Membrane Science Commons^™

Polymeric Biomaterials Approaches For Engineering The In Vitro Cellular Microenvironment For Mscs, Mahsa Letter-Mahsa Haseli

Graduate Theses and Dissertations

Cell therapy is a technology that relies on replacing diseased or dysfunctional cells with healthy functioning ones. One of the cells used for such advanced therapies are stem cells, owing to their ability to differentiate into specific cells required for repairing damaged or defective tissues or cells. The majority of cell-based products are intended to transiently persist in the patient, secreting factors which then allow the patient’s body to heal; in these products, the cells are subsequently eliminated from the body. Furthermore, unique manufacturing platforms, in addition to novel commercialization strategies, will be required to create a successful, sustainable cell …

Using Copper Oxide And Zwitterions To Prevent Membrane Fouling And Optimizing Ultrafiltration Membrane Fabrication With Green Solvents, Cannon Hackett

Graduate Theses and Dissertations

Membrane fouling and sustainable production of membranes are two of the most important challenges in membrane science. Chapter 1 of this dissertation introduces these challenges and covers previous research that has been done in those areas. Additionally, the objectives of this dissertation are stated. In chapter 2, a study was done in which polyethersulfone ultrafiltration membranes were functionalized with copper oxide nanoparticles and zwitterions for the purpose of reducing fouling on the membrane surface. Characterization confirmed the attachment of each component to the membranes. Dead-end filtration was performed with water and bovine serum albumin solution and showed that the functionalization …

Performance And Fouling During Bioreactor Harvesting, Da Zhang

Graduate Theses and Dissertations

Tangential flow filtration has many advantages for bioreactor harvesting as the permeate could be introduced directly to the subsequent capture step, the process is easy to scale up, and fouling of the filter is limited by the cross flow. However, membrane fouling has limited its widespread use. This is particularly problematic given the high cell densities encountered today. Here a reverse asymmetric commercial membrane, BioOptimal™ MF-SL (Asahi Kasei), where the more open surface faces the feed stream, and the tighter barrier layer faces the permeate stream, has been investigated for bioreactor harvesting. The open surface contains pores up to 40 …

Optimizing Virus Prefiltration For Biopharmaceutical Manufacturing, Solomon Isu

Graduate Theses and Dissertations

Virus filters are single-use devices that use a size-based separation process. In virus filters, contaminating virus particles are retained while the therapeutic molecules pass through the membrane pores. Virus filters are an essential component of the overall virus clearance strategy. Sections 1 and 2 of this dissertation provide an introduction and extensive review of monoclonal antibody (mAb) process development, where virus filtration is pivotal. In section 3, prefiltration studies were performed with an industrially relevant IgG1 type mAb using adsorptive and size-exclusion-based prefilters with different mechanisms of action. This mAb has an isoelectric point range of 7.1 to 8.0 and …

Phase-Field Modeling Of The Polymer Membrane Formation Process For Micro- And Ultra-Filtration, Michael Rosario Cervellere

Graduate Theses and Dissertations

Porous polymer membrane filters are widely used in separation and filtration process. Micro- and ultra-filtration membranes are commonly used in biopharmaceutical applications such as filtering viruses and separating proteins from a carrier solution. The formation of these membrane filters via phase inversion is a complex and interconnected process where varying casting conditions can have a wide variety of effects on the final membrane morphol- ogy. Tailoring membrane filters for specific performance characteristics is a tedious and time consuming process. The time and length scales of membrane formation make it extremely difficult to experimentally observe membrane formation. Modeling the membrane formation …

Investigation Of Membrane Based Processes For Biomedical Applications, Efecan Pakkaner

Graduate Theses and Dissertations

As substantial developments were achieved in nanotechnology and polymer engineering, especially in the last few decades, the use of membranes and membrane-based procedures was found to be expanding into more and more research and development areas; including biological engineering, life sciences and biomedical engineering. Not only have they been the main focus of meaningful research, but they have also been the main pieces of the solutions to very thorny problems encountered within a wide range of applications from microfluidics to water treatment, thanks to their versatility, cost-effectiveness and biocompatibility, when compared to conventional separation techniques. To celebrate and embrace these …

Surface Modified Polypropylene Membranes For Treating Hydraulic Fracturing Produced Waters By Membrane Distillation, Tharaka Hawpe Gamage

Graduate Theses and Dissertations

Membrane distillation is an emerging technology for treating hydraulic fracturing flowback and produced waters. Suppression of membrane fouling by inorganic and polar and non-polar organic compounds is a challenge. Here polyhydroxyethyl methacrylate, polyacrylic acid, polvinylallyl imidazolium bromide and polyvinylhexyl imidazolium bromide chains have been grafted from the membrane surface. Fouling is initially due to adsorption of organic compounds followed by scale formation. When challenged with produced water, membranes modified with polvinylallyl imidazolium bromide chains provided the greatest resistance to fouling. For EC pretreated produced water and synthetic produced water that contained mainly inorganic species, the flux decline was much less.

