Mechanisms Of Emulsion Destabilization: An Investigation Of Surfactant, Stabilizer, And Detergent Based Formulations Using Diffusing Wave Spectroscopy, Jordan N. Nowaczyk

Theses and Dissertations

Conventional approaches for studying emulsions, such as microscopy and macroscopic phase tracking, present challenges when it comes to establishing detailed mechanistic descriptions of the impact of emulsifier and stabilizer additives. Additionally, while a combination of sizing methods and macroscopic phase tracking can provide insights into droplet size changes and concentration, the use of multiple measurements can be cumbersome and error-prone. It is the focus of this work, to present a new method for studying water in oil (W/O) emulsions that involves using diffusing wave spectroscopy (DWS) to examine the impact of three different surface stabilizing additives at varying concentrations. By …

Therapeutic Injectable Iron-Chelating Hydrogels, Debbie Campbell-Rance

Theses and Dissertations

ABSTRACT

Therapeutic Injectable Iron-Chelating Hydrogels for Improved Central Nervous System Regeneration

By

Debbie S. Campbell-Rance

A dissertation submitted in partial fulfillment of the requirements of the degree of Doctor of Philosophy at Virginia Commonwealth University 2021.

Director: Xuejun Wen, M.D., Ph.D., AIMBE Fellow, Alice T. and William H. Goodwin Jr. Endowed Chair Professor in Regenerative Medicine, Institute for Engineering and Medicine, Department of Chemical and Life Science Engineering

Severe traumatic brain and spinal cord injuries are major global public health and socioeconomic problems in terms of mortality and morbidity. Currently there are two main lines of treatment under development for …

Nature-Inspired Material Strategies Towards Functional Devices, Sayantan Pradhan

Theses and Dissertations

Naturally sourced, renewable biomaterials possess outstanding advantages for a multitude of biomedical applications owing to their biodegradability, biocompatibility, and excellent mechanical properties. Of interest in this dissertation are silk (protein) and chitin (polysaccharide) biopolymers for the fabrication of functional biodevices. One of the major challenges restricting these materials beyond their traditional usage as passive substrate materials is the ability to combine them with high-resolution fabrication techniques. Initial research work is directed towards the fabrication of micropatterned, flexible 2D substrates of silk fibroin and chitin using bench-top photolithographic techniques. Research is focused on imparting electrochemical properties to silk proteins using conducting …

Applied Machine Learning In Extrusion-Based Bioprinting, Shuyu Tian

Theses and Dissertations

Optimization of extrusion-based bioprinting (EBB) parameters have been systematically conducted through experimentation. However, the process is time and resource-intensive and not easily translatable across different laboratories. A machine learning (ML) approach to EBB parameter optimization can accelerate this process for laboratories across the field through training using data collected from published literature. In this work, regression-based and classification-based ML models were investigated for their abilities to predict printing outcomes of cell viability and filament diameter for cell-containing alginate and gelatin composite hydrogels. Regression-based models were investigated for their ability to predict suitable extrusion pressure given desired cell viability when keeping …

The Critical Role Of Dynamic Surface Tension Of Surfactants On The Impact Dynamics Of Water Droplets, Amir Esmaeili, Reza Mohammadi

Graduate Research Posters

Due to their time-dependent surface tension, the addition of surface-active agents or surfactants to water for specific applications has made controlling the impact dynamics of these droplets a complex phenomenon. This work investigates the influence of the molecular weight, concentration, and ionic nature of the surfactants as well as the substrate surface characteristics on the impact dynamics of surfactant-laden droplets using a high-speed camera at 10000 frames per second. Sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, and n-decanoyl-n-methylglucamine were used as anionic, cationic, and nonionic surfactants, respectively. We used hydrophilic glass slides, hydrophobic polytetrafluoroethylene, and superhydrophobic alkyl ketene dimer (AKD) as substrates. …

Formulation And Validation Of Nanoparticle Controlled Delivery For Chemotherapeutic Drug Products, Shani L. Levit

