Engineering Commons^™

Polymer (Su-8) Optofluidic Device With Embedded Hydrogel Oxygen Sensing Elements, Zhan Gao, David B. Henthorn, Chang-Soo Kim

Chemical and Biochemical Engineering Faculty Research & Creative Works

The SU-8 photopolymer is an excellent alternative for traditional materials used in fluidic devices such as glass- or silicon-Based inorganic materials. We describe a new chemically anchored, lithographically patterned hydrogel sensing element embedded in a completed SU-8 fluidic channel structure after the channel bonding process. Polyethylene glycol (PEG) hydrogel films incorporating oxygen-responsive ruthenium-complex fluorophores are grafted and patterned by photopolymerization of solution-phase precursors on the modified SU-8 channel surface. the optofluidic sensing platform with this embedded sensing elements exhibited excellent performance in measuring dissolved oxygen content. a unique advantage of this method is the selective growth of various functional films …

Fibronectin For Use In Hemostatsis And Wound Stabilization In Trauma, Mohammed Halhouli

Department of Chemical and Biomolecular Engineering: Dissertations, Theses, and Student Research

Exploring the phase during wound healing when fibrinogen (FBG) and fibronectin (FN) interact forming a small thin layer for cells to migrate and proliferate at the injury site is necessary for the primary building blocks and initial stages of skin recovery. The aim of this thesis is to illustrate that administrating a reasonable amount of (FN) and FBG, in a semi-organizational technique, to the wound site will encourage cell population and ECM formation, as well as, improve the wound healing process. WE hypothesized that FBG and FN interactions will configure the construction of dermal cells and their final fate to …

Enhancing Oxygen Reduction Reaction Activity Via Pd-Au Alloy Sublayer Mediation Of Pt Monolayer Electrocatalysts, Yangchuan Xing, Yun Cai, Miomir B. Vukmirovic, Wei Ping Zhou, Hiroko Karan, Jia X. Wang, Radoslav R. Adzic

Chemical and Biochemical Engineering Faculty Research & Creative Works

New Pt monolayer electrocatalysts were prepared using galvanic displacement of a copper monolayer deposited at underpotentials on a Pd core. by performing underpotential deposition twice, two monolayers were deposited, forming a core-shell structure with double shells. the double shells consist of an outermost shell of Pt monolayer and a sublayer shell of Pd-Au alloy. It was found that by adjusting the compositions of the alloy sublayer, it is possible to mediate the oxygen reduction reaction (ORR) activity of the Pt catalysts. an alloy with 10% (atomic) Au was found to be the most active among the catalysts tested. Furthermore, the …

Labyrinthine Instability In Thin Liquid Films, P. Neogi

Chemical and Biochemical Engineering Faculty Research & Creative Works

When a thin liquid film on a solid surface has a thickness corresponding to a particular part the spinodal region of the disjoining pressure versus thickness isotherm, the film breaks down. One of the patterns that emerges on the breakdown has been referred to as wavy instability. It is compared here to the labyrinthine instability seen in magnetic films. the system is modeled following the procedure used in magnetic systems, and the pattern of wavy instability is broken down into a curved thick-thin film in equilibrium with a flat thin-thin film of constant thickness. Minimization of free energy leads to …

Optofluidic Biosensors Based On Color Imaging, Jongwon Park, Chang-Soo Kim

Electrical and Computer Engineering Faculty Research & Creative Works

A color CCD (charge-coupled device) camera is used as a chemical detector to quantify fluorescence emission intensities from two kinds of optofluidic device platforms. the fluorophores responsive to oxygen are immobilized in photo-patternable hydrogel matrices. the first device is a hydrogel sensor array formed within a commercial silicone elastomer imaging chamber. the second one involves a double-chamber fluidic device composed of a permeable membrane layer and dry film photoresist layers. the results suggest that digital color imagers, in combination with a simple color separation method, can serve as the high-quality chemical detectors for fluidic biosensors and biological culture platforms. © …

Color Intensity Method For Hydrogel Oxygen Sensor Array, Jongwon Park, Wonhak Hong, Chang-Soo Kim

Electrical and Computer Engineering Faculty Research & Creative Works

The oxygen imaging technique to obtain a 2-D distribution is a convenient method because it does not require individual addressing of each sensing element in a sensor array. Until recently, color charge coupled devices (CCDs) have rarely been used for oxygen imaging in spite of usefulness for analyzing the spectral content of images. in this work, a color CCD camera was used for luminescence intensity imaging. Two methods of color intensity analysis are investigated and compared. the first method is to analyze the total Red-Green-Blue (RGB) color intensity of the original color image. the second method involves extracting the red …

