Digital Commons Network^™

Study Of The Stability Of Heparin/Collagen Layer-By-Layer Coatings, Hector M. Apodaca Reyes

Chemical Engineering Undergraduate Honors Theses

Pairing heparin with collagen-based medical implants has opened a whole new area of research for enhancing the desired effect of current implants. In fact, heparin (HEP) and collagen (COL) layer-by-layer (LbL) coatings have shown impressive results in forming polyelectrolyte multilayers. It has been already seen on skin grafts, nerve guide conduits (NGCs), and drug delivery devices yielding promising results. Due to being a simple, cost-efficient, and versatile option to fabricate thin biomimetic films, this self-assembly technique is one of the most effective methods to immobilize extracellular matrix (collagen and heparin) onto medical devices and implants. Even though previous studies have …

Controlling Mechanical Properties In Thim Multilayer Hydrogels Through Network Structure, Maksim Dolmat

All ETDs from UAB

Polymer thin films possess unique properties, cost-effectiveness, and flexibility, making them vital for enhancing surface functionality. Layer-by-layer (LbL) assembly allows for synthesis of ultrathin polymeric films with precise control over film thickness, material selection, surface chemistry, and responsiveness. Current advancements in LbL assembly focus on understanding film formation and deposition conditions on film’s structure and properties. Covalent cross-linking of physically bonded LbL networks forms multilayer hydrogel networks capable of absorbing large amounts of water. The use of stimuli-responsive polymers has facilitated the advancement of "smart" materials capable of responding to external stimuli. Stimuli-responsive hydrogels exhibit reversible volume changes, making them …

Development And Evaluation Of A Functional Human Cardiac Tissue Equivalent Fabricated From Multi-Lineage Human Induced Pluripotent Stem Cell Derived Cells, Danielle Pretorius

All ETDs from UAB

The human heart is an exceptionally complex muscular organ that is vital for survival. Electrical impulses signal activation of mechanical contractions, pumping blood through the entire body and allowing for oxygen-exchange to occur. Unfortunately, certain disease states or traumatic injuries such as myocardial infarctions hamper the heart’s efficiency and function by damaging its structure. Ideal treatment would allow for the replacement or regeneration of the damaged tissue with cells and material harvested from the patient, thus avoiding the potential for immune rejection. Engineered cardiac tissues fabricated from human induced pluripotent stem cells have shown great promise for restoring function in …

Stimuli Response In Ph And Temperature-Responsive Hydrogels As Probed By Neutron Reflectivity, William Todd Higgins

All ETDs from UAB

Polymer materials can be used as platforms to incorporate sensing materials, and increasingly the structure and chemistry of polymer chains is exploited in new and novel way and the unique nanoscale properties are studied. Polymers which can be dissolved in water are particularly interesting as primary components or for modifications in biomaterial applications, as many of them can have variable solubility in response to pH, temperature, or other solution conditions. This can allow the formation of microcapsules, for example, which can release drug triggered via specific solution conditions to release chemotherapeutic drug; in comparison to traditional injection or slow-release bulk …

Synthesis, Stabilization, And Modification Of Zinc Oxide Nanoparticles For Biological Applications, Allison Kimberly Freese

MSU Graduate Theses

Nanoparticles have become very useful as delivery systems in biomedicine. The nanoparticles can be layered with different compounds to produce a vessel for transport of biological materials. Specifically, gold nanoparticles layered with a reducing agent, lysozyme, and polyelectrolytes can be synthesized to transport lysozyme into a cell. However, zinc oxide nanoparticles are cheaper, biocompatible nanoparticles that can be used for the same process. Here in, zinc oxide nanoparticle conjugates were synthesized, modified, and analyzed to be used as a biological material delivery system. The zinc oxide nanoparticles were synthesized using zinc chloride and sodium hydroxide. The particles were then layered …

Metal Complexation In Hydrogen-Bonded Microcapsules Of Poly(N-Vinylpyrrolidone) And Tannic Acid For Medical Imaging And Controlled Drug Delivery, Patrick Aaron Alford

