Biomedical Engineering and Bioengineering Commons^™

Development Of Porous Polymeric Implants For Use In Orthopedic Research And Development Applications, Alexander Caddell

Honors College

Current orthopedic implants comprised of plastic, ceramic, or metal alloys are susceptible to surface degradation at the implant-implant interface. The resulting microscopic fragments cause tissue irritation that can lead to osteolysis. In addition, existing percutaneous implants, such as pins used to stabilize fractures, are prone to bacterial infections due to the inability of the surrounding soft tissue to adhere to the implant and form a biologic seal. The goal of this Honors Thesis was to develop porous polymeric implants for orthopedic research and development applications that improve upon current designs in an attempt to remedy the issues detailed above. A …

Investigation Of A New Material For Heart Valve Tissue Engineering, Claire Brougham, Nian Shen, Allison Cudsworth, Thomas Flanagan, Stefan Jockenhoevel, Fergal O'Brien

Conference Papers

No abstract provided.

Photolithographic Surface Micromachining Of Polydimethylsiloxane (Pdms), Weiqiang Chen, Raymond H. W. Lam, Jianping Fu

Weiqiang Chen

A major technical hurdle in microfluidics is the difficulty in achieving high fidelity lithographic patterning on polydimethylsiloxane (PDMS). Here, we report a simple yet highly precise and repeatable PDMS surface micromachining method using direct photolithography followed by reactive ion etching (RIE). Our method to achieve surface patterning of PDMS applied an O2 plasma treatment to PDMS to activate its surface to overcome the challenge of poor photoresist adhesion on PDMS for photolithography. Our photolithographic PDMS surface micromachining technique is compatible with conventional soft lithography techniques and other silicon-based surface and bulk micromachining methods. To illustrate the general application of our …

Direct Pore‐Level Observation Of Permeability Increase In Two‐Phase Flow By Shaking, Igor A. Beresnev, William Gaul, R. Dennis Vigil

R. Dennis Vigil

Increases in permeability of natural reservoirs and aquifers by passing seismic waves have been well documented. If the physical causes of this phenomenon can be understood, technological applications would be possible for controlling the flow in hydrologic systems or enhancing production from oil reservoirs. The explanation of the dynamically increased mobility of underground fluids must lie at the pore level. The natural fluids can be viewed as two-phase systems, composed of water as the wetting phase and of dispersed non-wetting globules of gas or organic fluids, flowing through tortuous constricted channels. Capillary forces prevent free motion of the suspended non-wetting …

Improved Manufacturing Methods Of Bovine Femur Samples For Ultrasonic Testing And Assessment Of Materials Through Contract Angle Measurement, Kevin Mathew Lopez Galang

Biomedical Engineering

At California Polytechnic State University of San Luis Obispo (Cal Poly), the Biomedical Engineering department (BMED) requires its students to take the course listed as “BMED 420: Principles of Biomaterial Designs.” BMED 420 has a required laboratory section every week throughout the duration of the course that is meant to be a supplemental tool for learning. During the lab sections, students perform experiments and exercises that are currently being implemented in the industry. Despite accuracy of the methods and experiments relative to their use in the industry, there is always room for improvement. The objective of this project will illustrate …

Thickness Of Residual Wetting Film In Liquid-Liquid Displacement, Igor A. Beresnev, William Gaul, R .Dennis Vigil

R. Dennis Vigil

Core-annular flow is common in nature, representing, for example, how streams of oil, surrounded by water, move in petroleum reservoirs. Oil, typically a nonwetting fluid, tends to occupy the middle (core) part of a channel, while water forms a surrounding wall-wetting film. What is the thickness of the wetting film? A classic theory has been in existence for nearly 50 years offering a solution, although in a controversial manner, for moving gas bubbles. On the other hand, an acceptable, experimentally verified theory for a body of one liquid flowing in another has not been available. Here we develop a hydrodynamic, …

Forced Instability Of Core-Annular Flow In Capillary Constrictions, Igor A. Beresnev, William Gaul, R. Dennis Vigil