Surface Hydration: Principles And Applications Toward Low-Fouling/Nonfouling Biomaterials, Lingyan Liu, Jie Zheng

Chemical, Biomolecular, and Corrosion Engineering Faculty Research

Surface resistance to nonspecific protein adsorption, cell/bacterial adhesion, and biofilm formation is critical for the development and performance of biomedical and analytical devices. Significant needs and efforts have been made in the development of biocompatible and bioactive materials for antifouling surfaces, but much of the work retains an empirical flavor due to the complexity of experiments and the lack of robust theoretical models. In this review, two major classes of nonfouling materials (i.e. hydrophilic and zwitterionic materials) and associated basic nonfouling mechanisms and practical examples are discussed. Highly hydrated chemical groups with optimized physical properties of the surface, along with …

The Effect Of Ionic Dissolution Products Of Ca-Sr-Na-Zn-Si Bioactive Glass On In Vitro Cytocompatibility, S. Murphy, A. W. Wren, Mark R. Towler, D. Boyd

Chemical and Biochemical Engineering Faculty Research & Creative Works

Many commercial bone grafts cannot regenerate healthy bone in place of diseased bone. Bioactive glasses have received much attention in this regard due to the ability of their ionic dissolution products to promote cell proliferation, cell differentiation and activate gene expression. Through the incorporation of certain ions, bioactive glasses can become therapeutic for specific pathological situations. Calcium-strontium-sodium-zinc-silicate glass bone grafts have been shown to release therapeutic levels of zinc and strontium, however the in vitro compatibility of these materials is yet to be reported. In this study, the in vitro cytocompatibility of three different calcium-strontium-sodium-zinc-silicate glasses was examined as a …

Comparison Of Antibacterial Properties Of Commercial Bone Cements And Fillers With A Zinc-Based Glass Polyalkenoate Cement, A. W. Wren, N. M. Cummins, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Postoperative infection following invasive surgical procedures is a significant cause for concern, particularly in spinal reconstructive surgery. The objective of this study is to compare the antibacterial efficacy of a novel zinc-based glass polyalkenoate cement (Zn-GPC) based on 0.04SrO-0.12CaO-0.36ZnO- 0.48SiO₂ glass, to a number of commercially available bone cements and fillers including Simplex P + Tobramycin (S_Tob), Spineplex (S_pine) and Novabone Putty (N_Put). The agar diffusion test was performed on each material against Escherichia coli, Staphlococcus epidermidis, Pseudomonas aeruginosa and Staphlococcus Aureus. S_Tob was found to produce large inhibition zones in each …

Identification Of An Archaeal Presenilin-Like Intramembrane Protease, Celia Torres-Arancivia, Carolyn M. Ross, Jose Chavez, Zahra Assur, Georgia Dolios, Filippo Mancia, Iban Ubarretxena-Belandia

Publications and Research

Background: The GXGD-type diaspartyl intramembrane protease, presenilin, constitutes the catalytic core of the c-secretase multi-protein complex responsible for activating critical signaling cascades during development and for the production of b-amyloid peptides (Ab) implicated in Alzheimer’s disease. The only other known GXGD-type diaspartyl intramembrane proteases are the eukaryotic signal peptide peptidases (SPPs). The presence of presenilin-like enzymes outside eukaryots has not been demonstrated. Here we report the existence of presenilin-like GXGD-type diaspartyl intramembrane proteases in archaea.

Methodology and Principal Findings: We have employed in vitro activity assays to show that MCMJR1, a polytopic membrane protein from the archaeon Methanoculleus marisnigri JR1, …

A New Methodology For Hydrodynamic Similarity In Bubble Columns, Ashfaq Shaikh, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Bubble Columns Are Widely Used in Chemical, Petrochemical, and Biochemical Industries for Various Processes Such as Alkylation, Oxidation, Chlorination, Wet Oxidation of Effluents, Etc. a New Hypothesis for Hydrodynamic Similarity that Can Be Subsequently Used for Scale-Up of Bubble Column Reactors Was Proposed. This Hypothesis Was Evaluated using Advanced Diagnostic Techniques. the Conditions of Similarity Where overall Gas Holdup and Radial Gas Holdup Profiles Were the Same, and Mismatch Where overall Gas Holdup Was the Same But Gas Holdup Radial Profiles Were Different, Were Identified. the Condition that Two Systems Must Operate in the Same Flow Regime to Be Hydrodynamically …

