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A Multicomponent Bioactive Tissue-Engineered Blood Vessel: Fabrication, Mechanical Evaluation And Biological Evaluation With Physiological-Relevant Conditions, Walter Bonani 2012 University of Colorado at Boulder

A Multicomponent Bioactive Tissue-Engineered Blood Vessel: Fabrication, Mechanical Evaluation And Biological Evaluation With Physiological-Relevant Conditions, Walter Bonani

Mechanical Engineering Graduate Theses & Dissertations

The high long-term failure rate of synthetic vascular grafts in the replacement of small vessels is known to be associated with the lack of physiological signals to vascular cells causing adverse hemodynamic, inflammatory or coagulatory events. Current studies focus on developing engineered vascular devices with ability of directing cell activity in vitro and in vivo for tissue regeneration. It is also known that controlled molecule release from scaffolds can dramatically increase the scaffold ability of directing cell activities in vitro and in vivo for tissue regeneration. To address the mechanical and biological problems associated with graft materials, we demonstrated a ...


Mechanical Characterization Of The Small Intestine For In Vivo Robotic Capsule Endoscope Mobility, Benjamin Spencer Terry 2012 University of Colorado at Boulder

Mechanical Characterization Of The Small Intestine For In Vivo Robotic Capsule Endoscope Mobility, Benjamin Spencer Terry

Mechanical Engineering Graduate Theses & Dissertations

The state-of-the-art in enteroscopic surgery and therapeutic care continues to minimize invasiveness, cost, surgery time, and patient trauma. To this end, a new class of medical device, called the robotic capsule endoscope, is being pursued by multiple research groups. These potentially swallowable devices will radically expand the capabilities of natural orifice surgery by performing non-invasive tasks within the gastrointestinal tract that are now only possible with enteroscopic, laparoscopic, or open surgery. It is necessary for a robotic capsule endoscope to possess active, controlled mobility, which involves interactions between gastrointestinal tissue and engineering materials. Design challenges stem from the nonlinear and ...


Multiscale Modeling For Host-Guest Chemistry Of Dendrimers In Solution, Seung Ha Kim, Monica H. Lamm 2012 Iowa State University

Multiscale Modeling For Host-Guest Chemistry Of Dendrimers In Solution, Seung Ha Kim, Monica H. Lamm

Chemical and Biological Engineering Publications

Dendrimers have been widely used as nanostructured carriers for guest species in a variety of applications in medicine, catalysis, and environmental remediation. Theory and simulation methods are an important complement to experimental approaches that are designed to develop a fundamental understanding about how dendrimers interact with guest molecules. This review focuses on computational studies aimed at providing a better understanding of the relevant physicochemical parameters at play in the binding and release mechanisms between polyamidoamine (PAMAM) dendrimers and guest species. We highlight recent contributions that model supramolecular dendrimer-guest complexes over the temporal and spatial scales spanned by simulation methods ranging ...


Differences In Adhesion And Protrusion Properties Correlate With Differences In Migration Speed Under Egf Stimulation, Yue Hou, Sarah Hedberg, Ian C. Schneider 2012 Iowa State University

Differences In Adhesion And Protrusion Properties Correlate With Differences In Migration Speed Under Egf Stimulation, Yue Hou, Sarah Hedberg, Ian C. Schneider

Chemical and Biological Engineering Publications

Background: Cell migration plays an essential role in many biological processes, such as cancer metastasis, wound healing and immune response. Cell migration is mediated through protrusion and focal adhesion (FA) assembly, maturation and disassembly. Epidermal growth factor (EGF) is known to enhance migration rate in many cell types; however it is not known how FA maturation, FA dynamics and protrusion dynamics are regulated during EGF-induced migration. Here we use total internal reflection fluorescence (TIRF) microscopy and image analysis to quantify FA properties and protrusion dynamics under different doses of EGF stimulation.Results: EGF was found to broaden the distribution of ...