Theses and Dissertations

Taxol, a formulation of paclitaxel (PTX), is one of the most widely used anticancer drugs, particularly for treating recurring ovarian carcinomas following surgery. Clinically, PTX is used in combination with other drugs such as lapatinib (LAP) to increase treatment efficacy. Delivering drug combinations with nanoparticles has the potential to improve chemotherapy outcomes. In this study, we use Flash NanoPrecipitation, a rapid, scalable process to encapsulate weakly hydrophobic drugs (logP in vitro. Encapsulating either PTX or LAP into nanoparticles increases drug potency. When PTX and LAP are co-loaded in the same nanoparticle, they have a synergistic effect that is greater than …

Dendrimer-Based Therapeutic Delivery Vehicle For The Treatment Of Ocular Diseases, Remy C. Cooper

Theses and Dissertations

The treatment of ocular diseases poses a significant challenge to drug delivery design, due to the eye’s complex anatomy, with a semi-permeable blood-ocular barrier and associated immune privilege. To address some of the delivery challenges, polycationic dendrimers are explored as vehicle for the treatment of posterior chamber disease. Dendrimers are a class of polymeric nanoparticles that are highly branched, multivalent and monodisperse, whose three-dimensional globular architecture has given them the nickname of “synthetic proteins”. Dendrimers are synthesized by reacting monomers in a step-wise fashion to produce generationally and radially increasing structures, with core, interior and surface chains that are highly …

Self-Assembled Metal Nanoparticle/Polymer Nanocomposites As Nanoreactors For One-Pot Reactions, Andrew Harrison

Theses and Dissertations

Polymer nanoreactors incorporating gold nanoparticle catalysts were self-assembled via Flash Nanoprecipitation. The incorporated gold nanoparticles maintained catalytic activity, which was evaluated using reduction of 4-nitrophenol with sodium borohydride as a model reaction. The diffusion coefficient for 4-nitrophenol was determined by NMR and used to calculate the second Damköhler number, which indicated that the systems were not diffusion limited. Despite similar diffusion coefficients, catalytic performance was strongly affected by the co-precipitant. For example, the apparent reaction rate per surface area using castor oil was over 8-fold greater than polystyrene. Thus, we measured the partition coefficient of 4-nitrophenol between water and castor …

The Role Of Microenvironment Reagent Solubility On Reaction Kinetics Of 4-Nitrophenol Reduction, Michael P. Zeevi, Andrew Harrison, Christina Tang

Undergraduate Research Posters

The Role of Microenvironment Reagent Solubility on Reaction Kinetics of 4-Nitrophenol Reduction

Michael Zeevi¹ with Andrew Harrison¹ and Christina Tang, PhD¹

¹Department of Chemical and Life Science Engineering, VCU School of Engineering

Introduction: Nanoparticles are of increasing interest due to their high surface area to volume ratio, as well as that they enable fine-tuning of the reaction microenvironment. Through flash nanoprecipitation, core-shell polymer nanoreactors were formed by directed self-assembly. Using the reduction of 4-nitrophenol as a model reduction reaction, we investigated the effect of reagent solubility in the nanoreactor microenvironment’s on nanoreactor kinetics.

Methods: The standard …

Engineering Icephobic Coatings: Surface Characterization Of Pt Cured Silicones, Sithara Shylaja Nair

Theses and Dissertations

Ice buildup on structures leads to problems that include reduced performance, structural damage and power outages. It is therefore important to limit the energy required for removal of ice from substrates to minimize buildup. Understanding the mechanism of ice adhesion and its dependence on variables like coating thickness, stiffness, surface free energy and morphology is critical for minimizing adhesion. Despite several developments in “icephobic” coatings, which are those that have low ice adhesion, it is important to understand adhesion on the fundamental level to make way for advanced coatings. To do so, a study has been carried out that explores …

Smart Fabrics For Colorimetric Detection, Breland Edwards

Undergraduate Research Posters

Due to the prevalence of chemical warfare, soldiers often carry chemical sensing devices, to warn of oncoming nerve agents. However, these devices are cumbersome. A lightweight, wearable chemical sensing fabric that doubles as a protectant against toxins would be beneficial. This fabric can be created by incorporating (1) organophosphate hydrolase, an enzyme capable of degrading organophosphates and releasing an acidic by product, and (2) polyaniline, a color changing polymer that changes from purple to green in the presence of acid, into nylon or polyvinyl alcohol nanofibers. The first step is to produce fabrics containing polyaniline and demonstrate that the fabrics …

