Emerging applications of microfluidic techniques for in vitro toxicity studies of atmospheric particulate matter.

Exposure to atmospheric particulate matter (PM) is a leading global health risk. Despite extensive studies, it remains unclear as to what components or characteristics of PM best account for its toxicity. In vitro assays, including acellular and cellular assays, are widely used for PM toxicity evaluation. Acellular assays typically aim at assessing the oxidative potential (OP) of PM and linking OP to health endpoints. Cellular assays allow for elucidating the mechanisms of cellular signaling, response, and damage upon exposure to PM and linking cellular readouts to PM properties. Given the extraordinary chemical complexity and diversity of PM, there is a pressing need to efficiently evaluate OP and cellular response for PM emitted from different sources and formed under a variety of environmental conditions. Yet, current technologies are still not capable of high‐throughput, high‐content, and high time-resolution analysis, as well as mimicking physiologically relevant conditions. Microfluidic techniques are a valuable alternative technology to address some of the current challenges. In this article, we review the recent advances in applying microfluidic techniques for both cellular and acellular assays and discuss their advantages compared to conventional formats. Finally, we provide a prospective outlook on the future directions and challenges of using microfluidic techniques for in vitro toxicity studies of atmospheric PM. Copyright © 2021 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]