Date of Award

Winter January 2012

Access Restriction

Campus Access only Theses

Degree Name

Master of Science

Department

Mechanical Engineering

School or College

Seaver College of Science and Engineering

First Advisor

Mel I. Mendelson

Abstract

The novel and extraordinary physiochemical properties of engineered nanoparticles (ENPs) are certain; however, their unique characteristics raise growing concerns regarding potentially adverse effects on biological and ecological systems. It is becoming increasingly evident that, before the full potential of nanotechnology can be realized, standardized characterization of ENP behavior, fate, and effects on the ecosystem are essential to ensure the safe manufacturing and use of ENP products. Otherwise, the promise of such extraordinary advancements may find itself limited to applications such as electronics and sporting equipment, industries in which ENPs currently reside. The current toxicity profile of engineered nanomaterials is not only preliminary, but highly variable amongst researchers. Consequently, there is great need for the development of a highly organized, efficient, and precise approach to assess the hazardous potential ENPs may pose, while addressing the safety concerns surrounding and limiting nanotechnology. In response to such concerns, the present study took an engineering approach, in an otherwise traditionally viewed discipline, to assess the potential impact of one type of engineered nanoparticle, water-soluble (MUA) CdSe/ZnS- quantum dots (QDs), on tomato (Solanum lycopersicum) seedlings, by implementing a full factorial design of experiment (FDOE), in an effort to identify which factors, and their interactions, have a significant (p ≤ 0.05) effect on root and shoot elongation, and if any observed effects are a result of particle uptake, evaluated via fluorescence microscopy imaging. By implementing factorial experimental design methodologies, not only are we efficiently identifying the factors that affect phytotoxicity, we are providing, for the first time to our knowledge, the first scientific data to report the significant interaction effects between the factors responsible for ENP toxicity. (MUA) CdSe/ZnS quantum dots had a negative influence on root and shoot lengths of tomato seedlings exposed for 3 days, as well as those exposed for 6 days. The observed influence depended on QD concentration and exposure time, as statistical analyses found QD concentration, exposure time, and the concentration-exposure time interaction significantly (p ≤ 0.05) affected root and shoot lengths of tomato seedlings. Additionally, to minimize the observed phytotoxicity effects (i.e., to maximize tomato root lengths), our results suggest that exposure of tomato seeds to low QD concentration levels (125 mg/L) for short periods of time (maximum of 3 days) to yield maximum root lengths of approximately 2.21 cm, that is – minimal phytotoxicity effects.

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