Doctor of Philosophy (PhD)
The Gordon A. and Mary Cain Department of Chemical Engineering
Nanoparticles have made vast advances in the realm of nanomedicine and bioimaging, enabling technologies such as photothermal therapy of malignant tumors and noninvasive monitoring of living tissue. Many of these innovations have only arisen in the last few decades with potential for growth in many avenues. The research shown in this work addresses some of the existing literature's void. Particularly solving synthesis challenges that have existed for more than 20 years in synthesizing Au nanoshells and establishing the potential for molecular-level deep imaging of plants. A novel investigation of the role of light absorption and scattering in bioimaging led to addressing these problems. Au nanoshells are a class of nanoparticles used in many absorption-based nanomedicine applications, including in clinical trials for cancer treatment. In such applications, the use of scattering-dominant nanoshells mitigates efficiency. This limitation results from challenges that prevent the synthesis of smaller absorption-dominant nanoshells. The work presented provides a solution and overcomes the current limitations of nanoshell synthesis, providing a facile route to sub-100 nm nanoshells that are absorption dominant. Comparison to commercial nanoshells shows that sub-100 nm nanoshells have a 14-fold higher volumetric absorption coefficient and 40 % higher imaging depth. Plant imaging can benefit from molecular contrast at longer wavelengths. Such studies will lead to a better understanding of the stress factors' impact on plant growth. The work shown here proposes a platform for the molecular imaging of plants. After comparing the use of Au bipyramids as contrast agents in optical coherence tomography, a scattering-based technique, and photoacoustic imaging, an absorption-based technique for plant imaging. Significant background noise hindered optical coherence tomography. Meanwhile, photoacoustic imaging allowed the tracking of Au bipyramid movement within live lettuce plants for 5 days. Additionally, plant health tests showed no impairment seven days post Au bipyramid infiltration. Therefore, establishing a platform for molecular imaging of plants.
Manuel, Luis Dias Bumba, "Design and Synthesis of Plasmonic Nanoparticles for NIR Bioimaging: Investigating the Role of Absorption and Scattering" (2023). LSU Doctoral Dissertations. 6117.
Available for download on Saturday, April 04, 2026