[CCoE Notice] Ph.D. Defense Announcement - Nareg Ohannesian

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[Dissertation Defense Announcement at the Cullen College of Engineering]
Advances in Plasmonic Biosensing Towards Detection, Quantitative Analysis and Molecular

Nareg Ohannesian
6-29-2022; 10:00 am - 12:00 pm (CST)

Zoom: https://urldefense.com/v3/__https://uh-edu-cougarnet.zoom.us/j/97514918252?pwd=Q3JZTFQ5T0wwSFV3WEVuYXluMXhTUT09*success__;Iw!!LkSTlj0I!GbhqBAbAAxSG3XLK8cx7n0EwCBZ-VolumeXkGqLsIKGIpepRlCPvXPCk4M82wsb5AGIkTmf4ZnN2loi0ptAr33oUEaE$ 
Meeting ID: 975 1491 8252
Passcode: 032873

Committee Chair:
Wei-Chuan Shih, Ph.D.

Committee Members:
John C. Wolfe, Ph.D. | Xiaonan Shan, Ph.D. | Karen Martirosyan, Ph.D. | Steven H. Lin, MD-Ph.D.

Abstract

Exosomes are small (∼30 nm to ∼250 nm in diameter), single phospholipid-membrane, extracellular vesicles secreted by all mammalian cells into the bloodstream. Exosomes share the same topology as the parent cell, including selective surface proteins, lipids, and internally stored nucleic acids. Exosomes are responsible for intercellular communication through the transportation of genetic molecules (DNA, RNA, miRNA, etc.) and play a crucial role in human health from developing immunity to cancer. The transition of a parent cell from healthy to cancerous results in the dysregulation of exosomal surface proteins and stored genetic molecules. In turn, profiling exosomal properties can provide an insight into the state of the parent cell undergoing physical/property changes which include cancer progression. However, due to the nanoscale size of exosomes, currently available analytical tools suffer immense limitations such as detection due to insufficient light, low throughput/yield, and require extensive labeling for molecular content. To address these limitations, we developed plasmonic platforms based on arrayed substrates fabricated by our group called nanoporous gold disk (NPGD) array and arrayed gold nanodisks on invisible (AGNIS). Fabricated NPGD and AGNIS possess a remarkable plasmonic property called localized surface plasmon resonance (LSPR). LSPR describes the interaction of free electrons in the metal with electromagnetic waves and results in a strong absorption peak. Due to the highly tunable LSPR absorbance peak of the NPGD array, plasmonic microbubbles of controlled size are generated upon irradiating near-infrared (NIR) light. Plasmonic microbubble can direct and concentrate dispersed micro-/nanoparticles in the liquid at any location on the NPGD surface. Redistributing particles through plasmonic microbubbles facilitates profiling exosomes at concentrations below the dynamic range and the detection limit of the analytical system. Next, we used the AGNIS to develop an imaging technique called plasmonic nanoaperture label-free imaging (PANORAMA) that detects dielectric nanoparticles based on unscattered light. This procedure could determine the size, number, and availability of nanoparticles past 25 nm and measure their distance from the plasmonic surface within a few milliseconds. Combining PANORAMA with fluorescence microscopy allows label-free counting, sizing, and surface protein and cargo micro-RNA characterization at the single exosome level. Finally, using the PANORAMA-fluorescence imaging system, we identify healthy donor plasmas from cancer patients by label-free detection of retained exosomes and MIR-21 occurrence among retained exosomes from plasma.

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