All ETDs from UAB

Even the most effective and widely used drugs in modern disease treatment can be compromised by low bioavailability and off-target damage which leads to detrimental side effects. Polymeric drug carriers have been developing in recent times with the aim of rendering the therapeutic cargo inert and protecting it from the body’s natural defense mechanisms until arrival at the target site, upon which a specific stimulus will cause the drug to release from the carrier locally. To this end, antioxidant capability in drug carriers can help mediate the cascade of reactive oxygen species that meet injected materials and, in doing so, …

Synthesis And Characterization Of Novel Diphosphonium Polymers With The Emphasis On Supramolecular Assembly, Catherine Alexis Conrad

All Theses

Three different series of diphosphonium polymers were synthesized in order to analyze the supramolecular assembly of these polyelectrolytes with varying polyanions. Variation of the rigidity of the spacer between the phosphonium units determined that flexibility leads to increased absorption and consistency to film growth when observed through layer-by-layer assembly with UV-vis spectroscopy and atomic force microscopy. With the flexible ethylene spacer, films formed linearly up to 800 bilayers thick. An additional series of xylene based flexible diphosphonium polymers were synthesized with increasing numbers of methylene unit spacers. Analysis of materials was conducted through thermogravimetric analysis, X-ray crystallography, and layer-by-layer analysis …

Shaped Stimuli-Responsive Layer-By-Layer Hydrogels For Targeted Drug Delivery, Bing Xue

All ETDs from UAB

The development of polymeric delivery systems help overcome the intrinsic drawbacks of systemically-delivered therapeutic drugs, such as poor solubility and stability, multidrug resistance, inefficient accumulation in the diseased sites and unexpected toxicity to normal tissues. Polymeric vehicles possessing stimuli-sensitivity can prevent premature drug leakage and enable controlled cargo release. The modification with bioactive ligands aids to the accumulation of carriers in the targeted tissues to locally increase the concentration of therapeutics and decrease off-target toxicity. The manipulation of physical characteristics (e.g. size, shape) is also essential in the design of drug delivery systems since these properties play pivotal roles in …

Novel Sputtered Stationary Phases For Solid Phase Microextraction, And Other Coatings And Materials For Surface Applications, Anubhav Diwan

Theses and Dissertations

The primary focus of my work has been to prepare new solid adsorbents for solid phase microextraction (SPME) via sputtering of silicon. The orientation of the silica substrates/fibers and the sputtering pressure induced the formation of porous and columnar structures. Sputtering was performed for different times to yield fibers with different thicknesses. Piranha treatment of the surface increased the concentration of silanol groups, which underwent condensation with vapor deposited octadecyldimethylmonomethoxy silane to incorporate octadecyl chains onto the fiber surfaces. Silanized, sputtered fibers were preconditioned for 3 h at 320 °C to remove the unreacted chains. Comparison of the extraction efficiencies …

Metabolic Toxicity Studies Using High Throughput Bioreactor Assay And Liquid Chromatography Coupled With Mass Spectrometry (Lc-Ms/ Ms), Dandan Li

Doctoral Dissertations

Metabolic toxicity is one of main concerns in drug discovery and development. High efficient and low cost metabolic toxicity assessment is still a major challenge for pharmaceutical industry. This thesis focuses on the development of high throughput in vitro metabolic toxicity assay coupling with liquid chromatography tandem mass spectrometry for metabolic adducts generation, characterization and quantitation. The key technology was based on electrostatic fabrication of polyelectrolytes and biomolecules on magnetic beads to form bioreactors in 96 well plate format and acquired metabolites induced toxicity molecular information by LC-MS experiments.