Local Gas Holdup In A Draft Tube Airlift Bioreactor, Hu Ping Luo, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Airlift Column Bioreactors Are Gas-Liquid Contact Devices Characterized by a Rising Channel and a Down Flow Channel Due to Gas Holdup Differences in These Two Channels. Local Gas Holdup Distribution Strongly Affects the overall Gas-Liquid Flow Dynamics in Airlift Columns. in This Work, Local Gas Holdup Distributions in a Draft Tube Airlift Column Covering Both Bubbly Flow and Churn-Turbulent Flow Regimes Have Been Studied using Computed Tomography (CT) Technique as Well as Conventional Techniques. the Radial and Axial Evolutions of the Gas Holdup Distribution Will Be Discussed, Together with the Effects of Superficial Gas Velocity and Geometry Parameters. the Obtained …

A Spectroscopic Investigation Into The Setting And Mechanical Properties Of Titanium Containing Glass Polyalkenoate Cements, A. W. Wren, A. Kidari, N. M. Cummins, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Titanium (Ti) implants are extensively used in a number of biomedical and dental applications. This work introduces Ti into the glass phase of a zinc-based glass polyalkenoate cement (GPC) and investigates changes in handling and mechanical properties considering two molecular weight polyacrylic acids (PAA), E9 and E11. Considering the handling properties, the working time (T_w) increased from 50 s_E9, 32 s_E11 (BT 101, Ti-free) to 169 s_E9, 74 s_E11 with TW-Z (highest Ti content), respectively. The setting time (T_s) increased from 76 s_E9, 47 s_E11 (BT 101) …

The Effect Of Adding Organic Polymers On The Handling Properties, Strengths And Bioactivity Of A Ca-Sr-Zn-Si Glass Polyalkenoate Cement, A. W. Wren, N. M. Cummins, A. Coughlan, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

This work demonstrates the addition of a number of naturally occurring proteins/polymers to a zinc-based glass polyalkenoate cements (GPCs). Chitin (Chi.), collagen (Col.), cysteine (Cys.) and keratin (Ker.) were added with the intention of improving the bioactivity of this cement. Initial testing involved characterization of the glass with X-ray diffraction (XRD) and differential thermal analysis (DTA) before and after sterilization with γ-irradiation. No significant changes occurred as a result of sterilization. Handling properties of the modified cements were not significantly different from those of the control, BT 101 (Working T_w-36_s, and setting time T_s-70 …

Recombinant Factors For Hemostasis, Jennifer Calcaterra

Department of Chemical and Biomolecular Engineering: Dissertations, Theses, and Student Research

Trauma deaths are a result of hemorrhage in 37% of civilians and 47% military personnel and are the primary cause of death for individuals under 44 years of age. Current techniques used to treat hemorrhage are inadequate for severe bleeding. Preliminary research indicates that fibrin sealants (FS) alone or in combination with a dressing may be more effective; however, it has not been economically feasible for widespread use because of prohibitive costs related to procuring the proteins. To meet future demands for hemostatic therapies, FS will likely include recombinant human fibrinogen (rFI) and recombinant human Factor XIII (rFXIII). The underlying …

Influence Of Morphology And Processing On Xps Characterisation Of Sro-Ca-Zno-Sio2 Glass, F. R. Laffir, A. W. Wren, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

A study was conducted to demonstrate the influence of morphology and processing on X-ray photoelectron spectroscopic (XPS) characterization SrO-Ca-ZnO-SiO₂ glass. The glass formulation being investigated was originally synthesized for developing a novel glass polyalkenoate cement (GPC). High resolution photoelectron spectra of Zn 2p, Ca 2p, Sr 3d, Si 2p, O 1s, and C 1s were recorded for the different forms of glass. It was observed that there was preferential enrichment of Zn²⁺ with an increase in the proportion of NBO for the investigated BT101 glass. The relative atomic concentration of Zn in BT101 glass was high and resulted …

Synthesis Of Pegylated Single Wall Carbon Nanotubes By A Photoinitiated Graft From Polymerization, Pu Zhang, David B. Henthorn

Chemical and Biochemical Engineering Faculty Research & Creative Works

A considerable amount of research has been devoted to carbon nanotubes because of their unique electrical, mechanical, optical, and chemical properties. Here, in this report, we introduce a novel, simple ultraviolet initiated "graft from" polymerization method to synthesize PEGylated carbon nanotubes. This grafting procedure significantly enhanced nanotube aqueous dispersibility and long-term stability in solution. Mass of grafted polymer chains was easily modulated by adjusting polymerization reaction time, and nanomaterials containing up to 80% polymer by weight were synthesized. Nanotube morphology was characterized by SEM, TEM before and after the functionalization. in addition, the covalent bonding of polymer chains to the …

Rapid Diagnosis Of Tuberculosis In A Peripheral Setting, Elsje Pienaar

Department of Chemical and Biomolecular Engineering: Dissertations, Theses, and Student Research