Design And Development Of A High-Temperature High-Pressure Rolling Ball Viscometer/Densimeter And Evaluation Of Star Polymer-Solvent Mixtures, Matthew Stanton Newkirk

Theses and Dissertations

Modern automotive applications such as transmission clutch plates, combustion chambers, diesel fuel injector tips, and axle gears and friction plates operate at temperatures that can exceed 250°C and pressures of 40,000 psia. Industrial practice is to add homopolymers and copolymers to base oils to modify bulk fluid viscosity and frictional properties for these demanding applications. However, designing polymeric additives for lubricants and predicting their performance is limited by the lack of available high-temperature high-pressure (HTHP) viscosity and density data needed to test contemporary lubricity models. Thus, a major objective of this thesis is the design, development, and commissioning of a …

Designed Synthesis Of Nanoporous Organic Polymers For Selective Gas Uptake And Catalytic Applications, Pezhman Arab

Theses and Dissertations

Design and synthesis of porous organic polymers have attracted considerable attentions during the past decade due to their wide range of applications in gas storage, gas separation, energy conversion, and catalysis. Porous organic polymers can be pre-synthetically and post-synthetically functionalized with a wide variety of functionalities for desirable applications. Along these pursuits, we introduced new synthetic strategies for preparation of porous organic polymers for selective CO₂ capture.

Porous azo-linked polymers (ALPs) were synthesized by an oxidative reaction of amine-based monomers using copper(I) as a catalyst which leads to azo-linkage formation. ALPs exhibit high surface areas of up to 1200 …

Multi-Platform Arabinoxylan Scaffolds As Potential Wound Dressing Materials, Donald C. Aduba Jr

Theses and Dissertations

Biopolymers are becoming more attractive as advanced wound dressings because of their naturally derived origin, abundance, low cost and high compatibility with the wound environment. Arabinoxylan (AX) is a class of polysaccharide polymers derived from cereal grains that are primarily used in food products and cosmetic additives. Its application as a wound dressing material has yet to be realized. In this two-pronged project, arabinoxylan ferulate (AXF) was fabricated into electrospun fibers and gel foams to be evaluated as platforms for wound dressing materials. In the first study, AXF was electrospun with varying amounts of gelatin. In the second study, AXF …

Polysaccharide-Based Shear Thinning Hydrogels For Three-Dimensional Cell Culture, Vasudha Surampudi

Theses and Dissertations

The recreation of the complicated tissue microenvironment is essential to reduce the gap between in vitro and in vivo research. Polysaccharide-based hydrogels form excellent scaffolds to allow for three-dimensional cell culture owing to the favorable properties such as capability to absorb large amount of water when immersed in biological fluids, ability to form “smart hydrogels” by being shear-thinning and thixotropic, and eliciting minimum immunological response from the host. In this study, the biodegradable shear-thinning polysaccharide, gellan-gum based hydrogel was investigated for the conditions and concentrations in which it can be applied for the adhesion, propagation and assembly of different mammalian …

Toward Polymer Coating With Easy Ice Release, Chenyu Wang

Theses and Dissertations

Minimizing adhesion of ice has been the subject of extensive studies for applications such aircraft wings, wind turbine blades spacecraft, power transmission wires, while a growing interest concerns coatings for aerospace applications. The work described here describes progress for coatings and ice release test method development over the last few years. Major achievements include: (1) New Rigid Adherent-Resistant Elastomers (RARE), (2) A new Epoxied Cylinder (EC) adhesion test, (3) Validation of an ice release test, and (4) Study of ice adhesion strength on coating thickness for a PDMS elastomer. Rigid Adhesion-Resistance Elastomers (RARE) are comprised of 3F 1 terminated with …

Electrospinning Applications Air Filtration And Superhydrophobic Materials, Negar Ghochaghi, Adetoun Taiwo

Graduate Research Posters

Electrospinning is a widely applicable technique that generates non-woven fibers in the micro and nano range. In this project two of its applications are highlighted namely filtration media and enhancement of wettability. The first project demonstrates that electrospinning can be used to produce new fiber filtration media with controlled microstructure. The bimodal and unimodal orthogonal and random filters were made and characterized against their filtration efficiency and pressure drop. Figure of Merit (FOM) was also calculated and discussed. It is shown that the FOM increases when the electrospun fibers are arranged into alternating layers of aligned course and fine fibers. …