R. Dennis Vigil

Instability of fluid cylinders and jets, a highly nonlinear hydrodynamic phenomenon, has fascinated researchers for nearly 150 years. A subset of the phenomenon is the core-annular flow, in which a non-wetting core fluid and a surrounding wall-wetting annulus flow through a solid channel. The model, for example, represents the flow of oil in petroleum reservoirs. The flow may be forced to break up when passing through a channel’s constriction. Although it has long been observed that the breakup occurs near the neck of the constriction, the exact conditions for the occurrence of the forced breakup and its dynamic theory have …

Determining A Method For Rendering Low Cost Cdse(Zns) Core(Shell) Quantum Dots Aqueous Soluble Via Amphiphilic Polymer Wrapping, Patrick Mcbride

Materials Engineering

Herein is described the procedure of two amphiphilic polymer wrapping techniques that may be employed for obtaining aqueous soluble quantum dots (QDs) for use in biological fluorescent imaging applications. The advent of QDs has led to new nanoscale fluorescent materials that exhibit unparalleled quantum yields (QYs), high resistance to photobleaching, tunable emissions, and
absorption over a large optical range. However, the QD synthesis employed here at Cal Poly to obtain bright, photostable CdSe(ZnS) core(shell) QDs involves the use of organic solvents and surfactants, leading to hydrophobic QDs. Since all of biology relies on aqueous solubility, this hydrophobicity creates a major …

Characterization And Implementation Of Low Intensity Pulsed Ultrasound As A Tool To Apply Physical Load To Scaffolds And Bone Cells For Fracture Repair, Scott Frazee

Master's Theses

One current challenge in treating bone fractures is the effective treatment of non-unions and delayed unions. Low Intensity Pulsed Ultrasound (LIPUS) has been approved by the FDA to treat fresh fractures since 1994 and non-unions since 2000 and is an attractive treatment option because it is non-invasive. The mechanism by which it works, however, is not well understood; what is known is largely confined to the resultant changes in chemical output of cells. In this thesis several concepts and techniques were brought together to investigate the following hypothesis: LIPUS produces a measurable physical load that results in measurable deformation and …

Assessment Of Electrospinning As An In-House Fabrication Technique For Blood Vessel Mimic Cellular Scaffolding, Colby M. James

Master's Theses

Intravascular devices, such as stents, must be rigorously tested before they can be approved by the FDA. This includes bench top in vitro testing to determine biocompatibility, and animal model testing to ensure safety and efficacy. As an intermediate step, a blood vessel mimic (BVM) testing method has been developed that mimics the three dimensional structure of blood vessels using a perfusion bioreactor system, human derived endothelial cells, and a biocompatible polymer scaffold used to support growth of the blood vessel cells. The focus of this thesis was to find an in-house fabrication method capable of making cellular scaffolding for …

The Effect Of Particle Surface Area To Volume Ratio On Ion Release From Cocr Spheres, Darin J. Grandfield

Master's Theses

In 2005, over 200,000 Americans underwent a hip arthroplasty, the replacement of a hip joint with an artificial prosthesis. Of these arthroplasties, metal-on-metal type implants represent an increasing usage percentage. Metal-on-metal implants are selected largely for their low volumetric wear rate, durability, and resistance to corrosion. In spite of these advantages, little is known concerning the long-term consequences of heavy metal alloy use in the body, although early research indicates potentially carcinogenic results. This thesis is a preliminary investigation into these long term effects and their root causes.

An improved comprehension of the corrosion kinetics and the rate of ion …

Evaluating The Electrical Response Of Polyaniline To Mechanical Strain, Matthew L. Goebel

Master's Theses

This thesis focuses on the electrical output of polyaniline films subjected to uniaxial strain in hydrochloric acid solutions. Polyaniline belongs to novel class of materials known as conducting polymers. Alternating single and double bonds in the backbone of conducting polymers allow them to transmit electric charge when they are doped with negatively charged ions. Modifying the degree of doping and other electrical/chemical treatments allow conducting polymers to exhibit conducting, semi-conducting, or insulating electrical properties. Resilient mechanical properties, good processability, and low cost make conducting polymers good candidates for applications traditionally held by metals and semi-conductors.

