CAS-MNP: Discovering the mechanisms by which nanoplastics damage cell membranes

University Of Southern California, Los Angeles CA

Investigators

Abstract

Microplastic pollution—present on land, in waterways, and in the ocean—is the result of the environmental degradation of consumer and industrial plastic waste. Microplastics have been the subject of significant concern in recent years due to their potential incorporation into the food chain and their capacity to harm plants and animals. Microplastics can degrade further into environmental nanoplastics: particles of plastic waste smaller than a biological cell. Because they are so small, nanoplastics have been hard to isolate from the environment and have proven a stubbornly difficult class of materials to study. This project will develop a library of laboratory-created nanoplastic particles that mimic the size, shape, and composition of nanoplastics isolated from river water. This library will facilitate a detailed study of how nanoplastics can interact with, damage, and degrade the lipid bilayer membrane that serves as the boundary of cells. There is much evidence that engineered plastic nanoparticles can damage cell membranes, but these engineered particles are uniform in shape and composition. Environmental nanoplastics on the other hand are highly irregular and diverse. Identifying how these characteristics of irregular shape, size, and chemical composition control the interactions between environmental nanoplastics and cells is key to understanding how plastic pollution can be biologically harmful. The research project will incorporate a set of training and outreach efforts designed to train undergraduate and high-school students in the physical biology of environmental plastics. These efforts will include a summer undergraduate research program in collaboration with the Wrigley Institute at the university that will take students from field studies of plastic waste to laboratory investigations of nanoparticle-membrane interactions. Two high-school interns will engage in afterschool research in each year of the project. Sub-millimeter particles of plastic waste are broadly distributed in the environment, with particularly high concentrations in waterways, lakes, and oceans. Environmental nanoplastic particles are particularly concerning due to their capacity to infiltrate biological tissues on the sub-micron scale and to interact on the cellular level. In understanding these interactions, it is critical to consider how nanoparticles encounter and damage the key cellular interface—the plasma membrane. Research has demonstrated that nanoparticulate materials interact with cell membranes: they can deform, permeate, and damage cell membranes. The particles that have been studied so far, however, are engineered materials that are perfectly spherical, uniformly sized, with surface ligands that control charge and stability, and made of only polystyrene. Environmental nanoplastics are radically different: irregularly shaped, polydisperse in size, with surface properties determined by their environmental history, and with a diverse chemical makeup. This project leaps over this gap—transforming the understanding of membrane-nanoparticle interactions by putting real-world environmental nanoplastics under the literal microscope. This project executes three tasks: (1) Develop tools for creating plastic particles that mimic environmental nanoplastics and isolate these nanoplastics from environmental sources. (2) Discover how as-isolated mixtures of environmental nanoplastics can alter cell membrane morphology, integrity, permeability, and rigidity. (3) Understand how specific environmental nanoplastic characteristics (shape, size, protein coating) contribute to cell membrane damage. To accomplish these objectives, the team will use a suite of tools for understanding engineered nanoparticle-cell interactions and leverage new resources being developed at the University of Southern California to study environmental plastic pollution. The research project will incorporate a set of training and outreach efforts designed to train undergraduate and high-school students in the physical biology of environmental plastics. These efforts will include a summer undergraduate research program in collaboration with the Wrigley Institute at the university that will take students from field studies of plastic waste to laboratory investigations of nanoparticle-membrane interactions. Two high-school interns will engage in afterschool research in each year of the project. 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.