Biomedical Engineering and Bioengineering Commons^™

Shape Memory Behavior Of Dense And Porous Niti Alloys Fabricated By Selective Laser Melting, Soheil Saedi

Theses and Dissertations--Mechanical and Aerospace Engineering

Selective Laser Melting (SLM) of Additive Manufacturing is an attractive fabrication method that employs CAD data to selectively melt the metal powder layer by layer via a laser beam and produce a 3D part. This method not only opens a new window in overcoming traditional NiTi fabrication problems but also for producing porous or complex shaped structures. The combination of SLM fabrication advantages with the unique properties of NiTi alloys, such as shape memory effect, superelasticity, high ductility, work output, corrosion, biocompatibility, etc. makes SLM NiTi alloys extremely promising for numerous applications.

The SLM process parameters such as laser power, …

Structural Characteristics And Corrosion Behavior Of Bio-Degradable Zn-Li Alloys In Stent Application, Shan Zhao

Dissertations, Master's Theses and Master's Reports

Zinc has begun to be studied as a bio-degradable material in recent years due to its excellent corrosion rate and optimal biocompatibility. Unfortunately, pure Zn’s intrinsic ultimate tensile strength (UTS; below 120 MPa) is lower than the benchmark (about 300 MPa) for cardiovascular stent materials, raising concerns about sufficient strength to support the blood vessel. Thus, modifying pure Zn to improve its mechanical properties is an important research topic.

In this dissertation project, a new Zn-Li alloy has been developed to retain the outstanding corrosion behavior from Zn while improving the mechanical characteristics and uniform biodegradation once it is implanted …

Formulation And Testing Of Biodegradable Polymeric Coating On Zinc Wires In Cardiovascular Stent Application, Avishan Arab Shomali

Dissertations, Master's Theses and Master's Reports

Biodegradable and biocompatible poly (L-lactic-acid) (PLLA) coating was applied on a modified zinc (Zn) substrate by dip coating, with the intent to delay the bio-corrosion and slow the degradation rate of zinc substrate. 3-(Trimethoxysilyl) propyl methacrylate (MPS) was used for modification of the zinc substrate for promoting the adhesion between the metallic substrate and the polymer coating. It is hypothesized that the delay in Zn biodegradation could be useful in the first several weeks to prevent the early loss of mechanical integrity of the endovascular stent and to improve the healing process of the diseased vascular site. The PLLA coating …

Developing Afm Techniques For Testing Peg Hydrogels, Hannah L. Cebull, Jessica Stukel, Rebecca Willits

Williams Honors College, Honors Research Projects

Many instruments are used to find elastic properties of biological samples using methods such as tensile and bending tests, but using the atomic force microscope (AFM) is considered a non-destructive method because it can provide repeated local stiffness information without damaging the sample. It additionally allows the sample to be tested in an aqueous environment, which is optimal for soft materials such as hydrogels. The nanoindentation is performed via cantilever, measuring the deflection of the cantilever during the contact of the sample using a laser. Compared to hard samples, testing soft materials can present more challenges when working with the …

Investigation Of Polymeric Composites For Controlled Drug Release, Hsi-Wei Yeh

Theses and Dissertations

The Electrospray (ES) technique is a promising particle generation method for drug delivery due to its capabilities of producing monodisperse PLGA composite particles with unique configurations and high drug encapsulation efficiency. In the dissertation work, the coaxial dual capillary ES was used to generate drug-loaded core-shell PLGA particles to study the effects of particle filling materials, drug loading locations and particle shell thicknesses on the resultant in vitro release behaviors of the hydrophilic and/ or hydrophobic model drugs. Through release profile characterization of drug-loaded PLGA particles (particle size: 400 nm and 1 μm), it was confirmed that the co-encapsulation of …

Nanomedicine Drug Delivery Across Mucous Membranes, Michael G. Lancina Iii

Theses and Dissertations

NANOMEDECINE DRUG DELIVERY ACROSS MUCOUS MEMBRANES

By Michael G. Lancina III

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

Virginia Commonwealth Univeristy, 2017.

