Document Type

Thesis

Date of Degree Completion

Spring 2025

Degree Name

Master of Science (MS)

Department

Chemistry

Committee Chair

Dr. Samuel E. Lohse

Second Committee Member

Dr. Dion Rivera

Third Committee Member

Dr. Anthony Diaz

Abstract

Emerging materials contaminants, such as microplastics (MPs) and engineered nanoparticles (ENPs), are now recognized to contaminate oceans, seas, freshwater, and drinking water through many different exposure pathways. The extent of the materials' water contamination problem has only begun to be properly appreciated in the last decade. While comprehensive global data on the exact quantity of nano- and microcontaminants in drinking water is challenging to ascertain, studies have shown that microplastics and nanoparticles can now be found in drinking water sources worldwide.  Indeed, a well-publicized recent study has shown that 93% of bottled water around the world contains microplastic contamination.

Detecting these emerging materials contaminants in drinking water is critical due to their persistence and harmful effects on human health and the environment. Despite this pressing need, detection methods for materials contaminants are often expensive and time-consuming, limiting widespread monitoring efforts and leaving communities vulnerable to material contamination. By establishing a method for rapid detection of materials contaminants in drinking water, this research aims to empower communities with the tools needed to ensure water safety and protect public health.

This research aimed to address the detection challenge by developing a colorimetric sensor array capable of selectively and sensitively detecting materials contaminants in drinking water. Leveraging an array of chemo-responsive dyes, the sensor array offers a cost-effective and portable solution for detecting and identifying material contaminants in water samples. Previous work has shown that sensor arrays of this kind could identify and detect nanoparticles of different sizes and shapes. The research tested a similar sensor array's ability to distinguish between gold nanorods (AuNRs) functionalized with different polyelectrolytes (PE). The gold nanorods were synthesized in the lab and coated with four different polyelectrolytes (charged polymers): polyallylamine hydrochloride (PAH), polyacrylic acid (PAA), polystyrene sulfonic acid (PSS), and poly (diallyldimethylammonium chloride) (PDADMAC), then characterized to confirm the AuNRs’ size, shape, and surface chemistry. The colorimetric sensor array was developed utilizing commercially available pH indicators and the sensor’s ability to distinguish between the synthesized nanoparticles was then probed. The sensor’s interactions with the AuNRs produced a colorimetric fingerprint unique (by eye) to each AuNR surface chemistry in the test library. The performance of the sensor array was also assessed using figures of merit such as Limit of Detection (LOD), Limit of Quantification (LOQ), response time, and selectivity.

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