Interfacial Properties And Iron Binding To Bacterial Proteins That Promote The Growth Of Magnetite Nanocrystals: X-Ray Reflectivity And Surface Spectroscopy Studies, Wenjie Wang, Wei Bu, Lijun Wang, Pierre E. Palo, Surya K. Mallapragada, Marit Nilsen-Hamilton, David Vaknin 2012 Iowa State University

Interfacial Properties And Iron Binding To Bacterial Proteins That Promote The Growth Of Magnetite Nanocrystals: X-Ray Reflectivity And Surface Spectroscopy Studies, Wenjie Wang, Wei Bu, Lijun Wang, Pierre E. Palo, Surya K. Mallapragada, Marit Nilsen-Hamilton, David Vaknin

Chemical and Biological Engineering Publications

Surface sensitive X-ray scattering and spectroscopic studies have been conducted to determine structural properties of Mms6, the protein in Magnetospirillum magneticum AMB-1 that is implicated as promoter of magnetite nanocrystals growth. Surface pressure versus molecular area isotherms indicate Mms6 forms stable monolayers at the aqueous/vapor interface that are strongly affected by ionic conditions of the subphase. Analysis of X-ray reflectivity from the monolayers shows that the protein conformation at the interface depends on surface pressure and on the presence of ions in the solutions, in particular of iron ions and its complexes. X-ray fluorescence at grazing angles of incidence ...


Self-Assembly And Biphasic Iron-Binding Characteristics Of Mms6, A Bacterial Protein That Promotes The Formation Of Superparamagnetic Magnetite Nanoparticles Of Uniform Size And Shape, Lijun Wang, Tanya Prozorov, Pierre E. Palo, Xunpei Liu, David Vaknin, Ruslan Prozorov, Surya K. Mallapragada, Marit Nilsen-Hamilton 2012 Iowa State University

Self-Assembly And Biphasic Iron-Binding Characteristics Of Mms6, A Bacterial Protein That Promotes The Formation Of Superparamagnetic Magnetite Nanoparticles Of Uniform Size And Shape, Lijun Wang, Tanya Prozorov, Pierre E. Palo, Xunpei Liu, David Vaknin, Ruslan Prozorov, Surya K. Mallapragada, Marit Nilsen-Hamilton

Chemical and Biological Engineering Publications

Highly ordered mineralized structures created by living organisms are often hierarchical in structure with fundamental structural elements at nanometer scales. Proteins have been found responsible for forming many of these structures, but the mechanisms by which these biomineralization proteins function are generally poorly understood. To better understand its role in biomineralization, the magnetotactic bacterial protein, Mms6, which promotes the formation in vitro of superparamagnetic magnetite nanoparticles of uniform size and shape, was studied for its structure and function. Mms6 is shown to have two phases of iron binding: one high affinity and stoichiometric and the other low affinity, high capacity ...


Block Copolymer-Quantum Dot Micelles For Multienzyme Colocalization, Feng Jia, Yanjie Zhang, Balaji Narasimhan, Surya K. Mallapragada 2012 Iowa State University

Block Copolymer-Quantum Dot Micelles For Multienzyme Colocalization, Feng Jia, Yanjie Zhang, Balaji Narasimhan, Surya K. Mallapragada

Chemical and Biological Engineering Publications

To mimic the structure and functionality of multienzyme complexes, which are widely present in Nature, Pluronic-based micelles were designed to colocalize multiple enzymes. To stabilize the micelles as well as to enable characterization of single enzyme immobilization and multienzyme colocalization by Förster resonance energy transfer (FRET), quantum dots (QDs) were incorporated into the micelles to form Pluronic-QD micelles using a novel microreactor. Model enzymes glucose oxidase (GOX) and horseradish peroxidase (HRP) were respectively labeled with fluorescent dyes. The results indicated that FRET occurred between the QDs and dyes that labeled each type of enzyme in single enzyme immobilization studies ...


