Date of Award

2013-01-01

Degree Name

Master of Science

Department

Chemistry

Advisor(s)

Jorge Gardea-Torresdey

Abstract

Studies have shown that plants exposed to ENPs suffer different types of stress. Other studies have revealed that plants can take up and accumulate CeO2 NPs without modification. Thus, these NPs could enter the food chain through edible plants, posing a threat for human health. Cilantro (Coriandrum sativum) is a worldwide culinary and medicinal plant consumed either as a fresh herb or a spice. In this research, cilantro plants were germinated and cultivated for 30 days in organic soil treated with CeO2 NPs at concentrations varying from 0 to 500 mg kg!1. Subsequently, plant organs were analyzed by using spectroscopic techniques and biochemical assays. Results indicate that at 125 mg kg!1, the CeO2 NPs significantly increased the root size compared with the other treatments. The ICP-OES results showed that plants exposed to 500 mg kg!1 had significantly (p " 0.05) more Ce in shoots and roots compared to the other treatments. Results from the biochemical assays showed that at 125 mg kg!1, catalese activity significantly increased in shoots and ascorbate peroxidase in roots (p " 0.05). In addition, the FTIR analyses revealed that at 125 mg kg-1, the CeO2 NPs changed the chemical environment of the carbohydrates within the cilantro shoots, for which changes in the area of the stretching frequencies were observed. Moreover, analyses of antioxidant compounds showed a significant (p " 0.05) reduction on total phenolic content in shoots of cilantro plants treated with 500 mg CeO2 NPs kg-1. This suggests that the CeO2 NPs have the potential to diminish the ability of cilantro plants to scavenge reactive oxygen species. The multi-elemental analysis showed that plants treated with CeO2 at the 500 mg kg-1 treatment had a significant (p " 0.05) reduction in shoots' sulfur, silicon, and zinc accumulation. The results of this research indicate that the CeO2 NPs at 500 mg CeO2 kg-1 concentration cause a reduction in the antioxidant ability and nutritional properties of cilantro plants.

Language

en

Provenance

Received from ProQuest

File Size

62 pages

File Format

application/pdf

Rights Holder

Maria Isabel Morales

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Chemistry Commons

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