You have helped me in ways far beyond the call of duty and I must thank you from the bottom of my heart for everything you have done for me over the past four years. My committee members have been very helpful in the completion of this dissertation. Thank you for your valuable comments and suggestions. Doug, it was you who I followed to Alfred and as a fellow glass scientist, with all your humor and intelligence, you helped me in so many ways, some of which you may not even be aware of.
Paul, you have been an inspiration to me, you have such charm and character and are one of the strongest people I know. As we had similar thesis topics we shared literature and ideas, thank you Matt for your help and guidance. He was also my sounding board for many of life's little problems, thank you for lending an ear and giving me so much advice.
Daniel, as a fellow glass scientist, you have helped me study for countless exams, helped me with experiments and equipment setup, and given me things to think about in my research. You have unselfishly supported me in everything I have wanted to do and for all of that I am forever grateful.
Introduction
Considering the bulk silica structure, the surface structure is very different due to the fact that the bonds are changed by the discontinuity. Several optical properties of glasses are very dependent on the surface roughness, a smoother surface will reflect light more specularly. The chemical nature of the silica surface greatly affects the success of the separation in terms of time and resolution.
It is applications like these that require researchers to understand the surface chemistry of silica. Proteins are known to form the interface between glass and proliferating cells, and therefore proteins were chosen as the surface probe in the current study. More specifically, that certain groups on a protein interact with the surface silanols of the silica.
These surface treatments were intended to alter the surface chemistry of the silica by changing the type and population of surface silanols. The results were collected, analyzed and conclusions were drawn about the effectiveness of using proteins to characterize the surface of silica.
Literature Review
- Silica – Background and Forming
- Silica Surface 1. Surface Species
- Types of Surfaces
- Silica and Water
- Surface Treatments 1. “Cleaning”
- Characterization
- Common Surface Techniques for Powders
- Surface Characterization on Bulk Samples
- Atomic Force Microscopy
- Fluorescence
- Proteins
- Protein Background
- Proteins Used in this Study
- Characterizing Proteins
- Common Assays and Detection Methods
- Gel-Electrophoresis
- Fluorimetry of Proteins
- Circular Dichroism
- FTIR Spectroscopy of Proteins
- Chemical Force Microscopy
- Related Research
Most of the studied dusts induce cytotoxicity and morphological transformations in the SHE cells in varying strengths. Even among the same silica polymorphs, the degree of biological response varies, indicating that the structure and composition of the surface modulate the response. To the left of the tangent to the nose, temperature crystallization is avoided (at 10-6 volume fraction).
Schematic of silicate bond angles giving definitions of bond angle β in (a) and torsion angles α1. Beyond the initial fabrication of silica glass, there are post-treatments that the glass can undergo to induce different properties in the glass. The larger potassium ions create compaction in the surface layers and thus lead to the hardening of the glass.
Most of the studies found in the literature on silica surface species investigated colloidal powders or gels. Lange's description of the two types of adsorbed water, hydrogen-bonded (circled) and physically bonded (all above the solid black line).86. Just by placing silica in water, chemical reactions occur which change the structure of the surface and therefore change the active species on the surface.
One of the most popular methods of surface modification comes with the use of ion beam sputtering. Some of the surface techniques that were used in this study are described in more detail in the following sections. The difference between the two lies in the nature of the states between which the emission occurs.
To understand this difference, one must consider the spin states of the electrons involved in the transitions. The part of the motif that is most interesting concerns the connection between the secondary structures. Stereograms of (a) one monomer of streptavidin forms a β-barrel with extended hairpin loops and biotin (ball and stick molecule) is bound to the open end of the barrel.
This model assumes that the charge distribution on the surface of the sphere is continuous, which is incorrect due to the existence of specific charged groups on the surface. Changes in the intensity and location of this band indicate conformational changes in the C=O bonds of the protein.
Charge: Molecules nearer to their isoelectric pH may adsorb more easily
Structure
Other Chemical Properties
- References
After the first 20 minutes, it was found that protein uptake depends on the size of the molecules and is thus diffusion controlled. It was found that the initial reaction is related to the isoelectric pH of the protein and is faster for proteins with high isoelectric points. The initial reaction was found to be a function of the isoelectric pH of the protein, the rate increasing with increasing i.e.p.