Major Director: Dr. Hu Yang, Associate Professor, Chemical and Life Science Engineering

Control over the distribution of therapeutic compounds is a complex and somewhat overlooked field of pharmaceutical research. When swallowing a pill or receiving an injection, it is commonly assumed that drug will spread throughout the body in a more or less uniform concentration and find its way to wherever it is needed. In …

Fabrication Of Flexible, Biofunctional Architectures From Silk Proteins, Ramendra K. Pal

Theses and Dissertations

Advances in the biomedical field require functional materials and processes that can lead to devices that are biocompatible, and biodegradable while maintaining high performance and mechanical conformability. In this context, a current shift in focus is towards natural polymers as not only the structural but also functional components of such devices. This poses material-specific functionalization and fabrication related questions in the design and fabrication of such systems. Silk protein biopolymers from the silkworm show tremendous promise in this regard due to intrinsic properties: mechanical performance, optical transparency, biocompatibility, biodegradability, processability, and the ability to entrap and stabilize biomolecules. The unique …

Modulating The Innate Immune Response To Electrospun Scaffolds And Polymer Degradative Byproducts, Daniel Abebayehu

Theses and Dissertations

Implanted biomaterials often induce inflammation that frequently leads to the foreign body response, fibrosis, and the failure of the implant. Thus, it is important to evaluate how cells interact with materials to promote a more regenerative response. It is critical to determine how to modulate the response of tissue resident innate immune cells, as they are among the first cells to interact with implanted materials. Among tissue resident innate immune cells are mast cells, which are inflammatory sentinels that degranulate and orchestrate the fate of other cell populations, such as monocytes/macrophages and lymphocytes. Mast cells have also been reported to …

Pore-Confined Carriers And Biomolecules In Mesoporous Silica For Biomimetic Separation And Targeting, Shanshan Zhou

Theses and Dissertations--Chemical and Materials Engineering

Selectively permeable biological membranes composed of lipophilic barriers inspire the design of biomimetic carrier-mediated membranes for aqueous solute separation. This work imparts selective permeability to lipid-filled pores of silica thin film composite membranes using carrier molecules that reside in the lipophilic self-assemblies. The lipids confined inside the pores of silica are proven to be a more effective barrier than bilayers formed on the porous surface through vesicle fusion, which is critical for quantifying the function of an immobilized carrier. The ability of a lipophilic carrier embedded in the lipid bilayer to reversibly bind the target solute and transport it through …

An Enhanced Spring-Particle Model For Red Blood Cell Structural Mechanics: Application To The Stomatocyte–Discocyte– Echinocyte Transformation, Mingzhu Chen, Fergal Boyle

Articles

Red blood cells (RBCs) are the most abundant cellular element suspended in blood. Together with the usual biconcave-shaped RBCs, i.e., discocytes, unusual-shaped RBCs are also observed under physiological and experimental conditions, e.g., stomatocytes and echinocytes. Stomatocytes and echinocytes are formed from discocytes and in addition can revert back to being discocytes; this shape change is known as the stomatocyte–discocyte–echinocyte (SDE) transformation. To-date, limited research has been conducted on the numerical prediction of the full SDE transformation. Spring- particle RBC (SP-RBC) models are commonly used to numerically predict RBC mechanics and rheology. However, these models are incapable of predicting the full …

Development Of An Electrospun And 3d Printed Cellular Delivery Device For Dermal Wound Healing, Ryan M. Clohessy

Theses and Dissertations

The goal of this research was to develop a system of individualized medicine that could be applied to dermal wounds serving as a wound dressing and synthetic extracellular matrix while delivering stem cells to the wound bed. First, fabrication parameters for electrospinning polymer fibers were determined. This involved evaluating fiber morphology with respect to polymer selection and solution concentration. Next, construct fabrication was examined to produce an integrated void space, or cargo area, suitable to maintain stem cells. In vitro studies to ensure stem cell viability and phenotype were conducted, and results supported the notion that cells could be administered …

Electrospraying Extracellular Matrix To Form Nanoparticles, Patrick Link

Theses and Dissertations

Chronic Obstructive Pulmonary Disease (COPD) is a leading cause of death worldwide. Alveolar wall destruction is a significant contributor to COPD. Inflammatory macrophages are a major source of the Extracellular Matrix (ECM) proteolysis. ECM breakdown causes air to get trapped in the alveoli, obstructing airflow. One step in curing COPD may be to convert inflammatory to pro-regenerative macrophages. Recently, decellularized ECM scaffolds have shown the ability to induce a pro-regenerative phenotype.

