Chemical Engineering Commons^™

Magnetic Nanocomposites For The Remote Activation Of Sulfate Radicals For The Removal Of Rhodamine B, Pranto Paul, Marissa Nicholson, J. Zach Hilt

Chemical and Materials Engineering Faculty Publications

The widespread presence of numerous organic contaminants in water poses a threat to the ecological environment and human health. Magnetic nanocomposites exposed to an alternating magnetic field (AMF) have a unique ability for magnetically mediated energy delivery (MagMED) resulting from the embedded magnetic nanoparticles; this localized energy delivery and associated chemical and thermal effects are a potential method for removing contaminants from water. This work developed a novel magnetic nanocomposite—a polyacrylamide-based hydrogel loaded with iron oxide nanoparticles. For this magnetic nanocomposite, persulfate activation and the contamination removal in water were investigated. Magnetic nanocomposites were exposed to AMF with a model …

Adsorptive Properties And On-Demand Magnetic Response Of Lignin@Fe3o4 Nanoparticles At Castor Oil–Water Interfaces, Mohammad J. Hasan, Emily Westphal, Peng Chen, Abishek Saini, I-Wei Chu, Sarah J. Watzman, Esteban E. Ureña-Benavides, Erick S. Vasquez

Chemical and Materials Engineering Faculty Publications

Lignin@Fe3O4 nanoparticles adsorb at oil–water interfaces, form Pickering emulsions, induce on-demand magnetic responses to break emulsions, and can sequester oil from water. Lignin@Fe3O4 nanoparticles were prepared using a pH-induced precipitation method and were fully characterized. These were used to prepare Pickering emulsions with castor oil/Sudan red G dye and water at various oil/water volume ratios and nanoparticle concentrations. The stability and demulsification of the emulsions under different magnetic fields generated with permanent magnets (0–540 mT) were investigated using microscopy images and by visual inspection over time. The results showed that the Pickering emulsions were more stable at the castor oil/water …

Liquid-Liquid Equilibria Of Water + Ethanol + Castor Oil And The Effect Of Cellulose Nanocrystal/Fe3o4 And Lignin/Fe3o4 Nanoparticles, Mohammad J. Hasan, Fariba Yehaneh, Amy Ciric, Peng Chen, Erick S. Vasquez, Esteban E. Ureña-Benavides

Chemical and Materials Engineering Faculty Publications

Castor oil has been proposed as a renewable solvent for the liquid extraction of ethanol from water as an alternative to more traditional energy intensive distillation-based methods. The liquid–liquid equilibrium (LLE) of the ternary system water + ethanol + castor oil was determined at 295.15 K using high performance liquid chromatography (HPLC). Castor oil was herein treated as a pseudo-component with the molecular weight of the triglyceride of ricinoleic acid. The experimental data was fitted to the UNIQUAC and NRTL models to obtain parameters for castor oil, and binary interaction parameters for castor oil/ethanol and castor oil/water pairs. The separation …

Preparation, Cure, And Characterization Of Cyanate Ester-Epoxy Blends Containing Reactive Flame Retardants, Mustafa Mukhtar, Donald A. Klosterman

Chemical and Materials Engineering Faculty Publications

Cyanate ester resins are sometimes mixed with lower cost epoxy monomers to modify cost, toughness, and processing capabilities. Despite the high performance of these thermosetting polymers, flame retardancy remains an issue. This study examined blends of three different commercial cyanate ester monomers (LVT-100, LECy, and XU-71787.02) and diglycidyl ether of bisphenol A (DGEBA) at 50/50 wt% of each type. The blends were successfully reacted with two reactive flame retardants (FR): 9,10-dihydro-9-ox-9-phosphaphenanthrene-10-oxide (DOPO) and poly(m-phenylene methylphosphonate) (PMP) at phosphorus contents ranging from 0 to 3 wt%. The curing behavior of EP/CE blends was investigated using differential scanning calorimetry (DSC). It was …

