Author's School

School of Engineering & Applied Science

Author's Department/Program

Biomedical Engineering


English (en)

Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)

Chair and Committee

Younan Xia


This research placed emphasis on engineering the properties of novel plasmonic nanostructures, especially silver: Ag) and gold: Au) nanostructures with well-defined shapes, for biomedical applications in sensing, imaging and drug delivery. The first part of this work focused on the development of novel dimeric nanostructures of Ag for surface-enhanced Raman scattering: SERS) applications. In this section, I successfully demonstrated the synthesis of well-defined Ag dimers consisting of nanospheres with a broad range of sizes by using two methods. The first method was based on polyol process and the second was based on wet etching. The key for the dimerization process is to control the colloidal stability by adding appropriate amount of ionic species. I then investigated the SERS properties of the dimers of Ag nanospheres with various sizes and the application of using these dimers as SERS tags for Raman mapping of cancer cells. The second part of this work systematically investigated the use of Au nanocages as a novel class of optical tracers for noninvasive sentinel lymph node: SLN) imaging by photoacoustic: PA) tomography. The transport kinetics of Au nanocages in a lymphatic system was evaluated by PA imaging on the axillary region of a rat. Several experimental parameters, including the injection concentration, particle size, and surface charge were systematically studied. Quantification of the amount of nanocages accumulated in the lymph nodes was achieved by correlating the data from PA imaging with the results from inductively-coupled plasma mass spectrometry. In the final part of this work, I focused on the development of Au nanocages as a new platform for controlled drug release. Two temperature-regulated systems were developed by combining Au nanocages with high-intensity focused ultrasound: HIFU). Because it can penetrate more deeply into soft tissues than near-infrared light, HIFU is a potentially more effective external stimulus for rapid, on-demand drug release. The first system was based on nanocages covered with smart, thermally-responsive polymers, and the second was based on nanocages filled with a biocompatible phase-change material. The released dosage could be remotely controlled by manipulating the power of HIFU and/or the duration of exposure. Localization and depth capability of the HIFU-controlled release have also been investigated.


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