Date of Award


Document Type



Environmental and Forest Biology

Thesis Advisor

Lee A. Newman


Gold nanoparticles (AuNPs) can be introduced into our environment through many pathways and applications such as biosolids, pesticides, fertilizers, soil remediation, waste from consumer products, or through biomedicine applications. This creates regulatory concerns, as NPs possess unique chemical and physical properties that can impact living systems. The use of AuNPs is increasing, but there are insufficient studies looking at the toxic effects on food crops and the environment. It has been shown that AuNPs cause biotoxicity and necrosis as they have the potential to be internalized in the exposed plants. There are studies indicating bioaccumulation of AuNPs through trophic transfers in food chains from exposed plants. There are two objectives of this study: to look at the real world bioavailability that occurs in heterogeneous, soil-based systems and to determine how different times of exposure (4, 24, 72 h) impact the expression of stress response genes to AuNPs using the model crop, tomato. Tomatoes were exposed to 3.5 nm AuNPs for increasing times, while the controls were in water. In the soil study, tissues were analyzed by ICP-MS to determine the uptake of AuNPs. In the genetic study, q-RT-PCR was used to analyze the changes in gene expression levels. The results showed that difference in soil characteristics does affect the plant’s uptake; agriculture soils allowed the highest level of uptake AuNPs. For the genetic study, the stress response genes showed changes in expression at different exposure times. This shows that tomatoes grown in agriculture fields have the potential to take up AuNPs which can cause cellular toxic effects.

Included in

Soil Science Commons