Andrew HuFollow

Date of Completion

10-21-2013

Embargo Period

10-21-2013

Advisors

Mu-Ping Nieh, George Lykotrafitis, Devendra Kalonia

Field of Study

Mechanical Engineering

Degree

Master of Science

Open Access

Open Access

Abstract

Uniform nanodisc structures can be self assembled from mixtures of different phospholipids. This study focuses on the theoretical and experimental growth kinetics of phospholipid based nanodiscs. Motivation for this project comes from the nanodisc’s small size and their potential use as a carrier for drug delivery. It was observed that at high total lipid concentration the nanodiscs are stable at approximately 10 nm in radius and can remain stable for a long period of time. However, growth of these nanodiscs are observed at relatively low total lipid concentration. The observed growth mechanism is not well understood. In this thesis dynamic light scattering is used to monitor the size and growth rate of nanodiscs at different solution conditions. It is determined that disc-disc interactions play an important role in the stability of the disc structures. More importantly surface charge on the nanodisc prevent growth due to the electric repulsive force. The growth at low concentrations is caused by the transfer of charged lipids from the discs to the solution, therefore reducing the Columbic interaction between two interacting discs. The effect of size and different surface potentials can be modeled by the Smoluchowski transport equation along with the transport limited boundary conditions. Chapter 1 to 5 include the experimental method, results and mathematical model for this research. The last part of this thesis, chapter 6, presents the relevant microrheology experiments. The aim is to obtain viscoelastic properties of complex fluids in the frequency range between 103 to 105 Hz, gives insight into the frequency dependent particle-particle or disc-disc interactions in suspensions.

Major Advisor

Tai-Hsi Fan

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