OCE-PRF Chemical Imaging for Molecular Detection and Classification of Microplastics and their Influence on Zebrafish

Environmental impacts of plastic use are amongst the most concerning aspects of modern society as they can not only destroy marine populations but also harm human health. Microplastics (MP, plastic less than 5 mm) are common pollutants in marine environments and are expected to increase in prevalence, and decrease in size, with time. Bioaccumulation of MPs in marine life via direct ingestion and trophic transfer (transfer up the food chain) degrades the health of the oceans and, as a result, human food supply.

The first goal of this project is characterization of microplastic bioaccumulation and resulting tissue changes in fish across different polymer material, shape, and size combinations. This knowledge is important for determining which plastics are most harmful to the environment. Current methods for determining MP polymer identity are inefficient and time consuming.

The second goal of this study is to decrease the time and data required to identify plastics using the difference in intrinsic properties between materials. This study will not only provide information regarding the effect of MPs on fish health, but also provide preliminary information on how MPs affect humans.

Current studies of MP bioaccumulation in marine life decouple MP characterization and counting from chemical variations in tissues caused by MP exposure. The primary goal of this project is to use quantum cascade laser (QCL) based discrete frequency infrared imaging (DFIR) to characterize not only the location of MP bioaccumulation in zebrafish (Danio rerio), but also the resulting tissue changes in the same sample without the use of histochemical staining.

QCL based DFIR allows for time-efficient, data-rich, stainless biomedical imaging but has largely been limited to proof of concept using human tissue. QCL based DFIR is more time-efficient than standard Fourier transform infrared microscopy as it allows only IR bands of interest to be acquired. A library of control zebrafish tissue (including spleen, heart, gills, kidney, intestine, liver, muscle, and brain) will be imaged with DFIR and correlated with adjacent H&E-stained sections in order to develop an artificial intelligence (AI) pipeline to determine the types of cells and their variation into a first of its hind comprehensive zebrafish tissue chemical imaging (CI) database.

The effects of polyethylene terephthalate (PET) and polytetrafluoroethylene (PTFE) MPs with different geometries (sphere and fibers), average sizes (2 and 10 µm), doses (0.5 and 10 mg/L), and exposure times (3 and 14 days) on zebrafish tissue will be studied relative to the control tissue library. A secondary product of this project will be a time and data efficient AI pipeline for DFIR based MP composition analysis that is applicable to non-biologically associated samples.

The overarching goal of this work is to not only study MP bioaccumulation in a model species, but also to lay the groundwork for expansion of QCL based DFIR imaging to MP characterization and further zebrafish studies across biomedical sciences.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.