Chapter one will address the goals and significance of the metabolic …

Poly(N-Vinylcaprolactam) Based Thermoresponsive Nanostructured Materials, Xing Liang

All ETDs from UAB

Poly(N-vinylcaprolactam) (PVCL) is a temperature-responsive polymer displaying a low critical solution temperature (LCST) around 30 to 40℃ in aqueous solutions that is close to the human physiological temperature. In addition, compared to other ther-moresponsive polymers, PVCL is nontoxic and biocompatible. In this thesis, we will fo-cus on the synthesis, fabrication and characterization of PVCL-based thermoresponsive nanostructured materials, such as films, hydrogels and block copolymers and their poten-tial applications in biomedical and medical areas. In chapter 2, we report on nanothin multilayer hydrogels of cross-linked PVCL that exhibited distinctive and reversible thermoresponsive behavior. The single-component PVCL hydrogels were produced by selective …

Layer-By-Layer Assemblies For Membrane-Based Enzymatic Catalysis, Andrew R. Tomaino

Theses and Dissertations--Chemical and Materials Engineering

While considerable progress has been made towards understanding the effect that membrane-based layer-by-layer (LbL) immobilizations have on the activity and stability of enzymatic catalysis, detailed work is required in order to fundamentally quantify and optimize the functionalization and operating conditions that define these properties. This work aims to probe deeper into the nature of transport mechanisms by use of pressure-induced, flow-driven enzymatic catalysis of LbL-functionalized hydrophilized poly(vinyldiene) (PVDF)-poly(acrylic acid) (PAA)-poly(allylamine hydrochloride) (PAH)-glucose oxidase (GOx) membranes. These membranes were coupled in a sealed series following cellulose acetate (CA) membranes for the elimination of product accumulation within the feed-side solution during operation. …

Synthesis Of Ph-Responsive Multilayer Hydrogels And Amphiphilic Block Copolymers, Yun Wang

All ETDs from UAB

The research presented in this thesis is focused at the design and fabrication of pH-responsive layer-by-layer (LbL) hydrogels and the synthesis of the ABA block copolymer poly(2-methyloxazoline)-block-poly(dimethylsiloxane)-block-poly(2-methyl-oxazoline) (PMOXA-b-PDMS-b-PMOXA). Ultrathin stimuli-responsive layer-by-layer hydrogels, as compared to bulk hydrogels, can respond to external stimuli in a short time range (usually within seconds) which renders them particularly useful in sensing. Moreover, layer-by-layer technique allows the hydrogel film to be deposited with controlled thickness growth. However, the fabrication of LbL hydrogels with controllable cross-linking density and swelling degree still remains challenging. In chapter two, novel pH-sensitive LbL hydrogels based on poly(4-vinyl pyridine) (P4VP) were …

Ultrasonication Assisted Layer-By-Layer Technology For The Preparation Of Multi-Functional Anticancer Drugs Paclitaxel And Lapatinib, Xingcai Zhang

Doctoral Dissertations

In this dissertation, ultrasonication assisted Layer-by-Layer (LbL) technology for the preparation of multifunctional poorly water-soluble anticancer drug nanoparticles, paclitaxel and lapatinib, has been developed. Many FDA approved drugs are very low soluble in water; therefore, it is very difficult to load and control their release and targeting efficiently, which greatly confines their application. The development of this method will pave the way for the development and application of those low soluble anticancer drugs.

In the first part of this dissertation, the first approach for powerful ultrasonication, the top-down approach (sonicating bulk drug crystals in polyelectrolyte solution), was successfully applied for …

Surface Morphology Of Platelet Adhesion Influenced By Activators, Inhibitors And Shear Stress, Melanie Groan Watson

Doctoral Dissertations

Platelet activation involves multiple events, one of which is the generation and release of nitric oxide (NO), a platelet aggregation inhibitor. Platelets simultaneously send and receive various agents that promote a positive and negative feedback control system during hemostasis. Although the purpose of platelet-derived NO is not fully understood, NO is known to inhibit platelet recruitment. NO's relatively large diffusion coefficient allows it to diffuse more rapidly than platelet agonists. It may thus be able to inhibit recruitment of platelets near the periphery of a growing thrombus before agonists have substantially accumulated in those regions.