Yet these scaffolds are incapable for reaching the alveolar region of the lungs. To reach the alveolar region particles need a diameter of 1-5 μm or smaller than 300 …

Sugar Versus Lipid For Sustainable Biofuels, Yaşar Demirel

Yaşar Demirel Publications

Introduction

First‐generation biofuels, namely, ethanol and biodiesel, have led to far reaching impact on the peoples’ life world‐wide.[1] However, they inter-fere with the food supply chain and may not be sustainable although some of the biomass are converted to biofuels after those biomasses have met the human needs. Still, the first‐generation–based biofuels have proved that sugar and lipid platforms can be an answer to energy security and global warming concerns without the need for new infrastructure for feedstock delivery as well as for biomass‐to‐biofuel conversion tech-nologies. At the same time, we are discovering and assessing the long‐term environmental im-plications on …

A 3d Biomimetic Scaffold Using Electrospinning For Tissue Engineering Applications, Samerender Nagam Hanumantharao

Dissertations, Master's Theses and Master's Reports

Electrospinning holds great promise for designing functional 3D biomimetic scaffolds for tissue engineering applications. The technique allows for the reproducible fabrication of 3D scaffolds with control over the porosity and thickness. In this work, a novel method for the synthesis of a 3D electroactive scaffold using electrospinning from polycaprolactone (PCL), Polyvinylidene Fluoride (PVDF) and Polyaniline (PANI) is reported. Additional scaffolds involving different morphologies of PCL, PCL-PVDF and PCL-PANI-PVDF were also fabricated and evaluated. The scaffolds were characterized using electron microscopy to visualize the morphologies. Infrared spectroscopy was used to confirm the presence of polymers and their respective phases in the …

Activity Preservation Of Plasmonic Biosensors With A Metal-Organic Framework, Lu Wang

McKelvey School of Engineering Graduate Student Theses & Dissertations

Antibody-antigen recognition enables antibody-conjugated nanostructures to serve as plasmonic biosensors with tunable specificity. However due to the instability of antibodies, these biosensors are susceptible to changes in the environment such as heat and aridity, leading to constraints on the transportation and handling of these sensors. Here we establish a method using a metal-organic framework crystal to preserve biosensor activity under severe environmental conditions, including exposure to high temperatures, an organic solvent and a proteolytic agent. After zeolitic imidazolate framework-8 (ZIF-8) crystals formed for 12 hours on a biosensor of gold nanorods conjugated with a model antibody, rabbit IgG, 80% of …

Hollow Fiber Membranes For Artificial Lung Applications, Lauren Reed

Chemical Engineering Undergraduate Honors Theses

Artificial lungs are in use, but difficult issues remain in the field of membrane development related to fouling issues. Currently there are external artificial lungs circulating blood outside the body, taking out the carbon dioxide, and inserting oxygenated blood back into the body. An example of this type of machine is the ExtraCorporeal Membrane Oxygenation (ECMO) machine currently used in hospitals. The ECMO takes over the functions for both the lungs and the heart but is only available for short term use by patients with respiratory failure due to infections [1]. The fibers in the machine develop fouling due to …

Bi-Directional Fatigue Life Behavior Of Bovine Meniscus, Jaremy Creechley

Boise State University Theses and Dissertations

Meniscal injuries due to tissue tearing are prevalent in the U.S. yet the failure behavior of the meniscus is poorly understood. Clinical studies indicate that fatigue failure causes many of these tears. The highly circumferentially aligned fibers result in transversely isotropic material properties. Tears preferentially align bi-directionally to the fiber orientation. The aim of this study is to present the bi-directional fatigue life behavior of meniscal fibrocartilage. A novel fatigue life approach was developed to achieve this aim. Forty-eight bovine specimens were subjected to cyclic sinusoidal tension-tension stress at 2 Hz until rupture. Normalized peak tensile stresses were determined at …

Nanoindentation Techniques For The Evaluation Of Silicon Nitride Thin Films, Weston T. Mangin

Master's Theses

Silicon nitride thin films are of interest in the biomedical engineering field due to their biocompatibility and favorable tribological properties. Evaluation and understanding of the properties of these films under diverse loading and failure conditions is a necessary prerequisite to their use in biomedical devices. Three wafers of silicon nitride-coated silicon were obtained from Lawrence Livermore National Laboratory and used to create 96 samples. Samples were subjected to nanoindentation testing to evaluate the mechanical properties of the film. Samples were subjected to nanoimpact testing to compare the damage resistance of the film to separate nanoimpact types. Samples were subjected to …