The Effects Of Solution Condition On Virus Filtration Performance, Fnu Namila

Graduate Theses and Dissertations

Virus filtration is an integral part of the downstream purification of mammalian cell culture-derived biotherapeutics to assure the viral safety of the products. Virus filtration membranes remove viruses based on a size-exclusion mechanism. Commercial parvovirus filers possess unique membrane structure and are designed to remove smaller non-enveloped parvoviruses with size 18-26 nm. However, some filters face issues, such as pre-mature fouling, the decline of filtrate flux, and reduction in virus retention. This doctoral dissertation focused on identifying the factors that influence the filtrate flux and the virus retention capability of commercial virus filters. The effects of solution pH and ionic …

Investigation Of Electrospun Nanofibers For Separation Applications, Shu-Ting Chen

Graduate Theses and Dissertations

Electrospun membranes are an attractive alternative to flat sheet membranes as absorbent with numerous advantages like high porosity, large specific surface area and ease of functionalization. This doctoral dissertation focuses on fabricating novel polymeric membrane adsorbents for protein separations and ammonium ion removal. Three distinctly different preparation methods including UV-initiated polymerization, atom transfer radical polymerization, and mixed-matrix formation, have been employed to fabricate the electrospun membranes. Overall, this study aimed to develop electrospun membranes with excellent separation efficiency for application in protein purification and ammonium ion removal.

Chapter 2 details the stepwise development of weak anion exchange membranes and subsequent …

Peptoid And Antibody-Based Gfp Sensors, Solomon Isu

Graduate Theses and Dissertations

In this work, we have made and characterized a pair of immunobiosensors for detecting the green fluorescent protein (GFP) in an aqueous matrix. An anti-GFP antibody-based biosensor was assembled to detect GFP, while a novel peptoid (N-substituted oligomers of glycine designated as IOS-1) biosensor was also assembled for GFP detection. A quartz crystal microbalance (QCM) gold sensor was used as the supporting substrate for self-assembly of the immunobiosensors. Gravimetric measurements of the QCM gold sensor during immunobiosensor construction and operation were available in real-time using a QCM instrument. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and Fluorescence microscopy were used …

Interfacial Contact With Noble Metal - Noble Metal And Noble Metal - 2d Semiconductor Nanostructures Enhance Optical Activity, Ricardo Raphael Lopez Romo

Graduate Theses and Dissertations

Noble metal nanoparticles and two-dimensional (2D) transition metal dichalcogenide (TMD) crystals offer unique optical and electronic properties that include strong exciton binding, spin-orbital coupling, and localized surface plasmon resonance. Controlling these properties at high spatiotemporal resolution can support emerging optoelectronic coupling and enhanced optical features. Excitation dynamics of these optical properties on physicochemically bonded mono- and few-layer TMD crystals with metal nanocrystals and two overlapping spherical metal nanocrystals were examined by concurrently (i) DDA simulations and (ii) far-field optical transmission UV-vis spectroscopic measurements. Initially, a novel and scalable method to unsettle van der Waals bonds in bulk TMDs to prepare …

Functional Importance Of Lipin Phosphorylation, Stephanie Elizabeth Hood

Graduate Theses and Dissertations

Highly conserved throughout evolution, lipins are dual functioning proteins found from yeast to humans. Functioning in the cytoplasm as phosphatidate phosphatase enzymes (PAP), lipins produce diacylglycerol that serves as a precursor for neutral fats and membrane phospholipids. Alternatively, nuclear lipins are responsible for the regulation of metabolic genes. Interestingly, both the mammalian lipin 1 paralog and the single Drosophila Lipin ortholog are highly phosphorylated proteins. Target of rapamycin (TOR) has previously been identified as one of the kinases that controls the subcellular localization of both lipin 1 and Drosophila Lipin. However, other serine and threonine kinases are predicted to be …

Applications Of Ionic Liquids In Membrane Separation, Mohanad Kamaz

Graduate Theses and Dissertations

Ionic liquids represent an emerging attractive material in membrane technology. The central theme of this doctoral dissertation is to develope novel membranes using ionic liquids. Two different approaches were used to prepare ionic liquid membranes including the immobilization of ionic liquid within the membrane pores or the use of pressure assembly method to deposit a selective ionic liquid layer on the top membrane surface.

