Date of Award

Spring 2023

Document Type

Thesis

Terms of Use

© 2023 Christopher D. Chung. All rights reserved. This work is freely available courtesy of the author. It may only be used for non-commercial, educational, and research purposes. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts

Department

Chemistry & Biochemistry Department

First Advisor

Kathryn R. Riley

Abstract

Silver nanoparticles (AgNPs) are increasingly used commercially and medically due to their antimicrobial and antibacterial properties. With increased use comes increased release of AgNPs into the environment, and once released, AgNPs can form coronas with molecules ranging from biomolecules to proteins to natural organic matter (NOM). The molecules in the corona adsorb to the surface of the AgNPs, drastically altering their innate properties such as cytotoxicity and binding behavior. In this study, we characterize and quantify model AgNP-adsorbate systems by obtaining their relevant reaction parameters through three different affordable analytical techniques, including dynamic light scattering (DLS), UV-vis spectroscopy, and capillary electrophoresis (CE). Citrate-stabilized AgNPs with hydrodynamic diameters of 10 nm, 20 nm and 40 nm were used in this work. Kₐ values of AgNPs reacting with a model protein, bovine serum albumin (BSA) and a model NOM, Suwannee River humic acid (SRHA), were individually quantified using UV-vis spectroscopy. Nonequilibrium capillary electrophoresis of equilibrium mixtures (NECEEM) was also employed to obtain binding and rate constants pertaining to the individual reactions and compared with the values acquired through UV-vis spectroscopy. The AgNP size was shown to have an indirect relationship with their reactivity, with smaller AgNPs having higher Kₐ values. There was also remarkable agreement between the two quantitative analyses, validating the use of the novel NECEEM technique for use in other NP corona complexes. DLS was used to characterize the initial nanoparticles as well as those with a formed corona, and circular dichroism (CD) spectroscopy was used to monitor protein conformational changes upon adsorption of BSA to AgNPs and interaction with SRHA. Subsequently, in a field dominated by single adsorbate studies of the AgNP coronas, we strived to take this study a step further and investigate multiple adsorbate systems. Thus, a new CE-based pull-down assay was developed and optimized for quantitative analysis of the relative reactivity of multiple adsorbates interacting with AgNPs. Using this new technique, SRHA was found to decrease the amount of BSA adsorbed to AgNPs in solution across all sizes. Smaller sized AgNPs seemed to favor BSA adsorption over SRHA, but as the size of the AgNP increased, the affinity seemed to shift to favoring the adsorption of SRHA.

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