Synthesis Of A Phosphorus-Based Epoxy Reactive Flame Retardant Analog To Diglycidyl Ether Of Bisphenol A (Dgeba) And Its Behavior As A Matrix In A Carbon Fiber Composite, Mustafa Mukhtar

Chemical and Materials Engineering Faculty Publications

This paper describes the synthesis of a phosphorus-based flame retardant that is a chemical analog of diglycidyl ether of bisphenol A (DGEBA), as well as its incorporation as a matrix into carbon fiber laminates. Carbon fiber composites, if used for structural applications in mass transport vehicles (aircraft, trains), will require some aspects of improved fire performance to be used safely in those applications. The first phase of work involved the development of two separate synthesis routes to produce the flame retardant monomer, referred to as Phosphorus-DGEBA or simply P-DGEBA. The second step was to determine the viability of the compound's …

Identification Of Lithocholic Acid As A Molecular Glass Host For Room-Temperature Phosphorescent Materials, John J. Flynn, Zachary M. Marsh, Douglas M. Krein, Steven M. Wolf, Joy E. Haley, Erick S. Vasquez, Thomas M. Cooper, Nicholas P. Godman, Tod A. Grusenmeyer

Chemical and Materials Engineering Faculty Publications

Lithocholic acid was identified as a molecular glass host material for room temperature phosphorescent (RTP) chromophores. Differential scanning calorimetry (DSC) was performed on a series of structurally similar, biologically sourced molecules, including lithocholic acid, β-estradiol, cholesterol, and β-sitosterol, in an effort to identify new amorphous molecular glasses independent of plasticizing additives. DSC analysis revealed lithocholic acid and β-estradiol form stable molecular glasses post thermal processing unlike neat cholesterol and β-sitosterol. The ability of lithocholic acid and β-estradiol to stabilize high wt. % loadings of d10-pyrene and a mixture of d10-pyrene and an iridium chromophore, bis(2,4-difluorophenylpyridinato)-tetrakis(1-pyrazolyl)borate iridium(III) (FIr6), was also investigated. …

Non-Solvent Induced Phase Separation (Nips) For Fabricating High Filtration Efficiency (Fe) Polymeric Membranes For Face Mask And Air Filtration Applications, Ebuka A. Ogbuoji, Lauren Stephens, Amber Haycraft, Eric Woodridge, C. Escobar

Chemical and Materials Engineering Faculty Publications

Protection against airborne viruses has become very relevant since the outbreak of SARSCoV-2. Nonwoven face masks along with heating, ventilation, and air conditioning (HVAC) filters have been used extensively to reduce infection rates; however, some of these filter materials provide inadequate protection due to insufficient initial filtration efficiency (FE) and FE decrease with time. Flat sheet porous membranes, which have been used extensively to filter waterborne microbes and particulate matter due to their high FE have the potential to filter air pollutants without compromising its FE over time. Therefore, in this study, single layer polysulfone (PSf) membranes were fabricated via …

Aerosol Capture And Coronavirus Spike Protein Deactivation By Enzyme Functionalized Antiviral Membranes, Rollie Mills, Ronald J. Vogler, Matthew Bernard, Jacob Concolino, Louis B. Hersh, Yinan Wei, Jeffrey Todd Hastings, Thomas D. Dziubla, Kevin C. Baldridge, Dibakar Bhattacharyya

Chemical and Materials Engineering Faculty Publications

The airborne nature of coronavirus transmission makes it critical to develop new barrier technologies that can simultaneously reduce aerosol and viral spread. Here, we report nanostructured membranes with tunable thickness and porosity for filtering coronavirus-sized aerosols, combined with antiviral enzyme functionalization that can denature spike glycoproteins of the SARS-CoV-2 virus in low-hydration environments. Thin, asymmetric membranes with subtilisin enzyme and methacrylic functionalization show more than 98.90% filtration efficiency for 100-nm unfunctionalized and protein-functionalized polystyrene latex aerosol particles. Unfunctionalized membranes provided a protection factor of 540 ± 380 for coronavirus-sized particle, above the Occupational Safety and Health Administration’s standard of 10 …

