Date of Award

Spring 2012

Document Type


Degree Name

Doctor of Philosophy (PhD)


Biomedical Sciences

Committee Director

Xiao-Hong Nancy Xu

Committee Member

Christopher Osgood

Committee Member

Kenneth Brown

Committee Member

Lesley H. Greene


This dissertation focuses on the design of new in vivo assays for study of transport, biocompatibility and toxicity of nanoparticles (NPs) in zebrafish embryos. We synthesized and purified spherical silver (Ag) NPs with diameters, ranging from 12 to 95 nm, that are stable (non-aggregated) in egg-water media. We developed new imaging approaches to characterize the sizes of single Ag NPs in zebrafish embryos at nanometer resolution by measuring their size-dependent plasmonic spectra and scattering intensity using dark-field optical microscopy and spectroscopy (DFOMS). We used single Ag NPs because they exhibit the high quantum yield (QY) of Rayleigh scattering and resist photobleaching and blinking, allowing to be continuously monitored in vivo for any desired amount of time. These unique optical properties make them better than traditional imaging probes, such as fluorescence probes (e.g., fluorophores and semiconductor quantum dots), that are currently used for in vivo imaging and widely used in life science. With no need of fluorescence excitation, Ag NPs can be used to monitor transport in a living in vivo system and effectively avoids auto-fluorescence of the living organism, allowing us to monitor it in real-time in the developing embryo.

Using different properties of Ag NPs, size-dependent optical properties and charge-dependent surface properties, we studied transport and toxicity in living embryos in real-time for better understanding of biocompatibility of NPs in a living in vivo model system. Using Ag NPs, we continuously imaged nano-environments of developing zebrafish embryos for hours and discovered their transport patterns through the chorion and into the chorion space of the different stages of embryos. We demonstrated that the different types of Ag NPs caused a wide variety of deformities and caused an increase in death, and both in a concentration dependent manner in living zebrafish embryos. This determined that zebrafish embryos are a powerful in vivo assay to use to study the transport, biocompatibility and toxicity of nanomaterials.