Principles of Surface-Guided Protein Adsorption and Assembly Behavior on Nanopatterned Block Copolymers Revealed at The Single Protein Level
Protein adsorption on polymeric material surfaces is a ubiquitous process that plays a crucial role in many essential fields such as medical devices, biosensors, and food processing. Understanding and manipulating protein adsorption at the nanoscopic level has become more important yet complicated with the continuous development of miniaturized biomaterials. To this end, I have employed phase-separating block copolymer (BCP) in recent studies as a convenient template to present periodically patterned nanodomains for controlling nanoscale protein patterning and understanding competitive protein adsorption behaviors. Tapping mode atomic force microscopy (AFM) was used in all the studies as a main characterization tool for direct imaging at the single protein level.In Chapter One of this dissertation, I introduce the up-to-date background regarding protein adsorption fundamentals, protein nanopatterning templates, and protein adsorption investigation techniques. In Chapter Two, I present the distinct adsorption configurations of fibrinogen (Fg) proteins and the different organization behaviors between individual Fg molecules that are mediated by the changes in the periodicity and alignment of polystyrene-b-polymethylmethacrylate (PS-b-PMMA) nanodomains. I successfully created fully Fg-decorated BCP constructs analogous to two-dimensional Fg crystals and demonstrated the retained biofunctionality of the surface-bound Fg by using the Fg/BCP construct in Ca−P nanoparticle nucleation/growth and microglia cell activation. In Chapter Three, I present the competitive adsorption characteristics of a model binary protein mixture of bovine serum albumin (BSA) and Fg examined on both the macroscopic homopolymer and nanoscopic BCP surfaces. I evaluated a series of adsorption and displacement processes by systematically varying the protein concentration and incubation time and reported a novel finding of nanointerfaces-induced protein residence time increase. In Chapter Four, I present a more detailed competitive adsorption study of immunoglobulin G (IgG) and Fg on PS-b-PMMA. I unambiguously revealed the adsorption, desorption, and replacement events of the same protein molecules via single protein tracking and determined the key protein adsorption pathways and dominant tendencies of sequential protein adsorption, which was further substantiated by Monte-Carlo simulations. The combined results of my research can promote the fundamental understanding of protein-surface interaction and the development of medical implants, biosensors, and tissue engineering materials.
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UNIQUE POLARIZED LIGHT-MATTER INTERACTION IN SINGLE ONE-DIMENSIONAL SEMICONDUCTING OXIDE NANOMATERIALS AND APPLICATIONS OF INDIUM TIN OXIDE NANOROD NETWORKS AS SURFACE ENHANCED RAMAN SPECTROSCOPY AND PHOTODETECTION PLATFORMS Choi, Daniel So Ri (Georgetown University, 2016)With increasing demand of miniaturized optoelectronic, photonic, sensors and biodetection platforms, understanding and elucidating the fundamental material properties at nanoscale is crucial for development and advancement ...