Date of Award

Spring 2024

Document Type


Terms of Use

© 2024 Tyler M. Hicks. This work is freely available courtesy of the author. It may be used under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) license. For all other uses, please contact the copyright holder.

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Degree Name

Bachelor of Arts


Chemistry & Biochemistry Department

First Advisor

Kathryn R. Riley


Silver nanoparticles (AgNPs) are widely used within commercial products due to their distinct antibacterial and antimicrobial properties. As their utilization continues to increase, their inevitable improper disposal could present lasting environmental ramifications due to their nonspecific biotoxicity. One microorganism of interest is Caulobacter crescentus, a common freshwater bacterium found in locations where AgNPs end after their disposal. C. crescentus has two distinct cell types—a stalked and a swarmer form—each with their own unique function and metabolic outputs. Approximately 15% of the C. crescentus metabolome varies with cell cycle, thus making this an interesting and environmentally relevant model organism for this work. Adsorbates, like proteins and other metabolites readily adsorb to the surface of AgNPs forming eco-coronas, which can alter the biological fate of AgNPs. A process of synchronizing the bacteria to the same cell-cycle interval was accomplished and complex mixtures of excreted matter from the C. crescentus were isolated at different intervals in the cell cycle. These mixtures were then used to create C. crescentus eco-coronas. Electrochemical techniques such as linear sweep stripping voltammetry (LSSV) in combination with dynamic light scattering (DLS) were used to evaluate the impact of C. crescentus eco-coronas on AgNP size, charge, and dissolution. Later stages in the C. crescentus cell-cycle were shown to contain more complex mixtures of adsorbates and lead to higher AgNP dissolution rates, thus demonstrating the utility of C. crescentus to model the complex environmental reactivity of AgNPs.

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