Results from two studies in …

An Improved Layer-By-Layer Self-Assembly Technique To Generate Biointerfaces For Platelet Adhesion Studies: Dynamic Lbl, Juan Manuel Lopez

Doctoral Dissertations

Layer-by-layer self-assembly (LbL) is a technique that generates engineered nano-scale films, coatings, and particles. These nanoscale films have recently been used in multiple biomedical applications. Concurrently, microfabrication methods and advances in microfluidics are being developed and combined to create "Lab-on-a-Chip" technologies. The potential to perform complex biological assays in vitro as a first-line screening technique before moving on to animal models has made the concept of lab on a chip a valuable research tool.

Prior studies in the Biofluids Laboratory at Louisiana Tech have used layer-by-layer and in vitro biological assays to study thrombogenesis in a controlled, repeatable, engineered environment. …

Layer-By-Layer Assembly Of {Nanoclay-(Sol-Gel Oxide)}N And {Nanoclay-(Oxide Nanoparticle)}N Multilayers: Synthesis And Growth Mechanisms, Hao Chen

All Dissertations

Two new classes of all-inorganic nanostructured multilayers, {MMTx-(sol-gel oxide)}n and {MMTx-(oxide nanoparticle)}n, have been successfully synthesized for the first time. They were made by adapting a layer-by-layer (LbL) assembly method initially developed to synthesize polyelectrolyte-based multilayers. In most previous studies, this electrostatic-assisted LbL assembly method used polyelectrolytes/polymers as the 'structural glue' to prepare multilayers. The synthesis of {MMTx-(sol-gel ZrO2)}n multilayers demonstrates for the first time the feasibility of making sol-gel oxide 'glued' all-inorganic multilayers, thereby introducing an innovative nanoscale fabrication concept. The synthesis of {MMTx-(oxide nanoparticle)}n multilayers further illustrates the versatility of LbL assembly technique by achieving a second new …

Fabrication Of Bioactive Osteogenic Controlled-Release Systems, Cellular Platforms, And Cellular Capsules Using Layer -By -Layer Nanoassembly, Skylar Stewart-Clark

Doctoral Dissertations

There is an ever-increasing awareness that the field of tissue engineering offers many potential solutions to clinical problems. While advances along these lines have been made, the design and implementation of an "off the shelf" tissue is yet to be realized. Thus, the objectives of this work were largely aimed at the design and fabrication of biocompatible, bioactive structures which could be integrated into existing biomaterial products.

The electrostatic layer-by-layer (LbL) self-assembly technique was used to incorporate biologically relevant molecules within controlled release systems, cell culture platforms, and 3-D cellular capsules. Two delivery systems were investigated to determine the release …

Application Of Polyelectrolyte Multilayers For Photolithographic Patterning Of Diverse Mammalian Cell Types In Serum Free Medium, Vipra Dhir

Electronic Theses and Dissertations

Integration of living cells with novel microdevices requires the development of innovative technologies for manipulating cells. Chemical surface patterning has been proven as an effective method to control the attachment and growth of diverse cell populations. Patterning polyelectrolyte multilayers through the combination of layer-by-layer self-assembly technique and photolithography offers a simple, versatile and silicon compatible approach that overcomes chemical surface patterning limitations, such as short-term stability and low protein adsorption resistance. In this study, direct photolithographic patterning of PAA/PAAm and PAA/PAH polyelectrolyte multilayers was developed to pattern mammalian neuronal, skeletal and cardiac muscle cells. For all studied cell types, PAA/PAAm …

Microparticulate Drug Reformulation Using Electrostatic Layer -By -Layer Assembly And Co-Entrapment With Anionic Phospholipids In Calcium Carbonate Matrix, Krishna Gopal

Doctoral Dissertations

Non-invasive drug delivery systems for therapeutic drugs are gaining prominence. One such system, the nasal delivery system, shows good prospect for effective delivery of some drugs, however, it is yet to be well established for others. The preparation of a reformulated drug and studying its in vitro characteristics is a crucial step in the process of adapting the new drug for nasal delivery systems. The purpose of this research is to study the effect of electrostatic layer by layer assembly of polyelectrolytes on PROMAXX®insulin microparticles and to study the chemical, physical and corresponding release properties of the resulting formulations. PROMAXX® …