When tensile strain is applied …

Desulfovibrio Desulfuricans G20 Tetraheme Cytochrome Structure At 1.5 A˚ And Cytochrome Interaction With Metal Complexes, Mrunalini Pattarkine, J J. Tanner, C A. Bottoms, Y H. Lee, Judy D. Wall

Faculty Works

The structure of the type I tetraheme cytochrome c3 from Desulfovibrio desulfuricans G20 was determined to 1.5 A˚ by X-ray crystallography. In addition to the oxidized form, the structure of the molybdate-bound form of the protein was determined from oxidized crystals soaked in sodium molybdate. Only small structural shifts were obtained with metal binding, consistent with the remarkable structural stability of this protein. In vitro experiments with pure cytochrome showed that molybdate could oxidize the reduced cytochrome, although not as rapidly as U(VI) present as uranyl acetate. Alterations in the overall conformation and thermostability of the metal-oxidized protein were investigated …

Prospective Energy Densities In The Forisome, A New Smart Material, William Pickard, Michael Knoblauch, Winfried Peters, Amy Shen

Winfried S. Peters

Atp-Independent Contractile Proteins From Plants, Michael Knoblauch, Gundula Noll, Torsten Müller, Dirk Prüfer, Ingrid Schneider-Hüther, Dörte Scharner, Aart Van Bel, Winfried Peters

Winfried S. Peters

Studies On The Formation Of Dna-Cationic Lipid Composite Films And Dna Hybridization In The Composites, Murali Sastry, Vidya Ramakrishnan, Mrunalini Pattarkine, Krishna N. Ganesh

Faculty Works

The formation of composite films of double-stranded DNA and cationic lipid molecules (octadecylamine, ODA) and the hybridization of complementary single-stranded DNA molecules in such composite films are demonstrated. The immobilization of DNA is accomplished by simple immersion of a thermally evaporated ODA film in the DNA solution at close to physiological pH. The entrapment of the DNA molecules in the cationic lipid film is dominated by attractive electrostatic interaction between the negatively charged phosphate backbone of the DNA molecules and the protonated amine molecules in the thermally evaporated film and has been quantified using quartz crystal microgravimetry (QCM). Fluorescence studies …

Cationic Surfactant Mediated Hybridization And Hydrophobization Of Dna Molecules At The Liquid/Liquid Interface And Their Phase Transfer, Murali Sastry, Ashavani Kumar, Mrunalini Pattarkine, Vidya Ramakrishnan, Krishna N. Ganesh

Faculty Works

Hybridization of complementary oligonucleotides mediated by a cationic surfactant at the water/hexane interface leads to hydrophobic, double-helical DNA which may be readily phase transferred to the organic phase and cast into thin films on solid substrates.

Hybridization Of Dna By Sequential Immobilization Of Oligonucleotides At The Air-Water Interface, Murali Sastry, Vidya Ramakrishnan, Mrunalini Pattarkine, Anand Gole, K. N. Ganesh

Faculty Works

The hybridization of DNA by sequential electrostatic and hydrogen-bonding immobilization of single-stranded complementary oligonucleotides at the air-water interface with cationic Langmuir monolayers is demonstrated. The complexation of the single-stranded DNA molecules with octadecylamine (ODA) Langmuir monolayers was followed in time by monitoring the pressure-area isotherms. A large (and slow) expansion of the ODA monolayer was observed during each stage of complexation in the following sequence: primary single-stranded DNA followed by complementary single-stranded DNA followed by the intercalator, ethidium bromide. Langmuir-Blodgett (LB) films of the ODA-DNA complex were formed on different substrates and characterized using quartz-crystal microgravimetry (QCM), Fourier transform infrared …

Anion Induced Blue To Purple Transition In Bacteriorhodopsin, Mrunalini Pattarkine, Anil K. Singh

Faculty Works

Purple membrane (PM, λ" role="presentation">λmax" role="presentation">max 570 nm) of H. halobium on treatment with sulphuric acid changes its colour to blue (λ" role="presentation">λmax" role="presentation">max 608 nm). The purple chromophore can be regenerated from the blue chromophore by exogeneous addition of anions such as CI−" role="presentation">− and HPO42−" role="presentation">2−4. Chloride ion is found to be more effective than the dibasic phosphate ion in regenerating the purple chromophore. Nevertheless, one thing common to the anion regeneration is that both CI−" role="presentation">− and HPO42−" role="presentation">2−4 show marked pH effect. At pH 1.0 the efficiency of …