Preparation, Cure, And Characterization Of Cyanate Ester-Epoxy Blends, Donald A. Klosterman

Chemical and Materials Engineering Faculty Publications

Cyanate ester resins are often blended with lower cost epoxy monomers in order to modify the cost, toughness, and processing characteristics. There are also several choices of catalysts that can be used to improve processing, namely by reducing the cure temperature. This study was undertaken to illustrate how a designed experiment approach can be used to systematically investigate a wide range of material combinations and illuminate the basic cure behavior of some simple cyanate ester – epoxy blend combinations. Two commercial cyanate ester resin products were obtained. Each was blended with a bisphenol F based epoxy resin at two different …

Rapid Removal Of Pfoa And Pfos Via Modified Industrial Solid Waste: Mechanisms And Influences Of Water Matrices, Hongyi Wan, Rollie Mills, Kai Qu, James C. Hower, M. Abdul Mottaleb, Dibakar Bhattacharyya, Zhi Xu

Chemical and Materials Engineering Faculty Publications

Emerging perfluoroalkyl and polyfluoroalkyl substances contaminate waters at trace concentrations, thus rapid and selective adsorbents are pivotal to mitigate the consequent energy-intensive and time-consuming issues in remediation. In this study, coal combustion residuals-fly ash was modified (FA-SCA) to overcome the universal trade-off between high adsorption capacity and fast kinetics. FA-SCA presented rapid adsorption (teq = 2 min) of PFOX (perfluorooctanoic acid and perfluorooctanesulfonic acid, collectively), where the dynamic adsorption capacity (qdyn = qm/teq) was 2–3 orders of magnitude higher than that of benchmark activated carbons and anion-exchange resins. Investigated by advanced characterization and kinetic models, the fast kinetics and superior …

Strategy For Conjugating Oligopeptides To Mesoporous Silica Nanoparticles Using Diazirine-Based Heterobifunctional Linkers, Md Arif Khan, Ramy W. Ghanim, Maelyn R. Kiser, Mahsa Moradipour, Dennis T. Rogers, John M. Littleton, Luke H. Bradley, Bert C. Lynn, Stephen E. Rankin, Barbara L. Knutson

Chemical and Materials Engineering Faculty Publications

Successful strategies for the attachment of oligopeptides to mesoporous silica with pores large enough to load biomolecules should utilize the high surface area of pores to provide an accessible, protective environment. A two-step oligopeptide functionalization strategy is examined here using diazirine-based heterobifunctional linkers. Mesoporous silica nanoparticles (MSNPs) with average pore diameter of ~8 nm and surface area of ~730 m²/g were synthesized and amine-functionalized. Tetrapeptides Gly-Gly-Gly-Gly (GGGG) and Arg-Ser-Ser-Val (RSSV), and a peptide comprised of four copies of RSSV (4RSSV), were covalently attached via their N-terminus to the amine groups on the particle surface by a heterobifunctional linker, …

Entrepreneurially Minded Learning In The Unit Operations Laboratory Through Community Engagement In A Blended Teaching Environment, Erick S. Vasquez, Kelly Bohrer, Abraham Noe-Hays, Arthur Davis, Matthew Dewitt, Michael J. Elsass

Chemical and Materials Engineering Faculty Publications

Online and blended learning opportunities in Chemical Engineering curriculum emerged due to COVID-19. After eight weeks of in-person Unit Operations Laboratory sessions, a remote-learning open-ended final project was assigned to student teams. The assignment involved aspects related to entrepreneurial-minded learning (EML) and community-based learning (CBL). Results show correlations between self-directed learning and the EML framework. Continuous support and involvement of a community partner correlate to students' m

Analytical Model For Electromagnetic Induction In Pulsating Ferrofluid Pipe Flows, Huiyu Wang, John G. Monroe, Swati Kumari, Serhiy O. Leontsev, Erick S. Vasquez, Scott M. Thompson, Matthew J. Berg, Dibbon Keith Walters, Keisha B. Walters

Chemical and Materials Engineering Faculty Publications

No abstract provided.