Dispersion Of Alkyl-Chain-Functionalized Reduced Graphene Oxide Sheets In Nonpolar Solvents, Jean-Philippe Tessonnier, Mark A. Barteau 2011 University of Delaware

Dispersion Of Alkyl-Chain-Functionalized Reduced Graphene Oxide Sheets In Nonpolar Solvents, Jean-Philippe Tessonnier, Mark A. Barteau

Jean-Philippe Tessonnier

Alkyl chains were grafted onto reduced graphene oxide sheets to allow their dispersion in toluene, a common and representative nonpolar solvent. The grafting occurred on a variety of oxygen-containing functionalities already present on reduced graphene oxide, such as hydroxyl and epoxide groups. The structure and the defect density of the sheets were not significantly altered during the synthesis. When dispersed in water-toluene mixtures, phase transfer from the aqueous to the organic phase was observed upon grafting. In addition, the dry powder obtained readily disperses in common organic solvents without the assistance of any sonication treatment.


Cloning And Characterization Of A Panel Of Constitutive Promoters For Applications In Pathway Engineering In Saccharomyces Cerevisiae, Jie Sun, Zengyi Shao, Hua Zhao, Nikhil Nair, Fei Wen, Jian-He Xu, Huimin Zhao 2011 University of Illinois at Urbana-Champaign

Cloning And Characterization Of A Panel Of Constitutive Promoters For Applications In Pathway Engineering In Saccharomyces Cerevisiae, Jie Sun, Zengyi Shao, Hua Zhao, Nikhil Nair, Fei Wen, Jian-He Xu, Huimin Zhao

Zengyi Shao

Saccharomyces cerevisiae is an important platform organism for synthesis of chemicals and fuels. However, the promoters used in most pathway engineering studies in S. cerevisiae have not been characterized and compared in parallel under multiple conditions that are routinely operated in laboratory and the number of known promoters is rather limited for the construction of large biochemical pathways. Here a total of 14 constitutive promoters from S. cerevisiaewere cloned and characterized using a green fluorescent protein (GFP) as a reporter in a 2 µ vector pRS426, under varying glucose and oxygen concentrations. The strengths of these promoters varied no ...


Materials For Diabetes Therapeutics, Kaitlin M. Bratlie, Roger L. York, Michael A. Invernale, Robert Langer, Daniel G. Anderson 2011 Massachusetts Institute of Technology

Materials For Diabetes Therapeutics, Kaitlin M. Bratlie, Roger L. York, Michael A. Invernale, Robert Langer, Daniel G. Anderson

Kaitlin M. Bratlie

This review is focused on the materials and methods used to fabricate closedloop systems for type 1 diabetes therapy. Herein, we give a brief overview of current methods used for patient care and discuss two types of possible treatments and the materials used for these therapies-(i) artificial pancreases, comprised of insulin producing cells embedded in a polymeric biomaterial, and (ii) totally synthetic pancreases formulated by integrating continuous glucose monitors with controlled insulin release through degradable polymers and glucose-responsive polymer systems. Both the artificial and the completely synthetic pancreas have two major design requirements: the device must be both biocompatible ...


Aptamer Functionalized Microcantilever Sensors For Cocaine Detection, Kyungho Kang, Ashish Sachan, Marit Nilsen-Hamilton, Pranav Shrotriya 2011 Iowa State University

Aptamer Functionalized Microcantilever Sensors For Cocaine Detection, Kyungho Kang, Ashish Sachan, Marit Nilsen-Hamilton, Pranav Shrotriya

Mechanical Engineering Publications

A cocaine-specific aptamer was used as a receptor molecule in a microcantilever-based surface stress sensor for detection of cocaine molecules. An interferometric technique that relies on measuring differential displacement between two microcantilevers (a sensing/reference pair) was utilized to measure the cocaine/aptamer binding induced surface stress changes. Sensing experiments were performed for different concentrations of cocaine from 25 to 500 μM in order to determine the sensor response as a function of cocaine concentration. In the lower concentration range from 25 to 100 μM, surface stress values increased proportionally to coverage of aptamer/cocaine complexes from 11 to 26 ...