Characterization Of Molecular Communication Based On Cell Metabolism Through Mutual Information And Flux Balance Analysis, Zahmeeth Sayed Sakkaff

School of Computing: Dissertations, Theses, and Student Research

Synthetic biology is providing novel tools to engineer cells and access the basis of their molecular information processing, including their communication channels based on chemical reactions and molecule exchange. Molecular communication is a discipline in communication engineering that studies these types of communications and ways to exploit them for novel purposes, such as the development of ubiquitous and heterogeneous communication networks to interconnect biological cells with nano and biotechnology-enabled devices, i.e., the Internet of Bio-Nano Things. One major problem in realizing these goals stands in the development of reliable techniques to control the engineered cells and their behavior from the …

Use Of A Modified Greenscreen Tool To Conduct A Screening-Level Comparative Hazard Assessment Of Conventional Silver And Two Forms Of Nanosilver., Jennifer Sass, Lauren Heine, Nina Hwang

Environmental and Occupational Health Faculty Publications

BACKGROUND: Increased concern for potential health and environmental impacts of chemicals, including nanomaterials, in consumer products is driving demand for greater transparency regarding potential risks. Chemical hazard assessment is a powerful tool to inform product design, development and procurement and has been integrated into alternative assessment frameworks. The extent to which assessment methods originally designed for conventionally-sized materials can be used for nanomaterials, which have size-dependent physical and chemical properties, have not been well established. We contracted with a certified GreenScreen profiler to conduct three GreenScreen hazard assessments, for conventional silver and two forms of nanosilver. The contractor summarized publicly …

Lipid Coated Microbubbles And Low Intensity Pulsed Ultrasound Enhance Chondrogenesis Of Human Mesenchymal Stem Cells In 3d Printed Scaffolds, Mitra Aliabouzar, Lijie Grace Zhang, Kausik Sarkar

Medicine Faculty Publications

Lipid-coated microbubbles are used to enhance ultrasound imaging and drug delivery. Here we apply these microbubbles along with low intensity pulsed ultrasound (LIPUS) for the first time to enhance proliferation and chondrogenic differentiation of human mesenchymal stem cells (hMSCs) in a 3D printed poly-(ethylene glycol)-diacrylate (PEG-DA) hydrogel scaffold. The hMSC proliferation increased up to 40% after 5 days of culture in the presence of 0.5% (v/v) microbubbles and LIPUS in contrast to 18% with LIPUS alone. We systematically varied the acoustic excitation parameters—excitation intensity, frequency and duty cycle—to find 30 mW/cm2, 1.5 MHz and 20% duty cycle to be optimal …

Surface Engineering Of Titanium Alloy To Stimulate The Bone Regeneration, Yubin Meng, Zhenduo Cui, Zhaoyang Li, Xue Li, Jin Zhao, Xubo Yuan, Xianjin Yang

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Fluorescent Materials Design At Nanoscale For Biomedical Photonics In Near Infrared Window, Kohei Soga, Masao Kamimura

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Recent Approaches In Designing Bioadhesive Materials Inspired By Mussel Adhesive Protein, Pegah Kord Forooshani, Bruce P. Lee

Department of Biomedical Engineering Publications

Marine mussels secret protein-based adhesives, which enable them to anchor to various surfaces in a saline, intertidal zone. Mussel foot proteins (Mfps) contain a large abundance of a unique, catecholic amino acid, Dopa, in their protein sequences. Catechol offers robust and durable adhe-sion to various substrate surfaces and contributes to the curing of the adhesive plaques. In this article, we review the unique features and the key functionalities of Mfps, catechol chemistry, and strategies for preparing catechol-functionalized poly- mers. Specifically, we reviewed recent findings on the contributions of various features of Mfps on interfacial binding, which include coacervate formation, surface …

Long-Term Biocompatibility, Imaging Appearance And Tissue Effects Associated With Delivery Of A Novel Radiopaque Embolization Bead For Image-Guided Therapy, Karun Sharma, Zainab Bascal, Hugh Kilpatrick, Koorosh Ashrafi, Sean L. Willis, Matthew R. Dreher, Andrew L. Lewis

