Publication Date

2022

Document Type

Dissertation

Committee Members

Ioana E. Pavel, Ph.D. (Committee Chair); Norma C. Adragna, Ph.D. (Committee Co-Chair); Sushil R. Kanel, Ph.D. (Committee Member); Ji Chen Bihl, M.D., Ph.D. (Committee Member); Steven R. Higgins, Ph.D. (Committee Member)

Degree Name

Doctor of Philosophy (PhD)

Abstract

With the advent of nanotechnology, the potential applications of nanoscale gold in medicine have expanded substantially. Gold’s therapeutic and toxic properties have been widely studied; however, little is known regarding gold’s contribution to oxidative stress in red blood cells (RBCs). This is especially true for recently designed large (L) gold nanorods (GNRs), which possess unmatched theranostic capabilities. Here, we report on the effect of LGNRs at the level of cellular function, and particularly on ion transport and the glutathione (GSH) concentration in human (H) RBCs. Gold has been hypothesized to effectively react with RBCs sulfhydryl groups, thereby causing depletion of the antioxidant reserve represented by GSH and its pathway, through which GNRs induced cellular toxicity. The present study examined the effect of LGNRs on Rb+ and K+ metabolism and the GSH concentration in cord and adult human RBCs (HRBCs). In conclusion, the unique properties of LGNRs could be further enhanced in a precision medicine setting. Multiple regulatory agencies, including the U.S. National Institute for Occupational Safety and Health (NIOSH) and the U.S. Environmental Protection Agency (EPA), have outlined the need to improve the risk assessment and control associated with the heavy use of nanomaterial-based consumer products. The Nanotechnology Product Database indicates that silver nanoparticles (AgNPs) are the main component of ~ 70% of the reported biomedical products. This work addresses this knowledge gap by combining CytoViva and Raman hyperspectral imaging to study the uptake, distribution, and toxicity of silver nanoparticles in human red blood cells (RBCs). To achieve this, RBCs in 5% glucose solution were incubated at 37 °C, for 60 min, with 150 µg mL-1 of negatively charged, spherical AgNPs of an average diameter of ~ 16 nm. These citrate-capped AgNPs were selected as a nano-model due to their wide use, biocompatible capping agent, low cost, and simple fabrication. The physicochemical properties of AgNPs were characterized following the U.S. EPA recommendations after size-selecting, concentrating, and purifying them by tangential flow filtration (TFF) for improved homogeneity and reproducibility. CytoViva images showed that 48 ± 5 % of the total administered AgNPs was absorbed by cells, and ~ 70% of the interacting AgNPs were present at the cell membrane. A small CytoViva hyperspectral library of biochemical components characteristic to the RBC membrane was created and utilized in conjunction with a newly developed deconvolution approach for the qualitative and quantitative analysis of these cell biomarkers before and after their interactions with AgNPs. The deconvolution of the CytoViva hyperspectral data revealed significant cytotoxic changes in the content and/or spatial distribution of spectrin (520 nm), phospholipids (521 and 591 nm), and cholesterol (587 and 611 nm) components as a result of this interaction when compared to the negative controls. These toxicity effects of AgNPs were further confirmed through a cytotoxicity lipid peroxidation assay by increase malondialdehyde by ~133% and decrease in GSH levels by 50%. Overall, the results of this study suggest that citrate-capped AgNPs may remain concentrated in the blood circulatory system, and especially in the RBCs, despite their negative charge and biocompatible capping agent, and thereby raise major concerns with respect to the biomedical applications of AgNPs in humans.

Page Count

148

Department or Program

Department of Earth and Environmental Sciences

Year Degree Awarded

2022

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