In chapter 2, imidazolium ionic liquids with three different alkyl halides were successfully synthesized and used to prepare supported ionic liquid membranes (SILMs). SILMs preraper were tested for aqueous and nonaqueous applications. For nonaqueous applications, the …

Influence Of Single And Multiple Histidine Residues And Their Ionization Properties On Transmembrane Helix Dynamics, Orientations And Fraying, Fahmida Afrose

Graduate Theses and Dissertations

Since aromatic and charged residues are often present in various locations of transmembrane helices of integral membrane proteins, their impacts on the molecular properties of transmembrane proteins and their interactions with lipids are of particular interest in many studies. In this work, I used solid-state deuterium NMR spectroscopy in designed model peptide GWALP23 [GGALW(LA)6LWLAGA] with selective deuterium labels to addresses the pH dependence and influence of single and multiple “guest” histidine residues in the orientation and dynamic behaviors of transmembrane proteins. The mutations include Gly to His (G2/22 to H2/22), Trp to His (W5/19 to H5/19) and Leu to His …

Development Of Forward Osmosis Based Separations: A Novel Approach In Membrane Technology, Yu-Hsuan Chiao

Graduate Theses and Dissertations

Tackling the worldwide severe water shortage, the membrane technology is considered to be the most efficient approach and hence, used widely as a cost-effective sustainable solution. “Forward osmosis (FO)” has been the major attention in recent time. FO uses osmotic pressure as the driving force to draw the water passing the membrane and achieve the desired separation performance. In general, it is considered to be a process with tremendous potential to resolve the present-day water shortage with extremely low energy consumption. However, the challenges of membrane and draw solution regeneration associated with FO processes must be conquered prior to their …

Engineered Carbon-Nanocatalyst Composites And Carbon Mixed ‎Matrix Membranes ‎For Water And Wastewater Treatment ‎, Mojtaba Abolhassani

Graduate Theses and Dissertations

Carbonaceous materials such as graphene oxide, and activated ‎carbon have a wide range of ‎applications in water and wastewater treatment due to the high surface ‎area, unique structure, ‎and chemical and thermal stability. Carbon-based materials can be used as a ‎membrane, an ‎adsorbent, a support for nanomaterials, or ‎as a filler within membranes to remove contaminants ‎from water. In this research, the specific carbon materials and how their properties influence their ‎use and performance in ‎specific engineering applications is explored. ‎

Here, membrane filtration and adsorption/degradation of the water and wastewater using carbon-‎based material are investigated. The research firstly focuses …

Membrane-Based Separation Processes For Treating High Salinity Produced Waters, Kamyar Sardari

Graduate Theses and Dissertations

Produced waters (PW) generated in the oil and gas industry within the United States often contain extreme levels of total dissolved solids (TDS). These high TDS waste streams need to be treated cost-effectively as the costs associated with the current management techniques can exceed 15 USD per barrel of discharged PW. Thermally and osmotically-driven membrane separation technologies can show promising potential for treating high TDS waste streams, as onsite low-grade waste heat may be used for their operation. In this dissertation, the application of membrane distillation (MD), forward osmosis (FO) and a hybrid FO-MD process for treating synthetic and actual …

Design Of Peptoid-Based Coating To Reduce Biofouling In Gas Exchange Devices, Neda Mahmoudi

Graduate Theses and Dissertations

In recent decades, membrane technology has been used commonly in biomedical area. However, membrane fouling is a widespread problem in different applications. One method to minimize fouling is through surface modification of membranes. My research explores a novel polymer to minimize nonspecific protein adsorption in biomedical applications.

It firstly focuses on grafting the electrically neutral NMEG peptoid, containing 2-methoxyethyl side chains, to polysulfone (PSU) membrane via polydopamine. Contact angle measurements indicated that the hydrophilicity of the peptoid-grafted membranes was significantly improved while the pore size and strength of the membranes remained unchanged. The modified membranes showed an improved fouling resistance …

Characterization Of Bacteriorhodopsin And Halorhodopsin Reconstituted In Lipid Bilayer Membranes, Joel Domkam Kamwa

Graduate Theses and Dissertations

Motivated to produce electricity with photon activated ion pumps, the main purpose of this work was to characterize the photosynthetic membrane proteins bacteriorhodopsin (proton pump) and halorhodopsin (chloride pump). The proteins were re-suspended in lipid bilayers. For this work, an experimental set-up was built which included: chambers for lipid bilayer formation and characterization, lasers for ion pump activation, and an AxoPatch electrophysiology system for small photocurrent measurement. Lipid bilayer membranes were formed using mostly folding method: folding two monolayers together. The membranes were characterized by their resistance, capacitance, and generated photocurrent. Photocurrent was generated upon illumination of lipid-protein membranes with …