Facile Fabrication And Characterization Of Kraft Lignin@Fe3o4 Nanocomposites Using Ph Driven Precipitation: Effects On Increasing Lignin Content, Frankie A. Petrie, Justin M. Gorham, Robert T. Busch, Serhiy O. Leontsev, Esteban E. Ureña-Benavides, Erick S. Vasquez

Chemical and Materials Engineering Faculty Publications

This work offers a facile fabrication method for lignin nanocomposites through the assembly of kraft lignin onto magnetic nanoparticles (Fe3O4) based on pH-driven precipitation, without needing organic solvents or lignin functionalization. Kraft lignin@Fe3O4 multicore nanocomposites fabrication proceeded using a simple, pH-driven precipitation technique. An alkaline solution for kraft lignin (pH 12) was rapidly injected into an aqueous-based Fe3O4 nanoparticle colloidal suspension (pH 7) under constant mixing conditions, allowing the fabrication of lignin magnetic nanocomposites. The effects of increasing lignin to initial Fe3O4 mass content (g/g), increasing in ratio from 1:1 to 20:1, are discussed with a complete chemical, structural, and …

Advanced Research And Development Of Face Masks And Respirators Pre And Post The Coronavirus Disease 2019 (Covid-19) Pandemic: A Critical Review, Ebuka A. Ogbuoji, Amr M. Zaky, Isabel C. Escobar

Chemical and Materials Engineering Faculty Publications

The outbreak of the COVID-19 pandemic, in 2020, has accelerated the need for personal protective equipment (PPE) masks as one of the methods to reduce and/or eliminate transmission of the coronavirus across communities. Despite the availability of different coronavirus vaccines, it is still recommended by the Center of Disease Control and Prevention (CDC), World Health Organization (WHO), and local authorities to apply public safety measures including maintaining social distancing and wearing face masks. This includes individuals who have been fully vaccinated. Remarkable increase in scientific studies, along with manufacturing-related research and development investigations, have been performed in an attempt to …

Comparison Of Tensile Properties Of Triaxial Braided Carbon Fiber Composites Made From Vacuum Assisted Resin Transfer Molding (Vartm) And Autoclave Molding, Donald A. Klosterman, Charles Browning

Chemical and Materials Engineering Faculty Publications

Triaxially braided fiber composites are increasingly being used in aerospace, ballistic, and sporting good applications due to their inherent damage tolerance, torsional stability, and cost compared to woven fabrics and unidirectional preforms. There have been numerous publications over the past 15-20 years on the mechanical properties and failure mechanisms of triaxial braided composites. However, most of these have involved panels made with autoclave curing. In the present study, braided carbon fiber composites were made using autoclave curing and vacuum assisted resin transfer molding (VARTM). The goal of the study was to compare the physical and tensile properties of quasi-isotropic panels …

Detection And Aggregation Of Listeria Monocytogenes Using Polyclonal Antibody Gold-Coated Magnetic Nanoshells Surface-Enhanced Raman Spectroscopy Substrates, Robert T. Busch, Farzia Karim, Yvonne Sun, H. Christopher Fry, Yuzi Liu, Chenglong Zhao, Erick S. Vasquez

Chemical and Materials Engineering Faculty Publications

Magnetic nanoshells with tailored surface chemistry can enhance bacterial detection and separation technologies. This work demonstrated a simple technique to detect, capture, and aggregate bacteria with the aid of end-functionalized polyclonal antibody gold-coated magnetic nanoshells (pAb-Lis-AuMNs) as surface-enhanced Raman spectroscopy (SERS) probes. Listeria monocytogenes were used as the pathogenic bacteria and the pAb-Lis-AuMNs, 300 nm diameter, were used as probes allowing facile magnetic separation and aggregation. An optimized covalent bioconjugation procedure between the magnetic nanoshells and the polyclonal antibody was performed at pH six via a carbodiimide crosslinking reaction. Spectroscopic and morphological characterization techniques confirmed the fabrication of stable pAb-Lis-AuMNs. …

