INVESTIGATOR: Benjamin McDonald, Brown University 
MENTOR: Jason Dwyer, University of Rhode Island

TITLE: Photonic thin films for the colorimetric detection of waterborne pollutants
SCIENTIFIC THEME: Environmental Health Sciences
AWARD: Early Career Development (2022-2024)

ABSTRACT: Microbial and PFAS in drinking water, as well as marine and freshwater bodies of water, are persistent and increasing threats to ecological and human health around Rhode Island and the greater United States. To ensure public safety, concentrations of these entities are typically monitored at centralized testing
facilities, consuming considerable resources and limiting community engagement. A fully contained sensing system, that after simple exposure to the sample (e.g., immersion), can be read by a smartphone and provide quantitative information on both of these pollutants would address these challenges. Thin films, composed of nanorod colloids such as viruses and cellulose nanocrystals, show dynamic structural
color that rapidly respond to changes in their chemical environment. While such films have been shown to respond in seconds to minutes to part-per-million ( and up to part-per-trillion) concentrations, sensing in complex aqueous environments remain unrealized.

This proposal seeks to develop bottlebrush polymers as scalable and chemically tailorable constituent materials for photonic thin films that respond to representative microbial (E. Coli, Aim 1) and chemical contaminants (PFAS, Aim 2) in aqueous solutions. This work will provide fundamental design insights to
render bottlebrush polymers a general route to colorimetric sensors that operate in complex sample environments such as breath, urine, blood, bodies of water and ambient air. Ultimately, this work is intended to initiate the development of a unified sensing system for persistent environmental monitoring systems, wearable chemical exposure sensors, and point-of-care biomedical diagnostics.

RELEVANCE: Access to safe drinking and recreational water in the United States is a significant issue for much of the population. Consequently, simple and portable devices for the detection of harmful microbes and chemical pollutants are urgently needed. The proposed work will develop new materials that indicate quantities of
both entities by changing color after exposure and more generally will provide the foundation for a variety of portable chemical sensors.