)它可以有效地将PM2.5直接收集到小容量的 通过直接收集，它避免了与其他粒子收集系统相关的最常见的伪影；iii)它允许进行时间分辨收集和现场直接分析，从而能够对PM的氧化能力进行更令人满意的日常表征。能够以时间分辨的方式表征气溶胶的氧化潜力，将在评估与PM暴露引起的氧化应激反应相关的可能不利后果时提供更准确的结果。我们的目标将通过完成以下具体目标来实现：i)化学分析模块的设计、建造和离线优化；ii)化学模块与液体收集器的接口；iii)进行实验室控制研究，以评估OU方法是否允许近乎实时地测量环境PM的氧化能力

 DESCRIPTION (provided by applicant): The oxidative capacity of airborne particulate matter has been correlated with the generation of oxidative stress both in-vitro and in-vivo. In recent years, epidemiological studies have associated damaged caused by cellular oxidative stress with several common diseases such as asthma, chronic obstructive pulmonary disease (COPD), Alzheimer's and other neurological diseases. However, these studies are based on daily exposure and averaged oxidative capacity of ambient particulate matter. Oxidative potential of the particles depends considerably on their chemical composition, more specifically on their redox active compounds, such as transition metals and quinones. It is well known that physical-chemical properties of ambient particles vary with emission sources and the extent of photochemical aging. Thus, we expect diurnal variations in the ability of particulate matter to generate reactive oxygen species and exert oxidative damage are expected. Currently, there are several chemical and in-vitro assays to determine the oxidative capacity of ambient particles. However, significant amounts of sample are needed to obtain a quantifiable response. Using the common collection devices, long sampling periods are needed, usually 24 to 48 hours. With these long collection periods, chemical properties of the particles may be altered and peak exposures hidden. Recent studies on the association between airborne particle exposures and adverse health effects identify short-term peaks in particulate matter exposures as important factors in health threat, especially in lung diseases. An epidemiological study of the effect of short-term exposure to peaks in particulate matter concentrations found that asthma symptoms were more highly associated with 1-h and 8-h maximum PM10 (particles with diameter <10µm) exposures than with 24-h mean PM10 exposures. Based on these results, the development of instruments capable of measuring exposure to peak concentrations of health stressors is of vital importance. In this project we propose a new approach for an on-line monitor of the oxidative capacity of aerosols (o- MOCA). The main objective is to develop a field-deployable system that allows in-situ, time-resolved assessment of the capacity of airborne particles to generate ROS. Our approach capitalizes on our firm's new particle growth technology that enables direct particle deposition into liquids, obtaining concentrated suspensions ready for chemical and in-vitro assays. The aerosol collector uses the water condensational growth technology which allows the collection of particles as small as 10 nm into concentrated water suspensions with efficiencies >90%. The oxidative potential of the collected particles will be measured using the chemical assays commonly known as the DTT assay (dithiothreitol assay). The o-MOCA approach has several advantages over the existing laboratory and on-line systems: i) it can efficiently collect PM2.5 directly into a small volume of water, increasing the particle concentration and thus reducing the time needed for collection; ii) with direct collection it avoids the most common artifacts associated with other particle collectio systems; iii) it allows for time-resolved collection and in-field direct analysis, allowing for a mre satisfactory daily characterization of the PM oxidative capacity. The ability to characterize the oxidative potential of aerosols in a time-resolved manner will provide more accurate results when assessing possible adverse outcomes related to oxidative stress responses resulting from PM exposure. Our goal will be achieved by completing the following specific aims: i) design, construction and off-line optimization of the chemical assay module; ii) interface the chemical module with the liquid collector; iii) conduct laboratory controlled studies to evaluate whether ou approach allows for near-real time measurements of the oxidative capacity of ambient PM.