Peptoid-Modified Bicelles As Surrogate Cell Membranes For Membrane Protein Sensors And Analytics, Helya Najafi

Graduate Theses and Dissertations

Membrane-affiliated interactions are significant in understanding cell function, detecting biomarkers to diagnose disease, and in testing the efficiency of new therapeutic targets. Model membrane systems have been developed to study membrane proteins, allowing for stable protein structure and maintaining native activity. Bicelles, disc-shaped lipid bilayers created by combining long- and short-chain phospholipids, are the model membrane system of focus in this study. Bicelles are accessible from both sides and have a wide size range, which make them attractive for studying membrane proteins without affecting function. In this work, bicelles were functionalized with two peptoids to alter the edge and face …

Membrane Surface Engineering For Biochemical Applications, Anh T. Vu

Graduate Theses and Dissertations

Synthetic membranes have been frequently used for many fields, such as, the food and beverage, biopharmaceutical, and biofuel industries. In the beer industry, microfiltration frequently suffers from fouling due to the interaction between different species. It is shown that polyphenols can form cross-links with protein molecules, forming insoluble aggregates. However, by adding an optimal amount of polysaccharides these aggregates can be disrupted thus reducing fouling by the aggregates. Confocal laser scanning microscopy (CLSM) is a powerful technique to locate the foulants inside the wet membrane in order to understand more about the behavior of fouling in microfiltration.

Membrane surface modification …

Membranes For Food And Bioproduct Processing, Alexandru Marius Avram

Graduate Theses and Dissertations

Modified membranes for process intensification in biomass hydrolysis

Production of biofuels and chemicals from lignocellulosic biomass is one of the leading candidates for replacement of petroleum based fuels and chemicals. However, conversion of lignocellulosic biomass into fuels and chemicals is not cost effective compared to the production of fuels and chemicals from crude oil reserves. Some novel and economically feasible approaches involve the use of ionic liquids as solvents or co-solvents, since these show improved solvation capability of cellulose over simple aqueous systems. Membranes offer unique opportunities for process intensification which involves fractionation of the resulting biomass hydrolysate leading to …

Removal Of Endocrine Disrupting Compounds Using Membrane Bioreactor, Mohanad Ali Abdulsahib Kamaz

Graduate Theses and Dissertations

The presence of endocrine disrupting compounds (EDCs) and pharmaceutically active compounds (PhAC) such as pesticides, personal care products, antibiotics and pharmaceutical compounds, in sewage, industrial, and domestic waters has extensively become the major concern for health and environmental organizations. These compounds have the ability to interact with mammalian endocrine system and disrupting their functions. The traditional activated sludge processes are designed to degrade solids, organic carbon and nitrogen loading. Although several treatment steps in a wastewater treatment plant can contribute to partial removal of EDCs, effective removal has been a challenge due to their resistant chemical and biological degradation and …

Effects Of Magnetically Induced Micro-Mixing On Nanofiltration Performance, Guanghui Song

Graduate Theses and Dissertations

Nanofiltration (NF) is a relatively new membrane separation process mainly used for removing low molecular weight species from aqueous and non-aqueous solutions. NF membranes suffer from concentration polarization leading to membrane fouling thus compromised membrane performance. Magnetically responsive nanofiltration (NF) membranes functionalized with superparamagnetic nanoparticles (SPNs) attached to the chain ends of grafted polymer nanolayers have been shown to be effective in breaking concentration polarization at the membrane-liquid interface under an appropriate external oscillating magnetic field. Under an oscillating magnetic field, the movement of the polymer chains acts as micro-mixer leading to the suppression of concentration polarization and improved filtration …

Modified Polysulfone Nanofiltration Membrane Synthesis For Hydraulic Fracturing Water Recycle, Blake Alexander Johnson

Graduate Theses and Dissertations

The use of hydraulic fracturing has resulted in significant increases in the yield of oil and natural gas, as water pumped into wells at high pressure cracks the formations and releases the hydrocarbons that are locked in the rocks. This process has created large volumes of brackish water that is very difficult to process and is often disposed of into injection wells. Suspended solids and some dissolved solids are more readily removed, but the multivalent ions found in certain salts can precipitate in a well and complicate the reuse of flowback in future hydraulic fracturing operations.

Nanofiltration, a membrane separation …