Modeling Chemical Degradation And Proton Transport In Perfluorosulfonic Acid Ionomers, Milan Kumar 2011 University of Tennessee, Knoxville

Modeling Chemical Degradation And Proton Transport In Perfluorosulfonic Acid Ionomers, Milan Kumar

Doctoral Dissertations

The ionomer-membrane interface in a membrane electrode assembly connects the catalyst and membrane and allows hydrated protons to move between the catalyst and membrane. The continuous operation of the polymer membrane electrolyte fuel cell at high temperature and/or in frequent freeze/thaw cycles leads to membrane degradation and delamination of the interface, which lower the proton conductivity. In this dissertation, we modeled the chemical degradation and proton conductivity of perfluorosulfonic acid (PFSA) ionomers by ab initio calculations and macroscopic modeling. All ab initio calculations were performed using Gaussian 03 suites of program by employing B3LYP/6-311++G** method/basis ...


Polymorphic Structures Of Alzheimer's Beta-Amyloid Globulomers, Jie Zheng 2011 The University of Akron

Polymorphic Structures Of Alzheimer's Beta-Amyloid Globulomers, Jie Zheng

Chemical and Biomolecular Engineering Faculty Research

Misfolding and self-assembly of Amyloid-β (Aβ) peptides into amyloid fibrils is pathologically linked to the development of Alzheimer's disease. Polymorphic Aβ structures derived from monomers to intermediate oligomers, protofilaments, and mature fibrils have been often observed in solution. Some aggregates are on-pathway species to amyloid fibrils, while the others are off-pathway species that do not evolve into amyloid fibrils. Both on-pathway and off-pathway species could be biologically relevant species. But, the lack of atomic-level structural information for these Aβ species leads to the difficulty in the understanding of their biological roles in amyloid toxicity and amyloid formation.


Glucose Biosensor Using Electrospun Mn2o3-Ag Nanofibers, Shan Huang 2011 University of Connecticut

Glucose Biosensor Using Electrospun Mn2o3-Ag Nanofibers, Shan Huang

Master's Theses

The highly porous Mn2O3-Ag nanofibers were fabricated by a facile two-step procedure (electrospinning and calcination) and then employed as the immobilization matrix for glucose oxidase (GOD) to construct an amperometric glucose biosensor. A notable enhancement of direct electron transfer between GOD and the electrode is observed at the Mn2O3-Ag-GOD modified electrode with a fast electron transfer rate constant. The biosensor also shows fast response to glucose, high sensitivity (40.60 μA×mM-1×cm-2), low detection limit (1.73 µM at S/N=3), low Km,app value and excellent ...


An Enthalpy Landscape View Of Homogeneous Melting In Crystals, Alex M. Nieves, Talid Sinno 2011 University of Pennsylvania

An Enthalpy Landscape View Of Homogeneous Melting In Crystals, Alex M. Nieves, Talid Sinno

Departmental Papers (CBE)

A detailed analysis of homogeneous melting in crystalline materials modeled by empirical interatomic potentials is presented using the theory of inherent structures.We show that the homogeneous melting of a perfect, infinite crystalline material can be inferred directly from the growth exponent of the inherent structure density-of-states distribution expressed as a function of formation enthalpy. Interestingly, this growth is already established by the presence of very few homogeneously nucleated point defects in the form of Frenkel pairs. This finding supports the notion that homogeneous melting is appropriately defined in terms of a one-phase theory and does not require detailed consideration ...


High Throughput Screening For The Enhancement Of Adeno-Associated Virus Type 2 Transduction, Alexis J. Wallen 2011 University of Pennsylvania

High Throughput Screening For The Enhancement Of Adeno-Associated Virus Type 2 Transduction, Alexis J. Wallen

Publicly Accessible Penn Dissertations

Adeno-associated virus (AAV) is a promising vector for human gene therapy. Although more effective than non-viral vectors, AAV still requires improvement in efficacy in order to become a successful gene therapy vector. With this in mind, we have sought to identify and examine identified enhancers of adeno-associated virus type 2 (AAV2) transduction. Using a high throughput screening system with recombinant AAV2 carrying the luciferase reporter gene (AAV2-Luc), we found siRNA sequences and chemical compounds which increase AAV2 reporter gene expression. We specifically identified a hexamer seed region 5’-UGUUUC-3’ which facilitated AAV2 transduction. Chemical compound enhancers included ellagic acid, 1 ...


