Investigations into Protein-Surface Interactions via Atomic Force Microscopy and Surface Plasmon Resonance

Abstract

Protein surface interactions are important in many diverse applications. In this dissertation nonspecific and specific interactions of two proteins (fibrinogen and F1-ATP synthase) with a variety of surfaces have been investigated via atomic force microscopy and surface plasmon resonance. Chapter one provides background information on protein surfaces interactions. Chapter 2 summarizes the techniques and surfaces utilized in the investigations in the following chapters. Chapter 3 provides background and investigations on nonspecific fibrinogen to surfaces. Fibrinogen is an important plasma protein involved in the blood clotting cascade. To improve design of materials for biodevices and implants, more knowledge about the interactions controlling fibrinogen adsorption is essential. Nonspecific adsorption of fibrinogen was investigated on model surfaces of graphite and mica as well as on self-assembled monolayer (SAM) via atomic force microscopy (AFM) to determine conformation. Complementary studies were performed via surface plasmon resonance (SPR) to investigate the dynamics of this adsorption process on gold, and an amine-, carboxyl-, methyl- and hydroxyl-terminated SAM films. Chapter 4 provides background and investigation into F1-Adenosine triphosphate synthase (ATPase) adsorption to surfaces. ATPase is a tiny molecular motor which synthesizes ATP. This motor is of interest in the fabrication of hybrid nanobiodevices. Incorporation of this protein into devices requires precise control over immobilization properties such as location, concentration, orientation, and function. Orientation of ATPase adsorbed nonspecifically on a mica surface was observed via AFM. Control over placement within the device was investigated via nanopatterning of a 1-dodecene SAM surface. Control over orientation was performed via engineering a landing pad within a resist matrix with AFM. This involved patterning a dithiol into a methyl resist matrix and addition of maleimide-NTA with coordination to nickel ions and histidine tags in the protein. The chemistry of this process was validated with SPR and fluorescence microscopy. Information on the kinetic of ATPase-his binding to the NTA surface was obtained. Hopefully information learned from these investigations enables the development of enhanced biocompatible materials design and control over the fabrication of functional hybrid nanobiodevices.