Tuberculosis is an ancient and worldwide epidemic affecting millions of people in mainly the developing world, killing almost 2 million people in 2008. Current diagnostic techniques are outdated and have proven insufficient to control the disease. Smear microscopy has poor sensitivity and culture is slow to yield results. Modern diagnostic techniques are making great strides in shortening time to result but are restricted by two qualities: 1) prohibitively high costs prevent implementation in resource poor areas, and 2) equipment and technician requirements limit application to centralized laboratories. There exists a divide between new technologies and the people that need them …

Synthesis Of An Endothelial Cell Mimicking Surface Containing Thrombomodulin And Endothelial Protein C Receptor, Karl E. Kador

Department of Chemical and Biomolecular Engineering: Dissertations, Theses, and Student Research

Synthetic materials for use in blood contacting applications have been studied for many years with limited success. One of the main areas of need for these materials is the design of synthetic vascular grafts for use in the hundreds of thousands of patients who have coronary artery bypass grafting, many without suitable veins for autologous grafts. The design of these grafts is constrained by two common modes of failure, the formation of intimal hyperplasia (IH) and thrombosis. IH formation has been previously linked to a mismatching of the mechanical properties of the graft and has been overcome by creating grafts …

Mechanical Properties Of Hydroxyapatite-Zirconia Compacts Sintered By Two Different Sintering Methods, Declan J. Curran, Thomas J. Fleming, Mark R. Towler, Stuart Hampshire

Chemical and Biochemical Engineering Faculty Research & Creative Works

Microwave sintering is traditionally employed to reduce the sintering temperature required to densify powder compacts. The effect of microwave heating on hydroxyapatite (HA)-zirconia (ZrO₂) green bodies has been investigated in order to understand how microwave energy may affect the physical and mechanical properties of the resultant densified composites. Laboratory synthesised nano-sized HA and a commercial nano-sized ZrO₂ powder have been ball milled to create mixtures containing 0-5 wt% ZrO₂ loadings. Compacts were microwave sintered at either 700, 1000 or 1200°C with a 1 h hold time. Comparative firings were also performed in a resistive element furnace …

Effects Of Preparative Parameters On The Structure And Performance Of Ca-La Metal Oxide Catalysts For Oil Transesterification, Shuli Yan, Manhoe Kim, Siddharth Mohan, Steven O. Salley, K.Y. Simon Ng

National Biofuels Energy Laboratory

The effects of preparative parameters on the surface basicity, composition, and transesterification activities of several Ca-La metal oxide catalysts were investigated. Four different preparation methods: ammonia-ethanol-carbon dioxide precipitation, physical mixing, impregnation, and co-precipitation, were studied. It was found that the ammonia-ethanol-carbon dioxide precipitation method resulted in the highest BET specific surface area, base strength and base site concentration. Moreover, catalyst surface composition and basicity are a function of calcination temperature, precipitants, pH, and molar ratio of Ca to La in precursor solution, and storage conditions. XRD, XPS, basicity and BET tests revealed that catalyst structure and dispersion of Ca species …

Nonequilibrium Thermodynamics Modeling Of Coupled Biochemical Cycles In Living Cells, Yaşar Demirel

Yaşar Demirel Publications

Living cells represent open, nonequilibrium, self organizing, and dissipative systems maintained with the continuous supply of outside and inside material, energy, and information flows. The energy in the form of adenosine triphosphate is utilized in biochemical cycles, transport processes, protein synthesis, reproduction, and performing other biological work. The processes in molecular and cellular biological systems are stochastic in nature with varying spatial and time scales, and bounded with conservation laws, kinetic laws, and thermodynamic constraints, which should be taken into account by any approach for modeling biological systems. In component biology, this review focuses on the modeling of enzyme kinetics …

Evaluation Of Two Novel Aluminum-Free, Zinc-Based Glass Polyalkenoate Cements As Alternatives To Pmma Bone Cement For Use In Vertebroplasty And Balloon Kyphoplasty, Gladius Lewis, Mark R. Towler, Daniel Boyd, Matthew J. German, Anthony W. Wren, Owen M. Clarkin, Andrew Yates

Chemical and Biochemical Engineering Faculty Research & Creative Works

Vertebroplasty (VP) and balloon kyphoplasty (BKP) are now widely used for treating patients in whom the pain due to vertebral compression fractures is severe and has proved to be refractory to conservative treatment. These procedures involve percutaneous delivery of a bolus of an injectable bone cement either directly to the fractured vertebral body, VB (VP) or to a void created in it by an inflatable bone tamp (BKP). Thus, the cement is a vital component of both procedures. In the vast majority of VPs and BKPs, a poly(methyl methacrylate) (PMMA) bone cement is used. This material has many shortcomings, notably …