Pediatrics Faculty Publications

The objective of this study was to undertake a comprehensive long-term biocompatibility and imaging assessment of a new intrinsically radiopaque bead (LC Bead LUMI™) for use in transarterial embolization. The sterilized device and its extracts were subjected to the raft of ISO10993 biocompatibility tests that demonstrated safety with respect to cytotoxicity, mutagenicity, blood contact, irritation, sensitization, systemic toxicity and tissue reaction. Intra-arterial administration was performed in a swine model of hepatic arterial embolization in which 0.22–1 mL of sedimented bead volume was administered to the targeted lobe(s) of the liver. The beads could be visualized during the embolization procedure with …

Cartilage Engineering: Optimization Of Media For Chondrogenic Differentiation In Vitro, Evan Surma, Sherry L. Harbin, Hongji Zhang, Stacy Halum

The Summer Undergraduate Research Fellowship (SURF) Symposium

Lower back pain from intervertebral disc injury affects around 84% of the population at some point in their life, which at its worst may cause total immobilization. This pain can only be temporarily relieved by spinal fusion or intervertebral disc replacement; however, both of these cause loss of natural motion in patients by removing damaged fibrocartilage discs. While these techniques help mitigate pain briefly, no permanent solution exists currently to both relieve pain and preserve natural motion. My work may be a solution by eventually providing patient-specific implants that resemble native tissue in the regeneration process that could be absorbed …

Alginate Hydrogels As Three-Dimensional Scaffolds For In Vitro Culture Models Of Growth Plate Cartilage Development And Porcine Embryo Elongation, Taylor D. Laughlin

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

The establishment of in vitro culture models utilizes tissue engineering principles to design functional mimics of in vivo environments in vitro. Advantages for the use of in vitro culture models include ethical alleviation of animal models for therapeutic testing, cost efficiency, and a greater ability to study specific mechanisms via a systematic, ground-up approach to development. In this thesis, alginate hydrogels are utilized in the development of in vitro culture models of porcine embryo elongation and growth plate cartilage development. First, the effect of scaffold and modifications to the scaffold were explored in both projects. In order to modulate …

Prosthetic Leg Kit For Deployment In Developing Countries, Brian Murphy, Dominique Porcincula, Derek Morgan, Kendall Ruggles, Christian Aguayo

Biomedical Engineering

The World Health Organization estimates that over 30 million people require some sort of prosthetic technology. However, traditional prosthetic fitting practices take a lot of time and cost a lot of money, making them inaccessible to millions of people around the world. StandUP Worldwide is an interdisciplinary project team devoted to creating low-cost prosthetic technologies for use around the world, especially in resource poor areas. They are currently developing a low cost, below-the-knee prosthetic kit that can be easily deployed in a resource-poor area. The following presents their solution for a below-the-knee prosthetic socket, foot, and leg.

Chitosan As An Antiviral, Tayler Pauls

Biomedical Engineering Undergraduate Honors Theses

There is no broad-based antiviral medication available today; there are specific antivirals, for example, the antiretroviral for HIV. However, these specific antivirals are not available in each country and can be problematic for specific patients. Chitosan is proposed as a possible broad-based antiviral, which has already demonstrated antibacterial properties, antiviral properties in plants, is used for wound healing and as a hydrogel among other medical applications. The methods used are transfection of NIH-3T3 cells with GFP-adenovirus with 0.1%, 0.5%, and 1% chitosan added to virus prior to transfection. Fluorescence microscopy and flow cytometry data has validated that the use of …

Isolation Of Metallic Single-Walled Carbon Nanotubes For Electrically Conductive Tissue Engineering Scaffolds, Jakob Hockman

Biomedical Engineering Undergraduate Honors Theses

Metallic single-walled carbon nanotubes (m-SWNTs) were separated from pristine SWNTs using affinity chromatography for use in electrically conductive tissue engineering scaffolds. Approximately one third of SWNTs have metallic properties. Separations were achieved using a protocol modified from Liu & coworkers (2011) in order to improve the method for cell culture environments. Samples enriched in m-SWNTs were isolated and characterized. However, challenges still remain for the complete separation of m-SWNTs from their semiconducting counterpart (s-SWNTs) using this protocol. Approaches to improve separation and reduce the difficulties associated with processing the nanotubes were suggested. One of the ultimate destinations of these nanotubes …