Polymers And Solvents Used In Membrane Fabrication: A Review Focusing On Sustainable Membrane Development, Xiaobo Dong, David Lu, Tequila A. L. Harris, Isabel C. Escobar

Chemical and Materials Engineering Faculty Publications

(1) Different methods have been applied to fabricate polymeric membranes with non-solvent induced phase separation (NIPS) being one of the mostly widely used. In NIPS, a solvent or solvent blend is required to dissolve a polymer or polymer blend. N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) and other petroleum-derived solvents are commonly used to dissolve some petroleum-based polymers. However, these components may have negative impacts on the environment and human health. Therefore, using greener and less toxic components is of great interest for increasing membrane fabrication sustainability. The chemical structure of membranes is not affected by the use of different solvents, …

Fabrication And Characterization Of Electrospun Poly(Acrylonitrile-Co-Methyl Acrylate)/Lignin Nanofibers: Effects Of Lignin Type And Total Polymer Concentration, Suchitha Devadas, Saja M. Nabat Al-Ajrash, Donald A. Klosterman, Kenya A. Crosson, Garry S. Crosson, Erick S. Vasquez

Chemical and Materials Engineering Faculty Publications

Lignin macromolecules are potential precursor materials for producing electrospun nanofibers for composite applications. However, little is known about the effect of lignin type and blend ratios with synthetic polymers. This study analyzed blends of poly(acrylonitrile-co-methyl acrylate) (PAN-MA) with two types of commercially available lignin, low sulfonate (LSL) and alkali, kraft lignin (AL), in DMF solvent. The electrospinning and polymer blend solution conditions were optimized to produce thermally stable, smooth lignin-based nanofibers with total polymer content of up to 20 wt % in solution and a 50/50 blend weight ratio. Microscopy studies revealed that AL blends possess good solubility, miscibility, and …

Magnetically Induced Demulsification Of Water And Castor Oil Dispersions Stabilized By Fe3o4-Coated Cellulose Nanocrystals, Mohammad J. Hasan, Frankie A. Petrie, Ashley E. Johnson, Joshua Peltan, Meredith Gannon, Robert T. Busch, Serhiy O. Leontsev, Erick S. Vasquez, Esteban E. Ureña-Benavides

Chemical and Materials Engineering Faculty Publications

Superparamagnetic iron oxide (Fe3O4) nanoparticle (NP) coated cellulose nanocrystals (CNCs) were synthesized and used to prepare emulsions with magnetically controlled stability. Magnetite NPs were deposited onto the surface of wood pulp CNCs (WCNCs) and bacterial CNCs (BCNCs) by a one-step coprecipitation method. The effect of the CNC to Fe3O4 mass ratio (1:1, 1:2, and 1:4) was varied to optimize the colloidal, magnetic and emulsifying properties of the hybrid NPs. TEM images showed that the 1:4 ratios lead to greater coverage of Fe3O4 than lower Fe3O4 loadings (1:1, and 1:2). The CNCs and Fe3O4 appeared to interact via hydrogen bonding between …

Transforming Corn Stover To Useful Transport Fuel Blends In Resource-Limited Settings, Nicholas Munu, Noble Banadda, Nicholas Kiggundu, Ahamada Zziwa, Isa Kabenge, Jeffrey Seay, Robert Kambugu, Joshua Wanyama, Albrecht Schmidt

Chemical and Materials Engineering Faculty Publications

Development of local technologies is crucial to the sustainable energy agenda in resource-limited countries and the world. Strengthening local green technologies and promoting local utilization will reduce carbon emissions that could be generated during transportation and delivery of green products from one country to another. In this paper we developed bio-oil/diesel blends using a low-tech pyrolysis system designed for smallholder farmers in developing countries and tested their appropriateness for diesel engines using standard ASTM methods. Corn stover retrieved from smallholder farmers in Gayaza, Uganda were pyrolyzed in a batch rocket stove reactor at 350 °C and liquid bio-oil harvested. Bio-oil …

