Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Biomedical Engineering

Supervisor

Silvia Mittler

Abstract

In this thesis we described inexpensive alternatives to fabricate nanostructures on planar substrates and provided example applications to discuss the efficiency of fabricated nanostructures.

The first method we described is forming large area systematically changing multi-shape nanoscale structures on a chip by laser interference lithography. We analyzed the fabricated structures at different substrate positions with respect to exposure time, exposure angle and associated light intensity profile. We presented experimental details related to the fabrication of symmetric and biaxial periodic nanostructures on photoresist, silicon surfaces, and ion-milled glass substrates. Behavior of osteoblasts and osteoclasts on the nanostructures was investigated. These results suggest that laser interference lithography is an easy and inexpensive method to fabricate systematically changing nanostructures for cell adhesion studies. We also used laser interference lithography to fabricate plasmonic structures. Fabrication details of gold nanodisk arrays were described. Experimental and simulation results show that those structures are suitable to develop highly sensitive plasmonic sensors.

As a second fabrication method we described the growth of surface immobilized gold nanoparticles with organometallic chemical vapor deposition (OMCVD) on amine terminated surfaces. Samples fabricated using different deposition times were characterized by UV-Vis spectroscopy and scanning electron microscopy. Particle stability on the samples was tested by washing and rinsing treatments with various organic solvents. The size, interparticle distance, and shape of the gold nanoparticles demonstrated that OMCVD is a simple, economical, and fast way to fabricate surface-bonded and stable gold nanoparticles. The plasmonic properties, the stability of the particles and the biotin-streptavidin test showed that these OMCVD-grown gold nanoparticles are suitable for reproducible, low noise and highly sensitive biosensing applications.

We further investigated the similar-to-real-life biosensing capabilities of the OMCVD-grown nanoparticles. Conventional antibody immobilization methods using biotin-streptavidin affinity, introduces additional chemistry and distance between the surface and the recognition sites and decreases the sensitivity. With the new recognition chemistry, epidermal growth factor receptor (EGFR) antibody recognition sites were directly immobilized on AuNP surfaces to decrease the distance between the sensor surface and the recognition sites for detecting EGFR antigens. In comparison with the literature, we obtained increased signal response with further optimization possibilities.