Quantum dots (QDs) are crystalline nanoparticles made from semiconductor material with sizes ranging from 1 to 10 nm in diameter. QDs are attractive fluorophores for bioimaging and sensing due to their size-dependent optical properties, broad absorption bands, high extinction coefficients and superior photostability. The combination of imaging and drug delivery in a single particle can provide valuable information and improve the efficacy of existing treatments. This dissertation highlights the use of QDs for biomedical and agricultural applications. Chapter 1 of this dissertation presents a background of QDs and outlines the synthesis methods of producing and functionalizing QDs. A discussion of the advantages and limitations of each method for producing water-soluble QDs and the rationale for the proposed research is also presented. Chapter 2 describes an activatable QD design for tracking of drug delivery for cancer treatment. QDs synthesized by microemulsion (ME) were cross-linked in a one-step procedure. Enhanced binding affinity of the probe to cell lines overexpressing folate receptors was shown through fluorescence microscopy. However, this system is not practical for the large-scale synthesis due to its complexity and can not be translated for clinical development. Chapter 3 presents a sol-gel synthesis method for producing water-soluble QDs utilizing the thiol-based small molecule capping agent as the stabilizer as an alternative to ME technique. This method was designed to be a simple (one-step), cost-effective, and scalable for making both manganese doped CdS and ZnS QDs. QDs were synthesized through sol-gel method with a library of organic thiol coatings and characterized by size, surface charge, stability, and optical properties. These particles were compared to QDs produced from ME synthesis and were found to have similar properties. Chapter 4 reports the sol-gel QDs as slow-release antibiotic delivery system for application as agricultural bactericide. Utilizing electrostatic interactions, the QDs were shown to be capable of improving the leaf adhesion and slowing the rate of release of streptomycin. Chapter 5 presents a summary of the major findings of this research and discusses the future research directions.
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Doctor of Philosophy (Ph.D.)
College of Sciences
Length of Campus-only Access
Doctoral Dissertation (Campus-only Access)
Maxwell, Tyler, "Coated Quantum Dots: Engineering of Surface Chemistry for Biomedical and Agricultural Applications" (2019). Electronic Theses and Dissertations, 2004-2019. 6533.