Zheng Zeng – Ph.D. Preliminary Thesis Defense 04/26/2016 at 11:00 A.M.

JSNN – Zheng Zeng – Ph.D. Dissertation Preliminary Proposal Defense

Candidate: Zheng Zeng

Advisor: Dr. Jianjun Wei

Department: Nanoscience

Date: Tuesday, April 26, 2016

Time:11:00 A.M. – 1:00 P.M.

Location: JSNN Auditorium

2907 E. Gate City Blvd.,
Greensboro, NC 27401

Title: “Development of Plasmonic Nanoledge Structure Towards an Optimal Nano-optofluidic Platform for Blood Biomarkers Sensing.”

This project aims to develop an optimal nanoledge structure of a novel nanofluidic-nanoplasmonic platform to realize multiplexed monitoring of biological binding processes, specifically for detection of cardiovascular disease and cancer biomarkers in bio-fluids. In contrast to current large-sized, cumbersome surface plasmon resonance (SPR) sensing technology, the proposed device is comprised of a multilayer nanostructured array that combines the functions of nanofluidics for effective reagent transport and nanoplasmonics for sensing, concurrently. In order to achieve these goals, three key questions need to be addressed including high surface Plasmon (SP) for signal transduction; signal/noise ratio and sensitivity, and possibility and efficacy of protein biomarker flowing into the nanoledge structure. For the first two questions, localized surface plasmon resonance (LSPR) of nanostructured thin metal films (so-called nanoplasmonics) has attracted intense attention due to its versatility for optical sensing and device integration. A semi-analytical model that enables decomposition and quantitative analysis of SP under plane-wave illumination is applied to a new complex nanoledge aperture structure, thus providing insight on how to design such plasmonic devices for optimal plasmonic generation efficiencies and RI sensitivity. In concert with the analytical treatment, a finite-difference time-domain (FDTD) simulation and testing of the fabricated devices are used to validate the optical transmission spectra and RI sensitivity as a function of the nanoledge device’s geometric parameters, and preliminary studies present good agreement with the analytical model. For the last question, we will try to address the challenge of efficient delivery of target bio-molecules to the plasmonic cavity by a diffusion model and experimental verification. An analytical model is applied to test the friction rotation of the molecules (14 protein biomarkers) into the nanoledge structure based on the underlying diffusion and viscoelastic force knowledge. Experimental measurements, including nano-confined dye solution flow-through the subwavelength channel and fluorescence correlation spectroscopy (FCS) of labeled proteins in nanoslits, will be carried out to visualize the trapping of molecules and migration in nanoscale. The present study seeks to develop (design, fabricate, and test) a prototype of the nano-fluidic-plasmonics array integrated in a microfluidic channel, to adapt protocols for nano-confined flow-through transport validation and to culminate with a clear demonstration of improved plasmonic sensing of biomarkers. The nanostructure arrays and device optimization as well as integration with sample handling microfluidics for detecting multiple biomarkers in real biofluids will be planned for future research.