Reintroducing Explicit Solvent To A Solvent-Free Coarse-Grained Model, Seung Ha Kim, Monica H. Lamm 2011 Iowa State University

Reintroducing Explicit Solvent To A Solvent-Free Coarse-Grained Model, Seung Ha Kim, Monica H. Lamm

Chemical and Biological Engineering Publications

A unique coarse-grained modeling scheme that combines a systematic, solvent-free multiscale coarse-graining algorithm for a complex macromolecule with an existing coarse-grained solvent model is proposed. We show that this procedure efficiently and reliably describes the interactions for complex macromolecules, using the specific example of dendrimers binding phenanthrenes in water. The experimentally measured binding capacity is predicted by the unique coarse-grained modeling approach; the conditions for this simulation are beyond what could be reasonably simulated with an all-atom molecular dynamics simulation.


Phylogenetic And Experimental Characterization Of An Acyl-Acp Thioesterase Family Reveals Significant Diversity In Enzymatic Specificity And Activity, Fuyuan Jing, David C. Cantu, Jarmila Tvaruzkova, Jay P. Chipman, Basil J. Nikolau, Marna D. Yandeau-Nelson, Peter J. Reilly 2011 Iowa State University

Phylogenetic And Experimental Characterization Of An Acyl-Acp Thioesterase Family Reveals Significant Diversity In Enzymatic Specificity And Activity, Fuyuan Jing, David C. Cantu, Jarmila Tvaruzkova, Jay P. Chipman, Basil J. Nikolau, Marna D. Yandeau-Nelson, Peter J. Reilly

Chemical and Biological Engineering Publications

Background: Acyl-acyl carrier protein thioesterases (acyl-ACP TEs) catalyze the hydrolysis of the thioester bond that links the acyl chain to the sulfhydryl group of the phosphopantetheine prosthetic group of ACP. This reaction terminates acyl chain elongation of fatty acid biosynthesis, and in plant seeds it is the biochemical determinant of the fatty acid compositions of storage lipids.

Results: To explore acyl-ACP TE diversity and to identify novel acyl ACP-TEs, 31 acyl-ACP TEs from wide-ranging phylogenetic sources were characterized to ascertain their in vivo activities and substrate specificities. These acylACP TEs were chosen by two different approaches: 1) 24 TEs were ...


Bioreactor System Designs For Lipase-Catalyzed Synthesis Of Saccharide- Fatty Acid Esters In Solvent-Free Media, Ran Ye 2011 University of Tennessee, Knoxville

Bioreactor System Designs For Lipase-Catalyzed Synthesis Of Saccharide- Fatty Acid Esters In Solvent-Free Media, Ran Ye

Doctoral Dissertations

As nontoxic biobased surfactants derived from plant oils and cellulose or starch, saccharide-fatty acid esters are widely used in cosmetics, food, and pharmaceutical industries due to their biocompatibility, biodegradability as well as antimicrobial activity. Generally, saccharide-fatty acid esters are synthesized chemically under high pressure, temperature and the presence of alkaline or acid catalysts leading to low-quality products (chemo-degradation of double bonds and oxygenated moieties) and large amounts of byproducts. In contrast, biocatalytic synthesis enhances sustainability: near-ambient pressure and temperature, the absence of toxic, acids and bases catalysts, and improved selectivity of products. For lipase-catalyzed synthesis under nearly anhydrous conditions, the ...


Detection Of Specific Biological Antigens Using Ac Electrochemical Impedance Spectroscopy, Darrel Angelo Mazzari 2011 Marquette University

Detection Of Specific Biological Antigens Using Ac Electrochemical Impedance Spectroscopy, Darrel Angelo Mazzari

Dissertations (2009 -)

When certain antigens are present in our environment, a rapid, on-site, accurate, selective, and repeatable detection method can be invaluable in preventing illness or saving lives. Rapid detection of these antigens is important to avert spreading infections.

Currently, capturing a sample and sending it to a laboratory can take weeks to get results, which can be much too long. Conventional sensing methodologies include various electrical measurements as capacitive, potentiometric, piezoelectric, surface plasmon resonance (SPR), and quartz crystal microbalance (QCM). Of particular power and interest is Alternating Current (AC) Electrochemical Impedance Spectroscopy (EIS) which provides for the characterization of the electrical ...


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