Multicomponent Patterning Of Nanocomposite Polymer And Nanoparticle Films Using Photolithography And Layer-By-Layer Self -Assembly, Javeed Shaikh Mohammed

Doctoral Dissertations

In this dissertation, the fabrication, characterization, and application examples of 3D multicomponent nanocomposite micropatterns (MNMs) with precise spatial arrangements are described. The ability to produce such small-scale 3D structures with versatility in composition and structure is a new development based on the integration of nanoscale layer-by-layer (LbL) self-assembly and microscale photolithographic patterning, enabling construction of surfaces with microscale patterns that possess nanotopographies. The techniques used here are analogous to surface micromachining, except that the deposition materials are polymers, biological materials, and colloidal nanoparticles used to produce 3D MNMs. A key feature of the resulting 3D MNMs is that the physical …

Integration Of Micro Nano And Bio Technologies With Layer -By -Layer Self -Assembly, Dinesh Shankar Kommireddy

Doctoral Dissertations

In the past decade, layer-by-layer (LbL) nanoassembly has been used as a tool for immobilization and surface modification of materials with applications in biology and physical sciences. Often, in such applications, LbL assembly is integrated with various techniques to form functional surface coatings and immobilized matrices. In this work, integration of LbL with microfabrication and microfluidics, and tissue engineering are explored. In an effort to integrate microfabrication with LbL nanoassembly, microchannels were fabricated using soft-lithography and the surface of these channels was used for the immobilization of materials using LbL and laminar flow patterning. Synthesis of poly(dimethyldiallyl ammonium chloride)/poly(styrene sulfonate) …

Application Of Polyelectrolyte Layer-By-Layer Nano-Assembly For Surface Modification, Encapsulation And Controlled Release, Nikhil Anil Pargaonkar

Doctoral Dissertations

In this study, we applied the traditional Electrostatic layer-by-layer (ELBL) assembly procedure to fabricate nanothin films over flat surfaces, and modify particle surfaces to influence the drug particle size, and drug release. The ELBL assembly has previously been applied to fabricate multilayer nano-scale thin films, but its ability to instantaneously influencing particle size is unique. Other unique observations such as influence on drug release as a result of polymer complexation, and thermal changes occurring during layer fabrication are recorded.

The ELBL self-assembly process was applied to produce dexamethasone particles layered with various polyelectrolyte layer combinations. These combinations were further applied …

Novel Sensors For Neural Glucose Concentration Based On Enzyme Fluorescent Thin Films Fabricated On Nanoparticle Carriers Using Electrostatic Layer -By -Layer Assembly, Patrick Scott Grant

Doctoral Dissertations

Currently, there is no means by which rapidly fluctuating glucose and lactate levels can be monitored simultaneously. This dissertation demonstrates that by combining the broad-band versatility of fluorescence spectroscopy with nanoassembly methods, it is possible to construct micro- and nanoscale sensors with precise composition and short diffusion length constant. The work is significant because of its potential as a platform for discovery of basic normal physiological processes that have previously been hidden from researchers' views, more detailed studies of responses to drugs or other stimuli, and even clinical monitoring. The main goal of this work was to develop novel methods …

Patterning Layer -By -Layer Self -Assembled Multilayer By Lithography And Its Applications To Thin Film Devices, Feng Hua

Doctoral Dissertations

Nanoparticles are exciting materials because they exhibit unique electronic, catalytic, and optical properties. As a novel and promising nanobuilding block, it attracts considerable research efforts in its integration into a wide variety of thin film devices.

Nanoparticles were adsorbed onto the substrate with layer-by-layer self-assembly which becomes of great interest due to its suitability in colloid particle assembly. Without extremely high temperatures and sophisticated equipment, molecularly organized films in an exactly pre-designed order can grow on almost all the substrates in nature.

Two approaches generating spatially separated patterns comprised of nanoparticles are demonstrated, as well as two approaches patterning more …