The second process was therefore related to the permeability of the protein through the porous glass.376. These changes will determine the structure and behavior of the adsorbed layer and the new surface. 34; Surface and large infrared modes of crystalline and amorphous silica particles: A study of the relationship of surface structure to respirable silica cytotoxicity,” Environ.
Shulakov, "Atomic Structure of Glass Surface after Technological Treatments", J. Pantano, "RF-Plasma Treatments of Surface-Conducting Alkali-Lead Silicate Devices and Microchannel Plate Devices", Appl. Pantano, "Mechanisms for silanol formation at fracture surfaces of amorphous silica," J. 34; Adsorption of CO2 and Ar on glass surfaces. Computer simulation and experimental study", J. Weyl, Some practical aspects of glass surface chemistry.
Kallury, "Determination of Silanol Surface Concentration on the Surface of Amorphous Silica Using Static Secondary Ion Mass Spectroscopy," J. Zhuravlev, "Study of Surface and Bulk Hydroxyl Groups of Silica by Infrared Spectra and D2O Exchange," Trans. Frenzel, "Characterization of treated fiberglass surfaces using different investigation methods," Compos.
Jang, "A Study of Impact Properties of Composites Composed of Surface-Modified Glass Fibers on Vinyl Ester Resin." Dumesic, "Studies of Adsorption of Acetaldehyde, Methyl Acetate, Ethyl Acetate and Methyl Trifluoroacetate on Silica," J. Monti, "EXAFS Studies of the Local Structure of Er3+ Joons in Silica Xerogels Co-Doped with Aluminum," J.
Wasacz, Effects of the Environment on the Structure of Adsorbed Proteins: Fourier Transform Infrared Spectroscopic Studies, Vol. Penfold, “Neutron reflectivity study of the adsorption of beta-lactoglobulin at a hydrophilic solid/liquid interface,” J .
Experimental Procedure
- Surface Treatments
- Protein Solutions
- Binding Procedure
- Characterization Techniques
- Electrophoresis
- Fluorescence Spectroscopy
- Bicinchoninic Acid (BCA) Assay
- Glancing Incidence X-ray Analysis (GIXA)
- Atomic Force Microscopy (AFM)
- Chemical Force Microscopy (CFM) and Force Volume Imaging
- Experimental Procedure References
Once the precipitates were formed, they were allowed to settle to the bottom of the vessel and the supernatant was drawn off. The heat treatments of the silica samples were carried out in air in an electric furnace at 1000°C for 4 hours. All protein preparation was performed in a bio-guard hood to prevent both contamination of the protein and human exposure.
The recipe for the reducing tank buffer is shown in Table VI and a schematic of the Mini Cell is shown in Figure 3.5.1. Once the cover of the Mini Cell, which holds the wires to the power source, was secure, the power source was switched on. The standards were used to determine the unknown sample amounts and the markers were used to verify the molecular weights of the proteins.
A schematic diagram of the instrument that includes the path of the light is shown in Figure 3.5.3.1. For the first binding set, tris-buffered saline was forcefully forced in and out of the cuvette for cleaning between samples. Integration of the emission peaks for the standards gave a ratio of surface area to mass of protein.
It was then necessary to recalculate the actual concentration of the protein solution as it was diluted in each well with the working reagent. A phase image provides data on the interaction of the tip with the sample by measuring the phase delay. In contact mode, once the laser is positioned at the end of the tip, the signal is optimized and the instrument is focused on the surface and tip independently, the tip can be engaged with the surface.
For the measurement to be considered chemical in nature, some type of chemical group is typically placed on the end of the cantilever tip. Once the tip had engaged the surface, the microscope defaulted to imaging mode and a series of adjustments were made to optimize tip-surface contact. Adjustment of the Z-scan rate (recommended 4 Hz) and Z-scan size as well as other parameters in the "Z Scan Controls" box was performed until a good force curve was obtained.
Results
- Gel Electrophoresis (SDS-PAGE)
- Human Serum Albumin (HSA)
Spot 12™ molecular weight marker in the lane of a 4-20% gradient tris-glycine gel in the unstained state.