Copper Oxide Nanoparticle Diameter Mediates Serum-Sensitive Toxicity In Beas-2b Cells, Angie S. Morris, Brittany E. Givens, Aaron Silva, Aliasger K. Salem

Chemical and Materials Engineering Faculty Publications

Copper oxide (CuO) nanoparticles (NPs) are abundant in manufacturing processes, but they are an airway irritant. In vitro pulmonary toxicity of CuO NPs has been modeled using cell lines such as human bronchial epithelial cell line BEAS-2B. In 2D in vitro culture, BEAS-2B undergoes squamous differentiation due to the presence of serum. Differentiation is part of the repair process of lung cells in vivo that helps to preserve the epithelial lining of the respiratory tract. Herein, the effects of serum on the hydrodynamic diameter, cellular viability, cellular differentiation, and cellular uptake of 5 and 35 nm CuO NPs are investigated, …

The Characterization Of Purified Citrate-Coated Cerium Oxide Nanoparticles Prepared Via Hydrothermal Synthesis, Matthew L. Hancock, Robert A. Yokel, Matthew J. Beck, Julie L. Calahan, Travis W. Jarrells, Eric J. Munson, George A. Olaniyan, Eric A. Grulke

Chemical and Materials Engineering Faculty Publications

Hypothesis

Cerium oxide nanoparticles were synthesized using a hydrothermal approach with citric acid as a stabilizing agent. Citric acid adsorption onto the nanoceria particle surface can cease particle formation and create a stable dispersion for an extended shelf life. The product was dialyzed immediately following the synthesis to remove unreacted cerium that could contribute to biological effects. Nanoparticle characterization results are expected to help identify the surface citrate bonding structure.

Experiments

Many characterization techniques were utilized to determine size, morphology, surface properties, and citrate complexation on the nanoceria particle surface. These included transmission electron microscopy, electron energy loss spectroscopy, dynamic …

Investigation Of Various Techniques For Controlled Void Formation In Fiberglass/Epoxy Composites, Donald A. Klosterman, Charles Browning, Issa Hakim, Kyle Lach

Chemical and Materials Engineering Faculty Publications

The effect of porosity in composite materials has been studied for years due to its deleterious effects on mechanical properties, especially matrix dominated properties. Currently there is an increasing use of composites in infrastructure worldwide, for example bridge components, residential and building structures, marine structures such as piers and docks, and large industrial chemical tanks. Most of these applications use fiberglass composites. Unfortunately, most of the published literature has focused on carbon fiber composites, in which fiber diameter and gas-fiber interactions are different than fiberglass composites. Therefore, the present study was undertaken to revisit the effect of porosity but specifically …

Impact Of Team Formation Approach On Teamwork Effectiveness And Performance In An Upper-Level Undergraduate Chemical Engineering Laboratory Course, Erick S. Vasquez, Matthew J. Dewitt, Zachary J. West, Michael J. Elsass

Chemical and Materials Engineering Faculty Publications

This study focuses on the impact of team formation approach on teamwork effectiveness and performance spanning three years of instruction of the chemical engineering unit operations laboratory, which is an upper-level undergraduate laboratory course. Team formation approaches changed each year, and assessment tools, including peer-assessment, academic performance, and course evaluations, were employed to evaluate team performance. Approaches included three cases: instructor-selected teams based on GPA with the objective of a similar cumulative average GPA for each team, student self-selected teams, and a combination of self-selected teams with instructor-selected teams for a final experiment. For the third case, new teams were …

Organophosphorus-Hydrazides As Potential Reactive Flame Retardants For Epoxy, Alexander B. Morgan, Vladimir Benin, Donald A. Klosterman, Abdulhamid Bin Sulayman, Mustafa Mukhtar, Mary L. Galaska

Chemical and Materials Engineering Faculty Publications

For structural composites used in vehicles and aircraft, flame retardant chemistries which enhance char formation and reduce heat release are preferred. Phosphorus-based and phosphorus–nitrogen flame retardants for epoxies have been well studied to date, but phosphorus hydrazides have not been studied for their flame-retardant potential in epoxy. These hydrazides offer some novel structures and they can potentially offer a combination of vapor and condensed phase flame retardant action. A series of eight compounds were systematically investigated in this study as reactive flame retardants in a bisphenol F epoxy/aliphatic amine resin system at a level of 2.5 wt% phosphorus. Results suggest …

Assessing Magnetic Iron Oxide Nanoparticles Properties Under Different Thermal Treatments, Erick S. Vasquez, Evan M. Prehn, Keisha B. Walters

Chemical and Materials Engineering Faculty Publications

Magnetic nanoparticle structures have been examined as potential carrier vehicles and substrates in a wide range of applications where they undergo mechanical, chemical and/or thermal manipulation to allow for their modification, conjugation and transport. For safe and effective use, it is imperative to not only measure the initial physicochemical and structural properties of nanomaterials, but also identify and quantify any property changes related to a loss of chemical and/or physical integrity during processing and usage conditions. In this study an assessment of iron oxide magnetic nanoparticle thermal stability using modulated differential scanning calorimetry (mDSC) and a controlled-heating system is conducted …

Optothermal Microbubble Assisted Manufacturing Of Nanogap-Rich Structures For Active Chemical Sensing, Farzia Karim, Erick S. Vasquez, Yvonne Sun, Chenglong Zhao

Chemical and Materials Engineering Faculty Publications

Guiding analytes to the sensing area is an indispensable step in a sensing system. Most of the sensing systems apply a passive sensing method, which waits for the analytes to diffuse towards the sensor. However, passive sensing methods limit the detection of analytes to a picomolar range on micro/nanosensors for a practical time scale. Therefore, active sensing methods need to be used to improve the detection limit in which the analytes are forced to concentrate on the sensors. In this article, we have demonstrated the manufacturing of nanogap-rich structures for active chemical sensing. Nanogap-rich structures are manufactured from metallic nanoparticles …

Optimization And Structural Stability Of Gold Nanoparticle–Antibody Bioconjugates, Robert T. Busch, Farzia Karim, John Weis, Yvonne Sun, Chenglong Zhao

Chemical and Materials Engineering Faculty Publications

Gold nanoparticles (AuNPs) bound with biomolecules have emerged as suitable biosensors exploiting unique surface chemistries and optical properties. Many efforts have focused on antibody bioconjugation to AuNPs resulting in a sensitive bioconjugate to detect specific types of bacteria. Unfortunately, bacteria thrive under various harsh environments, and an understanding of bioconjugate stability is needed. Here, we show a method for optimizing Listeria monocytogenes polyclonal antibodies bioconjugation mechanisms to AuNPs via covalent binding at different pH values, from 2 to 11, and 2-(N-morpholino)ethanesulfonic acid (MES), 3-(N-morpholino)propanesulfonic acid, NaOH, HCl conditions. By fitting Lorentz curves to the amide I and II regions, we …

Computational And Experimental Approach To Understanding The Structural Interplay Of Self-Assembled End-Terminated Alkanethiolates On Gold Surfaces, Juganta K. Roy, Erick S. Vasquez, Henry P. Pinto, Swati Kumari, Keisha B. Walters, Jerzy Leszcynski

Chemical and Materials Engineering Faculty Publications

Applications of self-assembled monolayers (SAMs) on surfaces are prevalent in modern technologies and drives the need for a better understanding of the surface domain architecture of SAMs. To explore structural interaction at the interface between gold surfaces and a hydroxyl-terminated alkanethiol, 11-hydroxy-1-undecanethiol, (C11TH) we have employed a combined computational and experimental approach. Density functional theory (DFT) calculations were carried out on the thiol–gold interface using both the Perdew–Burke–Ernzerhof (PBE) and van der Waals (optB86b) density functionals. Our ab initio molecular dynamics (AIMD) simulations revealed that the interface consists of four different distinguished phases, each with different C11TH orientations. Experiments involved …